FEATURE

Field-portable methods formonitoring occupationalexposures to metals§

Millions of workers are employed in manufacturing, mining, construction, and other industries wheresignificant amounts of airborne metals and metal compounds are generated. Depending on the workpractices, processes, techniques, and locations, exposures to airborne and surface sources of a variety ofmetals can cause occupational illness. These exposures can lead to a plethora of adverse health effects suchas lung disease, anemia, cancer, asthma, dermal sensitization, dermatitis and neurological damage. Theability to monitor worker exposures to metals on-site in the field has been a goal of the National Institute forOccupational Safety and Health (NIOSH) since the early 1990s. In the last 15 years or so, several field-portable procedures for metals have been developed, evaluated and published as NIOSH methods. Thesemethods, published in the NIOSH Manual of Analytical Methods, describe field screening tests and on-siteanalysis for lead, hexavalent chromium and beryllium. Some of these methods have also been published inthe form of ASTM International voluntary consensus standards. This paper gives an overview of NIOSHresearch and development efforts on field screening and portable analytical methods for metals in theworkplace. The goal of such efforts has been to provide screening and analytical tools that can be used on-site in the field to aid in the prevention of excessive exposures to toxic metals in the workplace.

22 � Division of Chemical Health and Safety of the

Published by Elsevier Inc.

substances in myriad occupations.1

Depending on the work practices, pro-cesses, techniques, and locations, work-ers may be exposed to airborneconcentrations of a wide variety ofmetals and metalloids that may havetoxic effects. Laborers in constructionand mining are exposed to high con-centrations of airborne heavy metals,2

and workers in some industries sufferexposures from toxic elements such asberyllium3 and hexavalent chromium4

on surfaces as well. In the U.S. alone,occupational lead exposures continueto result in high blood lead levels inhundreds of thousands of workers.5

Exposures to aerosols and vapors con-taining inorganic toxic agents can leadto numerous deleterious health effects,such as lung disease and damage toother organs, anemia, asthma, cancer,and neurological effects, to cite a fewexamples.6,7

In 1970, the Occupational Safety andHealth Act (Public Law 91-596) gavethe National Institute for OccupationalSafety and Health (NIOSH) responsi-bility for the development and evalua-tion of samplingand analyticalmethodsfor workplace exposure monitoring.Occupational exposure monitoring totoxic substances is conducted by public

American Chemical Society

health professionals in order to deter-mine whether exposures are in excess ofpertinent occupational exposure limits(OELs), e.g., NIOSH RecommendedExposure Limits (RELs).8 Presently,the most commonly used method forassessment of worker exposures entailscollection of air samples, which is fol-lowed by subsequent laboratory analy-sis. Generally speaking, metallicaerosols are collected onto filters9

which are subsequently analyzed inorder to obtain an estimate of expo-sure.10 For aerosol collection, therehas been recent interest towards theuse of inhalable samplers, rather than‘total’ aerosol samplers.11,12 Samplingof smaller size fractions, e.g., respirableor thoracic, may also be pertinent forexposure assessment involving metallicaerosols.13 Apart from air samples, inrecent years there has been increasedinterest in monitoring of surface dust,14

since occupational exposures to toxicmaterials can sometimes occur viaworker contact with contaminated sur-faces. New work activities and pro-cesses have also resulted in a desirefor novel industrial hygiene samplingand analysis techniques.15 All of thesescenarios present new analytical chal-lenges that need to be addressed.

By Kevin Ashley

INTRODUCTION

Millions of workers in the UnitedStates are exposed to inorganic toxic

Kevin Ashley, Ph.D., is a research che-mist with the US Department of Healthand Human Services, Centers for Dis-ease Control and Prevention, NationalInstitute for Occupational Safety andHealth, 4676 Columbia Parkway, MailStop R-7, Cincinnati, OH 45226-1998,USA (Tel.: +513 841 4402;e-mail: KAshley@cdc.gov). Dr. Ashleyserves as chair of ASTM InternationalSubcommittee D22.04 on WorkplaceAir Quality.

§This article was prepared by US Gov-ernment employees as part of theirofficial duties and legally may not becopyrighted in the United States ofAmerica. Mention of company namesor products does not constitute endor-sement by the Centers for DiseaseControl and Prevention. The findingsand conclusions in this article arethose of the author and do not neces-sarily represent the views of theNational Institute for OccupationalSafety and Health.

