Part V Multimedia Exposure © 2007 by Taylor & Francis Group, LLC 319 14 Exposure to Pollutants from House Dust John W. Roberts Engineering-Plus, Inc. Wayne R. Ott Stanford University CONTENTS 14.1 Synopsis 319 14.2 Characteristics and Measurement of House Dust 320 14.3 Major Pollutants in House Dust 326 14.3.1 Lead: Sources, Pathways, Trends, and Effects 326 14.3.2 Reducing Lead Exposure from House Dust 330 14.3.3 Pesticides, Polycyclic Aromatic Hydrocarbons (PAHs), Phthalates, and Other Toxic Pollutants 332 14.4 Control of House Dust 337 14.4.1 Cleaning 337 14.4.2 Why Vacuum Cleaners Do and Do Not Work 338 14.5 Master Home Environmentalist™ Program 339 14.6 Health Care Cost Savings 341 14.7 Making a Plan to Reduce Your Personal Exposure 342 14.8 Questions for Review 342 14.9 Acknowledgments 343 References 343 14.1 SYNOPSIS House dust presents a special problem: it is not routinely measured; it has been found to contain a large number of toxic pollutants; and it presents potential health problems for infants and children who have small body mass and developing organs, spend large amounts of time near floors and carpets, and engage in hand-to-mouth activities. Specially designed vacuum cleaners, the HVS3 and HVS4, have been developed to collect large samples of house dust from carpets and bare floors, as well as dust from outdoor surfaces such as streets, sidewalks, and lawns. These standardized vacuums have been used since 1990 to collect house dust samples as part of numerous studies of American homes. The results demonstrate that concentrations of many toxic pollutants (lead, pesticides, and polycyclic aromatic hydrocarbons) in homes often exceed the soil “screening levels” established for Superfund sites. There has been a dramatic reduction in the lead in gasoline and children’s blood since 1990. However, one in three children under 6 years of age still lives in a house with a lead-based paint hazard. Homes built before 1940 present the most risk for toddlers. © 2007 by Taylor & Francis Group, LLC 320 Exposure Analysis A major cause of the high pollutant concentrations in house dust is the preferential “track-in” of small dust particles from outdoor soil containing exterior paint of older homes, pesticides from lawns and gardens, air pollution fallout, allergens, and vehicular pollutants found on streets and sidewalks. Deep dust in ordinary carpets acts as a sink and source of these pollutants and is the major source of pollutants in surface dust. Human activity in a room causes carpet dust to be resuspended. The present expenditure of public funds at most Superfund sites is not efficient in reducing total exposure. The exposures from indoor dust and air are usually much higher than those due to many Superfund sites. Fortunately, pollutant concentrations and loadings from house dust can be reduced in most homes by relatively simple steps, such as removing shoes before entering the home, using a commercial-grade door mat, reducing carpets indoors, selecting carpets and floor surfaces that are easy to clean, dusting, and vacuuming frequently with a vacuum cleaner equipped with an agitator brush and a dirt finder. Many environmental pollutants reach people through only one carrier medium. For example, we are exposed to carbon monoxide (CO) only through the air we breathe. For single-medium pollutants, a multimedia exposure analysis is not appropriate. For others, a multimedia analysis may be necessary to determine the concentrations of each pollutant in each medium, which may include house dust, ambient air, drinking water, and food. Pollutants for which multimedia exposure analyses are appropriate include lead (Pb) and polycyclic aromatic hydrocarbons (PAHs). 