Executive Health and Safety

Decontamination of agricultural sprayers

Prepared by the Health and Safety Laboratoryfor the Health and Safety Executive 2010

RR792 Research Report

Executive Health and Safety

Decontamination of agricultural sprayers

C T Ramwell P D Johnson H Corns A B A Boxall D A Rimmer V Sandys

Health and Safety Laboratory Harpur Hill Buxton Derbyshire SK17 9JN

It is now recognised that pesticide residues on the external surfaces of sprayers could present a significant route of exposure for the spray operator and these residues exist despite sprayers being washed. The current study was undertaken to examine factors influencing the removal of residues from sprayer surfaces, to trial any developments on decontamination techniques on working farms, and to quantify operator exposure to pesticides during the actual washing process.

This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.

HSE Books

© Crown copyright 2010

First published 2010

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner.

Applications for reproduction should be made in writing to:Licensing Division, Her Majesty’s Stationery Office,St Clements House, 2-16 Colegate, Norwich NR3 1BQor by e-mail to hmsolicensing@cabinet-office.x.gsi.gov.uk

ACKNOWLEDGEMENTS

The authors are grateful to the Health and Safety Executive who funded the study, to Hardi International Ltd for their co-operation and support, to Cranfield Centre for EcoChemistry and to all the farmers who participated in the study. The authors also appreciate the supply of chemicals from Dupont and Bayer Cropscience.

Opinions expressed within the report are those of the authors and do not necessarily reflect the opinions of the sponsoring organization. No comment within this report should be taken as an endorsement or criticism off any compound or product.

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CONTENTS

1 INTRODUCTION......................................................................................... 1

2 BACKGROUND .......................................................................................... 32.1 Current Policy developments................................................................... 32.2 Actual cleaning practices ......................................................................... 42.3 Advised cleaning practices ...................................................................... 42.4 Other research......................................................................................... 72.5 Synopsis .................................................................................................. 8

3 SMALL SCALE EXPERIMENTS ................................................................ 93.1 Experimental design ................................................................................ 93.2 Chemical Analysis ................................................................................. 103.3 Decontamination method....................................................................... 123.4 Drying time ............................................................................................ 153.5 Realistic ‘zero hour’ ............................................................................... 173.6 Formulation............................................................................................ 183.7 Quantification of acceptable residue levels............................................ 203.8 Discussion ............................................................................................. 21

4 TRANSFER EFFICIENCY OF PESTICIDES FROM SPRAYER SURFACES...................................................................................................... 234.1 Results................................................................................................... 234.2 Discussion ............................................................................................. 26

5 FIELD SAMPLING .................................................................................... 285.1 Methodology .......................................................................................... 285.2 Results................................................................................................... 295.3 Discussion ............................................................................................. 34

6 INTERNAL CONTAMINATION OF PROTECTIVE NITRILE GLOVES .... 356.1 Methodology .......................................................................................... 356.2 Data analysis ......................................................................................... 356.3 Results................................................................................................... 366.4 Discussion ............................................................................................. 37

7 OCCUPATIONAL EXPOSURE DURING DECONTAMINATION ............. 387.1 Methodology .......................................................................................... 387.2 Data Analysis......................................................................................... 397.3 Results................................................................................................... 407.4 Discussion ............................................................................................. 46

8 CONCLUSIONS........................................................................................ 50

9 APPENDICES........................................................................................... 51Appendix 1 – Sprayer Cleaning – Best Practice Guide .................................... 51Appendix 2 – Testing the application method................................................... 53

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Appendix 3 - Solvent effectiveness .................................................................. 54Appendix 4 – Full Results Set .......................................................................... 56

10 REFERENCES ...................................................................................... 66

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EXECUTIVE SUMMARY It is now recognised that pesticide residues on the external surfaces of sprayers could present a significant route of exposure for the spray operator and these residues exist despite sprayers being washed. The current study was undertaken to examine factors influencing the removal of residues from sprayer surfaces, to trial any developments on decontamination techniques on working farms, and to quantify operator exposure to pesticides during the actual washing process.

Objectives

• Examine factors influencing the removal of residues from sprayer surfaces.

• To trial any developments on decontamination techniques on working farms.

• Quantify operator exposure to pesticides during the actual washing process.

Main Findings & Recommendations

Small-scale experiments using 14 L clean water tanks as a representative sprayer surface were conducted to examine factors influencing the removal of six pesticides (azoxystrobin, carbendazim, flusilazole, isoproturon, pendimethalin and tebuconazole) with a range in physico­chemical properties. The results demonstrated that the ease with which residues could be removed was compound-dependent with the removal of tebuconazole being twice that of carbendazim. A cleaning agent consistently enhanced the removal of residues, and whilst the rotating jet was also efficient, there was the potential for it to cause damage to equipment. A brush was more efficient than a high pressure washer. In the small-scale studies a hosepipe was shown to be as efficient as a high pressure washer and it was postulated that this was a factor of the higher flow rate for the hosepipe.

Pesticides that were allowed to dry onto the surface were more difficult to remove than when they remained wet, and dried pesticides may require some means of penetrating the surface either chemically (e.g. a cleaning agent), or physically, such as a pencil jet. Formulation may influence removal rates, but the limited data set generated did not provide conclusive evidence to support this theory.

Worst-case scenario assumptions were used to calculate an ‘acceptable’ level of residues. These values were then used to identify the extent to which residues must therefore be removed. For the least contaminated parts of the sprayer (i.e. excluding the boom and the back of the sprayer) 35% of the residues would need to be removed. All cleaning methods investigated here could achieve this removal rate. However, for the more contaminated parts of the sprayer, 65% of the external residues should be removed. This level of decontamination may be achieved with a cleaning agent, but other typical cleaning methods such as a pressure washer would require a longer cleaning duration to achieve similar results. However, raising awareness of the need to treat the most frequently contaminated parts of the sprayer as potentially contaminated even after washing may also reduce potential operator exposure.

The transfer of pesticides from sprayer surfaces to cotton gloves was quantified to investigate the transfer efficiency with regards to potential operator exposure. Transfer efficiencies of the pesticides from the sprayer surface were compound-dependent. Azoxystrobin had the highest transfer efficiency of 80% compared to less than 30% for tebuconazole. Overall there was no increase in transfer efficiency if the surface was wet compared to dry. The data could be used to enhance exposure assessments if suitable scenarios were established.

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Sampling working sprayers supported the theory that a cleaning agent enhanced the removal of residues, although the results were not as significant as in the controlled, small-scale experiments. Natural variation in the high doses on the boom and nozzle may have masked the real effect of the cleaning agent which was observed more clearly when sampling the mudguards and tractor, both with lower initial doses. In the current study there were a lower proportion of residues detected above 1 g.m-2 compared to a previous, similar study, which could indicate that sprayer cleaning is being taken more seriously. The removal of residues from the most contaminated areas may still not be sufficient to reduce residues to acceptable levels and raising awareness of this finding could assist in reducing operator exposure to these residues.

Residues on the internal surfaces of the farmers’ nitrile gloves were not uncommon and they have the potential to be a significant route of exposure, but a larger scale study would be required to substantiate these initial findings.

It is recommended that the following indicative values should inform risk assessments for the cleaning of sprayers. The potential dermal exposure (P.D.E.) to pesticides (9 data) ranged between 41 and 802 μg.task-1, median 239 μg.task-1 and 95th percentile 740 μg.task-1. Actual dermal exposure (A.D.E.) to the hands (5 data), as collected on cotton gloves, ranged between 1 and 439 μg.task-1, median 29 μg.task-1 and 95th percentile 396 μg.task-1. A.D.E. to the feet (4 data), as collected on cotton socks, ranged between 3 and 123 μg per task, median 55 μg.task-1

and 95th percentile 114 μg.task-1. Exposure by inhalation to spray fluid was found in none of the samples.

The potential exposure of an operator to pesticides whilst cleaning a sprayer is not major, nor is it insignificant. However, a more accurate assessment would be required to confirm this theory.

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1 INTRODUCTION

It is recognised that pesticides are potentially harmful to both human health and to the environment hence national laws strictly regulate these compounds. During the approvals process the risks that pesticides may pose to both the spray operator and others are evaluated. The scenarios assessed commonly include mixing and loading of the concentrated product, application, re-entry and/or harvesting of a treated crop as well as inadvertent exposure to bystanders during spraying. During spraying, a proportion of the pesticides is deposited on the external surfaces of the sprayer, the quantity varying with factors such as wind speed/direction, air temperature, humidity, nozzle type, working pressure, and product formulation (Cooper & Taylor, 1998; Balsari et al., 2002). However, post-application exposure to these external residues does not form any part of the risk assessment of a compound. It is possibly assumed that, compared to other tasks a spray operator performs, the risks will be comparatively low, particularly as it is known that exposure during mixing and loading is greater than during spraying (Glass et al., 2002). However such an assumption may give rise to unacceptable exposure to pesticides. For example, if it is assumed that pesticide residues on the external surfaces are insignificant, then precautions such as wearing gloves may not be taken. This could be of particular consequence where the tractor transporting a spraying system is used for other tasks. A recent study has shown that pesticide residues were detected more often than not on all sprayers sampled, and the quantity of pesticides on the surfaces was in the order of milligrams, although this was likely to be an underestimate of the total residues due to the limited areas sampled and compounds investigated (Ramwell et al., 2004). A basic risk assessment indicated that residues existed at levels that may exceed acceptable exposure limits within a few hours of contact (Ramwell et al., 2005). Perhaps the most significant finding of the studies was that residues were detected even though the sprayers had been washed indicating that existing methods were not sufficient to decontaminate the external surfaces of sprayers and/or sprayers were not cleaned frequently enough, thus enabling residues to accumulate and to become difficult to remove. Moreover, after the sprayers had been washed, the operators considered the machines to be clean, thus they could be handled without gloves or other personal protective equipment (PPE).

The misconception that the external surfaces of sprayers are properly decontaminated under existing washing regimes initiated the current study to investigate factors affecting the removal of residues from sprayer surfaces and to propose improved washing techniques. In addition, operator exposure during the cleaning process would be monitored. Encouraging the decontamination of sprayers to reduce exposure to pesticides could potentially impact on the environment and this was taken into consideration where possible.

The study was performed in three phases:

1. A review examining the current situation, and any future proposals in the associated industries,

2. Experiments performed under controlled conditions to quantify the effectiveness of different cleaning methods and to investigate influential factors, and

3. A field phase where findings from the experimental work were tested in reality, and the implications of any changes to the operators’ cleaning regimes were monitored.

Within these three phases there were several discrete areas of work, namely:

• Review of practices

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• Small scale experiments

• Dislodgeability of residues from sprayer surfaces

• Field sampling

• Internal contamination of protective nitrile gloves

• Occupational exposure during decontamination

Each area of work has been reported in separate chapters to simplify the presentation of the results.

(As discussed above, the current study was initiated primarily due to the findings of a previous HSE-funded study: Exposure to pesticide residues on agricultural spraying equipment (Ramwell et al., 2002). This study is referred to as the previous HSE study throughout this report and no further full reference is given).

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2.1

2 BACKGROUND

In terms of reducing both operator exposure to pesticides and environmental pollution it is the end-user that will determine the extent to which this occurs. It would therefore be preferable that any proposed changes to existing washing practices could be implemented with minimum cost and inconvenience to farmers and spray operators. Consequently, it was imperative that all representative bodies concerned with pesticide application were consulted throughout the study, and a network of contacts in the UK and Europe was developed. Contacts were also established in the USA with researchers experienced in investigating internal decontamination methods.

CURRENT POLICY DEVELOPMENTS

Research into the decontamination of sprayers complements current policy developments at the national and European scale, namely the Voluntary Initiative (VI) in the UK and the proposed International Standard to evaluate the performances of sprayer cleaning systems (ISO TC 23/SC 6/WG 6).

The Voluntary Initiative is a program of measures, agreed by Government, to minimise the environmental impact of pesticides. One section of the VI that highlights the need for the current study is the introduction of the National Sprayer Test Scheme (NSTS) – the equivalent of a vehicle’s MOT. Farmers are being encouraged to have sprayers tested because damaged or worn nozzles can lead to over application, and drips or leaks can have environmental implications. Machine maintenance could not only assist in reducing the environmental impact of pesticides, but will also have financial savings for the operator. In addition to the annual test, operators are being encouraged to test the sprayer more regularly, particularly the output of the nozzles which has accounted for the majority of failures in the past (DEFRA, 2000). Both the regular checks and the annual test focus on sprayer parts that come into contact with either the concentrated product and/or the prepared liquid. Persons conducting the checks may be exposed to high levels of residues, and representatives of the NSTS have requested that sprayers are thoroughly washed down, inside and out prior to a test, but there is no guidance on how this may best be achieved. Moreover, in the previous HSE study, residues were detected with the greatest frequency and at the highest doses in the areas that would be scrutinised in the tests even though these areas had been washed. The introduction of the NSTS means that there will be dedicated staff for testing sprayers, thus these persons may be exposed to unacceptable levels of pesticides. In addition, in conducting more regular checks, spray operator exposure may increase.

The improper disposal of residues from the internal surfaces of the main tank and the hydraulic circuit was historically a significant source of pollution, forcing manufacturers to install or adapt cleaning devices allowing operators to clean, and dispose of the washings, in the field. To enable comparison between different manufacturers there must be a defined methodology to verify the efficiency of these cleaning systems hence the development of the new ISO standard. The document is divided into three parts: the internal cleaning of the complete sprayer, the external cleaning of the sprayer and the internal cleaning of tanks. The associated work focuses on developing standard protocols that are replicable, and, for practical reasons, the use of tracers has widely adopted. Although one study has been carried out as part of the ISO work looking at external cleaning (Holst et al., 2001) in terms of decontamination to reduce operator exposure, the study was not relevant due to the methodology employed. In Holst et al.’s study the washings generated during cleaning were collected and the mass of tracer quantified. The sprayer was given a further wash to, theoretically, remove the remaining residues and again the

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mass of tracer removed was noted. In this way it was possible to compare the cleaning efficiency of different methods relative to one another. However, unless the surface of the sprayer is actually sampled prior to and after cleaning it is not possible to absolutely quantify the cleaning efficiency. Furthermore, whilst tracers are suitable for the relative comparison of different cleaning methods, such compounds are unlikely to behave in a similar manner as tenacious pesticide formulations. The environmentally focused research of the ISO standard is not necessarily compatible to investigating methods for the decontamination of sprayers for health reasons and it highlights the need to consider health and environmental implications of spraying practices simultaneously.

In order to ensure that any guidelines on the decontamination of sprayers remain relevant in the future, consideration should be given to other research in the area of pesticide application, namely the use of biobeds as a means of reducing the environmental impact of spraying activities. A biobed is a pit filled with a compost of straw, topsoil and a peat-substitute and it works on the basis of natural degradation processes. Its use is encouraged during the filling and mixing of pesticides (if this cannot be completed in the field), and, if the biobed is lined, it may be used to collect the washings generated during the decontamination of the external surfaces. If a biobed is used during the washing of a sprayer then any decontamination methods should account for the fact that a) excess moisture levels are detrimental to the functioning of a biobed (Fogg et al., 2004), and b) bleach-based cleaning agents could potentially affect the performance of a biobed.

2.2 ACTUAL CLEANING PRACTICES

A survey undertaken as part of the Voluntary Initiative on spraying practices in the UK (Garthwaite, 2002) representing over 400 holdings found that 44% of all sprayers were cleaned a maximum of three times a year. At the other extreme, three self-propelled sprayers (1%) were reported as being cleaned over 100 times each year indicating that they were washed down after each application. Approximately a quarter of sprayers were cleaned with detergent, and sprayers used on 29% of the arable area had an external washing device.

The findings of the survey conducted in the previous HSE study on external residues were generally consistent with the survey by Garthwaite (2002) indicating that the external surfaces of sprayers are rarely washed which enables the accumulation of residues. There were no details given in Garthwaite’s survey as to the actual cleaning methods employed, but in the survey of the previous HSE study 69% of farmers stated they jet washed their sprayer compared to 25% using a hose pipe with the remainder equally divided between steam cleaning and sponging down.

2.3 ADVISED CLEANING PRACTICES Different sectors associated with the spraying industry were contacted to establish what advice was available to farmers and spray operators on the cleaning of the external surfaces of sprayers.

2.3.1 Sprayer manufacturers

Manufacturers are aware of the need to prevent the accumulation of residues on the surfaces of sprayers where possible. Generally, the internal surfaces are given a much higher priority than the external surfaces; although design changes such as minimising protrusions where deposits may accumulate (on the internal surface) will also benefit the cleaning of external surfaces. In

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the marketing literature for sprayers, terms such as ‘easy-clean tank’ are used, emphasising the fact that decontamination is necessary, although again, this is actually referring to in the internal surfaces. The use of water from the clean water tank is primarily directed to washing the internal surfaces of the spray tank and hose lines, thus only a limited quantity of clean water may remain for decontaminating the external surfaces. Experimental studies investigating factors influencing the removal of residues could provide guidance on the efficiency of different methods and/or techniques to optimise the use of a limited water supply.

During the course of the study it was noted that sprayer manufacturers were taking the issue of external contamination more seriously. There was greater variety in the external washing devices on new sprayers displayed at Spray and Sprayers in 2003 than 2002 and, by 2005, displaying an external washing device was the norm rather than the exception. Two noticeable features were 1) the use of Hozelock® fittings on the hose line so operators could choose between a variety of already widely-available compatible devices (e.g. brush or choice of nozzle type), and 2) the lance on one sprayer (SAM SLC Hillsider) was positioned behind a section of the main frame of the sprayer so it would largely be protected from pesticide deposits during use. A further advance in sprayer design noted during the course of the study was the increasing presence of hinged ‘shields’ over the pipe work and other irregularly shaped sprayer parts developed to assist in the removal of external residues. The shields presented a flat, smooth surface that could be easily cleaned whereas residues could easily lodge in difficult-to-clean places on the pipe work that would also provide a larger surface area on which residues could be deposited.

Whilst the increasing presence of external washing devices on new sprayers displayed at annual agricultural events is encouraging, it does not necessarily translate that there is an increased use of external washing devices. Sprayers are largely custom-built from a choice of alternatives, such as boom length, number of tanks, and the external washing device is just one of the choices as an optional extra.