1871-5532/$36.00

doi:10.1016/j.jchas.2009.07.002

To this end, much of the researcheffort in our laboratory has been direc-ted towards the development, evalua-tion and validation of user-friendlyprocedures that can be employed foron-site monitoring of toxic metals inoccupational environments. Construc-tion and mining industries have beenthe primary targets of application forfield-portable monitoring methods, butsuch procedures can be taken to otherworkplace environments as well, nota-bly manufacturing. On-site methodsfor the determination of lead16,17 andhexavalent chromium18,19 in filtersamples collected from workplace airhave been used successfully in fieldstudies. In addition to air filter sam-ples, portable anodic stripping voltam-metry (ASV) has also been shown toperform well for measuring lead in sur-face dust samples collected usingwipes.20 Portable X-ray fluorescence(XRF) can provide on-filter quantita-tive measurement of a number of heavymetals in samples collected from work-place atmospheres.21 In other work, amolecular fluorescence method for thedetermination of trace beryllium inworkplace air and wipe samples hasbeen developed and validated.22 Inseveral instances, field methods havebeen shown to meet NIOSH criteriafor method accuracy.23

The aim of this paper is to provide anoverview of the available field-portablemethods for metals that have beenpublished as NIOSH methods and/oras ASTM International (formerlyAmerican Society for Testing andMaterials) voluntary consensus stan-dards. Depending on the specific appli-cation, definitive (quantitative), semi-quantitative and screening methodsare all useful in the industrial hygienefield. Portable methods offeringdesired performance characteristicsare available for some metals, notablylead, beryllium and chromium. Fieldscreening test method performancehas been treated in a general fashionusing a rigorous statistical protocol,24

with applications having been demon-strated for examples entailing leadmonitoring in the workplace.25 Usinga statistical formalism to treat collecteddata, performance criteria and charac-teristics of field-portable methods canbe estimated for qualitative, semi-

Journal of Chemical Health & Safety, May/J

quantitative, and quantitative mea-surement procedures. The applicationis general for any analyte, and allowsfor results from screening tests to beused in making defensible decisionsconcerning potential human expo-sures to toxic substances. This researchprovides a basis for investigations onthe evaluation of field screening meth-ods for toxic inorganic species of inter-est in occupational safety and health.

NIOSH METHODS

Field-portable analytical methods formetals that have been approved andpublished in the NIOSH Manual ofAnalytical Methods include examplesof qualitative, semi-quantitative andquantitative procedures. Qualitativescreening methods have beendescribed by NIOSH for detecting leadin air filters, as well as for the detectionof lead or hexavalent chromium inwipe samples. A semi-quantitativeNIOSH method for estimating leadloadings in air filter samples, basedon the use of portable XRF, has alsobeen promulgated. Quantitative mea-surement procedures for metals thathave been approved as NIOSH meth-ods include: (a) lead determination inair samples by portable ASV; (b) deter-mination of hexavalent chromium inair by portable spectrophotometry;and (c) on-site determination of ber-yllium in air filters or wipe samples by amolecular fluorescence technique.Salient details regarding these meth-odologies are provided in the followingparagraphs.

A screening technique for testing forthe presence of lead in air filter sam-ples, NIOSH Method 7700,26 entailsthe use of a colorimetric chemicalspot-test kit applied to the particulatematter collected on the filters. A char-acteristic color change on the filter(i.e., from yellow/orange to pink/redhues) indicates the presence of lead inthe collected aerosol. To evaluate themethod, a commercial rhodizonate-based spot test kit was evaluated forits potential use in the detection of leadin airborne particulate matter.27 Bat-tery-powered personal samplingpumps were used to collect over 370air samples on cellulose ester mem-

une 2010

brane filters at various worksites wherelead was a suspected air contaminant.Each filter sample was tested with anindividual chemical spot test, and thesamples (test kit materials included)were then analyzed using referencemeasurement of lead by graphite fur-nace atomic absorption spectrometry(GFAAS) as described by NIOSHMethod 7105.28 The experimental datawere statistically modeled in order toestimate the performance parametersof the spot test kit. A positive readingwas found at 95% confidence for leadmass values above about 10 mg Pb perfilter, while 95% confidence of a nega-tive reading was found for lead massesbelow �0.6 mg Pb per filter.27 Giventhese performance measures, in thefield the spot test screening techniquecan be used to estimate, using short- ormedium-term sampling, whether leadexposures will be expected to exceedapplicable OELs, e.g., the Occupa-tional Safety and Health Administra-tion (OSHA) Personal ExposureLimits (PELs) for lead. Tl+, Ag+,Cd2+, Ba2+, and Sn2+ also form coloredcompounds with rhodizonate ion, butwith less sensitivity than that of Pb2+,and only the lead–rhodizonate com-plex gives the characteristic pink orred color.29

A similar colorimetric screeningmethod for the presence of lead inwipe samples has been described in aNIOSH procedure.30 The method wasdesigned as a handwipe method fordetecting lead collected from humanskin,31 but it is also applicable to wipesamples obtained from various non-dermal surfaces including floors, walls,equipment, furniture, etc. The methodhas been evaluated preliminarily usingcommercial wipes spiked with certifiedreference materials (CRMs), and hasbeen found to give a positive responsefor at least 10 mg of lead per wipe. Themethod has also been subjected tolimited field testing, and shows a posi-tive response for at least a few tens ofmicrograms of lead per wipe. Extre-mely heavy soiling on the wipe couldinterfere with visualization of the redcolor change due to darkening of thewipe, but the pink or red hues shouldstill be visible around the area of theheaviest soiling, provided lead is pre-sent. Difficult matrices (e.g., dust wipes

23

containing paint chips) may requireleaching in dilute nitric acid beforespot testing. In addition to the metallicinterferences mentioned above for airfilter samples screened using rhodizo-nate-based test kits, interferences fromthe wipe medium, e.g., surfactants, arealso possible.

