EXPOSURE ANALYSIS -CHAPTER 15 pdf

Many pesticides are SVOCs and vaporize when applied to indoor surfaces, and theremay be significant temporal and spatial variations of pesticide concentrations in a home.. Beforepesticid

Robert G Lewis

U.S Environmental Protection Agency (ret.)

CONTENTS

15.1 Synopsis 347

15.2 Introduction 348

15.3 Pesticide Regulation 348

15.4 Residential and Commercial Building Use 349

15.5 Air Monitoring Methods 350

15.6 House Dust Sampling Methods 355

15.7 Contact-Dislodgeable Residue Monitoring Methods 357

15.8 Handwipe Methods 361

15.9 Occurrence, Sources, Fate, and Transport in the Indoor Environment 363

15.10 Exposure Risks and Health Effects 368

References 370

15.1 SYNOPSIS

There are at least 600 different pesticides in use and 45,000 to 50,000 pesticide formulations that may include one or more pesticides as active ingredients (a.i.) Pesticides consist of a wide variety

of chemical compounds ranging from inorganic substances such as elemental sulfur and chromated copper arsenate, volatile organic compounds (VOCs) such as methyl bromide and paradichloroben-zene, semivolatile organic compounds (SVOCs) such as diazinon and chlorpyrifos, and nonvolatile organic compounds (NVOCs) such as 2,4-D and permethrin In the United States, the Environmental Protection Agency (USEPA) is responsible for registering new pesticides and reviewing existing pesticides for re-registration to avoid unreasonable risks to human health and the environment Potential human risks include acute (short-term) reactions, such as toxic poisoning or skin and eye irritation, as well as possible chronic (long-term) effects such as cancer, birth defects, or reproductive system disorders The Food Quality Protection Act (FQPA) sets tolerances for all pesticides residues

in food based on a “reasonable certainty” that they will do “no harm” to human health, but it also requires the USEPA to consider all routes of exposure when setting these tolerances

Conventional pesticides made up 18% of the total pesticide usage in the United States in 1999, far behind that for chlorine and hypochlorites at 52% Wood preservatives accounted for 16% of the quantity used, while specialty biocides and commodity pesticides amounted to 7% each Of the total of 414 million kg of active ingredients used in conventional pesticide formulations, home and garden use accounted for 36 million kg, compared to 320 million kg for agricultural use and

57 million kg for other nonagricultural uses Approximately 74% of all U.S households reported using pesticides in 1999 About 56% said they used insecticides and disinfectants inside the home, and over 38% reported applying herbicides to their lawns and gardens The major home and garden use of pesticide a.i by individuals consisted of herbicides (68%), insecticides and miticides (18%),

and fungicides (12%) An additional 14–16 million kg of paradichlorobenzene and 1–2 million kg

of naphthalene were used in moth repellents, insecticides, germicides, and room deodorizers.The major exposure of the general population of the United States to pesticides occurs in thehome The most commonly used pesticides are disinfectants Pesticides used indoors can vaporizefrom treated surfaces, such as carpets and baseboards, can be resuspended into air attached toparticles, and be tracked indoors where they accumulate in house dust Typical pesticide concen-trations in indoor air and house dust are 10–100 times higher than those found in outdoor air orsurface soil Many pesticides are SVOCs and vaporize when applied to indoor surfaces, and theremay be significant temporal and spatial variations of pesticide concentrations in a home Somepesticides, though banned, are found at appreciable concentrations in house dust

Dermal exposures may occur when homeowners apply pesticides around the home or whenresidents come into contact with contaminated surfaces Infants and toddlers constitute the popu-lation of greatest concern for incidental dermal exposure as they are more apt to have intimatecontact with floors, turf, and other residential surfaces — and generally wear less clothing indoors.Very young children also frequently engage in mouthing of their hands, which may result iningestion of dermal residues

With the recent banning of popular organophosphate pesticides, the current trend is toward theuse of pyrethroids and other pesticides that have very low vapor pressures Hence, exposure topesticides in house dust and through dermal contact with contaminated surfaces has become amajor focus for research in a field that respiratory exposure concerns once dominated

15.2 INTRODUCTION

A pesticide is defined as any substance used for controlling, repelling, or killing a pest (e.g., insect,weed, fungus, rodent) Pesticides cover a very large and varied range of substances and aresubclassified according to their modes of action into many classes, including insecticides, acracides,herbicides, fungicides, rodenticides, avicides, larvicides, repellents, plant growth regulators, ger-micides (disinfectants), and other types of biocides Pesticides are typically applied in formulations(which may include one or more active ingredients in solvents or on powdered substrates, alongwith other substances designed to enhance the effectiveness of the active ingredients Thus the 600

or so active ingredients in use may make up 45,000–50,000 different formulations on the market(Baker and Wilkinson 1990) The USEPA classifies pesticides as conventional (insecticides/miti-cides, herbicides/plant growth regulators, fungicides, nematicides/fumigants, other), chlo-rine/hypochlorites (disinfectants, water purifiers), wood preservatives (creosote, pentachlorophenol,and chromated copper arsenate), specialty biocides (disinfectants and sanitizers), and other (sulfuricacid, insect repellents, zinc sulfate, moth control chemicals) (Kiely, Donaldson, and Grube 2004).The scope of this chapter is limited to conventional pesticides used in and around homes and offices