2.3.2 Crop Protection Agency

The Crop Protection Agency (CPA) is a single body representing manufacturers, distributors and marketers within the UK agrochemical industry. One of its aims is to advocate best practices wherever pesticides are used, thus the CPA plays a prominent role in the Voluntary Initiative. The CPA has a high profile in the farming literature that is used to disseminate advice and raise awareness of relevant issues enabling policy to be put into practice. The CPA produces an educational leaflet on cleaning sprayers as part of their Best Practice Guides. The guide is detailed and precise as to how best clean a sprayer and it includes advice on washing the external surfaces (Appendix 1). The guide states that a low volume washing brush is more effective and uses less water than a high-pressure spray gun, but the CPA do not have data to substantiate this claim. The guide also specifies that ammonia-based agents will be required for deactivating some herbicides.

2.3.3 Cleaning devices

Pressure washers are commonly used in an attempt to remove external residues from sprayers. Hot water and steam give better results than cold water, thus any method developed to decontaminate sprayers using cold water would also succeed with hot water. A rotating jet is more powerful for the same pressure and water volume than an ordinary pencil jet, but it was

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commented that on older machines/tractors the pencil jet was capable of removing paint or rust thus it must be used with care.

2.3.4 Pesticide products

It is now part of the approvals process for pesticides submitted for registration in the UK to specify a cleaning method for the product, but this is only in reference to the internal surfaces. The need to ensure the complete removal of residues from the internal surfaces of the spray equipment is becoming more apparent with the introduction low-dose products that could cause crop damage if carry-over occurred. However, it is reasonable to assume that, within limits, any cleaning method or detergent advised for internal decontamination could be adopted for external surfaces. It is possible that pesticide residues may be more difficult to remove from the external surfaces where there is greater potential for drying to occur compared to the internal surfaces.

To assess the current situation with regard to advice on cleaning from the pesticide product, the labels of over 70 Bayer products were examined, but it reiterated that this largely refers to internal cleaning. Over half the labels specified to use a ‘suitable’ detergent or wetter but the usefulness of the instructions was limited as there was no indication of what products, or type of product was ‘suitable’. The notable exception was for compounds containing sulfonyl ureas (SUs). SUs are a relatively new class of low-dose compounds that are liable to cause crop damage if all traces are not completely removed from the sprayer. For these products, it specifies to either use an ammonium-based detergent, naming All Clear Extra (ACE) as an example (even though Bayer do manufacture ACE) or to use bleach. It also states to ensure that the external surfaces of the sprayer are also decontaminated, suggesting using water.

Guidance from the manufacturers of ACE (Dupont) under their SU Stewardship may support the misconception that external residues are not significant. In their step-by-step guide, it states to start with a clean sprayer which “means that the tank and the inside and outside of the lid, filters, nozzles, plumbing and hoses are all free of dirt and chemical deposits”. There are clearly many parts of the sprayer omitted from this description that an operator will come into contact with. Advice for after spraying is “Everything that has come into contact with sulfonylurea herbicide spray solution should be treated with All Clear Extra!” The first steps to achieving this are given as 1) Spray out and drain all sprayer solution immediately, 2) Wash any spray contamination off outside of tank, 3) Rinse inside of tank with clean water (continued). Advice for cleaning external surfaces was limited to the text in Step 2, and this did not qualify how best to remove the contamination, although the associated illustration is of a person jet washing. In addition, the guidelines infer that it is only necessary to clean areas that have come into contact with the spray solution and there is no effort to make account for deposits that could accumulate during spraying. The fact that some parts of the sprayer are named specifically as requiring cleaning could imply that it is not necessary to decontaminate those surfaces not specified. This includes the boom that is known to be highly contaminated during sprayer and remain so after washing.

2.3.5 Cleaning agents

Manufacturers of cleaning agents and devices could not recommend a particular product for decontaminating the external surfaces of sprayers. However, the product All Clear Extra® is widely known amongst the farming community for cleaning the internal surfaces of sprayers, and could possibly be used for external cleaning as well. The use of cleaning agents would need to take into consideration any potential impacts on the environment and/or the washings

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2.4

disposal area. All Clear Extra is approved for disposal onto land, and it has been shown to improve the rate of degradation in a biobed. However, bleach is detrimental to the performance of a biobed although it can recover (Fogg). It is not known to what extent the microflora in soil will be affected by adding chlorine-based agents thus it is unlikely that such products would be recommended.

In 2003 the active ingredients of All Clear Extra were modified, primarily for safety reasons. The product All Clear is chlorine-based, whilst All Clear Extra used to be ammonical. Accidental mixing of these two, similarly named products could have the undesired effect of releasing chlorine gas. Both versions of All Clear Extra are approved for disposal to land, but the effect of the new All Clear Extra on a biobed is not known. Also in 2003, one sprayer manufacturer (Hardi) launched their cleaning solution that was specified as being suitable for external as well as internal cleaning.

OTHER RESEARCH

Information from research centres in the US could provide a wider picture of the understanding of cleaning practices (Johnson et al., 1999; Johnson & Linn, 2001; Landers, 2002). The information available is aimed at frequent users of pesticides. On the whole, the information mirrors that available in Britain in that the emphasis on decontamination is on the internal surfaces, but decontamination of the external surfaces is proposed more frequently than on British Web sites. The advice is detailed and includes examples of generic cleaning agents (largely ammonia-based) that can be used with particular products, although, as with all the other literature available, an actual cleaning technique is not defined. A US-based, British researcher confirmed that there had been no work done in the US to quantify the efficiency of different cleaning methods and current advice was based on expert judgement. In addition, it was acknowledged that no cleaning method actually removed all pesticide residues, to the extent that it was recommended that, for any crops very susceptible to herbicide injury, a separate sprayer should be used (Daum, 1998); this practice is adopted in the UK by some farmers, particularly for beet. It is also worthy of note that in the information given by the US research centres on the decontamination of sprayers, the use of PPE is emphasised more heavily than on UK Web sites.

When trading as Aventis and Rhone Poulenc, Bayer commissioned two studies examining external contamination of sprayers during the application of isoproturon (Fogg, 1999; Mason et al., 2000). The sampling protocol was similar in both studies where swabs (10 x 10 cm) were taken from a pre-cleaned sprayer prior to use, immediately after application and after the sprayer had been washed down. Although the studies were limited compared to the previous HSE-funded study due to the investigation of a single compound and the fact that composite samples were not taken, the results provide further evidence of the inefficiency of current cleaning methods. For both studies, the spray operators were aware of the nature of the study and ‘thoroughly cleaned’ the sprayers by jet washing. One sprayer was also coated with a substance after washing and prior to spraying to reduce adhesion of residues. However, when sampled prior to spraying, residues were detected on both sprayers, and residues were highest in the boom area. The levels of residues increased after spraying, but again residues were detected after the sprayer had been jet washed. Indeed in the first study residues were detected at lower levels after washing than prior to spraying illustrating the natural variability that can occur in residue levels on the sprayer and the need therefore to take composite samples.

Work conducted in Sweden (unpublished) has also demonstrated that residues remain on the sprayer even when an ammonia based cleaning agent and pressure washer were used. The workers commented that, prior to the findings of this investigation and those of the previous HSE-funded study, they would have considered the sprayer to be decontaminated and safe to

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touch without gloves after, what was perceived to be, a thorough clean, but this assertion is now being revised.

2.5 SYNOPSIS

• Sprayers are not frequently washed allowing residues to accumulate, and/or reducing the effectiveness of cleaning when they are washed.

• Even after washing, residues can remain on the surface of the sprayer.

• A sprayer is considered to be clean after washing and handled accordingly (i.e. no gloves).

• There is an increased awareness of the need to clean the external surfaces of the sprayer and sprayer design has evolved to reduce the potential for accumulation of deposits and to provide a means of cleaning in the field.

• Spray operators are advised to clean the sprayer, but there are limited guidelines on how this may be actually achieved.

• The NSTS may increase the frequency of potential operator exposure to pesticides, particularly for Inspectors.

• There is an absence of data relating to factors influencing the removal of pesticides from the external surfaces of sprayers.

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3.1

3 SMALL SCALE EXPERIMENTS

The experiments were devised to control factors that would normally vary between sprayers including the quantity and type of active ingredient (a.i.), product formulation, washing method, and drying time (time between residue deposition on the external sprayer surface and washing). The general experimental set up is outlined below (3.1) with further details on each individual test in the relevant section.

EXPERIMENTAL DESIGN

The dimensions of the test material were primarily determined by the practical limitations of physically being able to move the surfaces in the area of the room available (4 m x 4 m). Consequently, pure water tanks (14 L -approximate dimensions 0.75 x 0.40 m) were used as a representative surface of the sprayer. These had the advantage of comprising the exact material used for the majority of a non-stainless steel spray tanks (polyethylene and painted metal), and the shape introduced a more challenging area to clean to test the different methods whilst remaining wholly representative of reality. The fittings in particular reduced access for cleaning, creating ‘shadow zones’ which would serve to emphasise any difference in the efficiency of decontamination methods. The materials were all new and supplied by the sprayer manufacturer, Hardi International A/S.

The results from the previous study were used to assess typical external residue levels on a sprayer. It is known that the nozzles were massively contaminated compared to the rest of the sprayer, as could be expected, and that residues on the boom and spray tank tended to be greater than elsewhere on the tractor, with the exception of the mudguards. It was therefore considered that the mass of residues on the spray tank and boom should represent a realistic worse case for the sprayer as a whole. For the compounds included in the current study (Table 1), the mean mass on the spray tank was 8.1 mg.m-2 and the 50th percentile was 6.9 mg.m-2. This compares to a mean and 50th percentile of 52 and 19 mg.m-2 respectively for the boom. A quantity in the order of 10 mg.m-2 was considered to be realistic. To enable the product to be measured out accurately with an auto pipette, a quantity of 5 mg per test surface was used which, when accounting for drift losses during application (Appendix 2), equates to c. 8 mg.m-2.

Stock solutions of each product were prepared individually and gravimetrically using distilled water for dilution. The pesticides were applied using an airbrush fitted with a glass vial reservoir (1.8 ml). The products were applied in two batches (Amistar, Folicur, Bavistin and Lyric, Trump, Permasect) as 0.5 ml of each product was used. After each application, the spray lines and vial were rinsed with 0.25 ml of distilled water and the rinsings sprayed onto the test surface. Prior to the experiments being undertaken a test was conducted to confirm that the method of application was replicable and that the proposed sampling method did remove all the pesticide applied. In addition, a test was conducted to assess whether there was any degradation of the pesticides during the 24 hours between application and initiation of the washing experiments. Full details of these tests are given in the appendices.

It was not physically possible to spray/sample more than one tank at a time and the time taken to swab a single tank was approximately 10 minutes. It was therefore not possible to completely randomise the experimental set up and it was necessary to adopt a systematic approach. Surfaces were treated every 20 minutes to allow time for both the washing and sampling of each surface. Controls were sprayed at the start, end and in the middle of each allotted time period for the entire experiment. For the remaining test surfaces, each test method was randomly allocated to a particular tank. It was considered that any unquantifiable error that may arise from, for example the positioning of the tanks, or the time of day, would be small

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compared to the error that may arise should the time between pesticide application and sampling be inconsistent, hence the need for a partially systematic approach to the experiments.

The duration of washing could vary widely between operators and it could be expected to be as short as possible. To compare the different methods, the same washing duration must be used. Holst et al. (2001) considered c. 15 minutes to be a reasonable length of time to expect to spend cleaning a sprayer. It was anticipated that a technique would be more readily adopted by the end-user if the duration required were short. For the purposes of the experiments it was necessary to define a single duration for cleaning each test surface. The time to clean an area of 0.49 m2 was calculated as being c. 5 seconds which equated to three passes of the lance across the sprayer surface.

To quantify residues remaining on the surfaces after washing, three cotton pads were used in the first instance to wipe the entire surface to dry it. Each surface was swabbed a further two times, using 3 cotton pads soaked in methanol (5 ml) thus a total of 9 pads was used to sample a single test surface and these were bulked into a single HDPE container (250 ml). Three replicates were used for each variable investigated. In addition, three surfaces not subjected to any cleaning served as controls. The quantity of pesticides on the swabs from the control surfaces was considered to be representative of the starting quantity on the remaining test surfaces. A screen was used to prevent any inadvertent splashing of adjacent surfaces. All samples were stored in a cool-box for transport to the laboratory where they were stored at -18°C prior to analysis.

3.1.1 Active ingredient

The active ingredients were chosen to represent a range in physico-chemical properties, particularly solubility, for commonly used pesticides. A range of pesticide types was also represented, namely insecticides (I), herbicides (H) and fungicides. A summary of the pesticides and their properties is given below (Table 1).

Table 1 Properties of the pesticide used in the experiments

Solubility mg.l-1

Koc ADI mg.kg-1 bw

App rate kg ai.ha-1

Type Product a.i. (g.l-1)

Formulation

Azoxystrobin 6 423 0.1 0.25 F Amistar 250 SC Carbendazim 29 or 8 225 0.03 0.25 I Bavistin 500 SC Flusilazole 54 650 0.001 0.2 F Lyric 250 EW Isoproturon 65 154 0.0062 2.0 H Trump 236 SC Tebuconazole 36 0.03 0.25 F Folicur 236 SC Pendimethalin 0.3 13400 0.1 2 H Trump 250 EW

CHEMICAL ANALYSIS

Samples were analysed for azoxystrobin, carbendazim, chlorothalonil, cyanazine, epoxiconazole, flusilazole, isoproturon, kresoxim-methyl, metazachlor, pendimethalin, pirimicarb, and tebuconazole.

10

3.2

3.2.1 Chemicals and Solutions

All pesticide standards were supplied (Qmx Laboratories Ltd, UK) as neat materials with certified purities ranging from 91 to 99.5%. The pesticides that could be analysed by liquid chromatography (LC), carbendazim and isoproturon, were used to gravimetrically prepare a 100 μg.ml-1 stock solution in methanol. Seven working standards, in the range 0.2-25 μg.ml-1, were prepared gravimetrically in methanol. The remaining pesticides can be analysed by gas chromatography (GC) and were used to gravimetrically prepare a 30 μg.ml-1 stock solution in methanol. Seven working standards, in the range 0.1-15 μg.ml-1, were prepared gravimetrically in methanol. All standards and stock solutions were stored at 2-8°C. The methanol used was Distol grade (Fisher Scientific, UK).

The LC mobile phase was prepared from acetonitrile (45%), water (45%) and methanol (10%). Water was prepared using a Milli-Q Gradient A10 (Millipore, UK) water purifier with a resistivity of 18.2 MΩ.cm and total organic carbon at 3 ppb. The other solvents were HPLC grade (Rathburn Chemicals Ltd, UK). The mobile phases were vacuum filtered through a 0.2 μm nylon filter immediately prior to use (Whatman International Ltd., UK).

The dichlorodimethylsilane (99%, Aldrich, UK) for the deactivation of glassware was diluted with cyclohexane to give a 5% solution. All the solvents used for deactivating glassware and extractions were Distol grade (Fisher Scientific, UK).

3.2.2 Instruments and Apparatus

All glassware was deactivated by rinsing thoroughly with a 5% solution of dichlorodimethylsilane in cyclohexane. The glassware was then rinsed three times in cyclohexane and washed (end-capped) with methanol. A TurboVap II Concentration Workstation (Zymark Corporation, UK) was set for an end-point of 0.5 mL with a bath temperature of 40oC for the concentration of samples under nitrogen. The syringe filters used were Whatman’s 0.45 μm, PTFE (Fisher Scientific, UK). A Decon FS400b ultasonic bath was used to extract the residues from the samples.

Nalgene™ Teflon bottles (125 and 250 ml) were used to desorb the samples (Fisher Scientific, UK). Hewlett Packard silanised, amber autosampler vials (2 ml) were used for both GC and LC analysis (Metlab, UK).

The liquid chromatography (LC) system used consisted of a Waters 600 controller, a Waters 510 HPLC pump, a Waters 717 plus autosampler, Waters 996 photodiode set at 242 nm and Millenium32 version 3.05.01. The column fitted was a Genesis AQ column (Jones Chromatography, UK), 10 cm x 4.6 mm with 4 μm pore size. The injection volume was 20 μl and the mobile phase was run isocratically at 1 ml.min-1 at ambient temperature. The total run time was 20 minutes (plus 2 minutes post time). The retention times were 2.499 minutes for carbendazim and 4.912 minutes for isoproturon.

The GC system consisted of a Hewlett Packard 5890 series II gas chromatograph fitted with a Hewlett Packard HP-5 MS column (cross linked 5% Phenyl Silicone, 30 m x 2.5 mm x 2.5 μm film thickness), a Hewlett Packard 5972 Series Mass Selective Detector (MSD) with Hewlett Packard G1034C MS ChemStation software. The injection (splitless) and transfer line temperatures were 250 and 280oC respectively and the injection volume was 1 μl. The oven temperature programme was 60oC for one minute, ramping at 20oC.min-1 to 300oC and holding for six minutes, total run time 19 minutes. Helium (>99.996%) was used as the carrier gas and

11

electronic pressure control in constant flow mode delivered 0.98 ml.min-1. Selected Ion Monitoring (SIM) data was collected between 8.0 and 18.0 minutes monitoring ions with m/z values of 266 and 264 for chlorothalonil (Rt 10.06 min), 166 and 238 for pirimicarb (Rt 10.14 min), 225 and 240 for cyanazine (Rt 10.83 min), 252 and 281 for pendimethalin (Rt 11.20 min), 209 and 277 for metazachlor (Rt 11.23 min), 233 and 315 for flusilazole (Rt 11.87 min), 116 and 131 for kresoxim-methyl (Rt 11.87 min), 125 and 250 for tebuconazole (Rt 12.68 min), 192 and 206 for epoxiconazole (Rt 12.85 min), 163 and 181 for cypermethrin (Rt 14.60 min) and 344 and 388 for azoxystrobin (Rt 16.38 min). The first ion listed for each analyte was for quantification and the second for confirmation.

3.2.3 Samples and Extraction

Swabs and cotton gloves were placed into Teflon bottles of an appropriate size and methanol (150 ml) was added. The samples were shaken vigorously for five minutes, placed in an ultrasonic bath and sonicated for 30 minutes. Approximately 5 ml of the extraction solution was filtered and 1 ml of the filtrate was transferred to 2 ml vials.

