EXPOSURE ANALYSIS -CHAPTER 15 pdf

347 15 Exposure to Pesticides 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%), © 2007 by Taylor & Francis Group, LLC 348 Exposure Analysis 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 the home. The most commonly used pesticides are disinfectants. Pesticides used indoors can vaporize from treated surfaces, such as carpets and baseboards, can be resuspended into air attached to particles, 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 or surface soil. Many pesticides are SVOCs and vaporize when applied to indoor surfaces, and there may be significant temporal and spatial variations of pesticide concentrations in a home. Some pesticides, though banned, are found at appreciable concentrations in house dust. Dermal exposures may occur when homeowners apply pesticides around the home or when residents 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 intimate contact 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 in ingestion of dermal residues. With the recent banning of popular organophosphate pesticides, the current trend is toward the use of pyrethroids and other pesticides that have very low vapor pressures. Hence, exposure to pesticides in house dust and through dermal contact with contaminated surfaces has become a major 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 are subclassified 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, along with 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 (sulfuric acid, 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 registering new pesticides and reviewing existing pesticides for re-registration to ensure that they will not present unreasonable risks to human health or the environment. FIFRA requires the USEPA to take into 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 from tests that may be specified by the agency. These required tests include studies to show whether a pesticide 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 © 2007 by Taylor & Francis Group, LLC Exposure to Pesticides 349 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. Before pesticides can be registered for residential or institutional use, the USEPA requires that studies be performed 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 the USEPA 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 all potential sources, including pesticide residues in specific foods of concern and those in other foods for which tolerances have already been set, residues in drinking water, and residues from other nondietary, 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 children from 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 to children, taking into account “potential pre- and post-natal toxicity.” It allows the USEPA to use a different margin of safety “only if, on the basis of reliable data, such margin will be safe for infants and 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 in residential 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 residential use, the USEPA reached an agreement with the manufacturer, DowElanco, in June 2000 to cancel and phase out nearly all indoor and outdoor residential uses of chlorpyrifos. This action eliminated the pesticide from products for indoor crack and crevice treatment, “broadcast” 1 flea control, total release 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 dietary exposure 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 are available “off the shelf” for use by the homemaker. However, in recent years they are most readily available in ready-to-apply formulations rather than concentrates that require the user to dilute them before use. Preparations include those for control of flies, roaches, ants, spiders, and moths within the home; flea and tick sprays and shampoos for pets; insecticides for use on house plants and home gardens; and herbicides, insecticides and fungicides for lawn treatment. Most homemakers use disinfectants routinely as kitchen and bathroom cleaners, room deodorizers, or laundry aids. Many homeowners and landlords utilize professional pest control services for routine indoor treatments or lawn care. In many parts of the United States, pre- or post-construction treatment for termite protection is essential. Excluding disinfectants and insect repellents, the most common indoor 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 to lawn 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 the majority 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. © 2007 by Taylor & Francis Group, LLC 350 Exposure Analysis 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 than 90% of U.S. homeowners used pesticides, with 84% using them inside the house, 21% in the garden, and 29% on the lawn (USEPA 1979). The survey found that over 90% of the households used 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 (Whit- more et al. 1993). It further showed that some 18 million U.S. households use pesticides on their lawns, 8 million in the garden, and 14 million on ornamental plants. About 15% of U.S. residences with private lawns employ commercial lawn care companies that apply pesticides. A survey of 238 households in Missouri in 1989–1990 revealed that 98% of all families used pesticides at least one time per year, and 75% used them more than five times per year (Davis, Brownson, and Garcia 