15.3 PESTICIDE REGULATION

The marketing, use, and disposal of pesticides are regulated by the USEPA, principally under the

Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) (7 U.S.C 136, et seq.) and the Food

Quality Protection Act (FQPA) of 1996 (P.L 104-170) The Agency is responsible for registeringnew pesticides and reviewing existing pesticides for re-registration to ensure that they will notpresent unreasonable risks to human health or the environment FIFRA requires the USEPA to takeinto account economic, social, and environmental costs and benefits in making decisions Regis-tration and regulatory decisions are based on evaluation of data provided by the registrants fromtests that may be specified by the agency These required tests include studies to show whether apesticide has the potential to cause adverse effects to individuals using pesticide formulations(applicators) and to persons who may be exposed post-application Potential human risks include

acute (short-term) reactions such as toxic poisoning or skin and eye irritation, as well as possiblechronic (long-term) effects such as cancer, birth defects, or reproductive system disorders Beforepesticides can be registered for residential or institutional use, the USEPA requires that studies beperformed to determine post-application dissipation rates and dislodgeable, or transferable, residues.The Food Quality Protection Act not only sets tolerances for all pesticide residues in food based

on a “reasonable certainty” that they will do “no harm” to human health, but it also requires theUSEPA to consider all routes of exposure (i.e., “aggregate” exposure) when setting tolerances.When setting a food tolerance level, the USEPA must aggregate exposure information from allpotential sources, including pesticide residues in specific foods of concern and those in other foodsfor which tolerances have already been set, residues in drinking water, and residues from othernondietary, nonoccupational uses of the pesticide (i.e., residential and other indoor/outdoor uses).FQPA further mandates that potential risks to infants and small children be specifically addressed

In order to assure “that there is a reasonable certainty that no harm will result to infants and childrenfrom aggregate exposure to the pesticide’s chemical residues,” FQPA calls for a “tenfold margin

of safety for pesticide residues and other sources of exposure” to be applied to estimating risks tochildren, taking into account “potential pre- and post-natal toxicity.” It allows the USEPA to use adifferent margin of safety “only if, on the basis of reliable data, such margin will be safe for infantsand children.”

An example of the USEPA regulatory process that relates to permissible indoor pesticide uses

is the action taken in the year 2000 on chlorpyrifos (e.g., Dursban®) The insecticide had been one

of the most heavily used pesticides for control of fleas and crawling insects indoors and grubs inresidential lawns It also was the primary termiticide that replaced chlordane after its discontinuation

in 1988 Because of concern over its toxicity and the high potential for exposure from residentialuse, the USEPA reached an agreement with the manufacturer, DowElanco, in June 2000 to canceland phase out nearly all indoor and outdoor residential uses of chlorpyrifos This action eliminatedthe pesticide from products for indoor crack and crevice treatment, “broadcast”1 flea control, totalrelease foggers, post-construction termite treatment, lawn insect control, and pet care (shampoos,dips, and sprays) Remaining uses are limited to certified professional and agricultural applicators.The agreement also restricted the uses of chlorpyrifos on certain foods that pose the greatest dietaryexposure risks to children Similar restrictions were placed on diazinon later in the year 2000

15.4 RESIDENTIAL AND COMMERCIAL BUILDING USE

Conventional pesticides are used both indoors and outdoors in homes, office buildings, schools,hospitals, nursing facilities, and other public institutions A wide variety of pesticide products areavailable “off the shelf” for use by the homemaker However, in recent years they are most readilyavailable in ready-to-apply formulations rather than concentrates that require the user to dilute thembefore use Preparations include those for control of flies, roaches, ants, spiders, and moths withinthe home; flea and tick sprays and shampoos for pets; insecticides for use on house plants andhome gardens; and herbicides, insecticides and fungicides for lawn treatment Most homemakersuse disinfectants routinely as kitchen and bathroom cleaners, room deodorizers, or laundry aids.Many homeowners and landlords utilize professional pest control services for routine indoortreatments or lawn care In many parts of the United States, pre- or post-construction treatment fortermite protection is essential Excluding disinfectants and insect repellents, the most commonindoor uses are for control of cockroaches and ants (crack and crevice treatment, baits), flies (sprays,pest strips), fleas (broadcast sprays and foggers), and rodents (baits) Outdoor uses in addition tolawn and garden care include perimeter and crawl space treatments for termites and crickets.The general populous of the United States, as well as that of most other countries, receives themajority of its exposure to pesticides inside the home Studies have shown that about 90% of all

1 Broadcast application refers to spreading of the pesticide over a wide area.

U.S households use pesticides (USEPA 1979; Savage et al 1981; Godish 1990; Whitmore et al.1993) A national survey conducted by the USEPA during 1976–1977, revealed that more than90% of U.S homeowners used pesticides, with 84% using them inside the house, 21% in thegarden, and 29% on the lawn (USEPA 1979) The survey found that over 90% of the householdsused disinfectants (antimicrobials), 36% used moth repellents, and 26% were treated with termiti-cides The USEPA-sponsored National Home and Garden Pesticide Use Survey in 1990 found that

