HSEHealth & Safety

Executive

Exposure to pesticide residues onagricultural spraying equipment

Prepared byCranfield Centre for EcoChemistryfor the Health and Safety Executive

CONTRACT RESEARCH REPORT

440/2002

HSEHealth & Safety

Executive

Exposure to pesticide residues onagricultural spraying equipment

Carmel T Ramwell BSc PhD*,Paul D Johnson BSc PhD**,

Alistair A B Boxall BSc PhD* andDuncan Rimmer BSc PhD MRSC CChem**

*Cranfield Centre for EcoChemistry, Shardlow Hall,London Road, Shardlow, Derbyshire DE72 2GN

**Health and Safety Laboratory, Broad Lane,Sheffield S3 7HQ

Pesticide residues on agricultural sprayers were quantified in order to assess potential workerexposure during post-application use and/or during maintenance.

Thirteen farms were visited on two occasions, and swab samples were taken from the nozzles, boom,spray tank, door, windscreen, rear window and mudguards of the spray equipment. Cotton glovesamples were also taken representing possible exposure whilst gaining entry to, and working in thecab, general contact with the external surface of the sprayer, and maintenance.

Pesticides were detected on all sprayers, but the doses varied widely between both sprayers andcompounds (<LOD to >1 g m-2). Highest doses were observed on the boom, nozzles, and, to a lesserextent, the spray tank. When considering the tractor, pesticides were detected at higher doses and withhigher frequency on the mudguards compared to the rest of the tractor body.

Quantities of pesticides on the cotton glove samples were reported as an equivalent number ofacceptable daily intakes (ADIs). 17% of the cotton glove samples contained residues that equated tomore than one ADI. Sampling inside the farmers’ nitrile gloves detected pesticides in all cases with onepair containing the equivalent of 17 ADIs.

No comment within this report should be taken as an endorsement or criticism of any pesticidecompound or product.

This report and the work it describes were funded by the Health and Safety Executive. Its contents,including any opinions and/or conclusions expressed, are those of the authors alone and do notnecessarily reflect HSE policy.

HSE BOOKS

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© Crown copyright 2002Applications for reproduction should be made in writing to:Copyright Unit, Her Majesty’s Stationery Office,St Clements House, 2-16 Colegate, Norwich NR3 1BQ

First published 2002

ISBN 0 7176 2376 9

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

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CONTENTS CONTENTS....................................................................................................................................... iii

EXECUTIVE SUMMARY................................................................................................................. v

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

2 METHODOLOGY...................................................................................................................... 3

2.1 Survey of UK Farmers ............................................................................................................ 3

2.2 Field Study .............................................................................................................................. 3

2.3 Sampling variability ................................................................................................................ 4

2.4 Chemical Analysis................................................................................................................... 4

2.5 Data analysis ........................................................................................................................... 6

2.6 Data interpretation................................................................................................................... 6

3 RESULTS ................................................................................................................................... 7

3.1 Questionnaire Survey .............................................................................................................. 7

3.2 Field Survey ............................................................................................................................ 9

3.3 Sampling variability .............................................................................................................. 11

3.4 Pesticide residue distribution over the sprayer...................................................................... 12

3.5 Dose range per individual compound.................................................................................... 14

3.6 Farmers’ gloves..................................................................................................................... 17

3.7 Detection vs non-use ............................................................................................................. 17

3.8 Organophosphates ................................................................................................................. 18

3.9 Health significance of detected residues ............................................................................... 18

4 DISCUSSION ........................................................................................................................... 21

5 CONCLUSIONS....................................................................................................................... 27

6 RECOMMENDATIONS .......................................................................................................... 29

7 APPENDICES........................................................................................................................... 31

APPENDIX 1 Questionnaire ........................................................................................................ 32

APPENDIX 2 – Acceptable daily intakes......................................................................................... 39

APPENDIX 3 – General farm attributes ........................................................................................... 40

APPENDIX 4 – Distribution of sprayer types .................................................................................. 40

APPENDIX 5 – Use of the equipment in addition to spraying......................................................... 41

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APPENDIX 6 – Number of months spent spraying.......................................................................... 42

APPENDIX 7 - Weed control on railways........................................................................................ 43

8 REFERENCES.......................................................................................................................... 47

List of Tables Table 1 Number of positive detections per sampling site on individual sprayers.............................12 Table 2 Percent of positive detections per compound.......................................................................16 Table 3 Compounds detected in the absence of recorded usage over the previous two seasons ......18 Table 4 Summary of ADI225 exceedances per compound and sampling site ....................................25 List of Figures Figure 1 Approximate location (X) of farmers participating in field sampling events .................... 10 Figure 2 Variability of the composite samples per sampling site showing the mean & SE.............. 11 Figure 3 Range of pesticide dose per sampling site for all sprayers and all compounds ................. 13 Figure 4 Range of pesticide dose on the cotton gloves for all sprayers and all compounds ............ 13 Figure 5 Range of pesticide doses on the delivery system................................................................ 14 Figure 6 Range of pesticide doses on the tractor body..................................................................... 15 Figure 7 Range of pesticide doses on the cotton gloves................................................................... 16 Figure 8 Distribution of pesticide mass per compound detected inside the farmers’ gloves ........... 17 Figure 9 Number of ADIs present on each pair of gloves................................................................ 19 Figure 10 Contribution of compounds to ADI classes for all glove samples................................... 20 Figure 11 Total number of compounds exceeding the ADI at 13 farms summing swab samples. .. 24

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EXECUTIVE SUMMARY After application, pesticide residues may be present on the external surfaces of the spray equipment. Persons using the machine for other purposes, or maintaining it, could be exposed to these residues. However, the risk to workers cannot be assessed as it is not known if residues exist at potentially hazardous levels. The aim of this study was therefore to quantify ‘typical’ pesticide residues on agricultural sprayers and to assess potential worker exposure. Thirteen farms were visited on two occasions and swab samples were taken from the nozzles, boom, spray tank, door, windscreen, rear window and mudguards of the spray equipment. Cotton glove samples were also taken representing possible exposure whilst gaining entry to and working in the cab, general contact with the external surface of the sprayer, and maintenance. Supporting information was obtained on pesticide usage, and the gloves used to handle pesticide concentrates were collected to analyse residues contained on the insides. Samples were analysed for azoxystrobin, carbendazim, chlorothalonil, cyanazine, cypermethrin, epoxiconazole, flusilazole, isoproturon, kresoxim-methyl, metazachlor, pendimethalin, pirimicarb, and tebuconazole. Pesticide doses on the sprayers varied widely between both sprayers and compounds (<LOD to >1000 mg m-2). Highest doses were observed on the boom, nozzles, and, to a lesser extent, the spray tank. When considering the tractor, pesticides were detected at higher doses and with greater frequency on the mudguards compared to the rest of the tractor body. Isoproturon had the highest number of detections above 1000 mg m-2 on the delivery system and 10 mg m-2 on the tractor body. This compound was also the most commonly used pesticide by weight. There was a correlation between the quantity of active used and the pesticide dose on the delivery system but there was no significant factor influencing pesticide quantities on the tractor body. The quantities of pesticides on the cotton glove samples were reported as an equivalent number of acceptable daily intakes (ADIs). 17% of the cotton glove samples contained residues that equated to more than one ADI. Sampling inside the farmers’ nitrile gloves detected pesticides in all cases with one pair containing the equivalent of 17 ADIs. Isoproturon was the pesticide most likely to contribute to the exceedance of the ADI, followed by flusilazole. Few farmers had a regular cleaning regime, but once washed the sprayer was considered to be clean by the operator and pesticide residues were not perceived to be of concern. This study demonstrated that pesticide residues were commonly detected on the external surfaces of agricultural sprayers, despite being subject to some form of washing, and it is possible that these may be at levels that are of concern to human health. Further work in this area is required with regard to cleaning practices.

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1 INTRODUCTION In the course of applying pesticides a proportion of the compounds used may be deposited on the application equipment. It is therefore possible that persons working with the machinery, either during or after use (e.g. spray contractors, maintenance workers, farm workers) could be exposed to pesticide residues on the equipment. Information detailing residues on equipment is limited, hence it is not currently possible to assess the significance of these residues in terms of occupational exposure. Cranfield Centre for EcoChemistry, in co-operation with the Health and Safety Laboratory, was therefore commissioned by the Health and Safety Executive to address this shortfall by quantifying pesticide residues on pesticide application equipment. The objectives of the study were to: �� Characterise typical residues of commonly used pesticides on spray equipment; �� Determine the potential for post-application exposure to pesticides of farm workers and

maintenance personnel; and �� Identify areas for future study with respect to cleaning techniques, maintenance etc.

This report details methodologies used in collecting samples, and summarises the results of the questionnaire and the chemical analysis. During the course of the study, the opportunity arose to sample a vehicle used for weed control on railways. The methodology and results for the spray train are included as a separate item in Appendix 7. After the initial sampling event, HSE requested that the swabs were re-analysed for organophosphates (OPs). This work was supplementary to the original study protocol and the results are reported separately within the main body of the report

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2 METHODOLOGY The study was performed in 2 phases – a desk based survey and field sampling of spray equipment. Details of the approaches are given below.

2.1 Survey of UK Farmers

A questionnaire was sent to 250 farmers throughout Britain selected randomly from sources such as the Yellow Pages, and the World Wide Web. Questions were designed to establish what pesticides were used on which crops and when spraying occurred, the type of spray equipment used, the method and frequency of cleaning the equipment, personnel involved, and equipment use and maintenance within and outside the spraying season. Farmers were also asked whether or not they would be willing to participate in further research. The questionnaire is detailed in Appendix 1.

2.2 Field Study

Residue samples were obtained from spraying equipment by swabbing pre-identified areas on the tractor and sprayer. Methanol (5 ml) was applied to a pre-washed cotton swab that was used to wipe a 100 cm2 area, or a set number of nozzles. Areas wiped included the nozzles, spray boom, spray tank, door, windscreen, rear window and mudguards. An approximation of the area (� 5 cm2) of each site sampled was attained using a measuring stick marked every five centimetres. Three swabs from each area were taken at random to provide a composite sample. Cotton glove samples were also taken to assess the potential of exposure of workers to the residues. The cotton glove samples represented 3 scenarios: �� very common practice (entering the cab, and using the steering wheel and other controls

within) – G cab, �� relatively common practices (areas sampled included power take-off unit (PTO), mountings

and fittings for mounted and trailed sprayers) – G general, and �� relatively infrequent maintenance practices (areas sampled included the bonnet, oil

filter/engine and wheels) – G maintenance. Samples were placed in Teflon bottles that were stored in a cool box immediately after collection and during transport. Samples were stored at -18�C on return to the laboratory.