3.2.4 Blank and Fortified Samples

Field blanks of surface and occupational samplers were taken whilst on site and analytical blanks were prepared in the laboratory. Blanks samplers were also fortified to determine recoveries by adding a known amount of each pesticide stock solution. The amount added was enough to give a 1 μg.ml-1 final solution. The fortified samples were then left uncovered for 1 hour to allow the solvent to evaporate. The blank and fortified samples were then treated in the same way as the other samples.

3.2.5 Analytical Performance

All calibration graphs were linear over the standard ranges with the linear correlation coefficients in ranging from 0.998-1.000. The limits of detection (LOD) range from 0.03 to 0.90 μg for pads using GC, and 0.8 to 3.5 μg for pads using LC. Recoveries were typically within the acceptable range of 70-110% (EU, 2000).

3.3 DECONTAMINATION METHOD

Methods currently used by farmers can be broadly categorised as rinsing (low pressure) both with and without brushes, pressure washing, and steam cleaning all either with or without a cleaning agent. The decontamination methods investigated were:

1. Low pressure (c. 4 bar) – hose.

This was achieved using an ordinary garden hose attached to a mains tap with a Hozelock® variable nozzle set at a jet spray.

2. Low pressure + brush (CPA advised) – brush.

A Hozelock® brush was fitted to the garden hose. 12

3. High pressure (c. 150 bar) – high p or hp.

A Karcher® industrial cold water pressure was used (model HD 855s) with the triple nozzle set at high pressure and the pressure at c. 150 bar.

4. Pencil spray – pencil.

The pressure washer nozzle was set at pencil spray. This delivers a narrower jet than the high-pressure jet for the same pressure.

5. High pressure + non-ammonia based detergent – detrg 1.

The detergent was applied at label-application rate (0.5%) thus the chemical take-up rate on the pressure washer was set to ‘1’. The chemical was applied using the ‘chemical’ nozzle on the washer. The chemical was left for 2.5 minutes on the tank after which it was subject to the standard high-pressure wash. The detergent used was All Clear Extra® (Dupont).

6. High pressure + ammonia-based detergent (detergent already known to many farmers for the decontamination of internal surfaces) – detrg 2.

The same procedure as above was used for applying the detergent. The detergent was an old, but still used, formula of All Clear Extra® (Dupont).

7. High pressure + initial wetting – wet + hp.

This comprised wetting the test surface with water for 2.5 minutes prior to a full pressure wash. This method served as a control for investigating the effect of detergents, but it could also be an additional method in its own right.

8. Pencil jet + initial wetting – wet + pencil.

The test surface was wetted with water for 2.5 minutes prior to washing with the pencil jet.

9. High pressure rotating spray – rotating.

This nozzle creates a narrow jet of water like the pencil jet, but the head rotates to create a larger washing area.

(The names in italics are used in the results).

Two cleaning agents were included to give an indication of the extent of its influence compared to differences in the use of pressure and/or a brush. The rotating pencil jet may not be as common as the ordinary nozzle, but it was anticipated that it could be a useful tool in the decontamination of sprayers as it is reported to clean a larger area for the same volume of water hence its efficiency was investigated. The experiments were conducted over two days, comparing a brush, hose, pencil jet and rotating jet on one day and the remaining techniques on the other; for each day a separate set of controls was created. The time between application and washing was 24 hours.

13

3.3.1 Results

The control samples illustrated that there were losses of the applied compounds within the 24 hours between application and sampling, most noticeably for pendimethalin. To account for these losses, the quantity of pesticide remaining on the test surface after washing was calculated as a percentage of the control (mean value of the controls for both sampling days; n=6) in order to compare methods more accurately. All methods removed some of the applied pesticides but to differing extents, and there were differences between the compounds within a single method (Figure 1). Tebuconazole was consistently removed with the greatest ease regardless of decontamination method used, with an overall average removal rate of 72%, which was twice that of carbendazim (35%).

Figure 1 The efficiency of different decontamination methods for individual pesticides

To give an indication of the overall effectiveness of the different decontamination methods, the results were bulked for the individual pesticides to illustrate the range in the results (Figure 2).

All decontamination methods removed at least c. 40% of the pesticide deposits with a maximum mean removal rate of 66% (detergent 2). The difference between results from the straight pencil jet and from pencil jet with an initial wetting was unexpected. These methods were tested on different days and these results could indicate that focus should be on the order of magnitude of the results rather than exact values.

14

3.4

Tota

l pes

ticid

e re

mov

ed (%

of c

ontro

l) 100

80

60

40

20

0 brush high p rotating wet + pencil deterg 2

hose pencil wet + hp deterg 1

Figure 2 Comparison of decontamination methods for all pesticides showing the mean & ± 1 S.E.

DRYING TIME

Guidance on the internal cleaning of sprayers recommends that sprayers are cleaned out immediately after use, partly because it is easier to remove a compound when the surfaces are still wet. It is conceivable therefore, that the longer residues are left on the outside of a sprayer the more difficult they will be to remove, although it is acknowledged that there will probably be a point after which the difference in the ease of removal is marginal. To investigate this notion, a range of ‘drying time’ scenarios (i.e. the time between pesticide application and washing) was considered:

• Immediately after spraying

• 30 minutes

• 6 hour

• 24 hour

• 1 week (168 hours)

• 4 weeks (672 hours)

In light of the results of the decontamination methods, three were used to investigate the effect of drying time; namely 1) with cleaning agent (non-ammonical), 2) pencil jet, and 3) high pressure with twice the standard duration of cleaning.

15

3.4.1 Results

The lag time between pesticide application and removal clearly influenced the efficiency of the decontamination method (Figure 3). When washing began immediately after application over 80% of the applied pesticides were removed irrespective of the method used. When the pesticides had been left for only half an hour, there was a reduction in removal rate of up to 20% (pencil). On the whole, there was little difference in removal rates between lag times of 6 hours, 24 hours, one week or four weeks. Considering differences between the decontamination methods, higher removal rates were achieved using the cleaning agent particularly once the residues were ‘dried’ on, i.e. where the lag time was greater than 6 hours. On the whole, with lag times of greater than 6 hours, there was little difference in the efficiency of pencil or high pressure with twice the duration decontamination methods, but with shorter lag times the high pressure was more efficient than the pencil jet.

100

80

60

40

Res

idue

rem

oved

(% o

f con

trol)

20 Detergent High pressure (2 x duration) Pencil

0 0 0.5 6 24 168 672

Drying time (h)

Figure 3 The influence of lag time and decontamination method on residue removal

Bulking the washing methods for each lag time again revealed that the compound did influence the removal rate, and that lag time remained an influential factor (Figure 4). The pesticide compound was least influential when washing began immediately after application to the test surfaces with only c. 10% difference between the highest mean removal rate (isoproturon 92%) and the lowest mean removal rate (pendimethalin 79%). With a lag time of 0.5 h, isoproturon still had the highest mean removal rate (83%) but the mean removal rate for pendimethalin was reduced to 60%. With lag times of greater than 6 hours tebuconazole was preferentially removed, followed by flusilazole and isoproturon. Azoxystrobin, carbendazim and pendimethalin had consistently lower removal rates with longer lag times. Whilst this pattern in behaviour for the compounds was evident with a lag time of 1 week, there was more variability between the replicates, thus differences between the compounds were less distinct than the 6 h or 24 h lag times.

16

Res

idue

s re

mov

ed (%

of c

ontro

l) 100

80

60

40

20

Carbendazim Flusilazole Isoproturon Pendimethalin

Azoxystrobin

Tebuconazole 0

0 0.5 6 24 168 672

Drying time (h)

Figure 4 The influence of lag time and compound on the residue removal rate

3.5 REALISTIC ‘ZERO HOUR’

The drying time experiment described above highlighted the ease with which residues could be removed if washing started almost immediately after application. It may therefore be presumed that cleaning the sprayer immediately after use would be sufficient to remove about 80% of the residues deposited which should negate any health implications of the residues. However, the experimental design was such that only one application of pesticides was made to the surface prior to cleaning. In reality, there would be a more continuous deposition of residues on the surface of the sprayer during use and it is possible that there may be some drying of the residues first deposited even if the sprayer is cleaned in the field as soon as the crop has been treated. Consequently, a study was undertaken to create more realistic conditions of the sprayer being used throughout the day and then cleaned immediately after use.

The pesticide stock solution was prepared so that when four applications to the tanks were made, the total mass was equal to that used in the previous experiments (8 mg m-2). The time between applications to a single tank was c. 1 hour. After the fourth application, the surface was washed immediately. Three washing methods were used: cleaning agent + high pressure, high pressure and a pencil jet.

3.5.1 Results

The results for the realistic 0 h drying time have been plotted against the results for 0 and 0.5 hours from section 3.4 for ease of comparison. The quantity of residues removed with a realistic drying time of 0 hours was approximately 60% or less of the quantity removed when no drying

17

3.6

time was allowed and the results were more comparable to drying times of greater than 6 hours compared to a 0 or 0.5 h drying time.

Figure 5 The quantity of residues removed under more realistic deposition conditions

FORMULATION

It was possible that the formulation of a product could influence the ease with which the active ingredient is removed from the external surface. For example, the solvents used in EC formulations can remove pesticides adhering to the sprayer surface (Bayer, 2002 – Decis label). The magnitude of this effect compared to differences in cleaning methods was not known. Quantifying any difference between formulations would identify the extent to which generic advice on decontamination methods may be possible.

To extend the range of formulations it was necessary to include mixtures of active ingredients within a single product; the choice of formulation was limited by the availability of products on the market. As a baseline comparison, the products were compared to the technical grade (TG) of the active ingredient. The compounds used are summarised in Table 2.

Three test surfaces per product were used to investigate the effect of the formulation on the residue removal rate. In addition, three surfaces were used as controls to provide a mean value of the initial quantity of pesticide present, giving a total of six test surfaces required for a single formulation. Consequently, only three products could be investigated in a single day. The pesticides were applied both as a single application and as a mixture with the following formulations:

Tebuconazole: EW SC TG

Tebuconazole + flusilazole: EW SC TG

Flusilazole EW SC EC 18

Table 2 Summary of formulations investigated

Active ingredient(s) Tradename A.I. content g/L

Formulation

Flusilazole Lyric 250 Oil in water emulsion (EW) Flusilazole + carbendazim Punch C 250:125 Suspension concentrate (SC) Flusilazole + fenpropimorph Colstar 160:375 Emulsifiable concentrate (EC) Tebuconazole Folicur 250 Oil in water emulsion (EW) Tebuconazole Folicur SC 432 432 Suspension concentrate (SC)

Res

idue

s re

mov

ed (%

of c

ontro

l)

A drying time of 24 hours was used for tebuconazole (single application) and, a drying time of 5 days was used for the remaining tests due to a power failure on the intended sampling day. The decontamination method used was high pressure.

3.6.1 Results

There was no significant difference in decontamination efficiency when tebuconazole was applied as either a mix or singly, but the oil-in-water emulsion was twice as easily removed than the soluble concentrate (mean removal = 68% and 32% of the control respectively) (Figure 6). Problems with the application of technical grade tebuconazole applied singly negated the use of the results.

The findings for flusilazole were contrasting. Comparing the four ‘formulations’ (TG, EW, SC and EC) and the application technique (mix or single) there was no significant difference between the quantities of residues removed with the exception of the SC applied as a mix where more residues were removed.

100

80

60

40

20

0 EW SC TG EC

ix

Flusilazole applied as a mix

Tebuconazole applied singly Tebuconazole applied as a mFlusilazole applied singly

Figure 6 The influence of formulation on residue removal

19

3.7 QUANTIFICATION OF ACCEPTABLE RESIDUE LEVELS

The results thus far have illustrated that pesticides can be removed from contaminated surfaces, but, even when washed immediately after spraying and with a cleaning agent, some residues can remain on the surface. Indeed, it is unrealistic to expect that a sprayer will be completely devoid of all residues after washing, and account should be given to the fact that the time available for decontamination may be limited. It was therefore necessary to define an acceptable level of residues on the sprayer, or, conversely, the extent to which residues must be removed, and this should be generic to account for the vast number of compounds used with differing toxicities, physico-chemical properties and formulations; in essence, the precautionary principle should be adopted.

An acceptable level of residues was theoretically calculated using the worst-case scenarios of:

• Acceptable operator exposure limit (AOEL) = 0.001 mg/kg bw/day

• Dermal sorption = 10%

• Body weight = 70 kg

The maximum mass of a pesticide that an operator could be exposed to without exceeding the AOEL would be 700 µg.

It was then necessary to determine what were typical levels of external residues, and what were typical dermal exposure levels in order to assess the quantity of residues that should be removed to attain the 700 µg limit. This was achieved using the results from the previous HSE study where cotton glove samples were used as an indication of the exposure, and the swab samples were used as a measure of external residue levels. The glove samples gave a mass of residue transferred from the sprayer surface in a contact time of c. 2 minutes for 3 scenarios (cab, maintenance and general). The 75th percentile for each scenario was calculated and the values were extrapolated linearly to give a potential exposure time in one hour (Table 3), the value of one hour being arbitrary but realistic. These exposure values were then compared to the theoretical threshold value of 700 µg to calculate the percentage of residues that would need to be removed to ensure that the threshold value was not exceeded. (In the absence of available data, it was assumed that there was a linear relationship between the quantity of residue transferred to the cotton gloves and external residues i.e. to reduce glove-residues by 50% it would be necessary to remove 50% of the residues from the sprayer surface). The results are presented in Table 3.

Table 3 The reduction in residues required to ensure the exposure threshold (700 µg) is not exceeded

Residue µg in 2 min µg.h-1 removal rate

required % Cab 7 210 0 General 65 1950 65 Maintenance 36 1080 35

20

3.8

This assessment is basic and unknowns remain with respect to the ease with which pesticides are transferred from the sprayer surface to the operator, how well this transfer is represented by the cotton glove sampling technique, and likely contact times of an operator with different parts of the sprayer. However in the absence of suitable scenario data for potential contact with external residues, it was not possible to accurately assess the risk of the residues and any assessment of exposure to external residues on sprayers must necessarily be basic and generalised. The assessment presented here gives an indication in terms of an order of magnitude of the extent to which pesticides need be removed from the sprayer surface.

DISCUSSION

The experimental work has demonstrated that pesticides can be removed from the surface of sprayers, but the extent of decontamination was dependent on the active ingredient, the method used and the lag time between pesticide deposition and washing. Considering the decontamination methods, it could have been expected that the high pressure method (c. 150 bar) would have removed more pesticides than the hose fitted to mains pressure, but this was not supported by the results. The similarity in the removal rates between these two methods could be explained by two factors: the width of the water jet and the water volume. The hose was set at a ‘jet’ spray (nominally 0°) whilst the high pressure spray had a wider angle spray (25°). Consequently, the actual pressure of the water per unit area hitting the test surface may be more similar than when considering the water pressure alone. In addition, the water volume for the hose was 14 L min-1 whereas for the pressure washer it was 9 L min-1 so the extra water could increase the potential to remove residues. In comparison to the hose and high pressure methods, the pencil jet, brush and the cleaning agents achieved higher removal rates which could be attributed to their ability to penetrate the pesticides in order to ‘lift’ them and to make them available to be removed by the water. For both the pencil jet and the brush this was achieved by physical means whereas for the cleaning agents this was achieved by chemical means.

The results of the lag time investigation supported the theory that external residues need to be ‘broken up’ before they can be removed, and that the residues are therefore more difficult to remove when dried on. When washing occurred immediately after application of the pesticides there was relatively little difference between decontamination methods (mean removal = 90, 86, 82% for cleaning agent, high pressure and pencil jet respectively). At this time the test surface was still visibly wet, thus the pesticides may still have been ‘in solution’. After half an hour, the test surfaces were visibly dry, thus some penetration of the pesticides may be required which could explain the lower removal rates overall and the better performance when a cleaning agent was used (mean removal = 78% c.f. 70% and 62% for high pressure and pencil jet respectively). There was relatively little difference in removal rates with drying times of 6, 24 or 168 hours indicating the rapidity with which pesticides can become ‘dried’ and the subsequent need for a decontamination method to efficiently penetrate the residues. The results of the realistic zero hour drying time support the theory of the importance of drying in affecting the removal of residues. The similarity of removal rates between decontamination methods with a drying time of 24 hours contrasts to the other lag times investigated where using a detergent enhanced the effectiveness of the decontamination. However, when comparing these results to the initial investigation of decontamination methods (section 3.3) (drying time = 24 h) the mean removal rates between the two experiments were comparable (58% and 59% for the detergent method, and 59% and 54% for the pencil method for the drying time experiment and decontamination method experiment respectively). Irrespective of drying time, using a cleaning agent enhanced the removal of residues from the test surface, and this was more noticeable once the pesticides were dried on.

21

The effectiveness of a decontamination method was dependent on the compounds investigated, but it was difficult to infer any relationship with the physico-chemical properties of the compounds. Of the compounds investigated, isoproturon had the highest solubility (65 mg.l-1) and the lowest Koc (154 mg.kg-1). It could therefore be expected that this compound would be preferentially removed from the test surfaces, but this only occurred with drying times of 0 h and 0.5 h. On the whole, tebuconazole was preferentially removed and it does have a relatively high solubility (36 mg.l-1). However, carbendazim also has a relatively high solubility (29 mg.l-

1), but it had one of the lowest removal rates. It is probable that the removal rate is determined by a combination of factors, and/or a larger number of compounds would need to be studied to provide sufficient data to perform more robust statistical analysis.

The findings of the small scale studies indicated that formulation may influence removal rates, as the two compounds formulated as oil-in-water emulsions (tebuconazole and flusilazole) were more readily removed than the other compounds, all formulated as a soluble concentrate. However, the results of the experiment conducted to investigate the effect of formulation were not conclusive. Again, a larger number of compounds would need to be investigated to assess the influence of formulation. The over-riding factor influencing the ease with which a pesticide product can be removed may vary between the compounds thus it is not possible to predict the behaviour of pesticides excluded from the current investigation.

The difference in removal rates for the compounds investigated gave some indication of the variability that could occur in reality. The findings highlighted the need to consider a range of products when conducting studies in this area in order to make generalisations, and it may be advisable to restrict extrapolation of the data to orders of magnitude rather than exact values.