14.2 CHARACTERISTICS AND MEASUREMENT OF HOUSE DUST It should come as no surprise to anyone who has cleaned the interior of a home that a layer of particles called “house dust” accumulates rapidly on surfaces, such as floors, shelves, and window- sills. We have all observed layers of dust that have settled on tables, chairs, sofas, light fixtures, bookshelves, floors, cupboards, figurines, and on other surfaces in a home. Even after just a few weeks, the layer of dust becomes thick enough to be visible to the eye and is easily picked up on fingers touching horizontal surfaces. Anyone who has operated a vacuum cleaner can remember emptying clumps of gray-brown matter from the collection bag after an hour or two of vacuuming. Indeed, removal of house dust is such a common household chore that the vacuum cleaner, a motorized air movement filtering system equipped with a moving agitator brush, was invented to help residents collect house dust. Feather dusters, invented to dislodge the dust from household objects and surfaces, simply spread dust around and are of dubious value. Area rugs have been used for thousands of years and can be cleaned by hanging them on a wire and beating them or washing them with water. Wall-to-wall carpets were not popular before the vacuum cleaner was invented, in part because they could not be cleaned adequately. How does one go about measuring quantitatively the exposures of children and adults to pollutants in house dust? In 1987, engineers John Roberts and Mike Ruby, working under a contract with the U.S. Environmental Protection Agency (USEPA), developed the High Volume Surface Sampler (HVS2), a special-purpose vacuum cleaner designed to collect house dust from surfaces in a standardized manner for subsequent chemical analysis for exposure assessment purposes (Roberts et al. 1991a). The HVS2 has a known and reproducible dust removal rate on various types of test surfaces and relatively constant efficiency at different loadings of surface dust. The HVS2 weighed 55 lbs, was expensive ($8,000), and difficult to operate. This first test model soon evolved into the HVS3, a 24-lb vacuum cleaner costing around $3,000 that could be used to collect a large, representative sample of house dust from indoor sources such as carpets, rugs, and bare floors, and dust from outdoor surfaces such as streets, sidewalks, lawns, and bare, packed dirt (Roberts et al. 1991b) (Figure 14.1). The HVS3 vacuum is recognized in American Standard of Testing Materials (ASTM) method 5438-00 and is now available commercially from CS3, Inc. (Sandpoint, Idaho). Due to its high airflow volume (17–20 cubic feet per minute [cfm] or 8.1–9.5 l/s), the HVS3 dust sampler can collect a 10-minute sample that is large enough (2–200 grams, [g]) to permit subsequent laboratory chemical analyses and bioassays. This specialized vacuum cleaner system © 2007 by Taylor & Francis Group, LLC Exposure to Pollutants from House Dust 321 maintains uniform sampling conditions by measuring and controlling the airflow and pressure drop across a 5-inch (14-cm) nozzle. A 3-inch (7.5-cm) cyclone collects more than 99% of the house dust that enters without any reduction in airflow. The cyclone “catch cup” can be used to transport the sample for laboratory analysis. The dust that is collected in the cyclone cup is usually sieved through a 100-mesh sieve so that only dust below 150 microns in diameter is analyzed. This cut point was selected because these particles stick to skin and hands better and present more risk. Approximately 140 of these specialized vacuum cleaners were in use throughout the world in 2005, and a number of scientific papers using the HVS3 have reported results for lead, pesticides, and other pollutants in house dust. These results can be compared with each other, since the operators of the HVS3 are all using the same standardized method. The HVS4, developed in 2001, is a 17-pound simplified version of the HVS3 that is easier to carry, operate, and purchase. House dust, because of its proximity to pets, children, and adults, has considerable potential for exposing the occupants of a home to toxic and hazardous pollutants. Pollutants in dust increase the potential exposure of all people and pets, especially infants and toddlers who crawl and mouth their hands and other objects. Dogs and cats that clean their fur with their tongue will also ingest pollutants in house dust and soil that they contact. These animals may have high health risks from Pb in an old house that is being painted or remodeled. The average infant’s daily dust ingestion rate, estimated to be 100 milligrams per day (mg/day), is more than two times that of adults. Eleven percent of toddlers may exhibit pica behavior, eating nonfood items, and may consume up to 10 g of soil and dust