1992). The Missouri survey also determined that 70% of the respondents used household pesticides during the first 6 months of a child occupant’s life. Direct purchases of conventional pesticides for home and garden use accounted for 19% of the more 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. Home and 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 by individuals, 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 by professional 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. In California during 1983–1986, nearly 300 cases of illness or injury reported to physicians were attributed to three popular household insecticides: chlorpyrifos, dichlorvos (DDVP), and propoxur (Edmiston 1987). In 1991, the American Association of Poison Control Centers received 78,177 calls 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). The removal of many acutely toxic pesticides and concentrated formulations from the home market and improvements 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-term exposures 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 high concentrations (e.g., occupational levels), integrative sampling is necessary in order to obtain a sufficient quantity of the pesticide for laboratory analysis. Pesticide air sampling typically involves the collection of pesticides from air onto a solid sorbent or a combination trap consisting of a particle 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. © 2007 by Taylor & Francis Group, LLC Exposure to Pesticides 351 Air sampling media that have been shown to be efficient for collection of conventional pesticides are 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 and Leidy 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, and Montgomery 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 and Bidleman 1980, 1983; Lewis and Jackson 1982; Lewis and MacLeod 1982; Roinestad, Louis, and Rosen 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 most pesticides. Polyurethane foam (PUF) has enjoyed the most widespread popularity because it is more 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 or liquid chromatographic analysis procedures are used, air volumes of 0.01–1 m 3 are sufficient for occupational exposure levels (i.e., 0.1–10 mg/m 3 ) and 1–10 m 3 for nonoccupational exposures (i.e., 0.01–10 µg/m 3 ). 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 Rank Pesticide Type a Quantity Used, 10 6 kg/yr 1 2,4-D (in e.g., Weed-B-Gone ® ) [2,4-dichlorophenoxyacetic acid and salts] H 4–5 2 Glyphosate (e.g., Roundup ® ) [isopropylamine salt of N-(phosphonomethyl)glycine] H 2–4 3 Pendimethalin (e.g., Prowl ® ) [N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidine] H 1–3 4 Diazinon [0,0-diethyl-O-{6-methyl-2-(1-methylethyl)-4-pyrimidinyl} phosphorothioate] I 2–3 5 MCPP (Mecoprop, in, e.g., Weed-B-Gone ® ) [2-(4-chloro-2-methylphenoxy) propionic acid H 1–2 6 Carbaryl (e.g., Sevin ® ) [Sevin ® — 1-naphthylmethylcarbamate] I 1–2 7 Dicamba (e.g., Banvel ® ) [3,6-dichloro-2-methoxybenzoic acid; 3,6-dichloro-o-anisic acid and salts] H 1–2 8 Malathion [diethyl(dimethoxythiophosphorylthio)succinate] I 0.5–1.4 9 DCPA (e.g., Dacthal ® ) [dimethyl-2,3,5,6-tetrachlorobenzen-1,4-dicarboxylic acid] F 0.5–1.4 10 Benefin (Benfluralin) [N-Butyl-N-ethyl-a,a,a-trifluoro-2,6-dinitro-p-toluidine] H 0.5–1.4 a H = herbicide, I = insecticide. © 2007 by Taylor & Francis Group, LLC 352 Exposure Analysis beds. They are designed to be used with personal sampling pumps at 0.2–1 L/min for a maximum sample volume of 60–240 L. Detection limits are in the 5–600 ng/m 3 range. There are two ASTM International methods designed primarily for determining airborne pes- ticides at nonoccupational levels. ASTM Standard D 4861 describes a sampling method and recommended analytical procedures for a broad spectrum of pesticides at concentrations in the 0.001–50 µg/m 3 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 is based on USEPA Compendium Method TO-10A, and is the method used in many large surveys conducted by the Agency (USEPA 1999a). The sampling device employed by both ASTM methods consists of a 22-mm × 76-mm polyurethane foam (PUF) cylinder (plug), which has been used with and without a particle filter attached to the inlet. The PUF cartridge with or without an open-face particle filter (see Figure 15.1) is commercially available from several vendors (e.g., Supelco Model Orbo 1000 ® ; SKC Cat. No. 226-124). A size-selective inlet for this method has been designed and used in several recent USEPA indoor air studies. It is an integral system incorporating either a 2.5 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 filter are contained in a rugged high-density polypropylene case, which is highly resistant to breakage and 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 m 3 . Depending on the analytical finish, the minimum detection limits of the ASTM methods range from 1 ng/m 3 to 100 ng/m 3 . The World Health Organization has published a method that is essentially similar to D 4861 (Lewis 1993). Either sampler is suitable for both area sampling and personal exposure monitoring. For the latter purpose, they are usually worn by the study subject in the breathing 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-Occupational Exposure Study, NOPES) have not used a particle filter; however, one is recommended