The basic risk assessment conducted in section 3.7 adopted the precautionary principle. The removal rates calculated as necessary to reduce residues to an acceptable level were therefore the maximum rates required. For areas of the sprayer that were not heavily contaminated (i.e. areas other than the boom and the back of the sprayer), the results of the small-scale experiments demonstrated that all decontamination techniques investigated would be suitable. However, for the more contaminated parts of the sprayer, up to 65% of the external residues should be removed. This level of decontamination may be achieved with a cleaning agent. It is probable that the required removal rate could also be achieved with other typical cleaning methods, such as a pressure washer, but these methods may require a longer cleaning duration to achieve similar results. Other means of reducing operator exposure to external residues would be to raise awareness of the need to treat the most frequently contaminated parts of the sprayer as potentially contaminated even after washing and to wear appropriate PPE when in contact with these areas.

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4 TRANSFER EFFICIENCY OF PESTICIDES FROM SPRAYER SURFACES

The theoretical exposure assessment outlined in section 3.7 assumed that there was a linear relationship between the total quantity of residues on the sprayer surface as determined by swabbing (removable residues) and the residues transferred to cotton gloves (dislodgeable residues). To examine the validity of this assumption an experiment was undertaken to quantify the dermal transfer of pesticides to cotton gloves from sprayer surfaces. The dermal transfer from both washed and unwashed surfaces was investigated. In light of the findings from examining drying times (3.4.1), pesticides may be removed more easily in the presence of moisture than when dry, thus residues may be more easily transferred to the operator immediately after washing when the surface of the sprayer is still wet compared to if the surface was allowed to dry. All tests were preformed in triplicate and pesticides were applied as described in section 3.1. Potential dermal transfer was determined by rubbing the entire surface of the pure water tank for 3 minutes whilst wearing cotton gloves. A 24 hour period was given between pesticide application and decontamination, or sampling, and the washing method used was high pressure. Six test conditions were established:

1. Removable residues – unwashed, dry surface

2. Removable residues – washed, dry surface

3. Dislodgeable residues – unwashed, dry surface

4. Dislodgeable residues – washed, dry surface

5. Dislodgeable residues – unwashed, wet surface

6. Dislodgeable residues – unwashed, wet surface

An unwashed, wet surface was created by applying 2.5 ml of distilled water to the contaminated surface using an airbrush that was sufficient to wet the surface without causing dripping.

The transfer efficiency was calculated by dividing the dislodgeable residues for each individual surface by the mean removable residues (n=3) for each compound.

4.1 RESULTS

4.1.1 Removable residues

The quantity of pesticide removed by methanol-wetted swabs varied between compounds despite the same quantity being deposited initially. Values ranged from approximately 2 mg for carbendazim, isoproturon and pendimethalin to c. 3.5 mg for azoxystrobin and tebuconazole (Figure 7).

23

Figure 7 Removable residues

4.1.2 Dislodgeable residues

On the whole, the maximum quantity of pesticide that could be dislodged was in the order of 1.5 mg with the exception of azoxystrobin where approximately 3 mg could be dislodged (Figure 8). More residues could be dislodged from the unwashed surfaces compared to the washed surface, as could be expected, but there were differences between the compounds.

Bulking the data for washed and unwashed surfaces there were no significant differences in the quantity of residues transferred depending on whether the surface was wet or dry before sampling. However, when the ‘washed’ and ‘unwashed’ data were analysed separately some differences were observed. For unwashed surfaces there were no significant differences between wet and dry surfaces, but for washed surfaces significantly (p<0.05) more residues of isoproturon and pendimethalin were removed from the surface when the surface was wet compared to dry.

24

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Washed - dry

Res

idue

s pe

r glo

ve p

air (

µg)

Washed - wet Unwashed - dry Unwashed - wet

Azoxystrobin Flusilazole Pendimethalin Carbendazim Isoproturon Tebuconazole

Figure 8 Dislodgeable residues showing the mean ± 1SE

4.1.3 Transfer efficiency

The transfer efficiency was compound-dependent. Over 50% of azoxystrobin, carbendazim and isoproturon residues were transferred to cotton gloves from the sprayer surface with an overall maximum mean entrainment of 80% for azoxystrobin. This compares to approximately only one quarter of ‘available’ tebuconazole and flusilazole residues being entrained by the cotton glove. There was a trend for the potential dermal transfer to be lower for washed surfaces than fully contaminated surfaces although this difference was only significant (p<0.05) for pendimethalin where mean residues removed by gloves as a percent of that removed by swabbing were 29% and 49% respectively for a washed and unwashed surface.

25

4.2

100

80

60

40

20

0 Azoxystrobin Carbendazim Flusilazole Isoproturon Pendimethalin Tebuconazole

Washed

Tran

sfer

Effi

cien

cy (%

)

Unwashed

Figure 9 Transfer efficiency of pesticides from a sprayer surface to cotton gloves showing the mean ± 1SE.

DISCUSSION

The transfer efficiencies quantified in this study (20 – 80%) were generally high compared to other published data (e.g. Snyder et al., 1999; Byrne et al., 1998; Williams et al., 2002), but the lower transfer efficiencies were comparable to those reported by Roff and Wheeler (2000) for similarly hard surfaces (22% for glazed tiles and 28% for rough tiles).

The tendency for fewer residues to be transferred from washed surfaces compared to unwashed surfaces indicated that the relationship between pesticide loading and transfer efficiency might not be linear. This contrasted with the findings of Roff and Wheeler (2000) where the transfer of strontium tended to be higher at low surface loadings. The contrasting results may partly be explained by the difference in compounds and/or sampling methods.

It was postulated that more residues could be removed if the surface was wet than if the surface was dry. Other work examining the influence of moisture on the transferability of chlorpyrifos from nylon carpet demonstrated that there was a strong correlation (p <0.01; r = 0.89) between the percent moisture and percent of transferable residue (Williams et al., 2002). Camman et al., (1996) also demonstrated an increase in chlorpyrifos transfer from carpet to water-moistened sampling media compared to dry sampling media. In the current study, an increase in transfer efficiency from a wet surface was only observed for the compounds isoproturon and pendimethalin where the surfaces had been washed. The fact that this was only evident for the washed surfaces supports the theory that factors affecting removal are of more importance when the total amount of residues available is relatively low. For isoproturon it is possible that its solubility could maintain residues in solution when the surface is wet enabling more residues to be transferred to the cotton glove. However, in contrast, pendimethalin has a low solubility (0.3

26

mg.l-1) and it is difficult to explain the observed finding. Although there was no relationship between the transfer efficiency and the solubility of the compound it is possible that this was significant due to the small sample size. The current study has demonstrated that there are differences between compounds thus it is not possible to extrapolate these findings, or those of other workers where only a single compound has been investigated, to predict the behaviour of other compounds.

There was an inverse relationship between the transfer efficiency and the Log octanol: water partition coefficient (Kow) (p <0.01; r = 0.57). This could indicate that some residues are lightly bound to the polyethylene surface of the spray tank (or dust particles therein) so the higher the Kow of a compound, the more difficult it is to remove in the absence of a suitable solvent (as used to quantify removable residues).

Comparison of the swab data to the cotton glove data provided insight into the transfer potential of residues from contaminated surfaces, and the results indicated that this was compound-dependent. Swab data (removable residues) provided a reliable measure of the total residues present, which could be used, in the absence of other available data, as a worse case scenario for potential dermal exposure. Whilst this would not be too unreasonable for compounds such as azoxystrobin where the transfer potential was about 80%, for compounds such as tebuconazole and flusilazole using data for swab samples could over-estimate potential exposure. The sampling method adopted in this study for quantifying dislodgeable residues (i.e. rubbing the entire surface) could also be perceived to be too worse case. However, there are several exposure scenarios where the operator could rub the surface of the sprayer such as using handles, turning valves or changing sprayer parts, all of which involve a grabbing action rather than incidental contact; assessing the extent to which the sampling methodology used here was representative of reality was beyond the scope of this study.

27

5.1

5 FIELD SAMPLING

The objective of the farm visits was fourfold:

1. to validate the findings of the ‘laboratory’ studies using more realistic surface conditions (aged, muddy etc);

2. to discuss the findings of the experimental work with spray operators, to allow the end-user to provide input into the overall study and to assess whether improvements could be made to the existing cleaning regime.

3. to quantify contamination on the internal surfaces of the protective nitrile gloves.

4. to quantify operator exposure to pesticide residues during the actual cleaning process.

METHODOLOGY

Samples were taken from the nozzle, boom, mudguards and driving unit (the tractor for mounted and trailed sprayers and the cab and bonnet section on a self-propelled). Methanol (5 ml) was applied to a methanol-washed cotton swab and a 10 x 10 cm area was wiped; for the nozzles, individual nozzles were wiped. On the boom, mudguards and nozzles, three different areas were wiped to create a composite sample. Due to the larger surface of the driving unit, four areas were wiped to create a single, composite sample. The position of sampled area was recorded to ensure the same area was not sampled twice. All samples were stored in HDPE bottles in a cool-box during collection and transportation, and they were stored at -18°C prior to analysis. Samples were analysed for azoxystrobin, carbendazim, chlorothalonil, cypermethrin, epoxiconazole, flusilazole, isoproturon, metazachlor, pendimethalin, pirimicarb and tebuconazole.

The sprayer was sampled, as described above, on three occasions in a single visit: prior to any cleaning, after the sprayer had been cleaned by the operator and after further decontamination using a detergent. The corresponding samples are referred to as dirty, clean and detergent-clean. Only pesticides used in the previous 12 months (according to the pesticide records) were included in the full data analysis. The raw data consisted of a dose per composite sample where a swab was used to wipe an area of 100 cm2. The data were adjusted to represent the corresponding dose in mg.m-2 units. Mann-Whitney was used to analyse the data.

In addition to the sampling of the sprayer, the results from the previous study were presented to the farmer and their health significance discussed. Attention was drawn to the fact that, by considering the number of contact hours required to reach the AOEL, it was apparent that external residues were not insignificant. It was proposed that there were a number of ways to reduce operator exposure to these residues. First, by being aware that the residues were present more caution could be taken in terms of personal hygiene when in contact with the sprayer and/or tractors. Second, consideration could be given to improving the cleaning regime where possible. The results of the experimental work were shown to the farmer, and the influence of drying time, water volume and cleaning agent highlighted. In addition, the results of a Danish study (Jensen & Spliid, 2003) were presented; this demonstrated that spraying out the water used to rinse the internal surfaces of the spray tank with the booms folded could reduce external residues (although this can depend on the direction of the nozzles and/or folding mechanism of the boom). Where appropriate, the spray operator/farmer was requested to adopt this technique after the first internal-rinse of the spray tank (it was anticipated that the pesticide concentration

28

in the first rinse would be such that overdosing may occur unless the rinsings were sprayed out with extended booms).

5.2 RESULTS

5.2.1 Cleaning regimes

The cleaning regimes varied between farms and sprayers and represented the range of scenarios typical of the UK farm (Table 4). One farm spent over an hour cleaning the sprayer. The operator indicated that they would wash the sprayer infrequently during the spraying season, but that they would give it a good wash when it was cleaned, and it was always washed before the sprayer was inspected; one reason stated for not cleaning the sprayer regularly was the potential environmental impact. For sprayers using an external hose on the sprayer, the size of the clean water tank and the flow rate through the lance determined the time spent cleaning; cleaning continued until the tank was empty.

Table 4 Summary of the sprayers and cleaning regimes

Type

Spray tank size (L)

Boom length

(m)

Cleaning place

Flow rate (l. min-1)

Time spent

cleaning (min)

Water volume used (L) Cleaning method

External hose on SP 1500 18 Field 16 12 192 sprayer with jet lance or

brush Field – Garden hose with jet

M 800 12 non­ 18 19 342 spray cropped

M 2000 20 Yard 8.3 25 208 Steam pressure wash Field – External hose on

SP 2500 24 non- 9.6 20 192 sprayer cropped Field – Hot pressure wash

T 2300 20 non- 9.9 77 762 cropped

Only one of the sprayers was suitable for testing the theory that spraying out the internal rinse water with the booms folded could reduce overall residues on the boom. For the majority of the sprayers, the nozzles were aligned so that there was no overlap with the boom, or the booms were positioned such that when they were folded they would hang over the cab doors. If the internal rinse was flushed out with the booms in this position, this could increase the quantity of residues in the vicinity of the cab that could serve to increase occupational exposure.

5.2.2 External residue doses

There was variation in doses between the different compounds and within a single compound (Figure 11 to Figure 13). Doses on the nozzles and boom were generally an order of magnitude greater than on the mudguard or tractor. The maximum dose was of isoproturon on the nozzles where levels were in excess of 1 mg per nozzle. Correspondingly, the maximum dose for the

29

100%

80%

60%

40%

20%

0%

Azo

xyst

robi

n

Azo

xyst

robi

nC

arbe

ndaz

im

Pen

dim

etha

lin

100%

80%

60%

40%

20%

0%

Figure 10 External residues on the tractor

Mudguard

Car

bend

azim

Chl

orot

halo

nil

Chl

orot

halo

nil

Cya

nazi

ne

Cya

nazi

ne

boom was isoproturon on the same sprayer although there were no positive detections of isoproturon on either the mudguards or tractor of this sprayer. Overall, the variation in the data was such that generic statements on the presence of a compound could not be made with great confidence.

Tractor

Cyp

erm

ethr

inC

yper

met

hrin

Epo

xico

nazo

leEp

oxic

onaz

ole

Flus

ilazo

leFl

usila

zole

Isop

rotu

ron

Isop

rotu

ron

Met

azac

hlor

Met

azac

hlor

Pend

imet

halin

Piri

mic

arb

Piri

mic

arb

Tebu

cona

zole

Te

buco

nazo

le

-2µg m> 100

> 10 to 100

> 1 to 10

LOD to 1

< LOD

µg m-2

> 100

> 10 to 100

> 1 to 10

LOD to 1

< LOD

30

Figure 11 External residues on the mudguards

Boom 100%

µg m-280% A

zoxy

stro

bin

> 100 60% > 10 to 100

Car

bend

azim

> 1 to 10 40% LOD to 1

Chl

orot

halo

nil

20% < LOD C

yana

zine

0%

Cyp

erm

ethr

in

Epo

xico

nazo

le

Flus

ilazo

le

Isop

rotu

ron

Met

azac

hlor

Pen

dim

etha

lin

Piri

mic

arb

Tebu

cona

zole

Figure 12 External residues on the boom

Nozzle

0%

20%

40%

60%

80%

100%

Azo

xyst

robi

n

Epo

xico

nazo

le

Flus

ilazo

le

Met

azac

hlor

Piri

mic

arb

Tebu

cona

zole

le

Car

bend

azim

Chl

orot

halo

nil

Cya

nazi

ne

Cyp

erm

ethr

in

Isop

rotu

ron

Pen

dim

etha

lin

> 100

> 10 to 100

> 1 to 10

LOD to 1

< LOD

µg per nozz

Figure 13 External residues on the nozzles

To give an indication of whether there were differences in cleanliness of the sprayers between farms (and therefore cleaning regime) the number of samples reported to be below the limit of detection per sprayer was calculated and normalised against the number of compounds used. These values are summarised below (Table 5). The results indicate that the external hose may be less efficient at removing residues than the other cleaning methods as the number of samples recorded as < the LOD was less than 0.5 per compound used.

31

Table 5 Average numbers of samples per sprayer <LOD per compound used

Average number of samples <LOD Cleaning method Farm

0.67 Steam pressure a 0.53 Hose b 0.57 Hose b 0.38 External hose c 0.7 Hot pressure d

0.65 External hose + brush e 0.69 External hose + brush e

To investigate the effect of cleaning on the quantity of residues overall, data for the individual compounds were bulked. To account for the variation in the data, the results were plotted to show the median, 75th and 25th percentile of the doses. The findings showed that for areas of the sprayer where relatively high residue levels can be expected (boom and nozzles), washing the sprayer did not have any apparent effect on reducing the external residues. However, for the lower dosed areas (mudguard and tractor) the data indicated that washing could reduce external residues and using a cleaning agent may enhance this effect.

32

Figure 14 Residues on the tractor before and after cleaning

Figure 15 Residues on the mudguard before and after cleaning

Figure 16 Residues on the boom before and after cleaning

Figure 17 Residues on the nozzles before and after cleaning

33

5.3 DISCUSSION

The level of external residues on the different parts of the sprayers followed the same pattern as the previous HSE study, i.e. doses on the nozzles were much greater than the boom that were greater than the mudguard and tractor. However, there were fewer detections in the current study of doses in the order of milligrams per metre squared compared to the previous HSE study. This may be a factor of the natural variation that can occur, or it may be indicative of the uptake of more rigorous cleaning regimes since it was discovered that external residues are more significant than originally thought.

Considering the number of doses that were recorded below the LOD, the results indicated that the external hose could be less efficient than other cleaning methods. Ordinarily the pump supplying the water to the lance from the clean water tank will have a low pressure, in the order of 10 bar; this compares to 100 bar or greater for standard pressure washers. It is probable that this low water pressure was less effective at removing residues compared to the other methods. Whilst one farm used only a hose to clean the sprayer, the flow rate from the hose was twice that of the external hose, hence its cleaning ability could be expected to be greater, as the results indicated. In terms of the quantity of residues below the LOD, the results for the steam pressure washer and brush were similar. However, the maximum dose on the boom of the sprayer cleaned by brush was c. 150 mg m-2 compared to 17 mg m-2 on the steam-washed sprayer. Although the data indicated that the hot pressure washer was particularly effective at removing residues, these results may also reflect the longer time spent cleaning at that farm.

Based on the results of the experimental work, it was expected that residues on the sprayer would be less after washing, and reduced further after the use of the cleaning agent. However, the field results did not wholly support this theory. There was an apparent lack of effectiveness of washing for the nozzles and the boom, but it is possible that this was an artefact of the sampling technique. It is highly likely that the deposition of residues around the sprayer will not be homogenous, and it was for this reason that a composite sample was taken. If the quantity of residue removed by washing is relatively small compared to the natural variation in residue levels across the sprayer, then any effect of the washing may be masked by this variation. Conversely, where residue levels were inherently lower (mudguard and tractor) the removal of residues could be quantified. The results of the farm visits for the tractor and mudguard indicated that the cleaning agent may assist in removing residues although it was not possible to determine whether this effect was due to the cleaning agent or further cleaning. The data sets were highly skewed containing a large number of values below the limit of detection and, at the other extreme, a small number of high values. Attempts to statistically analyse the data were therefore restricted to a non-parametric test, but this did not show any significant differences. The results of the field study highlight the difficulties in analysing ‘real’ data compared to laboratory data.