per day (Calabrese and Stanek 1991; Mahaffrey and Annest 1985). Potential risks to small children, when compared to adults, are further increased due to their smaller size, higher ratio of surface area to body weight, and the stage of development of their organs, nervous systems, and immune systems (Woodruff et al. 2003; Roberts et al. 1992). Figure 14.2 illustrates the role of house dust as a carrier medium for pollutants reaching a baby, compared with the quantity of food eaten, air breathed (6.3 m 3 /day), and water drunk (1 liter/day). House dust gets into indoor air, food, and water. However these routes of exposure to house dust are not important when compared with the 100 mg that the average infant ingests (Calabrese and Stanek 1991). A baby’s dust intake from indoor air is estimated to be 0.1 mg/day. A general finding from research conducted thus far is that house dust often contains a great variety of pollutants that should be of concern for the health of residents (Roberts et al. 1992; Camann and Buckley 1994; Rudel et al. 2003; Maertens, Bailey, and White 2004). Pollutants found in house dust include lead, cadmium, chromium, mercury, arsenic, other toxic metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichloro diphenyl trichloroethane (DDT), phthalates, fire retardants, and other persistent FIGURE 14.1 Special purpose vacuum, the HVS3, designed to collect a large quantity of dust in a standard- ized manner for laboratory analysis of the sample’s chemical composition and pollutant concentration. (Cour- tesy of Dr. Robert Lewis, USEPA; see also Chapter 15 and Figure 15.4.) © 2007 by Taylor & Francis Group, LLC 322 Exposure Analysis pesticides. House dust is a major pathway for children and adults for the flame retardants polybrominated diphenylethers (PBDEs) (Stapleton et al. 2005; Jones-Otazo et al. 2005). House dust also contains pollutants that come from window cleaners, laundry detergents, spot removers, plastics, electronics, and carpeting. Concentrations of these pollutants may exceed USEPA health- based standards (Rudel et al. 2003). Most of the pollutants in the ambient air may be deposited with particles on the roof and siding of houses and be washed down to the foundation soil and walkways. Measurements (Adgate et al. 1998) show that carrying the pollutant indoors on the shoes, or “track-in,” is one of the largest sources of house dust in most U.S. homes (Figure 14.3). There appears to be a preferential track-in of small particles because they stick to shoes better (Roberts et al. 1996). The small particles have a higher surface area (and toxicity) per unit mass. This is the best theory to explain why the concentration of toxic pollutants found in house dust are higher than those found in soil around the house and can equal or exceed street dust concentrations found in front of the house (Roberts et al. 1992). Most parents do not allow their infants to play in street dusts because of the known toxic pollutants in vehicle exhaust, motor oil, and asphalt. However, increased awareness of the pollutants in house dust may cause parents to put a clean sheet down before they allow a baby to play on a carpet and also to learn effective methods of cleaning to protect themselves and their children. House dust on carpets is easily resuspended into the air of a room where occupants breathe it as airborne particulate matter. In an experiment by one of the authors (Ott) in a Palo Alto, CA, home, two occupants purposely “stomped” on the carpet, plush shag, for 18 minutes after eating dinner and relaxing (Figure 14.4). The mass concentration of particulate matter of 5 micrometers or smaller (PM 5 ) measured at a height of 30 inches above the floor rapidly increased in the room as soon as the stomping began. The doors and windows were closed as usual, and the particle concentrations did not return to normal levels until about 1 1/2 hours later. Most people may be unaware of the ease by which particles are stirred up in their homes, or resuspended, after just a small amount of physical indoor activity. Because of their small size, resuspended fine particles are not easily seen by the eye, even though they may surround us indoors. Indeed, one might conclude that we live in a “sea of particles” in