At each farm visit, confirmation of the compounds used, and storage and cleaning practices was obtained. Detailed information on the quantities of pesticides used and, where possible, the timing of application was also obtained. It was intended that each farm would be visited on two occasions, once in the late spring/summer of 2000 and once in the autumn/winter. These timings were chosen to coincide with the main spraying periods. It was also anticipated that different pesticides would be applied during the different seasons, thus the two sampling periods would cover the whole range of pesticides used. However, due to widespread flooding in the autumn/winter of 2000 most farmers could not get on the land to spray, and the foot-and-mouth outbreak prevented visits in early spring 2001. With the

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exception of a single farm where the sprayer was sold, farms were visited on a second occasion in late spring/summer of 2001. Data from the two sampling periods were combined to create a single data set. On the second visit, the actual gloves that operators used for handling pesticide concentrates were collected and pesticides from the inside of the glove were extracted to determine the quantity present. These data are reported as a mass per glove.

2.3 Sampling variability

In order to gain a measure of the natural variability in pesticide doses on the sprayer a test was done on a single sprayer. Three composite samples were taken per sampling site, where a composite sample consisted of three individual swabs. It was anticipated that an overall total of nine swabs per sampling site would provide a good indication of actual doses present.

2.4 Chemical Analysis

Samples were sent to the Health and Safety Laboratories, Sheffield for analysis of azoxystrobin, carbendazim, chlorothalonil, cyanazine, cypermethrin, epoxiconazole, flusilazole, isoproturon, kresoxim-methyl, metazachlor, pendimethalin, pirimicarb, and tebuconazole. These pesticides were chosen on the basis that several could be analysed in a small number of suites, and the compounds represented commonly used pesticides on UK farms, as determined by a literature review and a preliminary analysis of returned questionnaires. In addition to the above pesticides, half the samples (14 sprayers) were also analysed for the following organophosphates (OPs): dichlorvos, fonofos, chlorpyrifos, heptenophos, diazinon, chlorfenvinphos, omethoate, disulfoton, quinalphos, demeton-s-methyl, tolclofos-methyl, triazophos, ethoprophos, pirimiphos-methyl, phosalone, phorate, fenitrothion, dimethoate, malathion.

2.4.1 Non-OP pesticides All pesticide standards were neat materials with certified purities ranging from 91 to 99.5%. Azoxystrobin, carbendazim, and isoproturon were analysed by liquid chromatography (LC). A stock solution (100 mg L-1) and seven calibration solutions, in the range 0.2-25 mg L-1, were prepared gravimetrically in residue grade methanol for these pesticides. Chlorothalonil, cyanazine, cypermethrin, epoxiconazole, flusilazole, kresoxim-methyl, metazachlor, pendimethalin, pirimicarb, and tebuconazole were analysed by gas chromatography (GC). A stock solution (30 mg L-1) and seven calibration solutions, in the range 0.1-15 mg L-1, were prepared gravimetrically in residue grade methanol for these pesticides. All stock and calibration solutions were stored at 2-8�C.

The main LC mobile phase (A) was prepared from acetonitrile (45%), deionised water (45%) and methanol (10%). Mobile phase (B) was deionised water and mobile phase (C) was acetonitrile. The solvents used were HPLC grade. The mobile phases were vacuum filtered through a 0.2 �m nylon filter immediately prior to use.

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The LC system comprised of a Hewlett Packard 1090 liquid chromatograph connected to a Hewlett Packard 1040 diode array detector, set at 242 nm, and with Hewlett Packard HPLC 3D ChemStation software, rev. A.03.03. A Genesis AQ column, 10 cm x 4.6 mm with 4 �m pore size, was used. The flow rate was set at 1.0 ml min-1 and the mobile phase was initially 70% (A), 25% (B) and 5% (C) at 40�C. After 15 minutes this was changed to 70% (A) and 30% (C). The injection volume was 20 �l and the total run time was 20 minutes (plus 2 minutes post time). 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, 2.5 �m film thickness), a Hewlett Packard 5972 Series Mass Selective Detector (MSD) with Hewlett Packard G1034C MS ChemStation software. The injection volume was 2 �l. The injection (splitless) and transfer line temperatures were 250 and 280oC respectively. The oven temperature programme was 120�C for one minute, ramping at 10�C min-1 to 300�C and holding for one minute; total run time was 20 minutes. Helium (>99.996%) was used as the carrier gas, and electronic pressure control in constant flow mode delivered 0.98 ml min-1. The MSD was operated in Selected Ion Monitoring (SIM) mode and data was collected between 8.5 and 20 min. Hewlett Packard silanised, amber 2 ml autosampler vials were used for both GC and LC analysis (Metlab, UK). Calibration graphs were linear over the standard ranges with the linear correlation coefficients ranging from 0.998-1.000. The limits of detection (LODs) ranged from 0.03 to 0.90 �g for pads using GC and 0.8 to 3.5 �g for pads using LC. Recoveries were typically within the acceptable range of 70-110%, with the exceptions of chlorothalonil, cyanazine and cypermethrin, which gave high results. Problems with the chromatography of chlorothalonil also resulted in a non-linear calibration and a high LOD, 160 �g per pad. To extract the pesticides, 100 ml of residue grade methanol was added to each composite sample using a dispenser. Spiked recovery samples were prepared by adding a known amount of each pesticide (c. 100 �g) to three solvent-washed cotton pads in a 125-ml Teflon bottle. These were then left uncovered to allow the solvent to evaporate. Spiked samples for pesticides analysed by GC and LC were made separately. Once created, spiked samples were treated identically to the field samples.

2.4.2 Organophosphates All pesticide standards were neat materials with certified purities ranging from 70 to 99.5%. A stock solution (10 mg L-1) and three working standards, in the range 0.2-3.0 mg L-1, were prepared gravimetrically in Distol grade methanol. All standards and stock solution were stored at 2-8oC. 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, 2.5 �m film thickness), a Hewlett Packard 5970 Series Mass Selective Detector with Hewlett Packard G1034C MS ChemStation software. The injection volume was 1 �l. The injection (splitless) and transfer line temperatures were 250 and 280oC respectively. The oven temperature programme was 60oC for one minute, ramping at 10oC min-1 to 300oC and holding for one minute; total run time was 25 minutes. Helium (>99.996%) was used as the carrier gas and electronic pressure control in constant flow mode delivered 0.98 ml min-1. Selected Ion Monitoring (SIM) data was collected between 8.5 and 25.0 min. Calibration graphs were linear over the standard ranges with the linear correlation coefficients typically 1.000. The LOD ranged from 0.01 to 0.15 µg for pads.

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2.5 Data analysis

Data from the composite swab samples (3 x 100 cm2) were manipulated to obtain a mean mass per metre squared. The nozzles were sampled ‘per nozzle’ and the data are largely reported as thus. However, to enable some comparisons to be made an estimated surface area of 10 cm2 per nozzle was used to convert the data into a mass per metre squared where relevant. For the gloves, the results equated to the mass of active substance per pair. Where results were reported as ‘less than’ or not detected, the corresponding value was halved before being manipulated as per the other data. Where results were reported as ‘not quantified’ the value for the limit of detection was used. If there was no record of use of a pesticide and it was also not detected, or a ‘detection’ was below the limit of quantification, it was assumed that this compound was not used and the data were excluded from analysis.

2.6 Data interpretation

To assess the potential health risk of the pesticide residues detected, the values reported were compared to the acceptable daily intake (ADI) for each compound (Appendix 2) assuming a body mass of 70 kg. For the glove samples, for each individual compound, the pesticide mass detected on each pair of gloves was divided by the ADI of the compound to give the number of ADIs present on the pair of gloves. For example, for a reported dose of 7 mg of azoxystrobin (ADI = 14) then 0.5 ADIs would be present on the pair of gloves. This calculation returns the equivalent number of ADIs per glove pair for each individual compound. The equivalent ADI values for each compound were then summed to give a single, total number of ADIs for each pair of gloves. For the farmers’ gloves where the results were originally reported for each individual glove, the ADIs for the individual compounds for both gloves were summed to give a total per pair of gloves.

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3 RESULTS

3.1 Questionnaire Survey

Of the 250 questionnaires sent out, 20% were returned (51 in total), and all were from farms within England even though questionnaires were also sent to Scotland and Wales. This was a reasonable response rate given that postal surveys can usually expect a return of up to only 30% (Thomas, accessed 1999). Of these 51 surveys, a third (17) indicated they were willing to participate in further research but as one was organic, only 16 were considered suitable. Of these 16 respondents, two rescinded co-operation at a later date. Those farmers agreeing to allow sampling of their sprayers are referred to as ‘participating’ farmers. The findings of the questionnaire have been divided into several headings: general farm, equipment type, equipment usage and maintenance, spraying practices, and cleaning practices. The results from all the questionnaires were compared to those from the participating farmers to assess how representative these farmers were of the whole.

3.1.1 General Farm Nearly half (47%) of all farmers were private owners/occupiers, and approximately a fifth (21%) described themselves as farm managers. A further 21% indicated they had several roles; namely owner and tenant, or owner, tenant and manager whilst 13% were purely tenants. This compares to 50% of participating farmers being farm managers, 29% owners, 14% tenants and 7% owner and tenant (Appendix 3). The most common farm size for all farmers was 201–400 ha, but 401–800 ha for participating farmers. Five farms in total were 401–800 hectares, and all these farms participated in further research. Most farms employed 1 to 3 workers (61%) with 24% employing 4 to 6 workers. This compared to 36% (1 to 3 workers) and 43% (4 to 6 workers) for those farms visited. Only 2 farms employed more than 6 workers (one employed 35 to 60 people depending on the season, farm size > 800 ha) and both these farms were included in the field survey (Appendix 3). Land treated by participating farmers accounted for 74% of the total treated area (all surveys). Cereals (wheat, barley, rye and oats) covered the largest area (61%), followed by oilseed rape (11%), potatoes (10%), beet (6%) and carrots (4%).

3.1.2 Equipment Type Half of all farmers owned mounted sprayers with self-propelled accounting for 31% and trailed for 19% of sprayers. There was a more even spread of sprayer type amongst the farms visited - 7 self-propelled, 5 trailed and 7 mounted sprayers – with some farms owning more than one sprayer type. Usage was biased towards the larger of the sprayer type owned, so a self-propelled would be used in favour of a trailed or mounted sprayer, and a trailed sprayer would be used in favour of a mounted sprayer (Appendix 4).

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The majority (72%) of all sprayer types had automatic boom folding mechanisms. This compared to 94% for those farms visited. When grouped by sprayer type, only one out of 13 self-propelled sprayers had a manual boom folding mechanism and this farm was not visited. Likewise, only one out of 6 trailed sprayers had a manual boom folding mechanism, and this sprayer was not sampled. The division of automatic and manual boom folding mechanisms was more equal amongst mounted sprayers for all farms (55 and 45% respectively). For those farms visited, a higher percentage of mounted sprayers had automatic boom folding mechanisms (71%).