Hexavalent chromium, Cr(VI), canbe detected colorimetrically at tracelevels using diphenylcarbazide, andthis chemistry has been applied tothe detection of Cr(VI) in wipe sam-ples.32 The method reportedly candetect masses as low as a microgramof Cr(VI) per sample, but unfortu-nately no evaluation data are available.In any case, a qualitative screeningprocedure could be useful to detecttraces of Cr(VI) in surface dust col-lected using wipes. Follow-up analysiswith more definitive methods is recom-mended.

Portable XRF measurement of leadin aerosols collected onto air filters hasbeen described in a NIOSH method.33

This methodology was validated onfield samples by collecting lead parti-culate samples from bridge lead abate-ment projects.34 Airborneconcentrations of lead within the con-tainment area of a sand blasting bridgelead abatement project ranged from 1to 10 mg/m3. Area and personal sam-ples were collected for periods of timeranging from 15 s to 2 hours. This sam-pling protocol yielded 65 filter sampleswith lead loadings ranging between 0.1and �1,500 mg of lead per sample. Thefilter samples obtained were first ana-lyzed using a non-destructive, field-portable XRF method, and the sampleswere subsequently subjected to refer-ence analysis by the laboratory-basedNIOSH Method 7105.28 The portableXRF method was statistically evalu-ated in accordance with NIOSHguidelines.23 The overall precision ofthe portable XRF method was calcu-lated at 0.054 (95% confidence interval(CI) = 0.035–0.073), and the bias was0.069 (95% CI = 0.006–0.152). Theportable XRF method accuracy wasdetermined to be �16%; however, atthe upper 90% CI, the accuracy is�27%. Since the confidence intervalexceeds �25%, meeting the NIOSHaccuracy criterion23 is inconclusive;hence, this measurement technique

24

may be regarded as ‘‘semi-quantita-tive’’.24 However, it is noted that thesamples used to evaluate the portableXRF method were field samples;laboratory-prepared aerosol samplesgive better precision.21 Additionally,it should be pointed out that the por-table XRF method is non-destructive;if required, samples analyzed on-site inthe field can subsequently be trans-ported and analyzed in a fixed-sitelaboratory using a method with greateraccuracy. Portable XRF may also beextendable to the detection of leadon surfaces after collection using wipemedia.35

Quantitative on-site analysis of airfilter samples for the determination oflead by field-based ultrasonic extrac-tion with ASV measurement has beenpublished as a NIOSH method.36 Thismethod was evaluated with lead aero-sol samples generated in the laboratory(�40 to �80 mg Pb per filter),37 andwith air particulate samples collectedfrom workplaces where abrasive blast-ing of leaded paint on highway bridgeswas being conducted.38 For the latter,lead masses covered the range frombelow the detection limit of 0.09 mgPb per filter to loadings in excess of1,500 mg Pb per filter. The method alsohas been evaluated with performanceevaluation materials and by interla-boratory testing.39 Lead recoveriesfrom CRMs were found to be quanti-tative (>90%) and equivalent to recov-eries obtained using confirmatoryanalytical methods (e.g., NIOSH710528). Thallium is a known interfer-ant, but its presence is unlikely in thevast majority of occupational air sam-ples. Extremely high concentrations ofcopper may cause a positive bias. Sur-factants can poison electrode surfaces,so if the presence of surfactants is sus-pected, such interferences must beeliminated during sample preparation.

A quantitative method describingthe trace determination of berylliumin air samples by field-based extractionand fluorescence measurement hasbeen published in the most recent edi-tion of the NIOSH Manual of Analy-tical Methods.40 The method entailsextraction of beryllium in air filter sam-ples for 30 min using dilute (1%, aqu-eous) ammonium bifluoride, withsubsequent fluorescent measurement