our homes. The “particle loading” is often higher inside than outside and in some homes is much higher than in others, depending on the activities of the occupants, the presence of pets, and the steps taken to reduce house dust. FIGURE 14.2 Estimated quantity of dust per day reaching a small child from dust ingestion, drinking water, breathing, food ingestion, and dermal contact. DRINKING WATER 1 liter/day BREATHING 6.3 m 3 /day FOOD DERMAL CONTACT WITH DUST 400 mg/day DUST INGESTION 100 mg/day EXPOSURE PATHWAYS FOR CHILDREN © 2007 by Taylor & Francis Group, LLC Exposure to Pollutants from House Dust 323 Overall, five important steps can help reduce the levels of house dust: •Wiping shoes twice on a commercial grade door mat before entering the home • Removing shoes while in the home • Frequent and thorough vacuuming of carpets and furniture • Removing deep dust from carpets with a vacuum with a power head and an embedded dirt finder • Cleaning all surfaces inside the home on a regular basis A commercial-grade doormat can be obtained by making a special order at a large hardware store. The “twister” mat often found in front of department stores is an example of a high-quality mat. FIGURE 14.3 Dust tracked in from outdoors contains lead, pesticides, and other pollutants. The dust collects on floors and surfaces and becomes embedded deep in the weave of carpets. It becomes resuspended when people walk on floors, exercise, or breathe particles. It can be ingested directly by toddlers engaging in hand- to-mouth activities. Using a doormat, removing shoes, and frequently cleaning with an agitator-equipped vacuum can reduce indoor concentrations of these pollutants. WY B8 20 C a l i forni a Dust containing pesticides ▼ ▼ Toddlers pick up toxics in dust ▼ Dust tracked-in by shoes ▼ Road dust containing lead and PAHs ▼ ▼ Lead washed down from paint and auto exhaust © 2007 by Taylor & Francis Group, LLC 324 Exposure Analysis Persons with allergies, asthma, and heart problems have special health risks due to resuspended particles indoors. Books such as Allergy-Free Living (Howarth and Reid 2000) list dozens of steps a resident can take to decrease exposure to the major interior allergens and irritants by creating a healthy, allergy-free home and lifestyle. Asthma is a leading cause of chronic disease and absen- teeism among schoolchildren in the United States, and an increasing incidence of asthma in the United States suggests that efforts to reduce fine particles (that include dust mites, mold, and cat dander) indoors could produce health benefits for both children and adults (Krieger et al. 2005). Although it is possible to reduce resuspension of carpet dust by frequent vacuuming and other practical steps, many people do not realize that an extremely thorough vacuuming is needed to remove embedded dust particles. Even after extensive vacuuming, large amounts of dust remain deeply embedded in the fabric of the carpet. Some new vacuum cleaners are equipped with an embedded dirt finder, an electronic sensor system with red and green signal lights that the operator can easily see while vacuuming. The light is red when the vacuum is picking up particles, but it turns green when the noise made by the particle stream hitting a sensor plate drops below a fixed level. Removing the deep dust from an old carpet for the first time may require vacuuming some areas of the carpet for surprisingly long time periods, sometimes up to 45 minutes per square meter (min/m 2 ) of carpet, to get a green light on the dirt finder. In two studies of 11 and 10 older carpets in the Seattle area, the median time to remove the deep dust was 8 and 20 min/m 2 , respectively (Roberts et al. 1999; Roberts, Glass, and Mickelson 2004). Once the “deep dust” is removed, it is relatively easy to keep it out by frequent vacuuming and use of a commercial grade doormat. A 6- meter long high-quality doormat reduced dirt track-in at an elementary school from 12 to 2 milligrams (mg) per person (Lehen 1983), a reduction of 83%. One of the authors (Roberts, Glass, and Mickelson 2004) developed a “3-spot test,” a method to estimate how much deep dust resides in a carpet and the time required to remove the dust. The method uses a vacuum cleaner