3.1.3 Equipment Usage and Maintenance The use of self-propelled sprayers for other farm purposes was generally restricted to fertiliser application. This contrasts to trailed and mounted sprayers where the tractors providing the transport of these sprayers were used for a multitude of other tasks. Overall, over 75% of farmers used the tractor for 4 or more other tasks (Appendix 5). A third of farmers reported that they were responsible for servicing/repairing the spray equipment and 28% stated that 2 or more persons were responsible for this job (e.g. farmer and spray operator); contractors and spray operators accounted for 25%. This compares to only a fifth of participating farmers alone reporting to service or repair equipment with 2 persons being more commonly responsible (40%). Half of the respondents indicated that the equipment was serviced once a year or at the start of the season. The remaining farmers were relatively equally spread between weekly, monthly and bi-annually. As well as the regular service, machines would also be serviced as and when required.

3.1.4 Spraying Practices With regard to persons who actually spray, for both all farms and those farms visited approximately one third stated that more than one person was responsible; usually the farmer and a spray operator. Only 3 farms employed a contractor, and of these, 2 participated in the sampling study. Where only one person was responsible for spraying, over half of all farmers (54%) conducted their own spraying; spray operators and farm workers accounted for 21% and 14% respectively. This compares to an equal number of farmers and spray operators being responsible for spraying for those farms visited (40%) which was double the number of farm workers (20%). A similar percentage of all farmers and those farmers visited (55% and 53% respectively) claimed that no qualifications for pesticide spraying were necessary as they were born before 31/08/64, although, of these, 24% and 40% respectively did have some form of qualification. Over half (58%) of all farmers stated they had PA2 (pesticide application by tractor). For those farms visited, the proportion was higher (73%). For some replies returned, farmers stated they had PA2 or PA6 (pedestrian powered pesticide application) but did not indicate they had PA1 (handling of pesticides). It is not possible to gain PA2 or PA6 without first achieving PA1. These questionnaires were amended to account for these omissions. The main spraying windows were between March and June, and in October/November. No farmer reported to spray in January and only one sprayed in December. Approximately one-third of all farmers spent 4 months of the year spraying which compares to 43% for the participating farmers. Only two farms spent 7 or more months spraying and both these farms were visited (Appendix 6).

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3.1.5 Cleaning Practices The majority of farmers (90%) stored spraying equipment undercover. This compares to participating farms where all farmers kept spraying equipment indoors. Cleaning practices varied depending on sprayer type. Discounting self-propelled sprayers that are by their nature whole units, 16% of farmers cleaned the spray equipment and tractor separately. Of those farmers who cleaned the spray equipment and tractor together 50% of mounted spray equipment was washed after use/daily, as were 50% of the self-propelled sprayers. This compares to only 25% for trailed sprayers. Where tractors were cleaned separately to the spray equipment, over 50% were cleaned on a monthly basis. The sprayer section was cleaned more frequently (daily or when changing pesticides) with the exception of one respondent. It became apparent when visiting the farms that the cleaning regime did not always correspond with that stated in the questionnaire. For example, for those farms stating a cleaning frequency of a month, in reality the sprayer was cleaned approximately every 10 to 13 weeks. Of the two farms visited that stated they cleaned the sprayer and tractor weekly, only one of these farms adhered to this cleaning regime, whilst the other farm cleaned the sprayer approximately once every 6 weeks. When questioned on the farm visit, the most common cleaning frequency was “when it’s dirty”! The frequency and method of cleaning also depended on the condition of the equipment, thus equipment would be hosed down unless particularly muddy when it would also be scrubbed. The discrepancies between replies to the questionnaires and those when verbally questioned indicate that the cleaning frequencies reported on the questionnaire should be treated as optimistic ideals. The majority of farmers (83%) stated that they cleaned the entirety of the spray equipment excluding the inside of the cab, which was cleaned by only 4% of respondents. Only 5 farmers (14%) restricted cleaning to the boom/spray tank area and did not clean any part of the tractor body. The remaining respondent cleaned only the tractor body and boom. Nearly three-quarters (69%) of respondents jet washed the spray equipment, whilst a hosepipe was the next most common method of cleaning (25%). Of those farmers jet washing their spraying equipment, 80% used a detergent; this compares to 45% where equipment was rinsed with a hosepipe. One farm steam-cleaned the spray equipment and tractor several times a year. Over 90% of farmers washed the equipment down 2 or 3 times, but 100 % declared their cleaning programme to be successful despite ‘Don’t know’ being an potential reply to this question! With regards to the cleaning process, throughout the season, spraying equipment was not regularly washed with the potential environmental impact of the washings cited as a major factor in influencing the minimal cleaning program. It was known that cleaning equipment in the field could reduce the environmental impact of washing the equipment but this option was deemed to be impractical given the distance between the farm and fields sprayed, and the amount of water that would be required.

3.2 Field Survey

The approximate locations of the 14 farms visited are illustrated in Figure 1. Whilst most regions of the country were represented, there was a concentration of farms around the Midlands. Timing of the field visits was determined by the availability of the farmers. The conditions of sampling, for example, when the spray equipment was last used and washed, therefore varied between farms. Only one farm was not visited on a second occasion due to the sale of the sprayer.

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Figure 1 Approximate location (X) of farmers participating in field sampling events

x

x

x

xx

xx x

x x x

x

x

x

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3.3 Sampling variability

An examination of the sampling technique indicated that any variability was limited to an order of magnitude (Figure 2), thus the values reported from the composite samples were representative of the sampling site as a whole.

Figure 2 Variability of the composite samples per sampling site showing the mean & SE

Pest

icid

e do

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g m

-2)

-5

5

15

25

35

45

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boom spray tank rear window windscreen door

AzoxystrobinCarbendazimCyanazineCypermethrinEpoxiconazoleIsoproturonPirimicarbTebuconazole

Pest

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er n

ozzl

e)

-100

0

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200

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AzoxystrobinCarbendazimCyanazineCypermethrinEpoxiconazoleIsoproturonPirimicarbTebuconazole

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3.4 Pesticide residue distribution over the sprayer

3.4.1 Frequency of detection To identify whether or not pesticide residues would collect on certain areas of the sprayer the number of positive detections per sampling site was calculated irrespective of dose or compound. A note was also made of the number of zero detections, i.e. an absence of residues (Table 1).

Table 1 Number of positive detections per sampling site on individual sprayers

Number of positive detections of all pesticides per sprayer

Number of zero detections per sprayer

Sample (n = 28) Boom 253 0 Nozzle 248 0 Spray tank 177 2 Mudguard 121� 4 Door 63 5 Rear window 50� 9 Windscreen 31 13 G cab 73 6 G maintenance 97 7 G general 147 3

The highest number of pesticide residue detections was found on the delivery system (nozzles, boom and spray tank) and, for all sprayers, pesticides were detected on the boom and nozzle. Broadly speaking, there was double the number of detections or more on the mudguards compared to the rest of the tractor body (door, rear window and windscreen). There was a higher number of positive pesticide detections on the cotton gloves worn when entering the cab than detected on the door or windows with swab samples, and only 21% of the sprayers had zero detections for the cab glove samples. After normalising the data by dividing the number of positive detections by the number of pesticides used, ANOVA indicated that sprayer type did not affect the number of pesticides detected on the delivery system, but, on the tractor body significantly (p < 0.01) more pesticides were detected on self-propelled sprayers than on mounted or trailed.

3.4.2 Quantity of detection To assess whether higher doses were particular to a sampling site, the mean pesticide dose was calculated for each sampling site, bulking all compounds (Figure 3). This calculation made no account of the different levels of detection for the compounds as this would be the same effect for all sampling sites.

� n=27 � n=26

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Figure 3 Range of pesticide dose per sampling site for all sprayers and all compounds The doses on the nozzles are not directly comparable to the rest of the swab samples due to the surface area of the nozzle (10 cm2) being a ‘best estimate’. However, these differences are accounted for when considering occupational exposure. Although the boom had the highest frequency of detections, actual doses were greater on the nozzles. Pesticide doses on the spray tank and mudguards were similar, and greater than doses on the rest of the tractor. The quantity of pesticides detected on the cotton glove samples followed the same order as the frequency of detection (G cab < G maintenance < G general) (Figure 4).

Figure 4 Range of pesticide dose on the cotton gloves for all sprayers and all compounds

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r per

noz

zle

-20

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NozzlesBoom

Spraytank Rear

window

WindscreenDoor

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G cab G maintenance G general

Mean+SEMean-SEMean

14

As a result of the above screening of the data, the data were split into the delivery system and the tractor body for subsequent data analysis to reduce the skewness. Furthermore, this split was considered to be appropriate when assessing the potential for personnel to be exposed to residues particularly where the tractor is used for purposes other than spraying.

3.5 Dose range per individual compound

3.5.1 Swab samples Potential health risks introduced by the presence of pesticide residues will vary depending on the toxicity of the compound. It was therefore necessary to address the compounds individually. To gain an overview of the range of pesticide doses found for an individual compound, each quantitative dose was assigned to a magnitude class and the frequency per class calculated. Data were excluded where details of pesticide quantities used were not available. Data for the delivery system and tractor body are presented separately and the pesticides are ranked in order of descending total quantity of use (Figure 5 andFigure 6).

Figure 5 Range of pesticide doses on the delivery system. Pesticides are listed (left to right) in descending order of usage (kg a.i.)

Azoxystrobin had the highest number of ‘detections’ below the limit of quantification on both the delivery system and tractor body despite it having a ‘medium’ use. On the delivery system, for isoproturon, pendimethalin, metazachlor and chlorothalonil there was a positive correlation between the quantity of pesticide used and the number of detections greater than 1000 mg m-2. A similar correlation was not apparent on the tractor body. Quantities of kresoxim-methyl and cyanazine were

0%

20%

40%

60%

80%

100%

Isop

rotu

ron

4112

Pen

dim

etha

lin 1

038

Met

azac

hlor

612

Chl

orot

halo

nil 5

12

Epo

xico

nazo

le 4

18

Azo

xyst

robi

n 38

0

Tebu

cona

zole

247

Kre

soxi

m-m

ethy

l 222

Car

bend

azim

182

Flus

ilazo

le 1

37

Prim

icar

b 11

7

Cyp

erm

ethr

in 9

2

Cya

nazi

ne 4

7

1000+100 to <100010 to <100>LOQ to <10<LOQ

mg m-2

15

lowest on the sprayer as a whole with quantities not exceeding 100 mg m-2 on the delivery system or 10 mg m-2 on the tractor body.

Figure 6 Range of pesticide doses on the tractor body. Pesticides are listed (left to right) in descending order of usage (kg a.i.)

On three occasions it was not possible to access the rear window of the sprayers and samples were therefore taken from the inside of the cab door. On one farm there were no detections on the inside, but, on the other two, doses inside the cab were comparable to those detected on the outside of the door and/or windscreen, although these doses were generally low (< 11 mg m-2). At one farm, residues were present only after recent use, whereas at the remaining farm, two compounds had remained inside the cab for over 100 days, according to the pesticide records.