Journal of Che

after reaction of dissolved berylliumdication with the high-quantum yieldfluorophore, hydroxybenzoquinolinesulfonate.22 Experiments were con-ducted using several commercial por-table fluorescence devices. Themethod was evaluated using berylliumoxide spiked onto mixed-celluloseester (MCE) filters at various levels(0, 0.02, 0.1, 0.2, 0.3, 0.4, 1.5, 3.0,and 6.0 mg; five samples at each level).Long-term stability of samples was ver-ified from spikes (number [n] = 30) of0.1 mg Be on MCE filters. Sampleswere analyzed at day one (n = 12)and then 1 week (n = 6), 10 days(n = 3), 2 weeks (n = 3), 3 weeks(n = 3), and 1 month (n = 3) after spik-ing. No diminution of fluorescence sig-nal was observed from samplesprepared and analyzed after havingbeen stored for up to 30 days. Inter-ference tests were carried out usingsolutions of 0 nmol/L, 100 nmol/L,and 1.0 mmol/L Be in the presence of0.4 mmol/L of Al, Ca, Co, Cu, Fe, Ti,Li, Ni, Pb, Sn, U, V, W, or Zn (separateexperiments were carried out for eachpotential interferant). Minor interfer-ence from iron can result if iron con-centrations are high (e.g., �100� theberyllium concentration). Sampleshigh in iron demonstrate a yellow orgold coloration. This interference canbe minimized by allowing the solutionto sit for 4 hours or more, during whichtime the solution clears, and then fil-tering the sample extract before use.Interlaboratory evaluations of themethod were also performed on bothsoluble and refractory beryllium com-pounds.22,41 When high-temperature(�90 8C) extraction is employed, themethod is effective for quantitative dis-solution and determination of high-fired (calcined) beryllium oxide inaerosol samples. Ultra-trace determi-nation of beryllium in air samples hasbeen achieved, with attainable methoddetection limits of less than a nano-gram of beryllium per sample.41 It ispertinent to note that the methoddetection limit of the portable fluores-cence method for beryllium is compar-able to that of inductively coupledplasma mass spectrometry (ICP-MS).42

A companion NIOSH method fordetermining beryllium in surface wipe

mical Health & Safety, May/June 2010

Table 1. NIOSHfield-portablemethods formetalsmeasurement insamplescollected inoccupational settings.26,30,32,33,36,40,43,45

Methodnumber

Samplemedium

Element/species Sample preparation Detection method Estimated MDLa

7700 Air filters Pb Extraction (weak acid) Colorimetry(chemical spot test)

<10 mg/sample

7701 Air filtersb Pb Ultrasonic extraction (dilute HNO3) Anodic strippingvoltammetry

0.09 mg/sample

7702 Air filtersc Pb None X-ray fluorescence 6 mg/sample7703 Air filters Cr(VI) Ultrasonic extraction

(sulfate or carbonate buffer)d; SPEeSpectrophotometry 0.08 mg/sample

7704 Air filters Be Extraction (dilute NH4HF2) Fluorescence 0.0008 mg/sample9101 Wipes Cr(VI) Extraction (dilute H2SO4);

pH adjustment (carbonate buffer)Colorimetry(chemical spot test)

1 mg/sample

9105 Wipes Pb Extraction (weak acid) Colorimetry(chemical spot test)

�10 mg/sample

9110 Wipes Be Extraction (dilute NH4HF2) Fluorescence 0.0008 mg/samplea Method detection limit.b With minor modification, method is also applicable to wipe samples.c With modification, method may also beapplicable to wipe samples.d For soluble or insoluble Cr(VI) compounds, respectively; addition of phosphoric acid is recommended forsamples high in iron.e Solid-phase extraction; for many sample matrices, this step can be omitted.

samples has also been promulgated.43

Method evaluation and validation oncellulosic filter materials were carriedout in a similar fashion as describedabove for air filter samples. Trace22

and ultra-trace41 quantitative determi-nation of beryllium in wipe sampleshas been demonstrated, along withexcellent intra- and inter-laboratoryreproducibility. A modification of theprocedure, in which longer-termextraction (4 hours) is carried out ina slightly higher concentration (3%) ofaqueous ammonium bifluoride,enables quantitative extraction of lar-ger particle sizes (up to >200 micronsaerodynamic diameter) of high-firedberyllium oxide.44 The method yieldedacceptable recoveries from refractoryBeO in several different samplingmedia tested.

A field-portable spectrophotometricNIOSH method for determiningCr(VI) in air filter samples entailsfield-based ultrasonic extraction inbasic buffer, followed by measurementof the chromium–diphenylcarbazideadduct.45 Strong anion-exchangesolid-phase extraction (SAE-SPE)46,47

enables isolation of Cr(VI) from othermetallic interferants such as trivalentiron, manganese and mercury. Thismethod was evaluated in the labora-tory with spiked filters47,48 and with aCRM containing a certified loading ofCr(VI).47 (This European CRM, con-sisting of Cr(VI) and Cr(total) in weld-ing dust loaded on a glass fiber filter,49

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is no longer available.) The NIOSHportable method for Cr(VI) has alsobeen evaluated in the field, where sam-ples collected during aircraft mainte-nance and painting operations wereanalyzed on-site.18,19 Filters used forsample collection can be pretreatedwith base to minimize Cr(VI) reduc-tion during sampling in high-iron oracidic environments.50 SAE-SPE canbe omitted if suspected metallic inter-ferences are not present, or can beminimized by other means, e.g., withinclusion of phosphoric acid duringextraction.51 Recent studies haveextended applications of the methodto extraction of insoluble Cr(VI) com-pounds52 and sequential extraction ofsoluble and insoluble Cr(VI) species.53

Table 1 summarizes the NIOSHfield-portable methods for metals mea-surement described above.