equipped with an embedded dust finder, such as the upright Hoover Vacuum Model U 6445-900. The 3-spot test consists of the following procedure: FIGURE 14.4 Particle mass concentration measured indoors before, during, and after 18 minutes of stomping activity by two people on an old shag carpet in an efficiency apartment in Palo Alto, CA, with the doors and windows closed. The piezobalance fine particle monitor was located at a height of 30 in. (0.76 m) and within 4 ft (1.2 m) of the two stomping persons, who rested before and after the stomping activity. Time (P.M.) 8:00 9:00 10:00 11:00 PM 3,5 Concentration (μg/m 3 ) 0 20 40 60 80 100 120 140 Outdoors Indoors Eating Dinner Talking, Relaxing Stomping Activity Begins Stomping Activity Ends Resting, Talking © 2007 by Taylor & Francis Group, LLC Exposure to Pollutants from House Dust 325 • Choose a spot in the center of the carpet. • Start the vacuum and a stopwatch at the same time. Hold the vacuum in one place until the light turns green. • Then move the vacuum quickly without stopping it to a second spot 3 feet away and hold it in one place until the light turns green. Repeat this procedure for a third spot. The three spots should form a triangle with equal sides. • Note the total time required to clean all three spots. When the time required for the dust detector light to turn green is less than 11 seconds for all 3 spots, the carpet is considered relatively clean with 6 seconds being an achievable goal. Roberts, Glass, and Mickelson (2004) found that the surface dust (g/m 2 ), deep dust (g/m 2 ), and dust collection rate (g/min) tended to drop rapidly at first and then much more slowly during vacuuming. An HVS4 was used to measure the surface dust. For this study the starting surface dust loading was 0.7–21.1 g/m 2 , which decreased by 85–99% when the deep dust was removed. Vacuuming times ranging from 2.3–95 min/m 2 were required to remove the deep dust. Until the deep dust is removed, it will tend to rise to the surface of the carpet and become surface dust. Activity in the room brings up deep dust. Lead concentrations from two sequential samples of surface dust on a carpet in a remodeled house increased from 180 parts per million (ppm) to 59,800 ppm (Roberts, Glass, and Mickelson 2004). The surface lead loading increased by a factor of 60 on the second sample. We theorized that a layer of lead paint from remodeling activity was uncovered as the deep dust was removed. Measuring the lead surface loading, in units of micrograms per square meter (µg/m 2 ), is one of the best ways to predict the amount of lead in the blood of an infant who crawls on such a carpet in an old house (Davies et al. 1990). Estimating deep dust with the 3-spot test and measuring the lead in the deep dust collected in the 3-spot test and a small area inside the 3-spot triangle, may also predict lead in the blood of an infant. Surface dust shows much more variation than deep dust. Since deep dust is the major source of the pollutants that appear in surface dust, removal of deep dust tends to reduce the risk from surface dust by more than 90% (Roberts, Glass, and Mickelson 2004). There may be an analogy between vacuuming the deep dust from a carpet in a home and digging at an archeological site; both efforts uncover the historical record of past events. Every individual who enters a home interacts with its dust history. They take dust from a room when they leave and make a unique contribution to the dust with skin scales, clothing fibers, dust falling off clothes, and tracked-in dust. The DNA in skin scales and unique clothing fibers can theoretically be used to identify past room occupants (National Institute of Justice 2002). They take away a “fingerprint” of the dust from the room that collects on their clothes. Replacing house carpets with bare wood floors will eliminate the tendency for carpets and backing to act as a reservoir for pollutants. Bare floors are easiest to clean. Flat and level loop carpets are also easy to clean, with carpet cleaning difficulties increasing for short plush carpets, deep plush, and shag carpets, respectively. Spilled liquids may initiate mold growth in a carpet that is not dried in 24 hours. Interface (www.interfaceinc.com) as well as Collins