3.5.2 Cotton glove samples The range of doses per compound on the cotton gloves (Figure 7) followed a similar pattern to that of the tractor body (Figure 6) when comparing doses below the LOQ and the highest ranked dose. For example, on the tractor body isoproturon, pendimethalin, chlorothalonil and carbendazim were all detected at doses greater than 100 mg m-2 and these were the only compounds to be detected at greater than 1 mg per pair of gloves. There was a significant correlation (R2=66%) between the frequency of detection per magnitude class for the cotton gloves and the tractor body, but not with the delivery system. However, when considering the actual doses and separating the glove samples, there was no significant relationship between the quantity of pesticides on the individual glove samples (i.e. G cab, G maintenance and G general) and the total pesticide quantities on the tractor body or delivery system.

0%

20%

40%

60%

80%

100%

Isop

rotu

ron

4112

Pen

dim

etha

lin 1

038

Met

azac

hlor

612

Chl

orot

halo

nil 5

12

Epo

xico

nazo

le 4

18

Azo

xyst

robi

n 38

0

Tebu

cona

zole

247

Kre

soxi

m-m

ethy

l 222

Car

bend

azim

182

Flus

ilazo

le 1

37

Prim

icar

b 11

7

Cyp

erm

ethr

in 9

2

Cya

nazi

ne 4

7

1000+100 to <100010 to <100>LOQ to <10<LOQ

mg m-2

16

Figure 7 Range of pesticide doses on the cotton gloves. Pesticides are listed (left to right) in descending order of usage (kg a.i.)

Summarising the data as the percentage of positive detections for each compound, for the delivery system, tractor and all cotton glove samples the ‘azoles’ (epoxiconazole, tebuconazole and flusilazole) had the highest number of positive detections (with the exception of isoproturon detections on ‘G maintenance’ being greater) (Table 2). Azoxystrobin clearly had the lowest number of positive detections.

Table 2 Percent of positive detections per compound

Positive detections (%) Compound

Delivery system

Tractor body

G cab

G maintenance

G general

Azoxystrobin 47 11 11 11 21 Carbendazim 69 11 0 8 25 Chlorothalonil 61 12 0 36 36 Cyanazine 63 26 33 33 56 Cypermethrin 85 25 10 15 35 Epoxiconazole 96 55 74 68 84 Flusilazole 97 48 62 54 85 Isoproturon 72 32 28 56 56 Kresoxim-methyl 90 28 54 46 77 Metazachlor 92 37 25 50 58 Pendimethalin 92 32 25 50 75 Pirimicarb 58 26 18 27 27 Tebuconazole 98 47 63 53 87

0%

20%

40%

60%

80%

100%

Isop

rotu

ron

4112

Pend

imet

halin

103

8

Met

azac

hlor

612

Chl

orot

halo

nil 5

12

Epox

icon

azol

e 41

8

Azox

ystro

bin

380

Tebu

cona

zole

247

Kres

oxim

-met

hyl 2

22

Car

bend

azim

182

Flus

ilazo

le 1

37

Prim

icar

b 11

7

Cyp

erm

ethr

in 9

2

Cya

nazi

ne 4

7

1+

0.1 to <1

0.01 to <0.1

>LOQ to <0.01

<LOQ

mg per glove pair

17

3.6 Farmers’ gloves

Pesticides were detected inside all of the farmers’ gloves examined (n=14 pairs). Cypermethrin had the highest number of detections above 1 mg per glove despite having a low application rate (c. 0.1 kg a.i. ha-1), and, in addition, 50% of the cypermethrin detections were greater than 0.1 mg per glove (Figure 8). The azoles, isoproturon and pendimethalin had the next highest number of residues above 0.1 mg per glove. Azoxystrobin and chlorothalonil had the least number of positive detections. There was no significant difference between residue quantities found in the right or left hand glove. At three farms, the gloves had not been used for a full season and were c. 6 months old. For two of these, only 3 out of 10 and 11 compounds used were detected and all residues were below 0.05 µg per glove. However, in the third pair of gloves, residue detections were relatively high with 9 out of the 12 compounds used being detected and a maximum detection of 0.5 mg (isoproturon) being observed in one glove.

Figure 8 Distribution of pesticide mass per compound detected inside the farmers’ gloves

3.7 Detection vs non-use

The above analyses have excluded data where there were no details of pesticide use from the records available. At 9 of the 13 farms visited twice, some compounds were detected although there was no record of use for the two seasons (Table 3). Whilst it is possible that the records made available may not have been fully up-to-date, it is also possible that the residues may have remained for years on the sprayer.

0%

20%

40%

60%

80%

100%

Isop

rotu

ron

Pend

imet

halin

Met

azac

hlor

Chl

orot

halo

nil

Epox

icon

azol

e

Azox

ystro

bin

Tebu

cona

zole

Kres

oxim

-met

hyl

Car

bend

azim

Flus

ilazo

le

Prim

icar

b

Cyp

erm

ethr

in

Cya

nazi

ne

1+0.1 to <10.01 to <0.1>LOQ to <0.01<LOQ

mg/glove

18

Table 3 Compounds detected in the absence of recorded usage over the previous two seasons

Car

bend

azim

Cya

nazi

ne

Cyp

erm

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in

Flu

sila

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Pend

imet

halin

Piri

mic

arb

Tebu

cona

zole

No. of detections 1 3 1 2 1 2 2 2 On four farms data were obtained on the dates of last use of the compounds detected but not used according to recent records. On all these farms, residues were greatest on the boom, and, generally, detections were limited to the delivery system. Carbendazim and flusilazole were detected even when they had not been used for 3 years. Eleven farms visited on a second occasion had residues on the sprayer that were detailed in the pesticide records for the first visit but not for the second visit. These ‘carry over’ residues were most commonly detected on the boom, nozzles and spray tank, although there were ‘carry over’ detections on all parts of the sprayer and on the cotton glove samples. The majority of detections were reduced by 75% or more, but others by only 25% or less. On some occasions, higher doses (as a percentage of the original dose) were detected on the second visit on individual sites although the majority of carry-over detections were less than the original. It is possible that this was a reflection of natural variability, particularly where doses were originally low.

3.8 Organophosphates

Of the 19 OPs analysed for only two were detected: chlorpyrifos and pirimiphos-methyl. These compounds were detected on 4 of the 14 sprayers sampled and there were 10 positive detections out of the 151 samples analysed. However, due to the lack of data on OP usage, it was not known which farms used OPs, nor the specific compounds used, thus the detection in relation to use cannot be determined. From the limited data available it was notable that, in accord with non-OP pesticides, compounds were primarily detected on the nozzle and boom, and the single detection on the tractor body was on the mudguard. Doses were below 1 mg m-2 with the exception of a dose of 5.2 mg m-2 detected on a boom. These doses were at the lower end of the overall range in pesticide doses (c.f. Figure 5 andFigure 6)

3.9 Health significance of detected residues

For the glove samples, the numbers (or fractions) of ADIs per compound that were present on each pair of gloves were summed to give a total number of ADIs per glove pair. Over half the gloves sampled (cotton samples and farmers’ gloves) contained residues that totalled more than one ADI (Figure 9). One pair of farmers’ gloves had the equivalent of 17 ADIs inside it, thus if only 6% of the pesticide residues were bioavailable over a day, the ADI may be exceeded.

19

Figure 9 Number of ADIs present on each pair of gloves

For the cotton gloves used to enter the cab, the total residues per glove pair were all below one ADI although 2 pairs had 0.85 and 0.91 ADIs. Approximately a third of glove samples (8 out of 25) representative of general use, which included touching handles in the proximity of the sprayer, had total ADIs of greater than one, with a maximum of 6.25 ADIs per glove pair. Gloves representative of maintenance had above one ADI for 5 out of the 25 pairs with a maximum of 5.44 ADIs per pair of gloves. Isoproturon accounted for the majority of cases where the number of ADIs per pair of gloves exceeded one, followed by flusilazole, cyanazine and cypermethrin (Figure 10). This excludes the limited data on OPs. However, the organophosaphates detected were less toxic than isoproturon, flusilazole and cyanazine (Appendix 2), and due to the low doses at which they were detected, these compounds were not as potentially harmful as some of the non-OP pesticides when using the ADI as an indicator.

Glove pair

Num

ber o

f AD

Is p

er p

air o

f glo

ves

-2

2

6

10

14

18

22

CabMaintenanceGeneralFarmers'ADI = 1

20

Figure 10 Contribution of compounds to ADI classes for all glove samples

0

5

10

15

20

25

30

35

40

45

Isoprot

uron

Pendim

ethalin

Metaza

chlor

Chloroth

alonil

Epoxic

onaz

ole

Azoxy

strob

in

Tebuco

nazole

Kresox

im-m

ethyl

Carbenda

zim

Flusila

zole

Primica

rb

Cyperm

ethrin

Cyana

zine

Freq

uenc

yADI range>10.1 to <0.50.01 to <0.1<0.01

21

4 DISCUSSION On the whole, the questionnaire results from the participating farmers were similar to the results from all the questionnaires indicating that the farms visited provided a fair representation of arable farming in the UK. A larger proportion of participating farmers were farm managers than the respondents as a whole (50% c.f. 21% respectively) and it is possible that, as farm managers (several of whom participate in other areas of research) they were more aware of their environmental and/or safety responsibilities, thus the sprayers sampled may have had lower residues than might be expected from the UK as a whole. However, in counterbalance, these farms were also more likely to use self-propelled sprayers which had a significantly higher usage (p < 0.05) than trailed or mounted sprayers in terms of the number of days spent spraying and hence the mass of active used. The higher usage may partly explain the significantly higher number of residue detections on the tractor body of self-propelled sprayers. Considering both these facts, it is reasonable to assume that the results from the field survey would be representative of farms in the UK. Potential exposure to pesticide residues would depend on the method and frequency of exposure. For example, persons most likely to be exposed to pesticide residues through actual spraying practices were farmers and spray operators (46% and 31% of persons spraying). Farmers were again the most likely to be exposed to pesticides when calibrating or servicing the equipment, but contractors were more likely to service the equipment than spray operators. In addition to the more obvious exposure route to residues during spraying and calibrating, persons could also be exposed to pesticide residues when the spray equipment was used for other purposes. Approximately half the self-propelled sprayers were also used for fertilising, but all tractors carrying mounted or trailed sprayers were used for at least one other purpose. Over 75% of respondents indicated that tractors carrying spray equipment were used for 4 or more purposes, other than spraying. It is during these periods, when there is no obvious risk of contamination by pesticides, and protective equipment may not be deemed as necessary, that the potential for occupational exposure to pesticides may be high. There were two distinct spraying periods in late spring/early summer (April – June) and autumn (October – November), but some farms did spray throughout the year. No respondent sprayed in January, and spraying in December or February occurred at only one farm each. However, the exact months when spraying occurred would be dependent on the weather. Although the actual timing of spraying is of minimal importance to occupational exposure to pesticide residues, it is worth noting the months in between the two main spraying periods would commonly involve heavy use of tractors (e.g. combining, drilling). Consequently, as most tractors were multipurpose, the potential for occupational exposure to pesticide residues could be present throughout a large part of a year. Overall, the results of the questionnaire indicated that farmers, followed by spray operators may be at most risk to being exposed to pesticide residues when accounting for spraying and other activities. However, it was not possible to ascertain the movements of the spray contractors from the questionnaires. By the nature of their job, spray contractors, whether they actually spray or solely maintain sprayers, would probably be exposed to equal, if not higher, pesticide residue doses than farmers, and with greater frequency. It is possible that contractors who service sprayers, as