ASTM METHODS

Voluntary consensus standards such asthose published by ASTM Interna-tional are considered by many to bethe most technically sound and mostcredible documents for use in theirparticular fields of application. Thiswas recognized by the U.S. Congressthrough passage of the National Tech-nology Transfer and Advancement Actof 1995 (Public Law104-113), whichdirects federal agencies to: (a) rely onconsensus standards in their guidelines

une 2010

and activities, and (b) participate in theconsensus standards development pro-cess. Experts from relevant federalagencies have contributed significantlyto the development of numerousASTM standards that apply to the fieldof industrial hygiene chemistry. WithinASTM International Committee D22on Air Quality, Subcommittee D22.04on Workplace Air Quality producesstandards that describe methods tocollect and measure chemical hazardsin the workplace.54 This subcommitteehas been active for decades, and itsmembers have developed manyneeded standards consisting of testmethods, practices, and guides. Theseconsensus standards are meant for useby industrial hygienists, chemists, engi-neers, health physicists, toxicologists,epidemiologists, and myriad other pro-fessionals. Experts from private indus-try, government, and academia have allcontributed extensively to the develop-ment of standards for workplace con-taminant monitoring. One of thevoluntary consensus standards pro-duced by ASTM International Sub-committee D22.04 describes field-portable procedures for trace beryl-lium monitoring. Also, ASTM Interna-tional Subcommittee E06.23 onMitigation of Lead Hazards has pub-lished several standards pertaining toon-site measurement of lead in occu-pational environments.55 Pertinentdetails on specific ASTM standardsdescribing on-site sample preparation

25

Table 2. ASTM standards pertaining to on-site metals determination in samples collected in occupational settings.56,58–61,63,64

Standardnumber

Type ofstandard Sample media

Element(s)/species Comments

D6966 Practice Wipes Metals Collected samples can be analyzed on-site(e.g., for Be, Pb)

D7144 Practice Micro-vacuumsample

Metals Collected samples can be analyzed on-site(e.g., for Be, Pb, Cr(VI))

D7202 Test method Air filters or wipes Be Based on NIOSH methods 7704/9110E1775 Guide Air filters, wipes,

paint, soilPb Outlines performance criteria for field-portable

measurement by electroanalysis or spectrophotometryE1792 Specification Wipes Pba Describes required characteristics of wipe media

to be used for collection of Pb on surfacesE1979 Practice Air filters, wipes,

paint, soilPb Ultrasonic extraction in dilute HNO3; can be

followed by electroanalysis (e.g., using ASTM E2051)E2051 Practice Air filters, wipes,

paint, soilPb Samples previously extracted (e.g., using ASTM E1979)

a Also applicable to other elements.

and analysis of beryllium and lead inoccupational environments are givenbelow.

ASTM D7202 describes a testmethod that is intended for use in thedetermination of beryllium by samplingworkplace air or surface dust.56 Themethod assumes that air and surfacesamples are collected using appropriateand applicable ASTM Internationalstandard practices for sampling ofworkplace air and surface dust. Thesesamples are typically collected using airfilter sampling,57 vacuum sampling58 orwiping59 techniques. The methodincludes a procedure for on-site extrac-tion (dissolution)ofberylliuminweaklyacidic medium (pH of 1% aqueousammonium bifluoride is 4.8), followedbyfieldanalysis ofaliquotsof theextractsolution using a beryllium-specificfluorescent dye, hydroxybenzoquino-line sulfonate.The procedure is targetedfor on-site use in the field for occupa-tional and environmental hygiene mon-itoring purposes, and can be used todetermine as low as a few nanogramsof beryllium in collected samples. Thisvoluntary consensus standard methodwas developed based on the aforemen-tioned NIOSH procedures40,43 for on-site determination of beryllium in theworkplace.

Lead contamination in paint, dust,soil and air represents a potentialhealth hazard to people, and field-por-table analytical methods for the deter-mination of this toxic metal inenvironmental samples are desired

26

for the on-site assessment of leadhazards. On-site determination of leadin occupational hygiene samplesobtained using consensus standardsampling techniques is described inASTM procedures for field-basedultrasonic extraction60 and electroana-lysis (e.g., ASV),61 respectively. TheseASTM standards were developedbased on the NIOSH method36

described earlier. Compared to tradi-tional digestion methods that employhot plate 57,62 or microwave diges-tion57 with concentrated acids, ultra-sonic extraction using dilute nitricacid60 is a simple, yet effective, methodfor extracting lead from air filter andwipe samples. Hence, ultrasonicextraction may be used in lieu of themore rigorous strong acid/high-tem-perature digestion methods, providedthat the overall method performance isdemonstrated using acceptance cri-teria as delineated in ASTM GuideE1775.63 In contrast with hot plateand microwave digestion techniques,the equipment required for ultrasonicextraction is field-portable, whichallows for on-site sample analysis.