and Aikeman (www.powerbond.com) make carpets with low volatile organic compound (VOC) emissions and waterproof backing that are around 50% easier to clean. The cost of installing a Powerbond carpet in a Seattle apartment in 2005 was $3.50/ft 2 . While there may be health advantages for bare floors, the homeowner must consider the costs and benefits of different types of floor coverings. Ceramic, solid hardwood, laminated hardwood, and linoleum floors are long lasting but more expensive. Vinyl tile floors are lower in cost but have VOC emissions. Carpets reduce noise, are softer to walk on, and may reduce falls. Bare floors in classrooms may require architectural and surface material changes to reduce noise. © 2007 by Taylor & Francis Group, LLC 326 Exposure Analysis 14.3 MAJOR POLLUTANTS IN HOUSE DUST 14.3.1 L EAD : S OURCES , P ATHWAYS , T RENDS , AND E FFECTS Lead is unique among the toxic heavy metals because of its abundance in the Earth’s crust. Because of its easy isolation and low melting point, lead was among the first metals to be used by humans thousands of years ago. The environmental significance of lead is a result both of its utility and its abundance. World production of lead, about 4 million tons per year, is larger than the commercial production of any other toxic heavy metal (USEPA 1986). Lead is present in food, water, air, soil, dustfall, paint, and other materials with which the general population comes into contact. Each of these is a potential pathway for human exposure to lead through inhalation or ingestion. The actual lead content in each environmental medium may vary by several orders of magnitude. Individual exposure is further complicated by different activity patterns and differences in indoor and outdoor microenvironments. Centuries of mining, smelting, and usage have made the natural background concentration of lead difficult to determine. Geochemical data indicate that the concentrations of lead in most surface soils in the United States range from 10–30 ppm or µg/g (USEPA 1986). Unlike gaseous pollutants, where 1 ppm denotes a part-per-million by volume, trace metals like lead usually are reported in mass ppm units, and 1 ppm by mass is equivalent to 1 microgram of lead per gram of soil, or 1 µg/g. Trace amounts of lead occur naturally in air and water as a result of wind and rain erosion, and in air as a result of volcanic dusts, forest fires, sea salt, and the decay of radon. Natural background concentrations of airborne lead have been estimated as approximately 0.0006 µg/m 3 or 5 × 10 –7 µg/g. Estimated natural fresh water and ocean water lead concentrations are about 0.5 µg/L of water (5 × 10 –4 µg/g water) and 0.05 µg/L (5 × 10 –5 µg/g water), respectively (USEPA 1986). As a consequence of the diverse uses of lead in products, including its extensive history of use in gasoline and house paint in the United States, the present concentrations of lead in air, soil, and water are higher than these estimated background levels. Typical average nonurban lead concen- trations in air are about 0.01 µg/m 3 (USEPA 2004). Prior to restrictions on the lead content in gasoline in the United States, typical ambient lead concentrations in U.S. cities averaged about 1.5 µg/m 3 (Woodruff et al. 2003). Concentrations of lead in most urban water supplies are well below 10 µg/L standard for water (0.01 µg/g water) (Woodruff et al. 2003). However, values above 50 µg/L have been reported in some locations on occasion. Suspended solids contain the major fraction of lead in river waters. Concentrations of lead in tap water may be considerably higher than those in municipal supplies. Lead values as high as 2,000 µg/L have been reported for homes with lead pipes and lead-lined storage tanks. Efforts to reduce the effect of lead solder joints in copper pipes and fittings and greater use of plastic pipe has reduced the levels of lead in residential tap water. Running the tap a few minutes before using tap water can help reduce lead concentrations in cases where lead is added by a home’s plumbing system. The contribution of food to human exposure to lead is highly variable and not well quantified. Estimates of the daily intake of lead from food vary from about 100–350 µg/day. Historically, foods