22

opposed to those that solely spray, are at greatest risk from being exposed to post-application pesticide residues if the residues are not perceived to be a health hazard. With regard to the detection of pesticide residues, the results illustrated the large variability in doses detected between farms and between compounds. The nozzles and boom had the highest frequency of positive detections and the highest doses. This is in accord with other work (Fogg, 1999; Mason et al., 2000), although only isoproturon was quantified in these studies. If processes contributing to the deposition of pesticides on the sprayer could be ascertained then it may be possible to predict which sprayers would be most likely to be highly contaminated and which pesticides might be a problem. Discriminant function analysis was used to identify whether factors such as the physico-chemical properties of the compound, the quantity of active used, time since use and/or cleaning and boom length could be used as predictors of the quantity of pesticide residues detected. When considering residues on the delivery system, the quantity of active used influenced residue detection, but no factor could be identified that could be used to predict pesticide residues on the tractor body as a whole. Furthermore, there was no significant relationship between the residue quantities detected on the delivery system, the tractor body or glove samples. Consequently, it was not possible to make generalisations that could be used to identify conditions resulting in high pesticide residue doses on the tractor or delivery system. An exception to this was that there were significantly more positive detections on self-propelled sprayers than mounted or trailed sprayers which is probably a reflection of their higher frequency of use and mass of active used. It was not possible to assess statistically the influence of cleaning method or frequency on pesticide residue doses detected, particularly considering the fact that the details given on the questionnaire were possibly more theoretical than actual. However, all farms visited stored the sprayer under cover so this was not a factor that could influence the removal of pesticides. Discussion of the cleaning practices examines the results from the actual visits rather than the questionnaires. With the exception of a single farm, no farm had a regular cleaning program for their sprayers. Reasons cited for not cleaning the sprayer were mainly lack of time and/or environmental implications. Whilst 80% of farms visited indicated they jet washed the sprayer, this may also be in addition to hosing down the sprayer particularly in muddy conditions. Consequently, the cleaning regime could change depending on the state of the vehicle but they would be washed until visibly clean. On the second visit, even though the sprayers had been cleaned, with the exception of the windscreen, the area sampled on the first visit was still clearly visible beneath a light coating of ‘dirt’. These results indicated that the build-up of dirt was not removed with the cleaning regime of those farms. One farmer spoke of the difficulty of removing pendimethalin (colloquially known as the ‘yellow devil’ due to its colour), thus the sprayer may have received a more intense wash after the use of this chemical to get it visibly clean. Pendimethalin had the second highest number of detections greater than 1000 mg m-2, thus it is possible that if it were not so highly coloured residues of this compound could potentially be higher. It could follow that, if pesticide residues were more visible, sprayers may be washed more often. For the farm with a regular cleaning program, the equipment was washed on, at least, a bi-weekly basis and it also steam cleaned several times a year (reportedly monthly). On the first visit, 6 out of the 10 compounds that had been used in the previous season were detected either on the nozzles or boom, and only one (0.13 mg m-2 tebuconazole) on the tractor body (mudguard). Of these compounds, only chlorothalonil had been used since its previous wash. On the second visit,

23

pesticides were detected on all the delivery system and again only the mudguards on the tractor body. With the exception of a detection of 28.5 mg m-2 of cypermethrin on the boom, which had been applied the day prior to sampling, even though several pesticides had been used since its last clean, the doses detected were only in the order or 1-10 mg m-2. This compares to other sprayers where residues tended to be detected on the body as well as the delivery system after recent use. On this sprayer there was a detection of flusilazole on the boom on the second visit of 0.77 mg m-2 compared to the first visit of 0.13 mg m-2 and there were no records of its use between the two visits. The results from this farm indicated that a regular cleaning program reduced the number of residues remaining on equipment and prevented a build-up, but did not necessarily eliminate residues altogether. This finding was supported by the fact that nearly half the sprayers swabbed on the second occasion had ‘carry-over’ residues detected at levels ranging in the order 25 – 75% of the original dose (as quantified on the first visit). Likewise, a study by Mason et al. (2000) reported that despite being thoroughly washed, isoproturon remained on the sprayer in their study. Considering the doses of the different compounds, isoproturon, pendimethalin and chlorothalonil were notable for their greatest frequency of detection of the highest doses for the delivery system and tractor body. In terms of occupational exposure, isoproturon was again notable as the compound that was potentially the most likely to result in the ADI being exceeded, followed by flusilazole and cyanazine. As the aim of the study was to quantify pesticide residues in terms of occupational exposure, further discussion on pesticide residue doses will be in terms of the ADI rather than the pesticide dose. The results from the cotton glove samples indicated that, in the procedure of getting into the cab, a worker was unlikely to be exposed to residues that would result in them exceeding the ADI for all compounds tested. However, this would assume that contact with the rest of the sprayer is limited which is unlikely in reality. Persons in contact with the spray equipment in general could pick up residues that would equal more than the acceptable daily intake, even if only half the residues were bioavailable, as the majority of those gloves samples that were above the ADI had pesticide doses equating to more than two ADIs. The number of total ADIs present on the gloves used to emulate maintenance of the tractor (changing the oil filter, wheels, opening the bonnet) was less than the general gloves with only a fifth of those sampled exceeding one ADI, with a maximum of 5.4 ADIs. Consequently, the results indicated that persons working with spray equipment may be exposed to residues that were sufficiently high to result in the acceptable daily intake being exceeded, although this was largely restricted to specific compounds, particularly isoproturon and flusilazole. Kresoxim-methyl and pendimethalin contributed the least to exceedance of the ADI. It is worth noting that, in taking the cotton glove samples, the contact time with the sprayer was short, handling each area only once. The resulting doses have then been compared to the acceptable daily intake. It is probable that during the course of a day, persons coming into contact with the surfaces of the sprayer would do so with more frequency than when sampled in this study. It is possible therefore that the cotton glove samples underestimated the quantity of residues transferred from the sprayer to the hand in a day. To assess the implication of pesticide residues quantified by the swab samples, for each given residue dose, an ‘exposure area’ was calculated whereby if a person was exposed to that surface area the ADI for that compound would be attained, assuming 100% bioavailability. For example, if the reported dose was 7 mg m-2 of azoxystrobin (ADI=14) then the contact (exposure) area needed to equal the ADI would be 2 m2. Exposure areas were calculated separately for the nozzles, boom, spray tank and mudguards, and a further exposure area was calculated for the mean dose on the

24

door, windscreen and rear window. An arbitrary threshold of 0.0225 m2 (0.15 m x 0.15 m) was used as the area touched in one day. If the calculated exposure area was less than this threshold then the ADI for that compound would be exceeded. A value of 0.0225 m2 is probably a smaller area than personnel would normally be exposed to during a working day, but this conservative measure was used in an attempt to counterbalance the assumption of 100% bioavailability. For the nozzles, where pesticide residues were reported as a mass per nozzle, 5 nozzles was used as the arbitrary threshold. It is acknowledged that the threshold of 0.0225 m2 is arbitrary, but in the absence of any relevant data this method provided a means for examining whether certain compounds were potentially more prone to resulting in the exceedance of ADIs. This threshold value has been termed ADI225. The number of compounds that exceeded the ADI225 on the boom, nozzles, spray tank, mudguards and tractor body (excluding mudguards) were summed to give a total number of exceedances per farm visit. A single farm accounted for a quarter of all ADI225 exceedances on both visits (Figure 11). For farms with no exceedance of the ADI225, one was subject to the strict cleaning regime discussed previously. It is worthy of note that the single farm with the greatest number of ADI225 exceedances also had the highest number of OP detections and the greatest dose. The lack of regular cleaning of the sprayer at this farm may be the largest factor determining the detection of pesticides.

Figure 11 Total number of compounds exceeding the ADI at 13 farms summing swab samples. Note there is only one set of results for Farm 13

Exceedance of the ADI225 depended on the compound and the sampling site (Table 4). The delivery system as a whole accounted for 92% of total exceedances. Isoproturon accounted for 36% of all ADI225 exceedances followed by flusilazole (25%). There were no ADI225 exceedances for epoxiconazole, azoxystrobin, kresoxim-methyl, pirimicarb, or cypermethrin. This contrast slightly to the results of the glove samples where both cypermethrin and cyanazine were detected at levels greater than the ADI. Calculation of the ADI225 highlighted differences between compounds and sprayer sampling sites. As could be expected, contact with the delivery system would be more likely to result in

0

1

2

3

4

5

6

1 2 3 4 5 6 7 8 9 10 11 12 13

Farm

Num

ber o

f AD

I 225

exce

edan

ces 1st visit

2nd visit

25

exceedance of the ADI. Most farmers indicated that when working in these areas they would tend to wear gloves. However, it is possible that this is only when spraying or immediately after spraying because, after the spray equipment had been washed it was considered clean, and all farmers responding to the questionnaire declared that their cleaning program worked well. From general observation it was noted that there was no hesitancy in touching the sprayer without gloves. This included, in some cases, handing over the nitrile gloves used to handle pesticide concentrates.