82% of the 66.8 million U.S households used pesticides and that about 20% of them (ca 16 million

households) were commercially treated for indoor pests such as cockroaches, ants, or fleas more et al 1993) It further showed that some 18 million U.S households use pesticides on theirlawns, 8 million in the garden, and 14 million on ornamental plants About 15% of U.S residenceswith private lawns employ commercial lawn care companies that apply pesticides A survey of 238households in Missouri in 1989–1990 revealed that 98% of all families used pesticides at least onetime per year, and 75% used them more than five times per year (Davis, Brownson, and Garcia1992) The Missouri survey also determined that 70% of the respondents used household pesticidesduring the first 6 months of a child occupant’s life

(Whit-Direct purchases of conventional pesticides for home and garden use accounted for 19% of themore than $11 billion spent on pesticide products in the United States in 2000 and 2001 (Kiely,Donaldson, and Grube 2004) Other nonagricultural commercial sales made up 14% of the total.Most of the latter was intended for commercial home, office, and institutional application Homeand garden use in 2001 consumed over 46 million kg of pesticidal active ingredients (a.i.), compared

to 306 million kg for agricultural use and 50 million kg for other nonagricultural commercial use

On the basis of quantity of a.i., herbicides made up 71% of the total home and garden use byindividuals, insecticides and miticides 17%, and fungicides 16% Not included in these figures are

27 million kg of other pesticides including 1,4-dichlorobenzene (paradichlorobenzene) (moth

repel-lent, insecticide, germicide, and deodorant), naphthalene (moth repellent), and N,

N-diethyl-m-toluamide (DEET) (insect repellent) The most commonly used pesticides by homeowners during

2001 are shown in Table 15.1 This does not include pesticides applied to private residences byprofessional applicators, the most common of which in 1999 were 2,4-D, glyphosate, copper sulfate,pendimethalin, chlorothlonil chlorpyrifos, diuron, MSMA triclopyr and malathion

Misuse of pesticides by homemakers and commercial applicators occurs all too frequently InCalifornia during 1983–1986, nearly 300 cases of illness or injury reported to physicians wereattributed to three popular household insecticides: chlorpyrifos, dichlorvos (DDVP), and propoxur(Edmiston 1987) In 1991, the American Association of Poison Control Centers received 78,177calls regarding pesticide poisonings at 73 centers across the United States (Litovitz et al 1991).Seventy percent of these involved insecticides Pesticide poisoning calls ranked seventh in frequency(behind cleansers, analgesics, cosmetics, plants, cough and cold medications, and bites) Theremoval of many acutely toxic pesticides and concentrated formulations from the home market andimprovements in packaging safety has reduced the number of poisoning incidents in recent years.However, of greater concern are potential chronic health effects that may derive from long-termexposures to pesticides in indoor environments

15.5 AIR MONITORING METHODS

Air sampling can be classified as instantaneous (grab), real-time (or continuous), or integrative(over a period of exposure) Except for a few reactive pesticides present in air at relatively highconcentrations (e.g., occupational levels), integrative sampling is necessary in order to obtain asufficient quantity of the pesticide for laboratory analysis Pesticide air sampling typically involvesthe collection of pesticides from air onto a solid sorbent or a combination trap consisting of aparticle filter backed up by a sorbent trap Solvent extraction and chemical analysis by gas chro-matography or high performance liquid chromatography are most commonly employed

Air sampling media that have been shown to be efficient for collection of conventional pesticidesare polyurethane foam (Bidleman and Olney 1974; Orgill, Sehemel, and Petersen 1976; Lewis,Brown, and Jackson 1977; Lewis and MacLeod 1982; Billings and Bidleman 1980; Wright andLeidy 1982; Lewis, Fortmann, and Camann 1994); Chromosorb 102 (Thomas and Seiber 1974;Hill and Arnold 1979); Amberite® XAD-2 (Farewell, Bowes, and Adams 1977; Johnson, Yu, andMontgomery 1977; Lewis and Jackson 1982; Billings and Bidleman 1983; Williams et al 1987;Leidy and Wright 1991; Wright, Leidy, and Dupree 1993; Lu and Fenske 1998); Amberlite XAD-

4 (Woodrow and Seiber 1978; Jenkins, Curtis, and Cooper 1993); Tenax®-GC or TA (Billings andBidleman 1980, 1983; Lewis and Jackson 1982; Lewis and MacLeod 1982; Roinestad, Louis, andRosen 1993); Poropak®-R (Lewis and Jackson 1982), and Florisil® (Yule, Cole, and Hoffman 1971;Lewis and Jackson 1982) These sorbents appear to be about equally efficient for trapping mostpesticides Polyurethane foam (PUF) has enjoyed the most widespread popularity because it ismore convenient to use and has much less resistance to airflow than the granular sorbents However,

a few of the more volatile pesticides may not collect efficiently on PUF

Samples may be collected over 24-hour periods or for shorter periods of exposure time,depending upon the design of the study and the sensitivity of the method When the usual gas orliquid chromatographic analysis procedures are used, air volumes of 0.01–1 m3 are sufficient foroccupational exposure levels (i.e., 0.1–10 mg/m3) and 1–10 m3 for nonoccupational exposures (i.e.,0.01–10 µg/m3)