if pesticides associated with respirable particulate matter are likely to be present. The backup PUF trap should always be used behind the particle filter, even for collection of nonvolatile pesticides (e.g., when sampling 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. © 2007 by Taylor & Francis Group, LLC Exposure to Pesticides 353 trimethylamine salt, has been detected on the backup PUF plug, presumably due to hydrolysis to the semivolatile free acid (USEPA 1999b). Except for herbicide salts, some pyrethroids, and a few other nonvolatile compounds, most pesticides will either be present in air primarily in the vapor phase or will volatilize from airborne particulate matter readily after collection on a filter (Lewis and Gordon 1996). Solid sorbent beds will collect most particulate-associated pesticides along with vapors; however, recent evidence suggests that some penetration of fine particulate matter (0.1 to 1µm) may occur with PUF and Florisil (Kogan et al. 1993). Fine particles were not found to penetrate XAD-2 beds, presumably due to their retention by static charge. It may be good practice, therefore, to use a particle filter in front of the sorbent bed. In this case, the filter and sorbent bed should be extracted together for analysis to provide for better detection and prevent misinterpretation of the analytical results with respect to original phase distributions. It should be noted that although very small particles have been shown to be poorly retained by the PUF plug, simultaneous, collocated sampling of residential indoor air with and without a quartz fiber particle filter showed no significant measurement differences 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. © 2007 by Taylor & Francis Group, LLC 354 Exposure Analysis required in order to obtain accurate estimates of human exposure. The sampler may be conveniently positioned on a table, desk, or countertop, during which time it may be operated by means of a power converter/charger. For monitoring periods longer than 8 hours, the latter procedure will usually 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 to prevent contamination by nonrespirable dustfall. If two or more samplers are to be used for collocated 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 homeowner objections. Equipment noise can also be an issue, depending on the size of the space being monitored, the acoustics of the area, and the presence of occupants. Noise from sampling equipment used 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 for personal respiratory exposure monitoring are quiet enough for this purpose, although additional acoustic insulation may be required for use in bedrooms and family rooms. Nonindustrial workplace monitoring is often more flexible to space and noise restrictions. Security of sampling equipment should be considered in the plan. Typically, samplers that cannot either easily be tampered with or changed 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 or passersby 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.) © 2007 by Taylor & Francis Group, LLC Exposure to Pesticides 355 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 have high levels of intimate contact with floors and other dust-containing objects and engage in frequent mouthing activities, nondietary ingestion of house dust may constitute a major exposure pathway for them, especially to low- and nonvolatile pesticides. Although analysis of pesticides in dust is more complicated than that for air samples, knowledge of the pesticide content of house dust can provide 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 drawing dust 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 is sometimes 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 larger quantities 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 pipe into 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 pesticide residue analysis and are not amenable to use on large surfaces such as floors. Consequently, the USEPA designed the HVS3 cyclone vacuum sampler (Figure 15.4), which is capable of collecting FIGURE 15.4 HVS3 cyclone vacuum sampler (CS 3 , 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. © 2007 by Taylor & Francis Group, LLC 356 Exposure Analysis enough dust for pesticide residue analysis, at a constant sampling rate, and in a highly reproducible manner (Roberts et al. 1991, USEPA 1995). The sampler consists of a 1-cm × 12.4-cm flat sampling nozzle, 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 level loop carpet and to trap 99% of the vacuumed dust in the cyclone catch bottle. Additional tests with spiked 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 the pesticides associated with it. It has been subjected to round-robin testing and is the basis of ASTM International 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, and Camann 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 dust loadings on the floor. Vacuuming of a 1 m 2 area of carpet typically collects 0.5–10 g of dust. The collected dust is retained in the catch bottle, which is capped and kept chilled or frozen until analyzed. 