Table 4 Summary of ADI225 exceedances per compound and sampling site

Is

opro

turo

n

Pend

imet

halin

Met

azac

hlor

Chl

orot

halo

nil

Epo

xico

nazo

le

Azo

xyst

robi

n

Tebu

cona

zole

Kre

soxi

m-m

ethy

l

Car

bend

azim

Flu

sila

zole

Piri

mic

arb

Cyp

erm

ethr

in

Cya

nazi

ne

Total count %

Boom 12 1 0 2 0 0 2 0 1 12 0 0 4 34 45 Spray tank 4 0 0 3 0 0 1 0 1 1 0 0 1 11 14 Nozzles 9 0 3 3 0 0 2 0 1 5 0 0 2 25 33 Body (excl. mudguard) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Mudguard 2 0 0 1 0 0 1 0 1 1 0 0 0 6 8 Total count 27 1 3 9 0 0 6 0 4 19 0 0 7 76 % 36 1 4 12 0 0 8 0 5 25 0 0 9

The attitude of farmers on the use of gloves for sprayer maintenance varied. The sprayers tended to be washed prior to being serviced, thus it would not always be deemed necessary to wear gloves except when working near greasy or oily areas. On one visit, the sprayer was being maintained at the time of the visit by a contractor – part of the boom had broken. This contractor, who did not have previous knowledge of the visit, was wearing disposable gloves, but the spray operator who was assisting him was not wearing gloves. The quantities of pesticides inside the farmers’ nitrile gloves were potentially the most concerning results of the study. Over half the pairs of gloves tested contained total pesticide residues that would result in being in contact with doses equating to more than one ADI, and the fraction that would need to be bioavailable for the ADI to be exceeded ranged from 50% to 6%. Furthermore, as nitrile gloves are non-breathable, the hands would be moist which could increase the bioavailability of the pesticides (Yoshida et al., 1990). The most contaminated pair was approximately 2 years old, but pesticides were also detected on the inside of the farmers’ gloves even when they had not been in use for a full season. It may therefore be more appropriate for disposable gloves to be used for the handling of pesticides. The farmers visited were made aware of the reason for the study, but there was no evident concern with regard to exposure to post-application pesticide residues. The apparent lack of awareness of the potential for pesticide residues to contribute to total measurements of pesticide exposure is evident within academia and industry, thus farmers can not realistically be expected to take measures of protection if it is not perceived to be worthy of such precautions.

26

An extensive survey (2700 participants) was carried out in the US investigating farmers’ attitudes about pesticides, water quality and related environmental effects (Lichtenberg & Zimmeran, 1999). Farm operators were asked four questions on how they regarded the seriousness of human illness or injury arising from various pesticide exposure scenarios: from mixing/loading pesticides, from applying pesticides, from residues on food, and from pesticides or residues in drinking water. What is notable by its omission is the potential for post-application residues to contribute to human illness. In a similar vein, searches on the Web and in the scientific literature for ‘pesticide residues/exposure’ uncovered a mine of information including the health effects of exposure during use, health effects of the families of pesticide users, residues from tank washings, and residues in food and water, but, again, there was a lack of information on the importance of external pesticide residues post-use. Indeed, pesticide registration in the UK does not require any risk assessment of residues post-application. A lack of information on post-application residues may contribute to the perception that pesticide residues on sprayers is not of concern, as there are no data to the contrary. For farmers, this assumption may be supported by more accessible information. For example, in the Farming News (March 31 2001), a double-paged article entitled ‘Get your sprayer into shape’ highlighted twelve key points for inspection using photographs as a guide. In the photographs, the worker was not wearing gloves or overalls, thus it could be inferred that this practice is safe. The little research that has examined external residues on sprayers has largely been in the context of the environmental implications. Ganzelmeier (1998) stated that only small amounts of spray adhere to the outside, and that, whilst it would be preferable to clean the sprayer, if it could not be cleaned then it should be parked under a roof to prevent any residues being washed off by rain. Rose et al. (2001) also supported this view. Such recommendations do not consider the health implications of pesticide residues. It would be preferable that future research on pesticide residues addresses both the environmental and health implications as the farmer would be required to abide by legislation on both accounts. The above discussions indicate that pesticide residues on typical farms throughout England vary widely and their presence cannot be easily predicted by other measurable factors. In several cases, the levels of pesticide detected could be of concern to human health but more work would be required to substantiate this finding. Furthermore, the results presented here were with reference to conventional sprayers. Some farmers spoke of the advent of front-boomed sprayers that would enhance manoeuvrability/visibility. Theoretically, front-boomed sprayers could result in significantly higher pesticide deposition on the sprayer and the results of the current study may be a gross under-representation of such sprayers. An understanding of the relevance of the doses detected in this study in terms of human health would be required to assess whether concern should be raised over the advent of front-boomed sprayers.

27

5 CONCLUSIONS �� All sprayers surveyed were contaminated with pesticide residues despite being subject to

some form of cleaning. �� Pesticide residues were detected most frequently and at higher doses on the boom and the

nozzles. �� The mudguards had higher residues than the rest of the tractor body (door, windscreen and

rear window). �� Pesticide doses varied widely between sprayers and between compounds. Detections on the

tractor body were largely less than 10 mg m-2, but on the delivery system over 1000 mg m-2 could be detected for some compounds.

�� There was a positive correlation between the mass of active used and the quantity of active detected on the delivery system, but no factor could be identified to influencing the deposition of residues on the tractor body

�� The quantity of total pesticides detected on the cotton glove samples equated to several times the acceptable daily intake in some cases.

�� Isoproturon had the greatest frequency of detections above 1000 mg m-2, and it was the most likely to contribute to the exceedance of the ADI. Pendimethalin also had high detections, but in terms of occupational exposure this compound was not as significant as flusilazole.

�� Chlopyrifos and pirimifos-methyl were not implicated as being potentially more harmful than non-OP pesticides when using the ADI as an indicator.

�� The majority of farms cleaned the sprayers on an ad hoc basis. Only one farm had a strict cleaning regime and pesticide doses on this sprayer were relatively low.

�� Once washed, the sprayer was considered to be clean by the user, and all farmers declared that their cleaning program worked well.

�� Farmers and spray operators could be exposed to residues post-application when using the equipment for other purposes.

�� Spray contractors/servicers may be exposed more frequently to residues due to the nature of their job.

�� Pesticides were detected on the inside of all the farmers’ gloves used for handling concentrates. Half of these contained pesticide totals that equated to more than one ADI per pair of gloves. One pair had the equivalent of 17 ADIs!

�� There is a paucity of information on pesticide residues on the external surface of sprayers, particularly in relation to occupational exposure. This is possibly an underlying factor of the apparent lack of concern with regard to post-application residues.

�� The results of this study indicated that pesticide residues on agricultural sprayers exist at levels that may have health implications, but further work in this area is required to confirm this finding.

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6 RECOMMENDATIONS

1 Effectiveness of cleaning procedures The results of the study indicated that a cleaning regime may reduce operator exposure to pesticide residues remaining on the sprayers. However, even where a rigorous cleaning regime was in operation, residues still persisted. The efficiency of different cleaning techniques should be examined including the frequency of cleaning necessary to prevent the build-up of residues. Cleaning solutions are used by the military to decontaminate against chemical agents. These solutions could be assessed for their suitability in the farming environment. It may be possible to reduce the actual time spent washing if a cleaning agent is particularly effective. Ideally, any cleaning method should be easy to adopt on farm, and, in parallel to such a study, it would be preferable to consider the environmental impact of cleaning sprayers, as the farmer would be expected to take this into account. The use of cleaning agents and/or detergents should be investigated. 2 Exposure during cleaning In addition to investigating the effectiveness of different cleaning methods for removing pesticide residues from the external surfaces of sprayers, it may also be necessary to examine exposure to pesticides during the cleaning process. Many farmers jet wash the sprayers to clean them. This process results in fine spray being produced which in itself may be a health concern. At one farm the sprayer was steam-cleaned. This method could introduce a significant inhalation hazard due to volatilisation through steam distillation and/or the production of fine particles, but there are no data currently available to assess any associated risks. An occupation exposure study should be conducted to determine the range of exposures and risks associated with current cleaning practices. 3 Refinement of exposure assessment The exposure assessment in this study was very simplistic and the risk may have been under- or over-estimated. Limitations of the exposure assessment were:

a. Short contact times; b. No allowance for repeated operations; c. No consideration of pesticide bioavailability; d. The exposure area threshold of 0.0025 m2 was arbitrary.

Knowledge of actual contact times with the equipment and the likely bioavailability of compounds is required in order to refine the exposure estimations. This should include an estimate of the level of ingestion from hand contact.

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4 Personnel Exposure to pesticide residues may differ depending on the work nature of the persons in contact with the sprayer. The risk caused by maintenance may be greater than during other farm work. Spray contractors who move from sprayer to sprayer could potentially be at most risk. The nature of the different maintenance operations requires further investigation in order for risk assessments to be undertaken. 5 Communication of results To gain feedback on the results of the current study and proposals for further work, communication with the farming community is required. An article should be placed in the media, such as Farming News. 6 Spray train The results of the sampling of the spray train should be discussed with the operator to examine the logistics of future work requirements.

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7 APPENDICES

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APPENDIX 1 QUESTIONNAIRE Please complete this questionnaire by ticking the appropriate box � or by writing in the space provided

About you and your farm Q1 Which of the following best describes your status?

Farmer – Owner/Occupier � 01 Farmer – Tenant � 02 Farm Manager � 03 Farm contractor � 04 Other (Please specify) � 05 ……………………………………………… ………………………………………………

If answer to Q1 Farm contractor go to Q5 Q2 What is the total land area of your farm? 0 to 100 acres (0-40 hectares) � 01 101 to 249 acres (40- 100 hectares) � 02

251 to 500 acres (100-202 hectares) � 03 501 to 1000 acres (202-405 hectares) � 04 1001 to 2000 acres (405-810 hectares) � 05

2001 acres or more (810 or more hectares) � 06 Q3 How many workers are employed on your farm?

1-3 � 01 Other (Please specify) � 05 4-6 � 02 …………………………………………….… 7-9 � 03 ………………………………………………. 10-15 � 04

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Pesticide usage

Q4 Please fill in the table below stating the approximate land area of each crop grown and the

pesticides that you commonly use on those crops?

Pesticides used Crop Land area (acres) Herbicides Insecticides Fungicides

e.g Wheat 200 acres Isoproturon Cyperkill 5 Epic e.g Onions 20 acres Ramrod Bravo 500

Q5 Which months represent the peak periods for pesticide use? (Please tick all that apply)

January � 01 July � 07 February � 02 August � 08 March � 03 September � 09 April � 04 October � 10 May � 05 November � 11 June � 06 December � 12

Q6 During the peak periods of pesticide use, how many days would the sprayer be in use?

1-10 days � 01 40-50 days � 05 10-20 days � 02 50-75 days � 06 20-30 days � 03 75-100 days � 07 30-40 days � 04 100 days or more � 08

Q7 Who carries out the spraying of crops on your farm? (Please tick all that apply)

Yourself (farmer) � 01 Other (Please specify) � 05 Spray operator � 02 ………………………………………………. Farm worker � 03 ……………..………………………………... Contractor � 04

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Q8 What training have you or your workforce received regarding application and handling of pesticides? (Please tick all that apply)

Not applicable as born before 31st December 1964 � 01 Lifetime experience � 02 Basis, certificate in crop protection � 03 Degree/HND � 04 PA1 � 05 PA2 � 06 PA6 � 07 Other (Please specify) � 08 ………………………………………………………………………………………………… …………………………………………………………………………………………………

Equipment Q9a What type of spraying equipment is used on your farm? (Please fill in the table below) Sprayer type Make Model Boom size

(m) Tank Size (lt)

e.g self propelled e.g Case e.g 2000SP e.g 24m e.g 2000lt 1) 2) 3) 4)

Q9b Which of the following apply? (Please fill in the table below)

Sprayer: 1) 2) 3) 4)

If a mounted sprayer, what is it mounted to: Boom folding mechanism: Manual/Automatic Does the sprayer have ‘in tank’ washers: Y/N Does the sprayer have ‘induction hoppers’: Y/N Has the sprayer a ‘direct injection mechanism’: Y/N

Q10 If your sprayer is a tractor mounted or a trailed sprayer what other operations, if any, does

the tractor carry out? (Please tick all that apply)

Ploughing � 01 Harvesting � 06 Cultivating � 02 Rotorvating � 07 Fertilising � 03 Other (Please specify) � 08 Drilling � 04 …………………………………………………... Desiccating � 05 …………………………………………………...