Methods for several pesticides at occupational levels in air are given in the NIOSH Manual of Analytical Methods (Eller and Cassinelli 1994) The NIOSH methods for organochlorine and

organophosphate utilize small traps with a particle filter backed up by two Amberlite® XAD-2 resin

TABLE 15.1

Approximate Annual Quantities of Conventional Pesticides Consumed by the

Homeowner Market in the United States during 2001

Quantity Used,

10 6 kg/yr

1 2,4-D (in e.g., Weed-B-Gone ® )

[2,4-dichlorophenoxyacetic acid and salts]

2 Glyphosate (e.g., Roundup ® )

[isopropylamine salt of N-(phosphonomethyl)glycine]

5 MCPP (Mecoprop, in, e.g., Weed-B-Gone ® )

[2-(4-chloro-2-methylphenoxy) propionic acid

6 Carbaryl (e.g., Sevin ® )

[Sevin ® — 1-naphthylmethylcarbamate]

7 Dicamba (e.g., Banvel ® )

[3,6-dichloro-2-methoxybenzoic acid; 3,6-dichloro-o-anisic acid and salts]

beds They are designed to be used with personal sampling pumps at 0.2–1 L/min for a maximumsample volume of 60–240 L Detection limits are in the 5–600 ng/m3 range.

There are two ASTM International methods designed primarily for determining airborne ticides at nonoccupational levels ASTM Standard D 4861 describes a sampling method andrecommended analytical procedures for a broad spectrum of pesticides at concentrations in the0.001–50 µg/m3 range (ASTM 2005a) and D 4947 is a specific method for chlordane and heptachlor(ASTM 2005b), which may still be found in the air inside homes built before 1978 D 4861 isbased on USEPA Compendium Method TO-10A, and is the method used in many large surveysconducted by the Agency (USEPA 1999a) The sampling device employed by both ASTM methodsconsists of a 22-mm × 76-mm polyurethane foam (PUF) cylinder (plug), which has been used withand without a particle filter attached to the inlet The PUF cartridge with or without an open-faceparticle filter (see Figure 15.1) is commercially available from several vendors (e.g., Supelco ModelOrbo 1000®; SKC Cat No 226-124) A size-selective inlet for this method has been designed andused in several recent USEPA indoor air studies It is an integral system incorporating either a 2.5

pes-µm or 10 µm inlet based on a design by Marple et al (1987) and can be used at flow rates up to

4 L/min for up to 24 hours (Camann et al 1994) The glass sampling cartridge and particle filterare contained in a rugged high-density polypropylene case, which is highly resistant to breakageand tampering The sampler, shown in Figure 15.2, is commercially available (URG Model 2000).The USEPA and ASTM methods are designed to be used with portable air sampling pumps capable

of pulling about 4 L/min of air through the collector for a total sample volume not to exceed 5–6 m3.Depending on the analytical finish, the minimum detection limits of the ASTM methods range from

1 ng/m3 to 100 ng/m3 The World Health Organization has published a method that is essentiallysimilar to D 4861 (Lewis 1993) Either sampler is suitable for both area sampling and personalexposure monitoring For the latter purpose, they are usually worn by the study subject in thebreathing zone with the inlets pointing downward (see Figure 15.3)

Most of the large studies employing TO-10A or ASTM D 4861 (e.g., the Non-OccupationalExposure Study, NOPES) have not used a particle filter; however, one is recommended if pesticidesassociated with respirable particulate matter are likely to be present The backup PUF trap shouldalways be used behind the particle filter, even for collection of nonvolatile pesticides (e.g., whensampling for airborne acid herbicides indoors) As much as 20% of airborne 2,4-D, applied as the

FIGURE 15.1 Simple air sampling cartridge with open-face particle filter 1: Glass sorbent cartridge;

2: Particle filter holder; 2a: Filter holder, front element; 2b: Filter holder, rear element 3: Sorbent (e.g., PUF); 4: PTFE filter gaskets; 5: Particle filter; 6: Filter support screen, stainless steel, 50% open area.

trimethylamine salt, has been detected on the backup PUF plug, presumably due to hydrolysis tothe semivolatile free acid (USEPA 1999b).

Except for herbicide salts, some pyrethroids, and a few other nonvolatile compounds, mostpesticides will either be present in air primarily in the vapor phase or will volatilize from airborneparticulate matter readily after collection on a filter (Lewis and Gordon 1996) Solid sorbent bedswill collect most particulate-associated pesticides along with vapors; however, recent evidencesuggests that some penetration of fine particulate matter (0.1 to 1µm) may occur with PUF andFlorisil (Kogan et al 1993) Fine particles were not found to penetrate XAD-2 beds, presumablydue to their retention by static charge It may be good practice, therefore, to use a particle filter infront of the sorbent bed In this case, the filter and sorbent bed should be extracted together foranalysis to provide for better detection and prevent misinterpretation of the analytical results withrespect to original phase distributions It should be noted that although very small particles havebeen shown to be poorly retained by the PUF plug, simultaneous, collocated sampling of residentialindoor air with and without a quartz fiber particle filter showed no significant measurementdifferences even when sweeping and vacuuming activities took place in the same room (Camann,Harding, and Lewis 1990)

Air samples should be taken within homes or other buildings in the best locations for estimation

of human exposure (e.g., family rooms, bedrooms, office spaces) Occupant activity logs may be

FIGURE 15.2 Air sampling assembly with size-selective inlet, particle filter, and glass sorbent cartridge.