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 used because larger particles adhere poorly to the skin and present less of an exposure potential than smaller 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 of most 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 not retain fine particles well. As much as 25–35% of the dust in the 2–4 µm size range may be lost during collection by penetration of the vacuum bags (IBR 1995). Additional losses of fine particles 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 that point. Side-by-side comparisons of the HVS3 and a conventional upright vacuum cleaner in university 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 dust collected 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 the National Cancer Institute (NCI) in house dust collected with the HVS3 from 15 homes and that collected from the homeowners’ vacuum cleaner bags (Colt et al. 1998). Another study of nine daycare centers yielded higher results for pesticides and polycyclic aromatic hydrocarbons (PAHs) in dust collected in standard vacuum cleaner bags in most cases (USEPA 1999c). In the NCI study, the HVS3 sample was collected from carpets throughout the house, while the USEPA collected the HVS3 sample from a single room on one day. In both cases the bag sample 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. © 2007 by Taylor & Francis Group, LLC [...]... discontinued in 1988); and the disinfectant O-phenylphenol © 2007 by Taylor & Francis Group, LLC 368 Exposure Analysis 15. 10 EXPOSURE RISKS AND HEALTH EFFECTS Pesticide residues found inside the home contribute significantly to the overall exposure of the general population Of the several possible routes of exposure to household pesticides, the air route is one of the most important The average resident... respectively Seven of the most prevalent pesticides shown in Table 15. 3 and Table 15. 4 made up more than 90% of © 2007 by Taylor & Francis Group, LLC Exposure to Pesticides 367 TABLE 15. 3 Most Frequently Detected Pesticides in Residential Indoor Air in Jacksonville, Florida, and Their Mean Concentrations (Non-Occupational Pesticide Exposure Study, 1986–1987) Summer Spring Winter % of Mean Conc., %... on surfaces or that are transferred to the skin may be ingested, resulting in exposures that may rival or exceed respiratory exposures Whereas occupational inhalation exposure guidelines have been established for many pesticides, the United States has no current guidelines for non-occupational indoor air exposures Workplace exposure limits are established by National Institute for Occupational Safety... (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious effects during a lifetime.” It is determined from Equation 15. 2: © 2007 by Taylor & Francis Group, LLC 370 Exposure Analysis RfD = NOAEL UF M F (15. 2) where NOAEL = the “no observable adverse effects level” (mg/kg/day)... persons, at least 90% of our daily cumulative exposure to pesticides occurs at home Results from simultaneous 24-hour indoor air and personal exposure monitoring in NOPES, showed that 85% of the total daily adult exposure to airborne pesticides was from breathing air inside the home (Whitmore et al 1994) While pesticide residues on residential surfaces represent an exposure risk to all occupants, small children... cm2 At the conclusion of the traverse, the PUF ring is removed from the detached axle cylinder and placed in a sealed container for transport to the laboratory for analysis © 2007 by Taylor & Francis Group, LLC 358 Exposure Analysis 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... estimate the exposures of small children to residential pesticides Better methodologies need to be developed and applied to more accurately determine surface-to-skin and skinto-mouth transfer efficiencies, pesticide bioavailability from ingested dust, and the relationship of child activity patterns to residential exposures Such studies are essential before reliable exposure assessments can be made 15. 9 OCCURRENCE,... the potential total, or aggregate, exposure from all sources Multimedia, multipathway models for human exposure via the air, water, and soil ingestion routes have been published (e.g., McKone and Daniels 1991), but there have been few, if any, reported studies in which such models have been field tested for pesticide exposures While models may be used to predict human exposure or health risks associated... and Toxicology, 22: 260–266 © 2007 by Taylor & Francis Group, LLC 372 Exposure Analysis Dewalt, G., Constant, P., Buxton, B.E., Rust, S.W., Lim, B.S., and Schwemberger, J.G (1995) Sampling and Analysis of Lead in Dust and Soil for the Comprehensive Abatement Performance Study (CAPS), in Lead in Paint, Soil and Dust: Health Risks, Exposure Studies, Measurement Methods, and Quality Assurance, Beard, M.E... Quantitative Estimation of Dermal Exposure to Pesticides in Housedust, Journal of Exposure Analysis and Environmental Epidemiology, 9: 521–529 Eller, P and Cassinelli, M., Eds (1994) NIOSH Manual of Analytical Methods, 4th ed., Publication No 94113, National Institute for Occupational Safety and Health, U.S Department of Health and Human Services, 3rd Supplement 2003 -154 , Schlecht, P.C and O’Connor, . 347 15 Exposure to Pesticides 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. 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,. sealed container for transport to the laboratory for analysis. © 2007 by Taylor & Francis Group, LLC 358 Exposure Analysis The drag sled (Figure 15. 6) is a simple device constructed of a 7.6-cm