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Q11 If your sprayer is a self propelled sprayer is it used for fertilising?

Yes � 01 No � 02

Q12 What other operations does your spray operator carry out? (Please tick all that apply)

Ploughing � 01 Harvesting � 06 Cultivating � 02 Rotorvating � 07 Fertilising � 03 Other (Please specify) � 08 Drilling � 04 …………………………………………………... Desiccating � 05 …………………………………………………...

Q13 How often is the spraying equipment checked for leaks?

At the start of the season � 01 Every 6 months � 06 Every time it is used � 02 Yearly � 07 Daily � 03 Other (Please specify) � 08 Weekly � 04 ………………………………………………. Monthly � 05 ……………..………………………………...

Q14 How often is your spraying equipment calibrated?

At the start of the season � 01 Every 6 months � 06 Every time it is used � 02 Yearly � 07 Daily � 03 Other (Please specify) � 08 Weekly � 04 ……………………………………

Monthly � 05 ……………..………………………………... Q15 Who carries out the calibration of your sprayer? (Please tick all that apply)

Yourself (farmer) � 01 Contractor � 04 Spray operator � 02 Other (Please specify) � 05 Farm worker � 03 ……………………………………………….

Q16 How often is your spraying equipment serviced/repaired?

At the start of the season � 01 Other (Please specify) � 06 Weekly � 02 ………………………………………………

Monthly � 03 ……………………………………………… Every 6 months � 04 Yearly � 05

Q17 Who carries out the service/repair work? (Please tick all that apply)

Yourself (farmer) � 01 Other (Please specify) � 04 Spray operator � 02 ……………..………………………………... Farm worker � 03 ………………………………………………. Contractor � 04

Q18 Do you exchange between floatation and narrow crop tyres during the year?

Yes � 01 No � 02

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Q19 Where would you normally store your spraying equipment? In the open � 01

Under cover � 02 Spraying

Q20 Where do you normally fill up your spraying equipment? In the farmyard � 01 Other (Please specify) � 04 In the field � 02 ………………………………………………. On a designated area � 03 ……………..………………………………... Q21 What is the application volume that you typically operate at?

100 l/ha � 01 500 l/ha � 05 200 l/ha � 02 Other (Please specify) � 06 300 l/ha � 03 ……………………………………………… 400 l/ha � 04 ……………………………………………… Q22 What spray quality do you normally operate at?

Very fine � 01 Coarse � 04 Fine � 02 Very coarse � 05 Medium � 03

Q23 What equipment is available for dealing with leaks and spills? (Please tick all that apply) Nitrile gauntlet gloves � 01 Shovel � 08 Coverall � 02 Absorbent material � 09 Apron � 03 Brush � 10

Rubber boots � 04 Bucket � 11 Respirator � 05 Face shield � 12 First aid provisions � 06 Other (Please specify) � 13 Clean water � 07 ……………..………………………………...

Cleaning and disposal Q24 How often do you clean your tractor and spray equipment? (Please tick all that apply)

Tractor Spray equipment At the start of the season � 01 At the start of the season � 01 Every time it is used � 02 Every time it is used � 02 At the end of the spray day � 03 At the end of the spray day � 03 When changing pesticides � 04 When changing pesticides � 04 Daily � 05 Daily � 05 Weekly � 06 Weekly � 06 Monthly � 07 Monthly � 07 Every 6 months � 08 Every 6 months � 08 Yearly � 09 Yearly � 09 Other (Please specify) � 10 Other (Please specify) � 10 ……………..…………………………… ………………..…………………………

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Q25 Do you wash out the spray equipment between applications?

Yes � 01 No � 02

Q26 Approximately, what volume of water would you use (each time) to thoroughly clean the

sprayer tank? 0-50 lt. � 01 150-200 lt. � 04

50-100 lt. � 02 200 lt. or more � 05 100-150 lt. � 03 Q27 How many washes would you apply to the sprayer tank to thoroughly clean it?

One � 01 Five � 05 Two � 02 Other (Please specify) � 11 Three � 03 ………………………………………………….. Four � 04 …………………………………………………..

Q28 What methods do you use when cleaning the tractor and/or spraying equipment? (Please

tick all that apply)

Rinsed with hosepipe � 01 Other (Please specify) � 04 Jet-washed � 02 ………………………………………………. Sponged down � 03 ……………..………………………………...

Q29 Do you use detergents when cleaning the tractor and/or spraying equipment?

Yes � 01 No � 02

Q30 Do you wash down your spraying equipment on a designated area?

Yes � 01 No � 02

Q31 What areas of the tractor and/or spray equipment do you apply the cleaning program to?

(Please tick all that apply)

All areas of Tractor � 01 Hoppers � 08 All areas of Sprayer � 02 Wheels and tyres � 09 Spray tank (inside) � 03 Sprayer piping � 10 Spray tank (outside) � 04 Others (Please specify) � 11 Booms and nozzles � 05 ………………………………………………. Cab (inside) � 06 ……………..………………………………... Cab (outside) � 07

Q32 What type of surface is your spraying equipment washed down upon?

Concrete � 01 Hardcore � 04 Asphalt � 02 Other (Please specify) � 05

Grassland/Soil � 03 ……………………………………………….

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Q33 Where does the waste washings from the cleaning program go? (Please tick all that apply) Treatment system � 01 Contract waste disposal � 06 Soakaway � 02 Other (Please specify) � 07

Drain to surface water � 03 ………………………………………………. Sprayed onto headland � 04 ……………..………………………………...

Grassland/Soil � 05 Q34 Where does the waste pesticide from spraying go? (Please tick all that apply)

Treatment system � 01 Contract waste disposal � 06 Soakaway � 02 Other (Please specify) � 07

Drain to surface water � 03 ………………………………………………. Sprayed onto headland � 04 ……………..………………………………...

Grassland/Soil � 05 Q35 Where do you dispose of the tank washings?

Treatment system � 01 Contract waste disposal � 06 Soakaway � 02 Other (Please specify) � 07

Drain to surface water � 03 ………………………………………………. Sprayed onto headland � 04 ……………..………………………………...

Grassland/Soil � 05 Q36 Does your cleaning program work well

Yes � 01 Don’t know � 03 No � 02

Q37 Would you be prepared to participate in research to further improve the potential risks to

the environment?

Yes � 01 No � 02

Optional

Please fill in the table below if you answered yes to Q37 or if you would like to be entered into the free prize draw. (Please return by 10th April 2000)

Name:…………………………………………………………………………………………… Address:…………………………………………………………………………………………. …………………………………………………………………………………………………... ……………………………………………………………………………………………………………………………Tel:…………………………… E-mail:………………………………….

I would again like to stress that the completed questionnaire will be treated in the strictest confidence and that only summary data will be provided to the funding organisations. Thankyou for your time

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APPENDIX 2 ACCEPTABLE DAILY INTAKES

Compound

ADI (mg kg body weight-1 d-1)

ADI (mg d-1 70 kg person)

Azoxystrobin 0.2 14 Carbendazim 0.03 2.1 Chlorothalonil 0.03 2.1 Cyanazine 0.002* 0.14 Cypermethrin 0.05 3.5 Epoxiconazole 0.05 3.5 Flusilazole 0.001 0.07 Isoproturon 0.0062 0.434 Kresoxim-methyl 0.4 28 Metazachlor 0.036 2.52 Pendimethalin 0.1* 7 Pirimicarb 0.02 1.4 Tebuconazole 0.01* 0.7 Chlorpyrifos 0.01 1.4 Pirimiphos-methyl 0.03 2.1

Sources: All except *: Tomlin, CDS, Ed,(1997). The Pesticide Manual, 11th ed, BCPC, Farnham, 1606 pp. *: ADI List, Commonwealth of Australia 2001. www.health.gov.au/tga/docs/pdf/adi.pdf

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APPENDIX 3 GENERAL FARM ATTRIBUTES

All surveys Farms visited Farm attribute Count % Count % Farmer – Owner/Occupier 18 47 4 29 Farmer – Tenant 5 13 2 14 Farm Manager 8 21 7 50 Farm Contractor 0 0 0 0 Mixed 8 21 1 7

Size of farm 0-40 hectares 2 5 0 0 40-100 hectares 7 18 1 7 100-202 hectares 9 24 1 7 202-405 hectares 11 29 4 29 405-810 hectares 5 13 5 36 810 hectares or more 4 11 3 21

No. of workers 0 4 11 1 7 1 to 3 23 61 5 36 4 to 6 9 24 6 43 7 to 9 1 3 1 7 10 to 15 0 0 0 0 Other 1 3 1 7

APPENDIX 4 DISTRIBUTION OF SPRAYER TYPES

All surveys Farms visited Swabbed Sprayer type Count % Count % Count Self-propelled 13 31 7 37 6 Trailed 8 19 5 26 4 Mounted 21 50 7 37 5 Boom folding mechanism Automatic 31 72 17 94 Manual 12 28 2 11

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APPENDIX 5 USE OF THE EQUIPMENT IN ADDITION TO SPRAYING

All surveys Farms visited

Activity Count % Count % Ploughing 27 71 8 57 Cultivating 34 89 13 93 Fertilising 35 92 13 93 Drilling 29 76 10 71 Desiccating 21 55 11 79 Harvesting 32 84 14 100 Rotorvating 15 39 7 50 Other 11 29 3 21

All surveys Farms visited Number of jobs Count % Count %

1 0 0 0 0 2 1 3 1 7 3 4 11 0 0 4 5 13 2 14 5 6 16 1 7 6 11 29 7 50 7 6 16 2 14 8 4 11 1 7

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APPENDIX 6 NUMBER OF MONTHS SPENT SPRAYING

All farms Farms visited No. months spraying Count % Count %

1 3 8 0 0 2 5 14 0 0 3 5 14 1 7 4 13 35 6 43 5 4 11 3 21 6 5 14 2 14 7 1 3 1 7 8 0 0 0 0 9 1 3 1 7

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APPENDIX 7 WEED CONTROL ON RAILWAYS

Introduction

Weed control on railways has historically been accomplished using a single, dedicated spray train. Occupational exposure to pesticide residues on this train would largely have been limited to maintenance workers and the crew operating it. In 1999 the newly developed multi-purpose vehicles (MPVs) were introduced. These are used for other work outside the spray season (usually April – September) such as rail de-icing, rail-head conditioning and removal of leaves. The multi-task nature of these vehicles may increase the potential for exposing a larger number of workers to residual pesticides over a longer time period, if residues remain on the vehicle. The operating speed of the MPV is between 4 and 30 mph. However, to reduce disruption to services, it is preferable that work is carried out at the higher speed; this contrast to agricultural situations where speeds are 4 to 6 mph. The higher speed of the MPV may increase turbulence enhancing the potential for vehicle contamination, although spray drift is said to be similar to that produced by agricultural sprayers (SRI, 2000)1. As part of the major investment into MPVs, some small-scale tests were conducted, one of which included vehicle contamination. However, the quantity of herbicides deposited on an MPV during a normal spray season was unknown. In June 2000, the operators of the MPVs (Serco Railtest Ltd) conducted a simple test to investigate the effectiveness of different cleaning methods by establishing the quantity of herbicides in the washings. The test was being carried out with regard to groundwater regulations, and it was the first time an MPV had been cleaned. It also provided an ideal opportunity to sample an MPV for pesticide residues both before and after cleaning with regard to occupational exposure.