Parts A and B are separable sections of shock-resistant case Internal parts: 1: Impactor for size-selective inlet; 2: PTFE O-ring; 3: Particle filter; 4: Stainless steel filter support screen; 5 and 8: Rubber O-ring seals; 6: PUF

or granular sorbent; 7: Glass sorbent cartridge.

required in order to obtain accurate estimates of human exposure The sampler may be convenientlypositioned on a table, desk, or countertop, during which time it may be operated by means of apower converter/charger For monitoring periods longer than 8 hours, the latter procedure willusually be necessary due to limited battery life and to cover the sleep period Air intakes (inlets)should be positioned 1–2 m above the floor or ground and oriented downward or horizontally toprevent contamination by nonrespirable dustfall If two or more samplers are to be used forcollocated sampling, intakes should be at least 30 cm apart for low-volume samplers (1–5 L/min)and 1–2 m apart for high-volume samplers (up to 1,000 L/min).

Indoor residential sampling can be restricted because of available space or by homeownerobjections Equipment noise can also be an issue, depending on the size of the space beingmonitored, the acoustics of the area, and the presence of occupants Noise from sampling equipmentused in residences, schools, offices, and other relatively noise-free areas should be limited to 35

db (1 sones) at 8,000 Hz (ASTM 2003b) Many battery-operated portable pumps designed forpersonal respiratory exposure monitoring are quiet enough for this purpose, although additionalacoustic insulation may be required for use in bedrooms and family rooms Nonindustrial workplacemonitoring is often more flexible to space and noise restrictions Security of sampling equipmentshould be considered in the plan Typically, samplers that cannot either easily be tampered with orchanged by the homeowner or office worker, are preferable to those with exposed sampling elements

or controls (e.g., the possibility of electrical power disruption or contamination by onlookers orpassersby should be considered in the sampling plan for any effort)

FIGURE 15.3 Open-face air sampler (left) and sampler with size-selective inlet (right) in use for personal

exposure monitoring (Courtesy of persons in the photograph.)

15.6 HOUSE DUST SAMPLING METHODS

House dust is the major reservoir of pesticide residues that may be accessible for human exposure

in the home environment (Lewis, Fortmann, and Camann 1994) Since infants and toddlers havehigh levels of intimate contact with floors and other dust-containing objects and engage in frequentmouthing activities, nondietary ingestion of house dust may constitute a major exposure pathwayfor them, especially to low- and nonvolatile pesticides Although analysis of pesticides in dust ismore complicated than that for air samples, knowledge of the pesticide content of house dust canprovide a good indication of the overall contamination of the home environment (including the air)and afford useful estimates of relative exposure risks to inhabitants (Lewis et al 1995; Lioy,Freeman, and Millette 2002)

Various methods have been used to collect dust from floors and upholstery (Que Hee et al.1985; USEPA 1989; Roberts et al 1991; Farfel et al 1994; Ness 1994; Lanphear et al 1995;USEPA 1995) The approach most commonly employed by industrial hygienists is based on drawingdust by means of a personal air sampling pump operating at 2–3 L/min onto a particle filter held

in a plastic cassette The filter cassette is held close to the surface being sampled The method issometimes referred to as the Dust Vacuum Method or DVM (Que Hee et al 1985) A modification

of this method developed by Midwest Research Institute (MRI) was the “Blue Nozzle” sampler,which utilized a 5-cm × 10-cm sampling nozzle and a 110 V rotary vane pump to draw largerquantities of dust through the same type of filter cassette (Constant and Bauer 1992; USEPA 1995).Its sampling efficiency was reported to be only 44–59% for dust sampled from bare concrete,linoleum, and wood floors Another MRI design pulled dust through a rigid 2.5-cm i.d plastic pipeinto a cyclone and deposited it onto a filter in a cassette holder at the bottom of the cyclone (Dewalt

et al 1995) A handheld vacuum cleaner was used as the vacuum source

Such vacuum sampling methods typically do not collect adequate quantities of dust for pesticideresidue analysis and are not amenable to use on large surfaces such as floors Consequently, theUSEPA designed the HVS3 cyclone vacuum sampler (Figure 15.4), which is capable of collecting

FIGURE 15.4 HVS3 cyclone vacuum sampler (CS3, Bend, OR) 1: Commercial vacuum cleaner; 2: Cyclone with 5-µm cut-point; 3: Sample catch bottle; 4: Flow control valve; 5: Vacuum gauges; 6: 10-cm suction nozzle; 7: Nozzle level adjustment screw; 8: Platform level adjustment knob.

enough dust for pesticide residue analysis, at a constant sampling rate, and in a highly reproduciblemanner (Roberts et al 1991, USEPA 1995) The sampler consists of a 1-cm × 12.4-cm flat samplingnozzle, particle collection cyclone, glass or PTFE catch bottle, and flow control system mounted

on a standard upright vacuum cleaner to provide suction The cyclone has a nominal cut point of