Field-portable techniques (such asASV) for the determination of lead inenvironmental and occupationalhygiene samples, notably air filtersand wipe samples, may allow for rapidassessments of lead hazards and corre-sponding cost reductions compared totraditional fixed-site laboratory-basedanalyses. Prior to analysis in accor-dance with ASTM standard protocols,

Journal of Che

the use of standardized sampling tech-niques for lead in air57 and on sur-faces58,59 is highly recommended.Moreover, for leaded dust wipe sam-pling, it is urged to use a standardizedwipe material.64 Standardization ofsampling materials, sample collectionprocedures, sample preparation proto-cols, and analytical methods is meant tooptimize overall analytical perfor-mance and interlaboratory comparabil-ity. Using these ASTM standardmethods, practices, guides and specifi-cations, on-site measurement of leadcontent in workplace samples may beused for compliance with applicablefederal, state, and local regulationsand guidelines, providing accepted per-formance criteria are demonstrated tobe met.

Table 2 provides an overview of theASTM standards relating to the field-portable methods for metals describedin this section.

CONCLUDING REMARKS

Traditionally, workplace samples forsubsequent metals determination havebeen sent away to fixed-site labora-tories for analysis. In some cases, theanalytical results can take many weeksto be reported. Such delays can com-promise worker health if exposures areexcessive. The use of field-portablemethods and instrumentation for on-site metals monitoring is meant to alle-viate such problems that may be

mical Health & Safety, May/June 2010

brought on by delayed analyticalresults. Methods relying on field-porta-ble instruments and tests allow forscreening and/or analysis of occupa-tional hygiene samples on location withsame-day speed.65 While most of themethods described in this paper donot rely on direct-reading monitoringtechniques, they are nonethelessinvaluable for obtaining rapid analysisresults. Additionally, samples that areanalyzed non-destructively in the fieldcan be sent for confirmatory analysis ifexposures appear to approach orexceed applicable OELs. This canreduce the number of samples that areconveyed to fixed-site laboratories andmakes the overall exposure assessmentprocess more cost-effective. Use offield-portable methods can also facili-tate the proper selection and evaluationof exposure controls to reduce thepotential for adverse health effectsamong workers. The NIOSH andASTM International methods and stan-dards highlighted in this article repre-sent accepted government andconsensus standard procedures foron-site monitoring of metals, notablylead, beryllium and hexavalent chro-mium.a While there is redundancybetween some of the NIOSH andASTM field-portable analytical meth-ods discussed here, the availability ofvoluntary consensus standards is oftendesiredbypotential users.Also, relianceon consensus standards may berequired by accreditation and certifica-tion bodies.

ACKNOWLEDGMENTSAppreciation is extended to LeroyDobson of the Wisconsin Occupa-tional Health Laboratory, as well asYvonne Gagnon, Bob Streicher andDave Utterback of NIOSH, for review-ing the draft manuscript.

REFERENCES1. U.S. Census Bureau. Statistical Ab-

stract of the United States–2000, 20thed. U.S. Census Bureau; Washington,2000.

a NIOSH methods and ASTM stan-dards are available online at www.cdc.gov/niosh/nmam and www.astm.org,respectively.

Journal of Chemical Health & Safety, May/J

2. King, R. W.; Hudson, R. ConstructionSafety Handbook; Butterworths; Lon-don, 1985.

3. Berlin, J. M.; Taylor, M. S.; Sigel, M. E.;Bergfeld, W. F.; Dweik, R. A. J. Am.Acad. Dermatol. 2003, 49, 939–941.

4. Flint, G. N.; Carter, S. V.; Fairman, B.Cont. Derm. 1998, 39, 315–316.

5. Alarcon, W. A.; Roscoe, R. J.; Calvert,G. M.; Graydon, J. R. Morbid. Mortal.Wkly. Rpt. 2009, 58, 365–369.

6. Ruegger, M. Schweiz Med. Wschr.1995, 125, 467–474.

7. Hathaway, G. J.; Proctor, N. H.;Hughes, J. P.; Fischman, M. L. ChemicalHazards in the Workplace, 3rd ed. VanNostrand Reinhold; New York, 1991.

8. National Institute for OccupationalSafety and Health (NIOSH). Recom-mendations for Occupational Safetyand Health—Compendium of PolicyDocuments and Statements; NIOSH;Cincinnati, 1992.

9. Lee, K. W.; Ramamurthi, M. Filtercollection, In P. A. Baron, & K. Willeke(Eds.), Aerosol Measurement—Princi-ples, Techniques, and Application.Van Nostrand Reinhold: New York,1992 Chapter 10.

10. Beliles, R. P. The metals, In G. D.Clayton, & F. E. Clayton (Eds.), Patty’sIndustrial Hygiene and Toxicology,Vol. II, Part C. (4th ed.). Wiley: NewYork, 1994.

11. Kenny, L. C.; Aitken, R.; Chalmers, C.;Fabries, J. F.; Gonzalez-Fernandez, E.;Kromhout, H.; Liden, G.; Mark, D.;Riediger, G.; Prodi, V. Ann. Occup.Hyg. 1997, 41, 135–153.

12. Harper, M.; Demange, M. J. Occup.Environ. Hyg. 2007, 4, D81–D86.

13. Maynard, A. D.; Jensen, P. A. Aerosolmeasurement in the workplace,In P. A. Baron, & K. Willeke (Eds.),Aerosol Measurement—Principles,Techniques, and Application. VanNostrand Reinhold: New York, 1992Chapter 25.