Methodology

Pesticide Residue Sampling The MPV sampled had completed a spray run in the morning and was refilled with herbicides on return to the depot, before cleaning could take place. The sampling protocol was largely determined by the very short time available in which to take samples, but in any case, was restricted to five sites on the train. Furthermore, Health and Safety regulations limited sampling to a single side of the train, i.e. the side adjacent to the platform. It was not possible to visit an MPV before the day of sampling, and observation of normal practice during the spray run identified areas where pesticide residues would be relevant to occupational exposure. These included the:

�� Hand rail �� Main body �� Doors �� Bogey (wheel area), and �� Inside the cab (door handle and window edge where opened).

1 SRI News, Issue 7 Spring 2000, 4 pp.

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Samples were taken prior to, and after jet washing of the MPV. Samples were taken by applying 5 ml of the appropriate solvent onto a pre-washed cotton swab. The solvents were distilled water and methanol for glyphosate and diuron respectively. The swab was used to wipe a 100 cm2 area before placing it into a Teflon bottle. All glyphosate and diuron samples were taken and bottled separately. Three swabs were taken per site to form a composite sample. Disposable gloves were worn during sampling and changed between each area swabbed. Samples for diuron and glyphosate were taken from immediately adjacent areas. Likewise, samples taken before and after cleaning were not taken from exactly the same area, but adjacent to the initial sampling site. This was easily achieved given that it was clearly visible where samples had been taken, even after washing. In addition to the sites sampled prior to, and after jet washing, filter papers were taped on to pre-cleaned areas of the walkway and hand rail before the spray run in an attempt to establish vehicle contamination during a single spray run. (The MPV investigated had been working for 6 weeks prior to cleaning). The filter papers were removed before cleaning of the train and bottled. All bottles were placed in a cool-box for transport to the laboratory where they were stored at -18�C on receipt. Samples were sent to the Health and Safety Laboratories, Sheffield for analysis of glyphosate and diuron.

Cleaning Cleaning of the MPV was limited to the outside of the train, and, again for Health and Safety reasons, to the side of the train adjacent to the platform. Serco employed a contractor to jet wash different parts of the train using a variety of methods; namely with detergent, with detergent followed by a high pressure clean, and no detergent but a longer duration of high pressure cleaning. Collection trays were placed at the base of the train beneath each section representing a different cleaning method. The washings were bottled separately for each tray and sent to Scientific Laboratories, Derby for analysis of glyphosate and diuron. The results of Serco’s study are not detailed within this report.

Results

The results of the analysis are tabulated below. The limits of detection were 0.4 µg and 2 µg per sample for glyphosate and diuron respectively.

Glyphosate (mg m-2) Diuron (mg m-2) Pre-clean Post-clean % Loss Pre-clean Post-clean % Loss Hand rail 1016 4.67 99.5 345.57 287.20 16.9 Main body 38.87 3.67 90.6 443.23 267.97 39.5 Doors 56 2.93 94.8 105.20 140.27 -33.3 Bogey 1184 10.07 99.1 573.90 314.03 45.3 Inside cab 9.2 8.77 Filter paper on rail 44.40 103.98 Filter paper on walkway

48.41 92.94

Control 1.8 0.27

Herbicide doses present on an MPV before and after cleaning

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The maximum doses of both glyphosate and diuron (1184 and 573.9 mg m-2) were found on the bogey area of the train. The second highest dose for glyphosate was found on the hand rail (86% of the highest measured dose), and for diuron, the main body (77% of the highest measured dose). Whilst both glyphosate and diuron quantities were relatively low on the doors (5 and 18% of the highest measured dose respectively), glyphosate doses were lower still on the main body of the train (3% of the highest measured dose). Glyphosate and diuron were detected inside the cab but at much lower levels than on the outside of the vehicle (< 10 mg m-2). Jet washing the MPV removed over 90% of glyphosate present, but the removal of diuron was not so successful with less than 50% being removed. Furthermore, on the door areas there was an apparent ‘gain’ of diuron after cleaning. Nearly twice the amount of diuron, compared to glyphosate was present on the filter papers, but deposition was comparable between the handrail and walkway for the individual compounds.

Discussion

Despite taking precautions to minimise the potential for contamination during sampling, glyphosate, and to a lesser degree, diuron were found in the control samples. This marginally reduces the reliability of the results and this is accounted for in the discussion. More importantly, the presence of herbicides in the control samples indicated how easily contamination could occur, even when precautions were taken, indicating that glyphosate and diuron residues were readily available for removal onto persons. This was also borne out by the presence of glyphosate and diuron inside the cab. The level of glyphosate in the control sample was approximately a fifth of the level found inside the cab. It is therefore reasonable to assume that glyphosate was present in the cab, although the actual levels cannot be specified. Diuron in the control sample was only 3% of that found inside the cab, thus it can be said that, during this study, diuron was present in the order of 8 mg m-2 on the edge of the window and the handles. As the sampled areas represented sites that were relatively frequently touched by hand, the levels of herbicide found could be indicative of quantities deposited by personnel during normal work routines whom have been contaminated whilst outside the cab. Observation during the spray run noted several practices where transfer of pesticide residue to personnel could potentially occur. The train was equipped with two cabs to enable travel in both directions and exchange occurred six times. This was achieved by either getting off the train and walking down the side of the track, or walking through the train to the opposite end. Stepping off the train involved using the handrail to assist in both the descent from, and ascent onto the walkway. This necessitated either one or both hands grabbing the rail in several places. The results demonstrated that both glyphosate and diuron were present on the hand rails, thus it is possible that contamination may have occurred during this procedure. Walking through the train also gave rise to potential contamination of workers. The gap between the railings and the body of the train was narrow, and contact with the side of the vehicle was inevitable. This was illustrated by a ‘clean’ band at shoulder height contrasting to the surrounding

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white deposit. Furthermore, this powder was clearly visible on clothing having walked through the narrow section. The results also indicated that exposure to residues from the doors would be less from the handrails, but some contamination could still occur. In the bogey area, herbicides levels were highest (1184 and 574 mg m-2 for glyphosate and diuron respectively). This could be expected given that the nozzles were mounted in this area. Operations that could result in persons being in contact with this area include removing herbicide deposit from the lens of the cameras, refilling with fuel and general maintenance. During the spray run in June 2000, all four cameras were cleaned twice and the vehicle refuelled once. Some maintenance also occurred although this was not limited to the bogey area. The operator cleaning the cameras did not wear gloves, but a different operator attended to the auxiliary power unit and they wore thick gloves. With regard to the level of herbicide detected at the different sites, it could be expected that the doors received relatively low doses, as these were facing inwards and may therefore have been more protected from drift. However, in the case of glyphosate, doses were lower on the main body. It is possible that the main body was more exposed to rainfall than the doors and, as glyphosate is highly water soluble (c. 11600 mg L-1), this compound may be removed by rainfall, whilst removal from the doors may be limited due to their more sheltered position. For diuron, quantities found on the main body were comparable to those on the hand rail. The degree of success of the cleaning program may also have been a reflection of the solubility of the herbicides. Over 90% of glyphosate residues were removed by jet washing compared to losses of only 17 to 45% of diuron which has a water solubility of only 36 mg L-1. This was also borne out in the quantities of herbicide detected in the washings, with glyphosate concentrations being more than double those of diuron (Batty, 2000)2. The apparent ‘gain’ in diuron on the doors after cleaning highlights the variability that can occur during normal sampling procedure. It was not possible to take a sample before and after cleaning from exactly the same area, as the initial sample should remove the compounds to be investigated. It is more likely that the higher value of diuron after cleaning is a result of natural variability in concentrations on the doors, rather than any potential error in the analysis. Quantities of herbicide deposited on the filter papers were lower than those found on the outside of the MPV as a whole indicating that herbicides gradually accumulate in the absence of cleaning. It is possible that some cross-contamination may have occurred. For example, as discussed above, there was a high possibility that pesticide residues may be picked up by personnel during normal working practice. This may then have been transferred to the filter paper, even though the residue was initially deposited on the MPV during previous spraying days.

2 Batty, W. (2000) Weed Spraying MPV - Washing Test, Crewe EWS Diesel Depot, 29 June 2000. Serco Railtest Ltd internal report, 13 pp.

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8 REFERENCES Fogg P. (1999). Pesticide residues from spray equipment. Soil Survey & Land Research Centre Research Report, 14 pp. Lichtenber E and Zimmerman, R. (1999). Information and farmers’ attitudes about pesticides, water quality, and related environmental effects. Agriculture Ecosystems and Environment, 73, pp. 227-236. Mason P J, Foster I D L, Carter A D, Walker A, Higginbotham S, Jones R L, Hardy I A J. (2000). Relative importance of point source contamination of surface waters: River Cherwell catchment monitoring study. Proceedings of the XI Symposium Pesticide Chemistry, Human and environmental exposure to xenobiotics, pp. 405-412. Rose S, Carter A and Basford, B. (2001). Development of a design manual for agricultural pesticide handling and washdown areas, Environment Agency R&D Report P2 200/TR/1. Thomas M R. (accessed 1999). Guidelines for the collection of statistics on the usage of plant protection products within agriculture & horticulture. www.csl.gov.uk/prodserv/cons/pesticide/intell/guide.pdf

Yoshida K, Fuzesi I, Suzan M and Nagy L. (1990). Measurements of surface contamination of spray equipment with pesticides after various methods of application. J. Environ. Sci. Health, B25(2), pp. 169-183.

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Printed and published by the Health and Safety Executive C1.25 06/02

CRR 440

£10.00 9 780717 623761

ISBN 0-7176-2376-9