5 µm at a flow velocity of 40 cm/sec In efficiency tests conducted according to ASTM F 608(ASTM 2003a), the sampler has been shown to collect 67–69% of test dust from plush and levelloop carpet and to trap 99% of the vacuumed dust in the cyclone catch bottle Additional tests withspiked test dust have demonstrated 97+% recoveries of several common pesticides (Roberts et al.1991) The method has been evaluated for efficiency at collecting and retaining floor dust and thepesticides associated with it It has been subjected to round-robin testing and is the basis of ASTMInternational Standard D 5438 for collection of dust from carpets and bare floors (ASTM 2005c).The method has been used in many large and small USEPA studies (e.g., Lewis, Fortmann, andCamann 1994; Nishioka et al 1999; Lewis et al 2001; Wilson et al 2004)

The amount of dust that can be collected by the HVS3 will vary greatly according to the dustloadings on the floor Vacuuming of a 1 m2 area of carpet typically collects 0.5–10 g of dust Thecollected dust is retained in the catch bottle, which is capped and kept chilled or frozen untilanalyzed The standardized methodology calls for the collected dust to be passed through a sieve

to exclude particles larger than 150 µm prior to extraction and analysis This cut-point is usedbecause larger particles adhere poorly to the skin and present less of an exposure potential thansmaller particles The sieved sample normally ranges from 10–60% of the bulk dust sample (avg

ca 50%) These amounts of dust will permit the quantitative measurement of 0.05 µg/g or less ofmost pesticides

Home vacuum cleaners have also been used to collect floor dust for pesticide residue analysis(Starr et al 1974; Davies, Edmundson, and Raffonelli 1975; Roinestad, Louis, and Rosen 1993;Colt et al 1998; Rudel et al 2003); however, standard (unlined) vacuum cleaner bags do notretain fine particles well As much as 25–35% of the dust in the 2–4 µm size range may be lostduring collection by penetration of the vacuum bags (IBR 1995) Additional losses of fineparticles may occur due to adherence to the walls of the vacuum bags The collection efficiency

of particles smaller than 5 µm is also low for the HVS3, since the cyclone inlet cuts off at thatpoint Side-by-side comparisons of the HVS3 and a conventional upright vacuum cleaner inuniversity dormitory rooms revealed the HVS3 to be more efficient for particles smaller than

20 µm (Willis 1995) It also showed that both types of vacuum devices collected particles down

to at least 0.2 µm in diameter Since concentrations of pesticides on house dust increase rapidly

on particles smaller than 25–50 µm in diameter (Lewis et al 1999), analytical results for dustcollected with household vacuum cleaners may be lower than those obtained with the HVS3.However, no significant differences in the concentrations of pesticides were found by theNational Cancer Institute (NCI) in house dust collected with the HVS3 from 15 homes and thatcollected from the homeowners’ vacuum cleaner bags (Colt et al 1998) Another study of ninedaycare centers yielded higher results for pesticides and polycyclic aromatic hydrocarbons(PAHs) in dust collected in standard vacuum cleaner bags in most cases (USEPA 1999c) Inthe NCI study, the HVS3 sample was collected from carpets throughout the house, while theUSEPA collected the HVS3 sample from a single room on one day In both cases the bagsample was taken from the home or facility vacuum cleaner and represented dust collected over

an unknown period of time and from multiple locations within the building Consequently,concentration differences in the two types of samples reported by the USEPA may have reflected

a lack of both spatial and temporal homogeneity of the dust

15.7 CONTACT-DISLODGEABLE RESIDUE MONITORING

METHODS

Pesticide residues are deposited onto indoor and outdoor residential surfaces after application of

a pesticide formulation or by transfer from treated areas to nontargeted surfaces (e.g., transferfrom lawn to carpet) Dislodgeable residues on exposed outdoor surfaces, such as turf, aretypically short lived Indoor surface residues, however, may persist for long periods of time sincethey are largely shielded from environmental degradation and dissipation in the indoor environ-ment Human contact with contaminated surfaces may dislodge a portion of these residues,resulting in their transfer to the skin or clothing, where they may be absorbed through the skin

or ingested through mouthing As in the case of house dust exposure, infants and toddlersconstitute the population of greatest concern for incidental dermal exposure as they are more apt

to have intimate contact with floors, turf, yard soil, and other residential surfaces and generallywear less clothing indoors (Fenske et al 1990; Lewis, Fortmann, and Camann 1994; Zartarianand Leckie 1998) Very young children also frequently engage in mouthing of their hands, whichmay result in ingestion of dermal residues

The term dislodgeable (or transferable) residue is defined as “that part of the residue of a

chemical deposited on a solid surface which may be transferred by direct contact to human skin

or clothing” (ASTM 2004) It is generally estimated by means of mechanical devices, althoughbare-skinned or clothed human subjects are sometimes used Methods for determining dislodge-able residue transfer have included bare hand presses (Lewis, Fortmann, and Camann 1994),gloved hand presses (Roberts and Camann 1989), choreographed whole body dermal contact(Vaccaro 1993), whole body garments combined with an aerobic exercise routine (Ross et al.1990), gauze wipes (Geno et al 1996; Lu and Fenske 1998), and various sampling media thatare pressed, dragged, or rolled across the surface at known contact pressures and rates or times(Hsu et al 1990; Ross et al 1991; Vaccaro 1993; Lioy, Wainman, and Weisel 1993; Edwardsand Lioy 1999)