Comparing the findings of the field sampling to the risk assessment in section 3.7, the results indicate that current cleaning techniques were achieving sufficient levels of reduction in residues for the mudguard and tractor. However, residue levels on the boom and nozzle were not obviously reduced and, either more time should be dedicated to cleaning these areas, or these areas should be treated with caution even after washing.

34

6 INTERNAL CONTAMINATION OF PROTECTIVE NITRILE GLOVES

6.1 METHODOLOGY

The nitrile gloves worn by the operator were sampled to determine the quantity of residues on the internal surfaces of the gloves. Distol grade methanol (200 ml) was poured into each glove and shaken vigorously for 5 minutes to extract the residues. An aliquot of the solution was filtered after extraction, transferred to a 2 ml autosampler vial and analysed as described in section 3.2.

6.2 DATA ANALYSIS

To enable the quantified residues to be put into some context, the doses detected were compared to the acceptable operator exposure limit (AOEL) (or acceptable daily intake (ADI) where an AOEL has yet to be defined). A body mass of 70 kg was assumed and the data were adjusted to account for the appropriate dermal sorption; a value of 10% was assumed where there were no figures available for dermal sorption. The values used in the calculation are given below (Table 6). The fraction of the AOEL that the residue inside the glove represented was calculated for the individual compounds. These values were summed to give a total per glove pair.

Table 6 AOEL, ADI and dermal sorption values

Dermal† AOEL† ADI + sorption % (mg.kg body weight-1 d-1)

Azoxystrobin 5 0.1 0.1 Carbendazim 1 0.04 0.03

Chlorothalonil 1 0.005 0.03 Cyanazine 10 - 0.006*

Cypermethrin 10 0.06 0.05 Epoxiconazole 10 0.02 0.0032

Flusilazole 10 - 0.001 Isoproturon 10 0.03 0.0062

Kresoxim-methyl 10 0.9 0.4 Metazachlor 10 - 0.036

Pendimethalin 10 0.045 -Pirimicarb 10 0.035 0.02

Tebuconazole 10 0.03 0.03

Source: † pers comm. Pesticide Safety Directorate (PSD); + Tomlin (2000) except * where source was PSD. Italics indicate no dermal sorption specified thus 10% assumed.

35

6.3 RESULTS

The quantity of pesticides on the inside of the nitrile gloves varied between and within compounds with a maximum dose of 3502 µg of metazachlor in a single glove pair (Figure 18). Pirimicarb was the only compound that was used but not detected inside the gloves during this study.

Pest

icid

e do

se (µ

g pe

r glo

ve p

air) 1000 3502 1719

800

600

400

200

0

Azo

xyst

robi

n

Car

bend

azim

Chl

orot

halo

nil

Cya

nazi

ne

Cyp

erm

ethr

in

Epox

icon

azol

e

Flus

ilazo

le

Isop

rotu

ron

Kre

soxi

m­

met

hyl

Met

azac

hlor

Pend

imet

halin

Piri

mic

arb

Tebu

cona

zole

Figure 18 Residue levels on the internal surface of the farmers’ nitrile gloves

The total fraction of the acceptable operator exposure level that the residues represented is illustrated in Figure 19. On some farms no residues were detected inside the nitrile gloves whereas, on one farm, the residues contained within the protective gloves represented over a fifth of the acceptable operator exposure level.

25

20

15

10

5

0Res

idue

leve

ls (%

of t

he A

OEL

)

a a b b

Farm c d e

Figure 19 Residue levels on the internal surfaces of nitrile gloves as a fraction of the AOEL. (The letters represent individual farms.)

36

6.4 DISCUSSION

Sampling of the internal surfaces of the farmers’ protective nitrile gloves indicated that residues were frequently detected, but there was variation between and within both compounds and farms. The basic risk assessment indicated that these residues could contribute to over one-fifth of the daily acceptable level of exposure to pesticides, thus the doses may be considered significant. However, the risk assessment conducted was simple and it assumed that the risk posed by the different compounds was additive; an assumption that is not necessarily valid, and one that remains open to debate (e.g. Wilkinson et al., 2000; Ross et al., 2001). As there is no definitive understanding of the toxicity of mixtures, the risk assessment conducted could provide a reasonable overview of the potential exposure. It is also likely that there were more residues on the inside of the gloves of compounds other than those investigated in this study. Moreover, the assessment conducted assumed a dermal sorption value of 10% or less, but this may be an under-estimate of the actual sorption because the absorption of pesticides can be in excess of 50% with a relative humidity of 90% (Meuling et al., 1997); nitrile gloves do not allow the skin to breathe and, when questioned, the operators reported that perspiration inside the gloves was commonplace.

The findings from this study have indicated that contamination inside the farmers’ nitrile gloves was not uncommon, but, due to the small samples size, it was not possible to predict under what circumstances residues would be more prone to being present. A study with a much larger samples size would be required to assess the contribution that nitrile gloves can make to operator exposure.

37

7 OCCUPATIONAL EXPOSURE DURING DECONTAMINATION

The overall aim of the study was to determine and, if appropriate, to reduce operator exposure to post-application residues on the external surfaces of sprayers. One method of achieving this is to increase the efficiency and/or frequency of decontaminating the sprayer after use, using a jet washer or similar. During the cleaning process it is highly probable that, due to the fine droplet sizes of water produced and splash back off the sprayer, some of the washings could be deposited on the person cleaning and/or be inhaled. Consequently, the actual decontamination process, could contribute to operator exposure to pesticides.

When balancing the options of leaving the residues on the sprayer or removing them, consideration should be given to the fact that, during cleaning the operator will commonly be wearing some PPE (e.g. gloves, visor, overalls) whereas at other times PPE may not be worn thus, if the sprayer was not cleaned, exposure could be relatively high. In addition to the hazard posed by the residues, other physical hazards could be introduced during the cleaning process such as electrocution (if using an electric-powered pressure washer) or tripping (water hose) and an assessment of any such hazards was also required.

7.1 METHODOLOGY

Samples were taken during the first clean representing hazards typically associated with cleaning the sprayer. Samples were also taken when the sprayer was re-cleaned thoroughly using All Clear Extra; it was considered that any residues transferred to the person cleaning would be representative of a worse case scenario because a) the cleaning agent should remove more residues than just water, and b) the time spent cleaning was longer than normal.

To quantify operator exposure to pesticides during the cleaning process Tyvek® semi-absorbent disposable suits were worn on top of ordinary work clothes along with lightweight cotton gloves (RS Electrical Components, UK), Wilson cotton sports socks and cotton “baker’s” hats worn next to the skin, beneath any protective clothing. For potential exposure by inhalation, air at 0.5 L min-1 was drawn through a Glass fibre (GF/A) filter (Whatman, UK), held in a modified UKAEA sampling head with a standard 45 mg Tenax® sorbent tubes (SKC, UK, part No. 226­35) down stream of the filter, mounted in the breathing zone of the operative, on the left shoulder (MDHS 94). These are collectively referred to as the occupational hygiene (OH) sampling devices and were worn by the person cleaning the sprayer. After cleaning the sprayer the sampling devices were bagged separately and sent to HSL for analysis. All samples were stored in freezers, at around –18oC, on arrival at the laboratory.

The glove, sock and hat samples were placed directly into Teflon bottles of an appropriate size and a known quantity of methanol added (gloves, 150 ml; socks and hats 225 ml). The GF/A filters and the Tenax® extracted from the sorbent tubes were placed in a silanized 4 ml glass vial and methanol (2 ml) added. The suit samples were firstly cut into thirteen sections (Figure 21). The hood (sub-sample 1) was cut from the main suit along the seam. The wrists (5 and 6) were cut 19 cm up from the cuff and the arms (3 and 4) were cut 35 cm up from wrist. The ankles (10 and 11) were cut 33 cm from the cuff and the legs (8 and 9) were cut 40 cm up from the ankle. Cuts were made along the chest seam and then along the sides to give the final four pieces upper front (2), lower front (7), upper back (12) and lower back (13). Each was placed in a Teflon bottle and methanol added, for sub-samples 5 and 6 this was 100 ml, for samples 10 and 11 this was 150 ml and for all the remaining samples this was 200 ml.

38

Figure 20 Sub-sample positions for Tyvek® suits

All samples were extracted by shaking vigorously for five minutes; they were then placed in an ultrasonic bath and sonicated for 30 minutes. The extraction solution was concentrated on a TurboVap and then filtered; approximately 1 ml of the filtrate was then transferred to 2 ml vials. The GF/A and Tenax® samples were filtered directly into 2 ml vials.

A total of nine sample sets were collected from seven farms looking at five different cleaning regimes. These are already described in more detail in section 5.2.1. Although several cleaning regimes are used it is reasonable to group all the data sets together as they all essentially represent the same task of cleaning a sprayer. Another variable that is difficult to account for is that several different types of sprayer are included, but again the basic principles of the task are not changed and so this should not prevent the use of the results as a single group of data sets.

DATA ANALYSIS

The sections of suit were analysed for the thirteen pesticides listed in section 5.1. From this information the deposition of splash back off the sprayers onto the coveralls (i.e. the potential

39

7.2

dermal exposure (P.D.E.)) was estimated. Unlike with the patch method (WHO, 1982) or the Dirichlet tessellation (Wheeler, 2002) method there is no need for further data analysis. Using a whole suit approach has the advantage that the measurements obtained give total contamination and do not require extrapolation, which can introduce errors. In addition because the suits are sectioned before analysis it is possible to determine which areas of the body are being exposed more accurately than with the patch method. The suit sections taken are based on the on the Dirichlet method and the areas each section represent are given below (Table 7).

Table 7 Areas of body parts for different suit sizes (cm2)

Medium Large XL XXL Head 1440 1520 1520 1530

Wrists (x2) 650 700 700 770 Arms (x2) 1930 2060 2090 2380

Ankles (x2) 1650 1700 1720 1770 Legs (x2) 2670 2840 3000 3190

Upper Front Torso 3680 3940 4410 4875 Upper Back Torso 3680 3940 4410 4875 Lower Front Torso 2535 2665 2900 3235 Lower Back Torso 2535 2665 2900 3235

Total 27700 29300 31100 34000

Source: Wheeler 2002

The results for gloves, socks and hats are measurements of actual dermal exposure (A.D.E.) as these sampling devices were worn next to the skin. Again no data analysis is required as the whole sample was analysed. The potential exposure by inhalation is calculated as a time-weighted average over the sampling period. The results from the Tenax® and GF/A samplers were summed to give a total value for vapour and aerosol.

7.3 RESULTS

The results for each sample set are summarised in Table 8. The values represent the total quantity of pesticide on each sampling device with no distinction having been made between compounds or their relative amounts. It is usual for this data to then be presented in terms of μg/min to determine a rate of exposure and this can easily be calculated as the times for each task are given. This however may lead to difficulties, as the time taken on each cleaning task would not necessarily be proportional to the exposure. If, for example, a pesticide sprayer were being used then the exposure to the pesticides would be expected to increase over time. With the cleaning task, however, there would be a point reached where further cleaning would not lead to any further exposure, as the sprayer is effectively clean. Additional work would just result in clean water being splashed back over the operator and would be measured as a lower rate of exposure than is true. The times given are of most use as an indication of when the operator believes the sprayer to be clean. So although the tasks represent a realistic situation the use of time-weighted averages would appear to be inappropriate here.

40

Table 8 Summary of results for dermal and respiratory exposure

Set Regime Time (min)

Pesticides Detected P.D.E.

ContaminationHands

(μg) Feet Inhaled

1 1 12 A, E, F, P1, T

57 ND ND ND

2 1 12 F, I, P1, T 802 1 3 ND 3 2 19 C1, F, P1 179 2 ND ND 4 2 19 F, P1 193 ND ND ND 5 3 20 F, I, P1. 41 ND ND ND 6 4 25 A, C4, E, F,

P1. 255 221 123 ND

7 2 19 E, F, P1, T. 239 439 64 ND 8 1 12 A, E, F, M,

P1, P2, T. 281 ND ND ND

9 5 77 A, C1, E, F, K, M, P1,

P2.

647 29 45 ND

The cleaning regimes referred to in Table 8 are as follows;

1 External hose with brush 2 Garden hose with jet spray 3 External hose on sprayer 4 Steam pressure wash 5 Hot pressure wash

The key for the pesticides is azoxystrobin (A), carbendazim (C1), chlorothalonil (C2), cyanazine (C3), cypermethrin (C4), epoxiconazole (E), flusilazole (F), isoproturon (I), kresoxim-methyl (K), metazachlor (M), pendimethalin (P1), pirimicarb (P2) and tebuconazole (T).

The data is further summarized in Table 9. In order to conduct a risk assessment, some estimates of a ‘worst case’ need to be made. It is recommended that the 95th percentile be used for this purpose (HSE, 1999) with other indicative points being the median and the 75th

percentile. With the 95th percentile, it is expected that only in a small number of cases, about 5%, will exposure exceed this value. The non-zero values have been excluded for the hands and feet data to attempt to give a “worse case” result. This approach has previously been used in several HSE OH surveys (HSE, 1999). The effect of this is that the values are higher than the true results, where zero values are included, but shows the levels found where there is contamination to the hands and feet. This does not apply to the P.D.E. to the body, as there were no zero results. Samples that produced not detected results have been assigned a zero value.

The pattern of deposition on clothing is reported in Table 10 using the body parts from the sectioning of the suits as described in section 3.2.3. This shows where the spray splashed back

41

from cleaning has been deposited on the various body surfaces. Percentage values are used here to allow a direct comparison of the data from each data set. These values are then presented as averaged and normalised ratios in Table 11 to give a clearer picture of where splash back from the sprayer is depositing.

Table 9 Exposure ranges and indicative values

Contamination (μg) P.D.E. Hands Feet Inhaled

Non-zero 9 5 4 0 Range 41 - 802 1 - 439 3 - 123 0

Median 239 29 55 0 75th percentile 281 221 79 0 95th percentile 740 396 114 0

Table 10 Distribution pattern of deposition on individual coveralls (all values as percentage)

Body Part Data Set 1 2 3 4 5 6 7 8 9

Head 3 1 15 3 0 1 0 1 0 L Wrist 6 4 9 4 0 5 0 0 1 R Wrist 3 0 2 30 10 5 0 0 0 L Arm 15 27 20 6 34 5 0 8 1 R Arm 2 12 3 4 56 3 0 3 8 L Ankle 2 6 3 48 0 17 31 19 2 R Ankle 2 5 3 3 0 14 20 14 31 L Leg 12 16 3 3 0 17 28 16 24 R Leg 11 5 5 5 0 3 21 17 13 U front 6 5 14 3 0 13 0 3 15 U Back 7 0 4 3 0 4 0 0 3 L Front 13 18 4 5 0 11 0 11 1 L Back 18 1 15 4 0 2 0 8 1

42

Table 11 Distribution pattern of deposition on coveralls (all values as percentage)

Body Part Non-zero Range Median Normalised Head 6 0-15 1 2

L Wrist 6 0-9 4 6 R Wrist 5 0-30 2 3 L Arm 8 0-34 8 12 R Arm 8 0-56 3 5

L Ankle 8 0-48 6 9 R Ankle 8 0-31 5 8 L Leg 8 0-28 16 25 R Leg 8 0-21 5 8 U front 7 0-15 5 8 U Back 6 0-7 3 5 L Front 7 0-18 5 8 L Back 7 0-18 2 3

As well as looking at the levels of contamination resulting from sprayer cleaning and the distribution pattern, it would be useful to show any connection between the levels of contamination on the sprayer and any occupational exposure. To attempt to do this the total quantity of residue on the swab samples from the uncleaned sprayers has been compared to the P.D.E. for each data set. This can be seen below in Table 12. To try and cut through the numbers the quantities have been described as high (H), medium (M) or low (L), although it should be noted that this is only in relative terms and not a comment on the actual values. The comparison is also made in terms of a percentage. This is only an attempt to put a value on the level of operator exposure relative to the sprayer contamination for demonstration purposes. It is not intended as an actual value for the transfer of residues from the sprayer to the operator.

Table 12 Comparison of the residue levels on the “dirty” sprayer and the operator.

Data Set Swab Samples (μg) OH Samples (μg) %

1 11500 M 57 L 0.5 2 11500 M 802 H 7.0 3 19800 H 179 M 0.9 4 19800 H 193 M 1.0 5 8600 M 41 L 0.5 6 4600 L 255 M 5.5 7 14500 H 239 M 1.6 8 5300 L 281 M 5.3 9 5200 L 647 H 12.4

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Table 13 Detections of residues on the “dirty” sprayer and the operator.

Pesticide Number of positive detections

Boom Nozzles Mudguards Tractor Total Operator Azoxystrobin 4 4 2 1 11 4 Carbendazim 4 4 0 1 9 2

Chlorothalonil 4 4 1 1 10 0 Cyanazine 2 1 0 1 4 0

Cypermethrin 3 3 0 2 8 1 Epoxiconazole 7 7 4 3 21 5

Flusilazole 7 7 3 3 20 9 Isoproturon 3 2 0 0 5 2

Kresoxim-methyl 5 4 0 1 10 1 Metazachlor 3 3 0 0 6 2

Pendimethalin 3 5 1 1 10 9 Pirimicarb 1 1 1 0 3 2

Tebuconazole 6 6 3 2 17 4

It has already been shown (section 3.8) that the removal of individual pesticides from the sprayer is compound dependant. Tables 13 and 14, therefore, look at the levels of individual pesticides found on the sprayers and compare this to the levels found on the operator. Table 13 does this by totalling the number of positive detections of each pesticide on the boom, nozzles, mudguard and tractor as well as the operator. This would show, regardless of the levels found, whether the pesticide residues present on the sprayer were being transferred to the operator.

Another approach is to look at the levels of each pesticide and see if a high residue level on the sprayer gives a corresponding high level on the operator. This is shown in Table 14. Because there is such a large amount of data it was decided not to carry out this type of data analysis on each pesticide for each data set. It was more likely that by treating the data sets as a whole rather than investigating each individually any correlation between sprayer levels and occupational exposure would be more obvious. All the individual data sets are given in Appendix 4.

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Table 14 Levels of pesticide residues on the “dirty” sprayer and the operator.