14. Wheeler, J. P.; Stancliffe, J. D. Ann.Occup. Hyg. 1998, 42, 477–488.

15. Draper, W. M.; Ashley, K.; Glowacki,P. R.; Michael, C. R. Anal. Chem. 1999,71, 33R–60R.

16. Sussell, A.; Ashley, K. J. Environ.Monit. 2002, 4, 156–161.

17. Drake, P. L.; Lawryk, N. J.; Ashley, K.;Sussell, A. L.; Hazelwood, K. J.; Song,R. J. Hazard. Mater. 2003, 102, 29–38.

18. Marlow, D.; Wang, J.; Wise, T. J.;Ashley, K. Am. Lab. 2000, 32(15), 26–28.

19. Boiano, J. M.; Wallace, M. E.; Sieber,W. K.; Groff, J. H.; Wang, J.; Ashley, K.J. Environ. Monit. 2000, 2, 329–333.

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20. Ashley, K.; Wise, T. J.; Mercado, W.;Parry, D. B. J. Hazard. Mater. 2001, 83,41–50.

21. Lawryk, N. J.; Feng, H. A.; Chen, B. T. J.Occup. Environ. Hyg. 2009, 6, 433–445.

22. Agrawal, A.; Cronin, J.; Tonazzi, J.;McCleskey, T. M.; Ehler, D. S.; Mino-gue, E. M.; Whitney, G.; Brink, C.;Burrell, A. K.; Warner, B.; Goldcamp,M. J.; Schlecht, P. C.; Sonthalia, P.;Ashley, K. J. Environ. Monit. 2006, 8,619–624.

23. Kennedy, E. R.; Fischbach, T. J.; Song,R.; Eller, P. M.; Shulman, S. Guidelinesfor Air Sampling and Analytical Meth-od Development and Evaluation;NIOSH; Cincinnati, 1995.

24. Song, R.; Schlecht, P. C.; Ashley, K. J.Hazard. Mater. 2001, 83, 29–39.

25. Ashley, K.; Song, R.; Schlecht, P. C.Am. Lab. 2002, 34(12), 32–39.

26. NIOSH. Method 7700: Lead in air bychemical spot test, NIOSH Manual ofAnalytical Methods. 4th ed. (Suppl. I)NIOSH; Cincinnati, 1996.

27. Ashley, K.; Fischbach, T. J.; Song, R. Am.Ind. Hyg. Assoc. J. 1996, 57, 161–165.

28. NIOSH. Method 7605: Lead by GFAAS,NIOSH Manual of Analytical Methods.4th ed. NIOSH; Cincinnati, 1994.

29. Feigel, F.; Anger, V. Spot Tests inInorganic Analysis; Elsevier; Amster-dam, 1972, pp. 282–287, 564–566, 569.

30. NIOSH. Method 9105: Lead in dustwipes by chemical spot test (colori-metric screening method), NIOSHManual of Analytical Methods. 4th ed.(Suppl. IV) NIOSH; Cincinnati, 2003.

31. Esswein, E. J.; Boeniger, M. F.; Ashley,K. Handwipe Disclosing Method forthe Presence of Lead. U.S. Pat.6,248,593 (2001).

32. NIOSH. Method 9101: Chromium,hexavalent, in settled dust samples,NIOSH Manual of Analytical Meth-ods. 4th ed. (Suppl. I) NIOSH; Cincin-nati, 1996.

33. NIOSH. Method 7702: Lead by field-portable XRF, NIOSH Manual ofAnalytical Methods. 4th ed. (Suppl.II) NIOSH; Cincinnati, 1998.

34. Morley, J. C.; Clark, C. S.; Deddens, J.;Ashley, K.; Roda, S. Appl. Occup.Environ. Hyg. 1999, 14, 306–316.

35. Harper, M.; Hallmark, T. S.; Bartoluc-ci, A. A. J. Environ. Monit. 2002, 4,1025–1033.

36. NIOSH. Method 7701: Lead by field-portable ultrasonic extraction/ASV,NIOSH Manual of Analytical Meth-ods. 4th ed. (Suppl. II) NIOSH; Cin-cinnati, 1998.

37. Ashley, K. Electroanalysis, 1995, 7,1189–1192.

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38. Ashley, K.; Mapp, K. J.; Millson, M. Am.Ind. Hyg. Assoc. J. 1998, 59, 671–679.

39. Ashley, K.; Song, R.; Esche, C. A.;Schlecht, P. C.; Baron, P. A.; Wise, T.J. J. Environ. Monit. 1999, 1, 459–464.

40. NIOSH. Method 7704: Beryllium inair by field-portable fluorometry,NIOSH Manual of Analytical Meth-ods. 5th ed. NIOSH; Cincinnati, 2007.

41. Ashley, K.; Agrawal, A.; Cronin, J.;Tonazzi, J.; McCleskey, T. M.; Burrell,A. K.; Ehler, D. S. Anal. Chim. Acta,2007, 584, 281–286.