Three of the most popular devices used in recent years to estimate skin-transferable pesticideresidues from carpets and floors are the polyurethane foam (PUF) roller (Hsu et al 1990; Lewis,Fortmann, and Camann 1994), the drag sled (Vaccaro and Cranston 1990), and the California roller(Ross et al 1991) All three methods have been rigorously evaluated and subjected to round-robintesting (USEPA 1997a) for inclusion in the FIFRA Subdivision K guidelines (USEPA 2000a)

The PUF roller (Figure 15.5) was designed to measure dislodgeable residues that may betransferred to a small child’s skin from contact with floor surfaces It is the basis of the ASTMStandard Practice D 6333 (ASTM 2004) Dislodgeable pesticide residues are collected by transfer

to an annular ring of medium density (0.029 g/cm3) open-cell, polyether-type polyurethane foam(8.9 cm o.d × 8 cm wide), which is rolled across the floor at a constant speed and applied pressure.The PUF sampling ring is slipped over a cylindrical metal axle that functions as the front wheel

of the PUF roller apparatus The apparatus is typically constructed of aluminum and consists of aframe with two permanent rear wheels and the detachable axle cylinder on the front Weights areattached to the roller frame to apply the desired downward force on the PUF roller ring (samplingpressure) A total weight of 3.9 kg provides a sampling pressure of 8,000 Pa, correspondingapproximately to that of a 9-kg child crawling (6,900 Pa) or walking (8,600 Pa) A handle isconnected at the rear of the roller frame to push or pull the device across the floor surface withthe aid of a template or similar measuring device to identify the area to be sampled The axlecylinder is fitted with a clean PUF ring, and the roller is pushed at a constant rate of approximately

10 cm/s over a distance of 1.0 m and then immediately pulled in the reverse direction back overthe same sampling area at the same rate of speed, ending at the original starting position The totalsurface area sampled is 800 cm2 At the conclusion of the traverse, the PUF ring is removed fromthe detached axle cylinder and placed in a sealed container for transport to the laboratory foranalysis

The drag sled (Figure 15.6) is a simple device constructed of a 7.6-cm × 7.6-cm × 1.9-cmthick block of wood or other material, which is used to hold down a 10-cm × 10-cm piece of denimcloth (sampling medium) as it is dragged across the floor The bottom of the block is covered withsolvent-rinsed aluminum foil and the denim patch is placed over the foil Staples or pushpins are

FIGURE 15.5 PUF roller with snap-in foam sampling ring and replaceable weights 1: PUF ring (8.9 cm o.d.

× 8 cm wide × 2.3 cm thick) on roller; 2: Weights (adjustable, 3.9 kg provide roller pressure of 8,000 Pa.); 3: Roller-axle (metal cylinder, spring-loaded, 4 cm dia × 8.5 cm long); 4: Frame (tiltable for roller loading and unloading); 5: Adjustable handle

FIGURE 15.6 Drag sled (Dow Chemical Co., Midland, MI) 1: Weight (3.6 kg); 2: Sled (7.6 cm2 × 2 to 4

cm high, typically made of wood covered with aluminum foil; 3: Collection medium (undyed denim cloth, 8

cm × 10 cm); 4: Drag line (e.g., fishing line).

typically used to secure the sampling medium to the block A 3.6-kg weight is centered on top ofthe block to provide a downward pressure of 4,500 Pa The sled is pulled at 8 cm/s to 12 cm/salong a 1.2-m path by means of an attached cord (e.g., a 60-cm to 90-cm nylon fishing line),sampling 925 cm2 of floor area

The California roller (Figure 15.7) is basically a large, weighted “rolling pin” that is used to

press a piece of polyester-cotton percale bedsheet onto the floor to collect residues The rollerconsists of a large (13-cm o.d × 63-cm long) cylinder constructed from polyvinyl chloride (PVC)pipe, covered with a foam cushion (1-cm thick × 51-cm long), and fitted with end caps and handles.The roller is weighted with 11.4 kg of steel shot ballast placed inside the cylinder to provide atotal weight of 14.5 kg The applied pressure is approximately 2,300 Pa The sampling medium is

a 43-cm × 43-cm square piece of bedsheet made from 50% combed cotton and 50% polyester, 180thread count When sampling, the bedsheet is placed on the floor surface, covered with a plasticsheet, and the roller is rolled over it ten times in each direction (20 passes) The California is veryheavy and difficult to maneuver It is also hard for the operator to use it without applying forcethat will translate to the roller and thereby increase the pressure applied to the collection sheet Aspart of its evaluation of the device, the USEPA designed a sled (see Figure 15.8) for the device tocircumvent the latter problem (USEPA 1997a)

The mode of sampling is different for each method The PUF roller picks up residues by rollingcontact of the pliable foam sampling medium with the floor surface, the drag sled operates through

a wiping motion with a thick cotton fabric, and the California roller presses a thin cloth sheetagainst the surface The characteristics of the three methods and their comparison with adult humanhand presses are summarized in Table 15.2 All three mechanical methods have been subjected tocomparative performance evaluation for collection of formulated pesticide residues from carpetsand vinyl flooring The performance of each method has also been compared to human hand presses(USEPA 1996d, 2000b) No biases have been observed with respect to the direction of traversewhen the samplers were used on plush or level-loop nylon carpets However, for carpets that do

FIGURE 15.7 The California roller (California Department of Pesticide Regulation, Sacramento, CA).