Pesticide Maximum level (μg)

Boom Nozzles Mudguards Tractor Operator Azoxystrobin 694 525 76 20 137 Carbendazim 2361 2527 ND 24 515

Chlorothalonil 2563 1550 1058 867 0 Cyanazine 1016 1739 ND 26 0

Cypermethrin 303 889 ND 180 137 Epoxiconazole 456 1336 18 25 47

Flusilazole 669 3271 19 68 92 Isoproturon 8637 4494 ND ND 426

Kresoxim-methyl 91 290 ND 2 16 Metazachlor 102 288 ND ND 5

Pendimethalin 423 503 17 8 101 Pirimicarb 8 4 1 ND 24

Tebuconazole 1538 5782 48 421 285

Table 15 Total residue levels as a percentage of the AOEL (or ADI).

Pesticide Data Set

1 2 3 4 5 6 7 8 9 Azoxystrobin <0.1 0 0 0 0 <0.1 0 0.1 <0.1 Carbendazim 0 0 <0.1 0 0 0 0 0 0.2

Chlorothalonil 0 0 0 0 0 0 0 0 0 Cyanazine 0 0 0 0 0 0 0 0 0

Cypermethrin 0 0 0 0 0 0.3 0 0 0 Epoxiconazole 0.1 <0.1 0 <0.1 0 0.4 1.9 0.2 <0.1

Flusilazole 4.6 15 13 12 0.3 <0.1 27 0.4 9.1 Isoproturon 0 2.0 0 0 5.2 0 0 0 0

Kresoxim-methyl 0 0 0 0 0 0 0 0 <0.1 Metazachlor 0 0 0 0 0 0 0 <0.1 <0.1

Pendimethalin <0.1 0.1 0.2 0.3 0.1 1.5 0.2 <0.1 0.4 Pirimicarb 0 0 0 0 0 0 0 <0.1 0.3

Tebuconazole <0.1 2.1 0 0 0 0 1.1 0.5 0

It section 6.2, the levels of individual pesticides were related to the AOEL, or the ADI where no AOEL has as yet been defined. Table 15 shows this approach being applied to the total quantity of pesticide detected for each data set.

The AOEL is defined as an internal value and is expressed in mg.kg-1.day-1 (EC, 2004). To compare the external exposure with the internal AOEL, the external data have to be turned into

45

7.4

internal levels. This requires an estimate of the dermal absorption and for this purpose a percentage dermal absorption has been applied. The AOEL, or ADI, values applied along with the appropriate dermal absorption estimates are listed in Table 6 and as before a 70 kg body weight is assumed.

DISCUSSION

It has been shown in the previous HSE report that there are high levels of pesticide residues remaining on the agricultural spraying equipment after it has been used. The potential for operator exposure due to splash back whilst cleaning this equipment therefore exists. There have, to date, been no studies quantifying the levels of exposure from the decontamination of spraying equipment. Despite this it has been assumed that exposure arising from this activity is negligible (FIOH, 1999).

Because a significant route for exposure to pesticides is the skin, surface deposition data were needed as well as personal air sampling. The results presented in this section are from measurements of the levels of exposure due to cleaning agricultural sprayers. Previous research into P.D.E. (e.g. Llewellyn, 1996; Garrod, 1998) shows the variability of this type of data to be greater than is anticipated. Given this variability, and the limited number of data sets, advanced statistical treatment was not deemed appropriate. The work reported here suggests the magnitudes and ranges of exposure than can be expected. It also attempts to place significance to health by comparing the data to established limits.

It has already been stated that although the data sets have been grouped together they do represent a variety of cleaning methods. It was decided to group them as they all represent the same task, i.e. that of cleaning agricultural sprayers. It may have been expected that this would have resulted in a wide range of results for the P.D.E. but as can be seen in Tables 8 and 9 this is not the case. The range for the P.D.E. over all nine data sets is only 41-802 μg with a median of 239. Here the spread of results is only over one order of magnitude, whereas for previous HSE studies (HSE, 1999) variation of three or more orders of magnitude is common. This suggests that although the number of data sets is relatively low the data is representative of the task of sprayer cleaning.

The purpose of this exposure study was to measure surface deposition and potential inhalation exposure of the operatives to splash-back during cleaning. It is recommended that the following indicative values should inform risk assessments for the cleaning of sprayers. The potential dermal exposure (P.D.E.) to pesticides (9 data) ranged between 41 and 802 μg.task-1, median 239 μg.task-1 and 95th percentile 740 μg.task-1. Actual dermal exposure (A.D.E.) to the hands (5 data), as collected on cotton gloves, ranged between 1 and 439 μg.task-1, median 29 μg.task-1

and 95th percentile 396 μg.task-1. A.D.E. to the feet (4 data), as collected on cotton socks, ranged between 3 and 123 μg per task, median 55 μg.task-1 and 95th percentile 114 μg.task-1. Exposure by inhalation to spray fluid was found in none of the samples. The median is used to indicate a typical exposure and the 95th percentile is used to give a “worst case” value.

The distribution of the pesticide over the body would be expected to vary according to the cleaning method employed. Figure 21a shows the use of a hose attached to a brush and little splash back can be seen. Contamination is mainly concentrated down the left arm and the lower half of the body. This can be explained by the fact that the brush is being held in the left hand and any splash back would therefore concentrate around the left arm, with the nitrile gloves protecting the wrists but not the arms. The water from the hose can be seen to be quite gentle and it is most likely that the contamination pattern is the result of “dirty” water flicking off the bristles and run off rather than splash back. Figure 21b shows the use of the jet spray, here there

46

is more likely to be splashing as a stronger stream of water is used. A more uniform distribution would be expected as a result. This is shown in Table 10 to some degree, but again there is a concentration on the arms and lower body. For data set 4 there is a high point of exposure on the right wrist, the photograph in Figure 21b is from this data set and shows the operator holding the hose in his right arm and not wearing any protective gloves.

Finally the pressure washers are represented in Figure 21c. It can be seen that the spray is blasted back into a cloud concentrating more around the legs but also hitting the front of the operator. This distribution pattern is confirmed by the data. So overall, the use of hoses and brushes results in exposure of the arms and lower body particularly on the one side (in this study, the left); jet sprays give a similar pattern and pressure washers are slightly more evenly distributed but tend to concentrate more on the lower half of the body. Table 11 shows this with well over a third of the pesticide being deposited on the left arm and left leg, three times what was measured on the right side.

There are also high levels of pesticides to be found on several of the hand and feet samplers. It can be seen that in some cases (Figure 21b) the operators do not wear nitrile gloves, but section 6 also shows that they can be exposed because they wear “old” nitrile gloves. This contamination may also be the result of touching the sprayer before putting on the nitrile gloves or by pulling on contaminated boots. The foot contamination is most likely to be from wearing contaminated footwear rather than as a direct result of the cleaning task. Whatever the cause of this exposure, what is being measured is A.D.E., which is directly onto the skin. It may not be a direct result of cleaning but is occurring at the same time and therefore needs to be included in the overall exposure.

Table 12 attempts to show any relationship between the levels on the sprayer and the resulting exposure of the operator. The percentage figures used give a quite varied result with an average of 3.9 and a standard deviation of 4.1 (RSD ± 105%). This might well have been expected, as although the variability between the OH data sets has been shown to be relatively low, there are still many variables to be considered regarding the transfer of pesticides from the sprayer. The distribution of residues on the sprayer, the power of the water, the type of sprayer etc. will all have effects on the exposure of the operator regardless of the “dirtiness” of the sprayer. What the data does indicate is that regardless of the residue levels on the sprayer there is always potential for the operator to be exposed to what is there.

Considering the transfer of individual pesticides during cleaning there again seems to be no obvious pattern. Table 13 shows no correlation between residue levels on the sprayer and residues on the operator. The ratio of the total detections to the operator detections averages 3.4 with a standard deviation of 2.9 (RSD ± 85%). Using the maximum residues from Table 14 does not improve the ‘relationship’, nor does considering the water solubility of the compounds. It is likely that the variables discussed previously are responsible for there being no correlation.

47

Figure 21 The various sprayer-cleaning methods employed in the field study a) Hose with brush

b) Hose on jet spray

c) Pressure washer

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To put the exposure levels into context the approach demonstrated in Section 6 was employed. This relates the exposure to the AOEL, or the ADI, to show if the amount of pesticide can be considered significant. Table 15 converts the total exposure, i.e. P.D.E. and A.D.E. into a percentage of the AOEL. It can be seen that, for most of the pesticides, it is unlikely that the residues will be of significance to health, with the majority of the residues contributing to approximately 1% or less of the AOEL; for epoxiconazole, isoproturon and pendimethalin this contribution was between 2 and 5%. However, flusilazole residues were equivalent to 27% of the AOEL for data set 7 and over 10% for several other data sets. This is a reflection of the fact that flusilazole has a low ADI rather than the residue levels being particularly high. When combined with other activities around the sprayer, such as the contact spraying, mixing, maintenance work, or indeed simply by wearing old nitrile gloves, the 27% contribution can be seen to be very significant.

The risk assessment conducted here highlights the complexity of determining the significance of this type of exposure because in a real situation the operator will not necessarily be aware of the pesticides involved. It would only take the presence of one pesticide with a high toxicity to turn what is assumed to be an innocuous activity into one with potential risks. This also needs to be considered in the context of the “cocktail effect”, where the total effect caused by the presence of several pesticides may be greater than the sum of their individual effects.

It should be noted that the values in Table 15 are based on the combined P.D.E. (suit) values and the A.D.E. (glove and sock) values, so to a large extent work clothes and PPE should reduce exposure to the pesticides. The level of PPE, and indeed work clothes, can vary greatly depending on the individual and on the weather so it cannot automatically be assumed that the pesticide will be prevented from contacting the skin.

In summary, the exposure levels from this task cannot simply be dismissed as negligible because of the variation in the quantities and toxicities of the pesticides. In addition to the exposure from splash back it can be seen that other sources such as contaminated PPE contribute to exposure. The distribution of the contamination in this study was largely down the left side and lower half of the person, but does reach all parts of the body to some extent. This makes the wearing of PPE important, although this should be new or cleaned PPE. The potential exposure of an operator to pesticides whilst cleaning a sprayer is not major, nor is it insignificant. However, a more accurate assessment would be required to confirm this theory.

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8 CONCLUSIONS

Communication with industry, environmental bodies, farmers etc have raised the profile of external residues on sprayers.

Cleaning the external surfaces of sprayers is now recognised to be a normal part of the spraying operation and it is being encouraged through the Voluntary Initiative.

The removal of pesticides from sprayer surfaces is compound-dependent highlighting the need to investigate the behaviour of several compounds in order to formulate reasonable, generic conclusions.

A brush and a pencil jet on a pressure washer were comparable cleaning methods. The standard pressure washer could perform as well given a longer washing duration. A cleaning agent significantly enhanced the removal of residues.

Pesticides were more difficult to remove once they had dried onto the sprayer surface and, in ambient temperatures for the UK, this drying could occur within one hour.

A basic risk assessment indicated that up to 65% of residues could need to be removed from the most contaminated part of sprayers to reduce the quantities to ‘acceptable’ levels. Current cleaning practices may not always achieve this, thus it may be advisable to encourage better cleaning of these areas and/or to raise awareness of these findings so the operator can take suitable precautions when in contact with the sprayer.

The transfer efficiency of residues from sprayer surfaces was compound-dependent ranging from c. 30% to 80%. The data generated in this study could be used to support the development of exposure scenarios in risk assessments.

Residues on the internal surfaces of the farmers’ nitrile gloves were not uncommon and they have the potential to be a significant route of exposure, but a larger scale study would be required to substantiate these initial findings.

It is recommended that the following indicative values should inform risk assessments for the cleaning of sprayers. The potential dermal exposure (P.D.E.) to pesticides (9 data) ranged between 41 and 802 μg.task-1, median 239 μg.task-1 and 95th percentile 740 μg.task-1. Actual dermal exposure (A.D.E.) to the hands (5 data), as collected on cotton gloves, ranged between 1 and 439 μg.task-1, median 29 μg.task-1 and 95th percentile 396 μg.task-1. A.D.E. to the feet (4 data), as collected on cotton socks, ranged between 3 and 123 μg per task, median 55 μg.task-1

and 95th percentile 114 μg.task-1. Exposure by inhalation to spray fluid was found in none of the samples.

The potential exposure of an operator to pesticides cannot be dismissed as insignificant during the decontamination of sprayers. However, a more accurate assessment would be required to examine the extent of the concern.

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9 APPENDICES

APPENDIX 1 – SPRAYER CLEANING – BEST PRACTICE GUIDE

51

Copyright © 2004 of the Crop Protection Association

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APPENDIX 2 – TESTING THE APPLICATION METHOD

To calculate the mass balance of each test surface it was necessary that the pesticide quantity applied to each individual surface was as accurate as possible. The cylindrical shape of the test surfaces negated the possibility of spraying all the surfaces at once using a suitably long boom. Consequently, a small sprayer was used in which there was sufficient solution to spray a single surface, where the entire contents could be accurately applied to the surface. A margin of error could be associated with measuring out the required solution individually, but this was minimised by using an auto-pipette. Each pesticide product was made up in a single batch, from which aliquots were taken, thus the same quantity of active should be applied to each surface. Potentially, the distribution of the spray within each test surface could vary as each surface was sprayed individually. However, the distribution was not vitally important as the entire surface was sampled; an even distribution would be more important if ‘representative’ sub-samples were taken. Nevertheless, attempts were made to keep the application as even as possible to reduce the number of variants between replicates.

Two methods were considered for applying the compounds to the surface – using a modified, household spray gun or using an airbrush. Experimenting with water indicated that the spray gun gave a coarser droplet than the airbrush thus potential losses due to drift should be reduced. However, the airbrush gave a more even coverage and a finer spray reducing the potential for the solution to drip down the side of the treated surface. Both methods were tested, as described below, to identify the most appropriate method to employ.

Herbicide products were weighed out separately (2.5 mg) using the %w/w1 as a guide, and a solution made to 10 mg ml-1. For the spray gun method, an aliquot (0.5 ml) of each solution was added to a 30 ml Universal container to which the head of the spray gun was fitted. For the airbrush aliquots (0.5 ml) of product were also taken, but, due to the size of the reservoir (1.8 ml), the products were applied in two batches: Amistar, Folicur, Bavistin and Lyric, Trump, Permasect. For each application method, five tanks were sprayed. These tanks were swabbed after all tanks had been sprayed giving a drying time of approximately one hour. In the first instance, three swabs were used to wipe the entire tank and these three swabs formed a single composite sample. This procedure was repeated a further two times giving a total of 3 sequential composite samples. This was done in order to assess the effectiveness of the swabbing technique.

The results indicated that there was no significant difference in the mean pesticide quantity detected when considering application by spray gun or air brush, however there was less variation between replicates when the air brush was used (sampling 1 hour after application mean CV = 9% c.f. 21% for the spray gun). There was an apparent difference in mass detected depending on the active ingredient with pendimethalin levels being approximately 20% less than the highest levels (cypermethrin). If losses were due to drift during application it could be expected that the losses would be similar, particularly for pendimethalin and isoproturon as these compounds were contained in the same quantity in a single product. The disparity in levels detected of isoproturon and pendimethalin (approximately 5%) indicate that the physico­chemical property of the active ingredient could influence the observed findings. In addition, the results indicated that there was loss of the active ingredient if samples were not taken until 24 hours after treatment. Pendimethalin showed the greatest loss of c. 60% with isoproturon and carbendazim the least (c. 10%). It is possible that the losses were due to several factors depending on the compound. Pendimethalin has a high vapour pressure (4 Pa) and Koc (13400) and may therefore be lost to the atmosphere and/or retained within the matrix of the test surface.

1 %w/w is the ratio of active ingredient to product in terms of weight 53

Cypermethrin also has a high Koc (61000) and partitioning to the polyethylene may account for losses of this compound, particularly as it is known that organic compounds with a high Koc will measurably partition to plastic (Ramwell, unpublished data).

Figure 22 Pesticide quantities on treated surfaces when swabbed 1 and 24 hours after application

0

200

400

600

800

1000

le

1h 24h

µg p

er s

amp

Pen

dfim

etha

lin

Flus

ilazo

le

Tebu

cona

zole

Cyp

erm

ethr

in

Azo

xyst

robi

n

Car

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azim

Isop

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ron

When considering sequential swabs, 82% of the total pesticide recovered was removed in the first swab and a further 13% in the second swab. A third and fourth swab removed 3% and 2% respectively.

APPENDIX 3 - SOLVENT EFFECTIVENESS

The fact that methanol may not have removed all the pesticide from the surface of the tank was also considered and a test was done to assess the effectiveness of two further solvents; ethyl acetate and cyclohexane. Six previously swabbed tanks were nominally divided into thirds and re-swabbed using 5 ml each of methanol, cyclohexane and ethyl acetate. The position (top, middle or bottom) of the area swabbed with each solvent was alternated between the tanks.

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24

20

16

12

8

4

0 Pendimethalin Tebuconazole Azoxystrobin Isoproturon

Flusilazole Cypermethrin Carbendazim

µg p

er s

ampl

e

Methanol Ethyl acetate

Cyclohexane

Ethyl acetate removed significantly more residues than methanol for 5 of the 7 compounds; however, this solvent also removed paint! Ethyl acetate is therefore not suitable for removing residues from sprayers. On the whole, cyclohexane was not an improvement on methanol as a solvent. Both ethyl acetate and cyclohexane also reacted with the rubber in the syringes, thus these solvents may also be unsuitable for use on sprayers on the grounds of the presence of rubber piping. Overall, methanol was the most suitable solvent.