stored in lead-soldered cans or stored or served in imported glazed pottery were identified as having high lead content (ATSDR 1989). In the United States there have been efforts to reduce the contact between lead-containing containers and foods. Use of lead as an antiknock additive in gasoline historically accounted for a major share of U.S. lead production. Consequently, motor vehicles constituted the major source of atmospheric lead emissions. As a result of legislation that limited the lead content of gasoline, the production and use of alkyl lead additives decreased in the United States beginning around 1978. Beginning at this same time, concentrations of lead in ambient air have shown a similar downward trend. In 1977 ambient air lead concentrations at 78 sites in the United States averaged 1.5 µg/m 3 . By 1984 ambient air lead levels in the United States had dropped to an average of 0.3 µg/m 3 . In 1995 ambient © 2007 by Taylor & Francis Group, LLC Exposure to Pollutants from House Dust 327 air lead concentrations in the United States had continued to decline, reaching an average of about 0.1 µg/gm 3 , which is close to the background concentrations measured years earlier in nonurban areas (USEPA 1986; Woodruff et al. 2003). Lead happens to be one of the few environmental pollutants for which long-term data are available on an important biomarker of dose, the concentrations in the blood of U.S. citizens. Elevated blood lead levels are a predictor of adverse health effects, including anemia and brain damage. The U.S. National Center for Health Statistics periodically conducts the National Health and Nutrition Examination Survey (NHANES). In this survey, as many as 22,000 respondents are statistically selected and given a physical examination that includes a detailed questionnaire about their current health, diet, and activities. Blood drawn from a subset of the NHANES respondents is analyzed by the U.S. Centers for Disease Control (CDC) to determine blood lead concentrations. The results indicate a downward trend for blood lead concentrations of Americans over the 14-year period from 1976–1990 (Figure 14.5). This downward trend is continuing to the present time and roughly correlates with a similar downward trend in the lead content of gasoline (Woodruff et al. 2003). Measurements of average blood lead levels for the U.S. population based on NHANES-II, NHANES-III, and follow-up national surveys indicate that average blood lead levels for the U.S. population have continued to drop through 1999, but at a lower rate (Figure 14.6). The median blood lead concentration of children 5 years old and younger dropped from 15 micrograms per deciliter (µg/dL) for the 1976–1980 period, to 2.2 µg/dL for the 1999–2000 period. However, 10% of children during 1999–2000 still had blood lead concentrations above 4.8 µg/dL, a level which is still of considerable concern (Woodruff et al. 2003). The data presented in this chapter suggest that over 50% of adults 25–35 years of age in 2005 have had their intellectual potential reduced by exposure to lead in childhood. Despite this downward trend in blood lead levels nationwide, many children and adults still live in older homes that contain risks from lead-based paints. The possibility that elevated blood FIGURE 14.5 Measurements of blood levels in Americans based on the National Health and Nutrition Examination Survey (NHANES) from NHANES-II (1976–1980) and NHANES-III (1988–1991), compared with the amount of lead used in U.S. gasoline. (Personal communication with David M. Mannino, Centers for Disease Control, Atlanta, GA, 2002.) 100 80 60 40 20 0 18 16 14 12 10 8 6 4 2 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 Gasoline lead Blood lead YEAR LEAD USED IN GASOLINE (thousands of tons) MEAN BLOOD LEAD ( μg/dL) ▼ ▼ © 2007 by Taylor & Francis Group, LLC [...]