1: Roller (PVC pipe, 13 cm dia × 63 cm long); 2: Foam cover, 51 cm long and 1 cm thick); 3: Handles; 4: Collection medium (percale bed sheeting, 43 cm × 43 cm, 50% combed cotton and 50% polyester, 180 thread count); 5: Plastic sheet (over collection medium).

not have uniform and level surfaces, some directional bias may be encountered, especially in thecase of the drag sled

The three dislodgeable residue samplers were also evaluated for use on turf grass (USEPA1997b) The drag sled could not be used because it tended to capsize when pulled through grass.The PUF roller and California roller performed better, but problems were encountered with grassclippings and other debris that adhered to the sampling media and had to be mechanically removedprior to extraction and analysis of the sampling media The problem was particularly serious forthe PUF roller The California roller also collected small amounts of clippings and debris, but thesecould be easily removed by the laboratory analyst Both the PUF roller and a modified version ofthe California roller have been used to determine turf dislodgeable pesticide residues (Nishioka et

al 1996; Fuller et al 2001)

Surface wipes are appropriate for determining dislodgeable residues from bare floors and otherhard residential surfaces (e.g., table and countertops, windowsills, cabinets, appliances, dinnerware,and children’s toys) However, residential wipe sampling techniques for pesticides have not yetbeen standardized and are unlikely to accurately reflect the transferability of surface residues toskin Typically, cotton gauze or filter materials, dry or wetted with solvents, held in the hand areused to wipe a defined area (McArthur 1992) Surface areas of 100–1,000 cm2 are normally definedfor wiping by marking with tape or using a template (Ness 1994)

The U.S Occupational Safety and Health Administration (OSHA) recommends glass-fiber filtermaterial (air sampling filters), dry or wetted with 2-propanol, for determining surface residues ofpesticides (OSHA 1999) A USEPA method uses two 10-cm × 10-cm surgical gauze sponges made

FIGURE 15.8 California roller in USEPA custom sled designed to eliminate influence of user on applied

pressure.

of 6-ply cotton, each wetted with 10 mL of 2-propanol, to collect pesticide residues from residentialhuman hands and indoor surfaces (Geno et al 1996; Lewis et al 2001) For indoor surfaces, thesampled area is wiped with a straight-line hand motion with each of the two gauze dressings,frequently turning them to provide fresh wiping faces The first gauze dressing is used to wipe inone direction; the second for wiping in a direction orthogonal to the first The same technique hasbeen used with the acetonitrile/phosphate buffer previously mentioned as the wetting agent to collectlawn herbicide residues deposited on windowsills and 29-cm × 29-cm Formica® sheets placed ontabletops inside homes (Nishioka et al 2001).

Comparison of various wipe materials have found them to be comparable for hard, smoothsurfaces but not for rough surfaces (Chavalnitikul and Levin 1984) Wet wipe sampling is generallynot recommended for carpet, upholstery and other fabric-covered or soft surfaces because thesolvent may be absorbed into the surface being sampled Wipes of soft surfaces also are less likelythan wipes of hard surfaces to reflect the dermal exposure potential (Ness 1994)

Human hand presses have also been used to determine the transfer of pesticides from surfaces

to skin (Lewis, Fortmann, and Camann 1994; USEPA 2000b) However, they are generally notpractical monitoring tools for determining transferable pesticide residues The nature of humanskin varies between individuals, as do the size and geometry of the hand; it is difficult to determineand control the pressure applied; the hand can only be pressed infrequently (e.g., once or twiceper day) on treated surfaces for both safety and health considerations and because solvents used

to recover the pesticide residue may affect the nature of the skin; and pesticide residues may beabsorbed into the skin to the extent that they are not fully recoverable

15.8 HANDWIPE METHODS

Hand rinses or washes have long been employed for collecting hand residues from agriculturalworkers and pesticide applicators (e.g., Durham and Wolfe 1962; Fenske et al 1998) Variousaqueous surfactant solutions, 1% aqueous sodium bicarbonate, or alcohols (either 2-propanol or

TABLE 15.2

Characteristics of the Three Principal Dislodgeable Residue Methods and Hand Press Property PUF Roller Drag Sled California Roller

Human Hand Press

Sampling medium

(material)

Polyurethane foam cylinder (open-cell, polyether type, 0.029 g/cm 3 ) 8.9-cm o.d × 7.6-cm long

Denim weave cloth (predominantly cotton) 10-cm × 10-cm

Percale bed sheet (50% cotton, 50%

polyester) 43-cm × 43-cm

sampled carpet area

Sampling speed over

carpet