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APPENDIX 4 – FULL RESULTS SET

Site: 1 Notes: All results given in μg.sample-1 (water results in mg.l-1) Date: 16/02/2004 Results corrected for recovery Work Sheet: 04-0144 ND = not detected

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

00585/04 SWAB 63 ND 83 5 50 12 34 400 ND ND ND ND 15 00586/04 SWAB 26 ND ND ND 64 90 328 4,494 ND ND 17 4 5,782 00587/04 SWAB 6 ND ND ND ND 2 8 ND ND ND ND 0.8 8 00588/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00589/04 SWAB 16 43 ND 5 44 5 37 374 ND ND ND ND 12 00590/04 SWAB 12 ND ND ND ND ND 29 ND ND ND ND ND ND 00591/04 SWAB ND ND ND ND ND ND 3 ND ND ND ND ND ND 00592/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00593/04 SWAB 12 ND ND ND 53 3 23 ND ND ND ND ND 5 00594/04 SWAB ND ND ND ND ND ND 5 ND ND ND ND ND ND 00595/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00596/04 SWAB ND ND ND ND 50 ND ND ND ND ND 6 ND ND 00612/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00606/04 R. GLOVE ND ND ND ND ND ND ND ND ND ND ND ND ND 00607/04 L. GLOVE ND ND ND ND ND ND ND ND ND ND ND ND ND 00608/04 R. SOCK ND ND ND ND ND ND ND ND ND ND ND ND ND 00609/04 L. SOCK ND ND ND ND ND ND ND ND ND ND ND ND ND 00610/04 HAT ND ND ND ND ND ND ND ND ND ND ND ND ND 00611/04 HOOD ND ND ND ND ND ND 1.8 ND ND ND ND ND ND 00611/04 L. WRIST 0.4 ND ND ND ND 0.2 1 ND ND ND 1.6 ND 0.5 00611/04 R. WRIST 0.3 ND ND ND ND ND 0.7 ND ND ND 0.8 ND ND 00611/04 L. ARM ND ND ND ND ND ND 6.5 ND ND ND 1.2 ND 0.6 00611/04 R. ARM ND ND ND ND ND ND 1.4 ND ND ND ND ND ND 00611/04 L. ANKLE ND ND ND ND ND ND 0.9 ND ND ND ND ND ND 00611/04 R. ANKLE ND ND ND ND ND ND 0.9 ND ND ND ND ND ND 00611/04 L. LEG 1.8 ND ND ND ND 0.6 1.6 ND ND ND 1.9 ND 1.1 00611/04 R. LEG 1.4 ND ND ND ND 1.1 2.9 ND ND ND ND ND 0.6 00611/04 U. FRONT ND ND ND ND ND 1.3 1 ND ND ND 1.4 ND ND 00611/04 U. BACK ND ND ND ND ND ND 3.5 ND ND ND 0.6 ND ND 00611/04 L. FRONT 1.2 ND ND ND ND 4.9 1.4 ND ND ND ND ND ND 00611/04 L. BACK ND ND ND ND ND 1.7 2.9 ND ND ND 4.1 ND 1.5 05005/04 SUIT BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 05006/04 TENAX 2T ND ND ND ND ND ND ND ND ND ND ND ND ND 05007/04 TENAX BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 05008/04 GFA 2T ND ND ND ND ND ND ND ND ND ND ND ND ND 05009/04 GFA BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 00597/04 HAT BLK ND ND ND ND ND ND 5.9 ND ND ND ND ND ND 00598/04 R. GLOVE ND ND ND ND ND ND 0.3 ND ND ND ND ND ND 00599/04 L. GLOVE ND ND ND ND ND ND ND ND ND ND ND ND ND 00600/04 R. SOCK ND ND ND ND ND ND 5.3 ND ND ND ND ND ND 00601/04 L. SOCK ND ND ND ND ND ND ND ND ND ND ND ND ND 00602/04 HAT ND ND ND ND ND ND ND ND ND ND ND ND ND 00603/04 GLOVE BLK ND ND ND ND ND ND ND ND ND ND ND ND ND

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00604/04 HOOD ND ND ND ND ND ND 8.6 ND ND ND ND ND ND 00604/04 L. WRIST ND ND ND ND ND ND 3.7 12 ND ND ND ND 18 00604/04 R. WRIST ND ND ND ND ND ND ND ND ND ND ND ND ND 00604/04 L. ARM ND ND ND ND ND ND 11 172 ND ND ND ND 35 00604/04 R. ARM ND ND ND ND ND ND 5.7 49 ND ND 10 ND 34 00604/04 L. ANKLE ND ND ND ND ND ND 6.4 13 ND ND ND ND 28 00604/04 R. ANKLE ND ND ND ND ND ND 6.1 7.2 ND ND ND ND 26 00604/04 L. LEG ND ND ND ND ND ND 8.8 77 ND ND ND ND 39 00604/04 R. LEG ND ND ND ND ND ND 6.9 ND ND ND ND ND 35 00604/04 U. FRONT ND ND ND ND ND ND 9.4 ND ND ND ND ND 34 00604/04 U. BACK ND ND ND ND ND ND ND ND ND ND ND ND ND 00604/04 L. FRONT ND ND ND ND ND ND 8 96 ND ND ND ND 36 00604/04 L. BACK ND ND ND ND ND ND 5.7 ND ND ND ND ND ND 00605/04 L. NITRILE ND ND ND ND ND 1.4 9.8 ND ND ND 13 ND 65 00605/04 R. NITRILE ND ND ND ND ND 1.8 9.6 ND ND ND 15 ND 85 00604/04 TENAX ND ND ND ND ND ND ND ND ND ND ND ND ND 05010/04 GFA ND ND ND ND ND ND ND ND ND ND ND ND ND

Site: 2 Date: 18/02/2004 Work Sheet: 04-0148

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

06022/04 HOOD ND 16 ND ND ND ND 10 ND ND ND ND ND ND 06022/04 L. WRIST ND 13 ND ND ND ND 3 ND ND ND ND ND ND 06022/04 R. WRIST ND ND ND ND ND ND 4 ND ND ND ND ND ND 06022/04 L. ARM ND ND ND ND ND ND 14 ND ND ND 22 ND ND 06022/04 R. ARM ND ND ND ND ND ND 6 ND ND ND ND ND ND 06022/04 L. ANKLE ND ND ND ND ND ND 5 ND ND ND ND ND ND 06022/04 R. ANKLE ND ND ND ND ND ND 6 ND ND ND ND ND ND 06022/04 L. LEG ND ND ND ND ND ND 6 ND ND ND ND ND ND 06022/04 R. LEG ND ND ND ND ND ND 8 ND ND ND ND ND ND 06022/04 U. FRONT ND ND ND ND ND ND 7 ND ND ND 18 ND ND 06022/04 U. BACK ND ND ND ND ND ND 8 ND ND ND ND ND ND 06022/04 L. FRONT ND ND ND ND ND ND 7 ND ND ND ND ND ND 06022/04 L. BACK ND ND ND ND ND ND 7 ND ND ND 19 ND ND 06023/04 L. GLOVE ND ND ND ND ND ND ND ND ND ND ND ND ND 06024/04 R. GLOVE ND ND ND ND ND ND ND ND ND ND ND ND ND 06025/04 L. SOCK ND ND ND ND ND ND ND ND ND ND ND ND ND 06026/04 R. SOCK ND ND ND ND ND ND ND ND ND ND ND ND ND 06027/04 HAT ND ND ND ND ND ND ND ND ND ND ND ND ND 06028/04 HOOD ND ND ND ND ND ND 7 ND ND ND ND ND ND 06028/04 L. WRIST ND ND ND ND ND ND 7 ND ND ND ND ND ND 06028/04 R. WRIST ND ND ND ND ND ND 5 ND ND ND 15 ND ND 06028/04 L. ARM ND ND ND ND ND ND 11 ND ND ND ND ND ND 06028/04 R. ARM ND ND ND ND ND ND 7 ND ND ND ND ND ND 06028/04 L. ANKLE ND ND ND ND ND ND 6 ND ND ND 86 ND ND 06028/04 R. ANKLE ND ND ND ND ND ND 5 ND ND ND ND ND ND 06028/04 L. LEG ND ND ND ND ND ND 7 ND ND ND ND ND ND 06028/04 R. LEG ND ND ND ND ND ND 9 ND ND ND ND ND ND 06028/04 U. FRONT ND ND ND ND ND ND 6 ND ND ND ND ND ND

57

06028/04 U. BACK ND ND ND ND ND ND 6 ND ND ND ND ND ND 06028/04 L. FRONT ND ND ND ND ND ND 9 ND ND ND ND ND ND 06028/04 L. BACK ND ND ND ND ND ND 7 ND ND ND ND ND ND 06029/04 L. GLOVE ND ND ND ND ND 1 1 ND ND ND ND ND ND 06030/04 R. GLOVE ND ND ND ND ND ND ND ND ND ND ND ND ND 06031/04 L. SOCK ND ND ND ND ND ND ND ND ND ND ND ND ND 06032/04 R. SOCK ND ND ND ND ND ND ND ND ND ND ND ND ND 06033/04 HAT ND ND ND ND ND ND ND ND ND ND ND ND ND 06034/04 GLOVE BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06035/04 SOCK BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06036/04 GFA ND ND ND ND ND ND ND ND ND ND ND ND ND 06037/04 TENAX ND ND ND ND ND ND ND ND ND ND ND ND ND 06038/04 GFA ND ND ND ND ND ND ND ND ND ND ND ND ND 06039/04 TENAX ND ND ND ND ND ND ND ND ND ND ND ND ND 06040/04 GFA BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06041/04 TENAX BLK ND ND ND ND ND ND ND ND ND ND ND ND ND

Site: 2 Date: 18/02/2004 Work Sheet: 04-0155

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

00613/04 SWAB ND 453 ND 1016 303 114 669 8637 21 102 ND ND 80 00614/04 SWAB ND ND 1421 1739 889 396 3271 ND 50 105 35 ND 336 00615/04 SWAB ND ND ND ND ND ND 11 ND ND ND ND ND ND 00616/04 SWAB ND ND ND 26 44 8 68 ND ND ND ND ND ND 00617/04 SWAB ND 565 ND 1138 306 86 777 5284 18 43 3 ND 47 00618/04 SWAB ND 1356 1234 1424 311 208 1697 9010 25 34 2 ND 72 00619/04 SWAB ND ND ND ND ND ND 7 ND ND ND ND ND ND 00620/04 SWAB ND ND ND ND 105 7 32 ND ND ND ND ND ND 00621/04 SWAB ND 783 ND 1150 254 106 597 #### 22 36 ND ND 45 00622/04 SWAB ND 1160 5165 1292 393 221 2165 5601 36 105 4 ND 250 00623/04 SWAB ND ND ND ND ND ND 6 ND ND ND ND ND ND 00624/04 SWAB ND ND ND ND ND 3 25 ND ND ND ND ND ND 00625/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND

00626/04 R RT. NITRILE 13 ND ND 22 209 95 61 284 59 30 88 ND 44 00626/04 L LT. NITRILE 11 ND ND 18 176 59 55 334 37 23 75 ND 24

Site: 3 Date: 02/03/2004 Work Sheet: 04-0164

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

00230/04 SWAB 198 294 581 ND 113 45 4 ND 22 ND 46 8 710 00231/04 SWAB 525 132 1550 ND 478 262 47 ND 45 13 48 ND 1940 00232/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND 11 00233/04 SWAB 20 24 867 ND 180 25 17 ND 2 ND 8 ND 421 00234/04 SWAB 1126 80 2494 ND 490 71 15 ND 30 ND 250 27 2371 00235/04 SWAB 729 300 4052 ND 719 256 230 ND 46 33 478 15 3529 00236/04 SWAB 31 ND 590 ND 113 7 7 ND ND ND 7 ND 118 00237/04 SWAB 5 ND 209 ND 23 3 12 ND ND ND ND ND 15

58

00238/04 SWAB 577 68 580 ND 378 77 27 ND 20 ND 143 43 1760 00239/04 SWAB 610 75 2324 ND 909 254 37 ND 33 22 325 6 2504 00240/04 SWAB 62 ND 182 ND 138 12 8 ND 3 ND 7 ND 222 00241/04 SWAB ND ND ND ND ND 3 6 ND ND ND ND ND 12 00242/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND

00243/04 R RT NITRILE ND ND ND ND ND ND ND ND ND ND ND ND ND 00243/04 L LT NITRILE ND ND ND ND ND ND ND ND ND ND ND ND ND

Site: 3 Date: 02/03/2004 Work Sheet: 04-0165

Sample No.

06043/04 06044/04 06045/04 06046/04 06047/04 06048/04 06048/04 06048/04 06048/04 06048/04 06048/04 06048/04 06048/04 06048/04 06048/04 06048/04 06048/04 06048/04 06049/04 06050/04 06051/04 06052/04 06053/04 06054/04

Sample

L. GLOVE R. GLOVE

HAT L. SOCK R. SOCK HOOD

L. WRIST R. WRIST

L. ARM R. ARM

L. ANKLE R. ANKLE

L. LEG R. LEG

U. FRONT U. BACK L. FRONT L. BACK

GLOVE BLK SOCK BLK

GFA TENAX

GFA BLK TENAX BLK

Azox

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Carb

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Chlo

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Cyan

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Cype

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Epox

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Flus

ND ND ND ND ND ND ND ND ND ND 1 1

ND ND ND ND ND ND ND ND ND ND ND ND

Isop

ND ND

1084 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Kres

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Meta

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Pend Piri Tebu

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 4 ND ND

ND ND ND ND ND ND 13 ND ND 22 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Site: Date: Work Sheet:

HSL, Buxton 04/03/2004 04-0214

Sample No. Sample Carb Chlo Epox Flus Isop Kres Meta Pend Piri Tebu

00207/04 SWAB 2340 4771 ND ND 529 ND 3286 3353 ND ND 2479 ND 3226 00208/04 WATER 7.9 8 ND ND ND ND 3.5 9.5 ND ND 0.1 ND 5.3 00209/04 SWAB 1244 4853 ND ND 518 ND 2300 2518 ND ND 1747 ND 1675 00210/04 WATER 7.1 7.9 ND ND ND ND 2.7 9.7 ND ND 0.1 ND 4.4 00211/04 SWAB 1073 3109 ND ND 442 ND 2527 1898 ND ND 1643 ND 1934 00212/04 WATER 5.4 7.2 ND ND ND ND 2.6 9.8 ND ND 0.1 ND 4 00213/04 SWAB 1016 2243 ND ND 395 ND 2225 1270 ND ND 1513 ND 1472 00214/04 WATER 3.5 4.1 ND ND ND ND 1.8 5.8 ND ND 0.1 ND 2.5

Azox Cyan Cype

59

00215/04 SWAB 997 2350 ND ND 419 ND 1960 1431 ND ND 1162 ND 1425 00216/04 SWAB 2226 4594 ND ND 598 ND 3695 3022 ND ND 2480 ND 3567 00217/04 WATER 4.9 7.1 ND ND ND ND 2.7 8.4 ND ND 0.1 ND 3.8 00218/04 SWAB 993 1782 ND ND 433 ND 2390 1002 ND ND 1541 ND 1764 00219/04 WATER 3.8 7 ND ND ND ND 2.1 7.2 ND ND 0.1 ND 3.2 00220/04 SWAB 1120 1592 ND ND 434 ND 2363 1093 ND ND 1424 ND 1759 00221/04 WATER 2.3 3.3 ND ND ND ND 1.3 3.8 ND ND ND ND 2.1 00222/04 SWAB 897 1553 ND ND 352 ND 1607 604 ND ND 1292 ND 793 00223/04 WATER 2.6 4.1 ND ND ND ND 1.5 5.1 ND ND ND ND 2.6 00224/04 SWAB 976 2798 ND ND 471 ND 2274 1339 ND ND 1517 ND 1201 00225/04 WATER 4.2 3.3 ND ND 2.1 ND 3.9 8.4 ND ND 0.1 ND 4.8 00226/04 SWAB 743 1935 ND ND 424 ND 1717 516 ND ND 1241 ND 1146 00227/04 SWAB 1836 4594 ND ND 362 ND 2921 2310 ND ND 2082 ND 2775 00228/04 SWAB 1376 2963 ND ND 40 ND 1615 1953 ND ND 1681 ND 1555 00229/04 SWAB 1287 4272 ND ND ND ND 1558 2695 ND ND 1612 ND 1500

Site: 4 Date: 21/04/2004 Work Sheet: 04-0523

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

00627/04 SWAB ND 1766 ND ND ND 154 ND ND ND ND 423 ND ND 00628/04 SWAB ND 1466 ND ND ND 276 ND ND ND ND 503 ND ND 00629/04 SWAB ND ND ND ND ND 18 ND ND ND ND 17 ND ND 00630/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00631/04 SWAB ND 251 ND ND ND 41 ND ND ND ND 165 ND ND 00632/04 SWAB ND ND ND ND ND 339 ND ND ND ND 354 ND ND 00633/04 SWAB ND ND ND ND ND 6 ND ND ND ND 23 ND ND 00634/04 SWAB ND 105 ND ND ND ND ND ND ND ND ND ND ND 00635/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND

00636/04 L LT NITRILE ND 180 ND ND ND ND ND ND ND ND 16 ND ND 00636/04 R RT NITRILE ND 97 ND ND ND ND ND ND ND ND 37 ND ND 00637/04 L LT NITRILE 236 69 ND ND ND 88 8 ND 2 30 775 ND 174 00637/04 R RT NITRILE 284 ND ND ND ND 125 12 ND 4 50 944 ND 270

Site: HSL, Buxton Date: 18/05/2004 Work Sheet: 04-0524

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

00638/04 SWAB 2528 3536 ND ND ND ND 2302 1368 12 72 1586 ND 2523 00639/04 WATER 1 ND ND ND ND ND 1.7 ND ND ND ND ND 4.9 00640/04 SWAB 1872 3714 ND ND ND ND 1044 726 5 39 904 ND 685 00641/04 WATER 0.8 ND ND ND ND ND 1.7 ND ND ND ND ND 4.6 00642/04 SWAB 1797 3797 ND ND ND ND 1478 1037 9 53 1190 ND 1083 00643/04 WATER 0.6 ND ND ND ND ND 1.3 ND ND ND ND ND 3.7 00644/04 SWAB 1604 3701 ND ND ND ND 1276 987 6 50 1124 ND 907 00645/04 WATER ND ND ND ND ND ND 1.1 ND ND ND ND ND 2.6 00646/04 SWAB 1315 4082 ND ND ND ND 966 831 4 35 793 ND 541 00647/04 SWAB 2060 4493 ND ND ND ND 2019 1510 10 57 1272 ND 2380 00648/04 WATER ND ND ND ND ND ND 1 ND ND ND ND ND 2.8