... Toxics in Dust, Journal of Exposure Analysis and Environmental Epidemiology, 1(1): 143 –155 © 2007 by Taylor & Francis Group, LLC Exposure to Pollutants from House Dust 345 Roberts, J.W., Budd, W.T., Ruby, M.G., Camann, D.E., Fortmann, R.C., Lewis, R.G., Wallace, L.A., and Spittler, T.M (1992) Human Exposure to Pollutants in the Floor Dust of Homes and Offices, Journal of Exposure Analysis and Environmental... few multimedia exposure analyses available in the literature Multimedia exposure analyses can be extremely important for setting regulatory policies Determining the amount of exposure attributable to each carrier medium can help provide a decision maker with guidance about reducing total exposure in a manner that protects public health © 2007 by Taylor & Francis Group, LLC 330 Exposure Analysis effectively... 342 Exposure Analysis and may also be a large source of benzo(a)pyrene, pesticides, and other carcinogens Cancer rates for children have increased 26% from 1975–1998 (Woodruff et al 2003) It is prudent to reduce exposure to the toxic material in house dust by cleaning while searching for a safe method for protecting small children against sensitization 14. 7 MAKING A PLAN TO REDUCE YOUR PERSONAL EXPOSURE. .. Wilford, B (2005) Is House Dust the Missing Exposure Path for PBDEs? An Analysis of Urban Fate and Human Exposure to PBDEs, Environmental Science and Technology, 38 (14) : 5121–5130 Krieger, J., Takaro, T.K., Song, L., and Weaver, M (2005) The Seattle-King County Healthy Homes Project: A Randomized, Controlled Trial of a Community Health Worker Intervention to Decrease Exposure to Indoor Asthma Triggers, American... 332 Exposure Analysis was built before 1940 This inconsistency between widespread exposures to high concentrations of several toxic pollutants in one’s own home, compared with rare and unlikely exposure from most Superfund sites, has not been fully addressed or balanced in existing environmental laws The spending of public funds on Superfund site cleanup has not been efficient in reducing the total exposure. .. Immunology, 110(4): 576–581 Takaro, T.K., Krieger, J., Song, L., and Beaudet, N (2004) Effect of Environmental Interventions to Reduce Exposure to Asthma Triggers in Homes of Low-Income Children in Seattle, Journal of Exposure Analysis and Environmental Epidemiology, 14( supp 1): S133–S143 Tucker, D (2003) Personal communication, Director of Laboratories, The Hoover Company, North Canton, OH USEPA (1986) Air... original swaths increases effectiveness (Tucker 2003) 14. 5 MASTER HOME ENVIRONMENTALIST™ PROGRAM Many scientists throughout the world are researching human exposure to environmental pollutants, including scientists at the USEPA National Exposure Research Laboratory in Research Triangle Park, NC Public and private organizations also have become involved in exposure reduction activities For example, the American... Paid indigenous community health workers (CHW) have also been used to reduce home exposures The CHWs were successful in empowering lowincome families with asthmatic children to reduce exposure to dust mites, dust, and other asthma triggers in the home (Takaro et al 2004) © 2007 by Taylor & Francis Group, LLC 340 Exposure Analysis Information is essential but often not sufficient to cause a family to change...328 Exposure Analysis BLOOD LEAD LEVELS IN THE U.S POPULATION 1976–1999 18 Blood Lead Level (μg/dL) 16 14 12 10 8 6 4 2 Median Blood Lead for Children Aged 5 Years or Less (1999 to 2000 Period) 0 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 Year FIGURE 14. 6 Measurements of blood lead levels in Americans based on the... department as appropriate if there are high costs or health risks involved 14. 8 QUESTIONS FOR REVIEW 1 Why are relatively few examples of multimedia exposure analyses found in the published literature? 2 Identify pollutants other than lead and PAHs for which multimedia exposure analyses would be appropriate These are pollutants for which exposure occurs through more than one environmental carrier medium 3 . Not Work 338 14. 5 Master Home Environmentalist™ Program 339 14. 6 Health Care Cost Savings 341 14. 7 Making a Plan to Reduce Your Personal Exposure 342 14. 8 Questions for Review 342 14. 9 Acknowledgments. Synopsis 319 14. 2 Characteristics and Measurement of House Dust 320 14. 3 Major Pollutants in House Dust 326 14. 3.1 Lead: Sources, Pathways, Trends, and Effects 326 14. 3.2 Reducing Lead Exposure from. from House Dust 330 14. 3.3 Pesticides, Polycyclic Aromatic Hydrocarbons (PAHs), Phthalates, and Other Toxic Pollutants 332 14. 4 Control of House Dust 337 14. 4.1 Cleaning 337 14. 4.2 Why Vacuum