42. Ashley, K.; Brisson, M. J.; Howe,A. M.; Bartley, D. L. J. Occup. Environ.Hyg., in press, doi:10.1080/15459620903022605.

43. NIOSH. Method 9110: Beryllium insurface wipes by field-portable fluoro-metry, NIOSH Manual of AnalyticalMethods. 5th ed. NIOSH; Cincinnati,2007.

44. Goldcamp, M. J.; Goldcamp, D. M.;Ashley, K.; Fernback, J. E.; Agrawal, A.;Millson, M.; Marlow, D.; Harrison, K.J. Occup. Environ. Hyg., in press,doi:10.1080/15459620903012044.

45. NIOSH. Method 7703: Chromium,hexavalent, by field-portable spectro-photometry, NIOSH Manual of Analy-tical Methods. 4th ed. (Suppl. IV)NIOSH; Cincinnati, 2003.

46. Wang, J.; Ashley, K.; Marlow, D.;England, E. C.; Carlton, G. Anal.Chem. 1999, 71, 1027–1032.

47. Wang, J.; Ashley, K. Method for theDetermination of Hexavalent Chro-mium using Ultrasonic Extraction andStrong Anion Exchange Solid PhaseExtraction. U.S. Pat. 6,808,931 (2004).

48. Wang, J.; Ashley, K.; Kennedy, E. R.;Neumeister, C. Analyst, 1997, 122,1307–1312.

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49. Commission of the European Commu-nities, Institute for Reference Materialsand Measurements (EC/IRMM). Certi-ficate of Analysis, CRM 545—Cr(VI)and Total Leachable Cr in WeldingDust Loaded on a Filter; EC/IRMM;Brussels, 1997.

50. Ashley, K.; Howe, A. M.; Demange, M.;Nygren, O. J. Environ. Monit. 2003, 5,707–716.

51. Deutsche Forschungsgemeinschaft(DFG). Methods for the determinationof hexavalent chromium—Cr(VI)method no. 3, Kettrup, A. Ed., Analysisof Hazardous Substances in Air, vol. 4,Wiley-VCH: Weinheim, 1993.

52. Hazelwood, K. J.; Drake, P. L.; Ashley,K.; Marcy, D. J. Occup. Environ. Hyg.2004, 1, 613–619.

53. Ashley, K.; Applegate, G. T.; Marcy, A.D.; Drake, P. L.; Pierce, P. A.; Carabin,N.; Demange, M. J. Environ. Monit.2009, 11, 318–325.

54. Ashley, K.; Harper, M. J. Occup. En-viron. Hyg. 2005, 2, D44–D47.

55. ASTM International. ASTM Standardson Lead Hazards Associated withBuildings; ASTM International; WestConshohocken, PA, 1998.

56. ASTM International. ASTM D7202,Standard Test Method for the Determi-nation of Beryllium in the Workplaceusing Field-based Extraction andFluorescence Detection; ASTM Inter-national; West Conshohocken, PA,2006.

57. ASTM International. ASTM D7035,Standard Test Method for the Determi-nation of Metals and Metalloids inWorkplace Air by Inductively CoupledPlasma Atomic Emission Spectrome-try; ASTM International; West Con-shohocken, PA, 2004.

Journal of Che

58. ASTM International. ASTM D7144,Standard Practice for Collection ofSurface Dust by Micro-vacuum Sam-pling for Subsequent Metals Determi-nation; ASTM International; WestConshohocken, PA, 2005.

59. ASTM International. ASTM D6966,Standard Practice for Wipe Samplingof Surfaces for Subsequent Determina-tion of Metals; ASTM International;West Conshohocken, PA, 2003.

60. ASTM International. ASTM E1979,Standard Practice for Ultrasonic Extrac-tion of Paint, Dust, Soil, and AirborneParticles for Subsequent Determinationof Lead; ASTM International; WestConshohocken, PA, 2003.

61. ASTM International. ASTM E2051,Standard Practice for the Determina-tion of Lead in Paint, Settled Dust,Soil, and Air Particles by Field-Por-table Electroanalysis; ASTM Interna-tional; West Conshohocken, PA, 2001.

62. ASTM International. ASTM E1644,Standard Practice for Hot Plate Diges-tion of Dust Wipe Samples for theDetermination of Lead; ASTM Inter-national; West Conshohocken, PA,2004.

63. ASTM International. ASTM E1775,Standard Guide for Evaluating thePerformance of On-Site Extractionand Electrochemical or Spectrophoto-metric Determination of Lead; ASTMInternational; West Conshohocken,PA, 2007.

64. ASTM International. ASTM E1792,Standard Specification for Wipe Sam-pling Materials for Lead in SurfaceDust; ASTM International; West Con-shohocken, PA, 2003.

65. Lawryk, N. J.; Ashley, K.; Drake, P. L.Synergist, 2005, 16(5), 54–61.

mical Health & Safety, May/June 2010