60

00649/04 SWAB 1649 3528 ND ND ND ND 1318 834 6 29 982 ND 884 00650/04 WATER ND ND ND ND ND ND 0.9 ND ND ND ND ND 2.6 00651/04 SWAB 1237 3246 ND ND ND ND 1193 878 5 28 936 ND 653 00652/04 WATER ND 21 ND ND ND ND 1.8 ND ND ND 1.3 ND 5.5 00653/04 SWAB 1561 2715 ND ND ND ND 336 284 ND ND 521 ND 253 00654/04 WATER 1.2 ND ND ND ND ND 2.5 ND ND ND 1.7 ND 7 00655/04 SWAB 1661 2415 ND ND ND ND 324 332 ND ND 434 ND 199 00656/04 WATER 2.2 ND ND ND ND ND 3.9 0.5 ND ND 2 ND 9.2 00657/04 SWAB 1882 3228 ND ND ND ND 518 354 ND ND 481 ND 307 00658/04 WATER 1.5 ND ND ND ND ND 2.3 ND ND ND 1.3 ND 6 00659/04 SWAB 1804 2097 ND ND ND ND 384 274 ND ND 455 ND 275 00660/04 WATER 3.3 ND ND ND ND ND 4.1 0.1 ND ND 1.3 ND 6.8 00661/04 SWAB 1468 2400 ND ND ND ND 590 242 ND ND 500 ND 361 00662/04 WATER 2.3 ND ND ND ND ND 3.9 0.8 ND ND 1.1 ND 7.2 00663/04 SWAB 1210 2095 ND ND ND ND 972 271 4 21 704 ND 609 00664/04 SWAB 2865 3356 ND ND ND ND 2213 1426 11 47 1456 ND 2579 00665/04 SWAB 5665 9579 ND ND ND ND 4019 3535 26 199 4689 ND 4656 00666/04 SWAB 5614 9353 ND ND ND ND 4148 3715 27 210 4850 ND 5016 00667/04 WATER ND ND ND ND ND ND ND ND ND ND ND ND ND 00668/04 WATER ND ND ND ND ND ND ND ND ND ND ND ND ND 00669/04 WATER ND ND ND ND ND ND ND ND ND ND ND ND ND 00670/04 WATER ND ND ND ND ND ND ND ND ND ND ND ND ND

Site: 4 Date: 21/04/2004 Work Sheet: 04-0525

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

06097/04 L. GLOVE ND ND ND ND ND ND ND ND ND ND 74 ND ND 06098/04 R. GLOVE ND ND ND ND ND ND ND ND ND ND 147 ND ND 06099/04 HAT ND ND ND ND ND 12 ND ND ND ND 74 ND ND 06100/04 L. SOCK ND ND ND ND ND ND ND ND ND ND 60 ND ND 06101/04 R. SOCK ND ND ND ND ND ND ND ND ND ND 63 ND ND 06102/04 HOOD 0.4 ND ND ND ND ND ND ND ND ND 1 ND ND 06102/04 L. WRIST ND ND ND ND 8.1 2.7 ND ND ND ND 2.3 ND ND 06102/04 R. WRIST 0.2 ND ND ND 9 2.3 ND ND ND ND 2.7 ND ND 06102/04 L. ARM ND ND ND ND ND 6.7 ND ND ND ND 5.4 ND ND 06102/04 R. ARM ND ND ND ND ND 3.2 ND ND ND ND 4.5 ND ND 06102/04 L. ANKLE 1.2 ND ND ND 26 7.1 0.2 ND ND ND 10 ND ND 06102/04 R. ANKLE 1.2 ND ND ND 19 5 ND ND ND ND 8 ND ND 06102/04 L. LEG 0.8 ND ND ND 31 5.8 ND ND ND ND 6.4 ND ND 06102/04 R. LEG 0.4 ND ND ND ND 2.8 ND ND ND ND 3.9 ND ND 06102/04 U. FRONT 1.2 ND ND ND 21.6 4.7 ND ND ND ND 6 ND ND 06102/04 U. BACK ND ND ND ND ND 2.8 ND ND ND ND 7.6 ND ND 06102/04 L. FRONT ND ND ND ND 21.8 2.6 ND ND ND ND 3.8 ND ND 06102/04 L. BACK ND ND ND ND ND 1.5 ND ND ND ND 2.5 ND ND 06103/04 GLOVE BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06104/04 SOCK BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06105/04 GFA ND ND ND ND ND ND ND ND ND ND ND ND ND 06106/04 TENAX ND ND ND ND ND ND ND ND ND ND ND ND ND 06107/04 GFA BLK ND ND ND ND ND ND ND ND ND ND ND ND ND

61

06108/04 ND ND ND ND ND ND ND ND ND ND ND ND NDTENAX BLK

Site: HSL, Buxton Date: 03/07/2004 Work Sheet: 04-0532

Sample No. Sample Carb Chlo Epox Flus Isop Kres Meta Pend Piri Tebu

00284/04 SWAB 403 1571 ND ND ND 34 712 478 2.6 27 652 ND 604 00285/04 SWAB 35 ND ND ND ND ND 55 15 ND ND 36 ND 38 00286/04 WATER ND 0.5 ND ND ND ND 0.7 0.1 ND ND 0.4 ND 0.5 00287/04 WATER 2.9 2.9 ND ND ND ND 0.7 1.2 ND ND ND ND 1.6 00288/04 SWAB 537 2757 ND ND ND ND 918 775 4.3 34 766 ND 1082 00289/04 SWAB ND ND ND ND ND ND 27 11 ND ND 16 ND 13 00290/04 WATER ND 0.3 ND ND ND ND 0.7 0.3 ND ND 0.4 ND 0.3 00291/04 SWAB 357 2049 ND ND ND ND 632 526 2.6 24 567 ND 527 00292/04 SWAB ND ND ND ND ND ND 26 4.8 ND ND 14 ND 15 00293/04 WATER ND ND ND ND ND ND 0.4 0.1 ND ND 0.2 ND 0.3 00294/04 WATER 2.4 2.9 ND ND ND ND 1 1.4 ND ND ND ND 2.2 00295/04 SWAB 455 2599 ND ND ND ND 790 747 2.8 28 643 ND 848 00296/04 SWAB ND 84 ND ND ND ND 24 4.8 ND ND 13 ND 13 00297/04 WATER ND ND ND ND ND ND 2.2 ND ND ND 3.4 ND 4.8 00298/04 SWAB 263 1543 ND ND ND ND 506 441 2.1 20 456 ND 418 00299/04 SWAB ND ND ND ND ND ND 31 7.3 ND ND 18 ND 21 00300/04 WATER ND ND ND ND ND ND 0.4 0.2 ND ND 0.5 ND 0.3 00301/04 WATER 2.2 3.2 ND ND ND ND 0.6 1.3 ND ND ND ND 1.4 00302/04 SWAB 400 3072 ND ND ND ND 751 819 2.8 25 570 ND 813 00303/04 SWAB ND 116 ND ND ND ND 31 16 ND ND 16 ND 15 00304/04 WATER ND ND ND ND ND ND 0.5 0.4 ND ND 0.3 ND 0.2 00305/04 SWAB 886 4947 ND ND ND ND 1455 1695 7.5 85 1810 ND 1833 00306/04 SWAB 951 5154 ND ND ND ND 1557 1797 8.4 103 2085 ND 1955 00307/04 SWAB ND ND ND ND ND ND 5.2 ND ND ND 3.3 ND 3.6 00308/04 SWAB 946 5351 ND ND ND ND 1538 1738 8.2 95 1950 ND 1740 00309/04 SWAB 884 5023 ND ND ND ND 1583 1715 8.8 100 2050 ND 2021

Azox Cyan Cype

Site: 1 Date: 27/07/2004 Work Sheet: 04-0556

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

00310/04 SWAB 694 ND 2563 ND ND 363 30 ND 59 ND ND ND 512 00311/04 SWAB 344 ND 296 ND ND 64 16 ND ND ND ND ND 261 00312/04 SWAB 76 ND ND ND ND 13 ND ND ND ND ND ND ND 00313/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00314/04 SWAB 250 ND 520 ND ND 98 15 ND 2 ND ND ND 134 00315/04 SWAB 321 ND 1064 ND ND 42 20 ND ND ND ND ND 580 00316/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00317/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00318/04 SWAB 751 ND 660 ND ND 169 22 ND 2 ND ND ND 752 00319/04 SWAB 83 ND ND ND ND 41 14 ND ND ND ND ND 236 00320/04 SWAB ND ND ND ND ND 30 ND ND ND ND ND ND ND 00321/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND

62

00322/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00323/04 L LT NITRILE ND ND ND ND ND ND ND ND ND ND ND ND ND 00323/04 R RT NITRILE ND ND ND ND ND ND ND ND ND ND ND ND ND

Site: 2 Date: 23/07/2004 Work Sheet: 04-0557

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

00671/04 SWAB ND 2361 955 ND ND 456 307 64 91 34 ND ND 1538 00672/04 SWAB ND 2527 1058 ND ND 1336 604 719 123 ND ND ND 2106 00673/04 SWAB ND ND 121 ND ND 16 19 ND ND ND ND ND 48 00674/04 SWAB ND ND ND ND ND 2 3 ND ND ND ND ND 9 00675/04 SWAB ND 3478 448 ND ND 251 144 24 46 25 ND ND 1238 00676/04 SWAB ND 2320 1639 ND ND 2050 611 678 235 15 ND ND 2374 00677/04 SWAB ND ND ND ND ND 9 6 ND ND ND ND ND 20 00678/04 SWAB ND ND ND ND ND 2 5 ND ND ND ND ND 10 00679/04 SWAB ND 1379 512 ND ND 195 83 15 41 12 ND ND 700 00680/04 SWAB ND 2081 843 ND ND 920 324 628 94 ND ND ND 1317 00381/04 SWAB ND ND ND ND ND ND 3 ND ND ND ND ND 7 00382/04 SWAB ND ND ND ND ND ND 2 ND ND ND ND ND ND 00683/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND

00684/04 L LT NITRILE ND ND 222 ND ND 132 60 ND 14 ND ND ND 37 00684/04 R RT NITRILE ND ND 156 ND ND 165 73 ND 19 ND ND ND 40

Site: 2 Date: 23/07/2004 Work Sheet: 04-0567

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

06182/04 HOOD ND ND ND ND ND ND ND ND ND ND ND ND ND 06182/04 L. WRIST ND ND ND ND ND ND ND ND ND ND ND ND ND 06182/04 R. WRIST ND ND ND ND ND ND ND ND ND ND ND ND ND 06182/04 L. ARM ND ND ND ND ND ND ND ND ND ND ND ND ND 06182/04 R. ARM ND ND ND ND ND ND ND ND ND ND ND ND ND 06182/04 L. ANKLE ND ND ND ND ND ND 2.1 ND ND ND 0.8 ND 71 06182/04 R. ANKLE ND ND ND ND ND 1.9 2.3 ND ND ND 0.5 ND 43 06182/04 L. LEG ND ND ND ND ND 5.8 2 ND ND ND ND ND 58 06182/04 R. LEG ND ND ND ND ND 3.4 ND ND ND ND ND ND 48 06182/04 U. FRONT ND ND ND ND ND ND ND ND ND ND ND ND ND 06182/04 U. BACK ND ND ND ND ND ND ND ND ND ND ND ND ND 06182/04 L. FRONT ND ND ND ND ND ND ND ND ND ND ND ND ND 06182/04 L. BACK ND ND ND ND ND ND ND ND ND ND ND ND ND 06183/04 L. GLOVE ND ND ND ND ND 165 108 ND ND ND 15 ND ND 06184/04 R. GLOVE ND ND ND ND ND 74 69 ND ND ND 7.7 ND ND 06185/04 L. SOCK ND ND ND ND ND 16 4.5 ND ND ND 20 ND ND 06186/04 R. SOCK ND ND ND ND ND ND ND ND ND ND 23 ND ND 06187/04 HAT ND ND ND ND ND ND ND ND ND ND ND ND ND 06188/04 GLOVE BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06189/04 SOCK BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06190/04 HAT BLK ND ND ND ND ND ND ND ND ND ND ND ND ND

63

06191/04 GFA ND ND ND ND ND ND ND ND ND ND ND ND ND 06192/04 TENAX ND ND ND ND ND ND ND ND ND ND ND ND ND 06193/04 GFA BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06194/04 TENAX BLK ND ND ND ND ND ND ND ND ND ND ND ND ND

Site: 1 Date: 27/07/2004 Work Sheet: 04-0568

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

06199/04 HAT ND ND ND ND ND ND ND ND ND ND 22 ND ND 06200/04 L. GLOVE ND ND ND ND ND ND ND ND ND ND ND ND ND 06201/04 R. GLOVE ND ND ND ND ND ND ND ND ND ND ND ND ND 06202/04 L. SOCK ND ND ND ND ND ND ND ND ND ND ND ND ND 06203/04 R. SOCK ND ND ND ND ND ND ND ND ND ND ND ND ND 06204/04 HOOD 1.6 ND ND ND ND ND ND ND ND ND ND ND ND 06204/04 L. WRIST 0.9 ND ND ND ND ND ND ND ND ND ND ND ND 06204/04 R. WRIST 0.5 ND ND ND ND ND ND ND ND ND ND ND ND 06204/04 L. ARM 10 ND ND ND ND 2.8 ND ND ND 3 ND ND 5.7 06204/04 R. ARM 4.6 ND ND ND ND ND ND ND ND ND ND ND 4.5 06204/04 L. ANKLE 28 ND ND ND ND 4.8 0.5 ND ND ND ND 0.3 19 06204/04 R. ANKLE 17 ND ND ND ND 4.4 0.5 ND ND ND ND ND 12 06204/04 L. LEG 25 ND ND ND ND 4.1 0.4 ND ND ND ND ND 17 06204/04 R. LEG 20 ND ND ND ND 5.6 0.8 ND ND ND ND ND 21 06204/04 U. FRONT 3.2 ND ND ND ND 0.9 ND ND ND ND ND ND 3.4 06204/04 U. BACK ND ND ND ND ND ND ND ND ND ND ND ND ND 06204/04 L. FRONT 16 ND ND ND ND 3.4 0.4 ND ND ND ND ND 11 06204/04 L. BACK 9.8 ND ND ND ND 2.2 ND ND ND ND ND ND 11 06205/04 GLOVE BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06206/04 SOCK BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06207/04 HAT BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06208/04 GFA ND ND ND ND ND ND ND ND ND ND ND ND ND 06209/04 TENAX ND ND ND ND ND ND ND ND ND ND ND ND ND 06210/04 GFA BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 06211/04 TENAX BLK ND ND ND ND ND ND ND ND ND ND ND ND ND

Site: 5 Date: 12/08/2004 Work Sheet: 04-0579

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

00324/04 SWAB 200 ND ND ND ND 264 235 ND 66 32 217 ND 429 00325/04 SWAB 93 783 ND ND ND 595 963 ND 290 288 347 ND 380 00326/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00327/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00328/04 SWAB 221 ND ND ND ND 261 289 ND 88 27 129 ND 306 00329/04 SWAB 117 143 ND ND ND 550 920 ND 153 175 122 ND 540 00330/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00331/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00332/04 SWAB 166 ND ND ND ND 137 268 ND 53 32 146 ND 310 00333/04 SWAB 156 ND ND ND ND 698 1009 ND 277 214 194 ND 509

64

00334/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00335/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND 00336/04 SWAB ND ND ND ND ND ND ND ND ND ND ND ND ND

00337/04 L LT NITRILE ND ND ND ND ND ND ND ND ND 17 14 ND ND 00337/04 R TR NITRILE ND ND ND ND ND ND ND ND 31 3485 133 ND ND

Site: 5 Date: 12/08/2004 Work Sheet: 04-0586

Sample No. Sample Azox Carb Chlo Cyan Cype Epox Flus Isop Kres Meta Pend Piri Tebu

05118/04 HAT ND ND ND ND ND ND 15 ND ND ND 74 ND ND 05119/04 R. GLOVE ND ND ND ND ND ND 4.5 ND ND ND ND ND ND 05120/04 L. GLOVE ND ND ND ND ND ND 12 ND ND ND ND 12 ND 05121/04 R. SOCK ND ND ND ND ND ND 9.6 ND ND ND ND 2.9 ND 05122/04 L. SOCK ND ND ND ND ND ND ND ND ND ND ND 32 ND 05123/04 GLOVE BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 05124/04 SOCK BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 05125/04 HAT BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 05126/04 TENAX ND ND ND ND ND ND ND ND ND ND ND ND ND 05127/04 TENAX BLK ND ND ND ND ND ND ND ND ND ND ND ND ND 05128/04 HOOD ND ND ND ND ND ND ND ND ND ND ND ND ND 05128/04 L. WRIST ND ND ND ND ND 1.1 0.9 ND ND ND 1 1.3 ND 05128/04 R. WRIST ND ND ND ND ND ND ND ND ND ND 0.4 ND ND 05128/04 L. ARM ND ND ND ND ND ND ND ND ND ND 0.5 2.5 ND 05128/04 R. ARM 5.6 ND ND ND ND ND 5.1 ND 16 4.7 15 6.7 ND 05128/04 L. ANKLE 1.4 ND ND ND ND 0.9 2.4 ND ND ND 2.7 2.6 ND 05128/04 R. ANKLE 1.5 191 ND ND ND ND 2.9 ND ND ND 3.9 2.4 ND 05128/04 L. LEG 1.6 144 ND ND ND ND 3.5 ND ND ND 5.9 2.9 ND 05128/04 R. LEG ND 85 ND ND ND ND ND ND ND ND ND ND ND 05128/04 U. FRONT ND 95 ND ND ND ND 0.8 ND ND ND 1.2 ND ND 05128/04 U. BACK 3.4 ND ND ND ND ND 3.3 ND ND ND 9.7 4.1 ND 05128/04 L. FRONT 1 ND ND ND ND ND 1.6 ND ND ND 4.7 1.7 ND 05128/04 L. BACK 1.2 ND ND ND ND ND 2.2 ND ND ND 2.9 ND ND

65

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Published by the Health and Safety Executive 04/10

Executive Health and Safety

Decontamination of agricultural sprayers

It is now recognised that pesticide residues on the external surfaces of sprayers could present a significant route of exposure for the spray operator and these residues exist despite sprayers being washed. The current study was undertaken to examine factors influencing the removal of residues from sprayer surfaces, to trial any developments on decontamination techniques on working farms, and to quantify operator exposure to pesticides during the actual washing process.

This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.

RR792

www.hse.gov.uk