EPA s Dust Study

This regulatory action was supported by the Dust Study just discussed. Therefore, EPA conducted a peer review in accordance with the Final Information Quality Bulletin for Peer Review of the U.S. Office of Management and Budget (OMB). EPA requested this review from the Clean Air Scientific Advisory Committee (CASAC) Lead Review Panel. The CASAC, which is comprised of seven members appointed by the EPA Administrator, was established under the Clean Air Act as an independent scientific advisory committee. The CASAC s comments on the Dust Study, along with EPA s responses, have been placed into the public docket for this action. More information on the CASAC consultation process, along with background documents, is available on EPA s website at www.epa.gov/lead/pubs/casac.htm. 

In the 2006 Proposal, EPA proposed to conclude that any renovation activity that disturbs lead-based paint can create significant amounts of leaded dust, that most activities created lead-based paint hazards, and that some activities can be reasonably anticipated to create lead-based paint hazards. EPA s proposed conclusions were based upon the results of the Environmental Eield Sampling Study, which examined, on a variety of components using a variety of tools and methods, activities that EPA had determined were representative of the paint-disturbing activities that typically occur during renovations. The activities were ... 

The researchers noted the consistency of their results with EPA s Wisconsin Childhood Blood-Lead Study. EPA notes that this confirms that keeping visible dust and debris contained to the work area is important for Hmiting children s exposures to lead dust, rather than providing substantial arguments for the effectiveness of visual inspection. 

The Dust Study evaluated dry hand scraping, which is restricted under EPA s lead abatement program. In contrast to the results of the activities using power planing and high temperature heat gun, average post-job dust lead levels in the two experiments in which paint was disturbed by dry hand scraping... 

In response to the comment that the Disposable Cleaning Cloth Study used professional inspectors or other highly trained individuals following specified protocols, EPA intends to include cleaning verification in its training course for renovators and will use the results of the Dust Study and the agency s observations on the experience of the contractors in the study in its development of this course. 

Some commenters were concerned that the cleaning verification protocols are too impractical, burdensome, or time-consuming for many contractors to perform. However, the Dust Study found that cleaning verification only took, on average, slightly less than 13 minutes for experiments where the proposed rule requirements were followed. EPA s Final Economic... 

FDA estimated that in 1990, toddlers (2-year-olds) received 16% of their total lead exposure from food (5 tg/day), 1% from soil, 7% from water, and 75% from dust. EPA estimated that in 1990 lead intake from U S. drinking water would be 11.9 pg/day for a 6-year-old child and 7.5 pg/day for an infant less than 1 year old (Cohen 1988b). A study of lead in the diet of Canadian infants found an average intake by children 0-1 years of age to be 16.5 pg/day when both food and water ingestion were considered (Dabeka and McKenzie 1988). 

A worktable that can be used to calculate a cumulative exposure estimate on a site-specific basis is provided in Table 2. To use the table, environmental levels for outdoor air, indoor air, food, water, soil, and dust are needed. In the absence of such data (as may be encountered during health assessment activities), default values can be used. In most situations, default values will be background levels unless data are available to indicate otherwise. Based on the U.S. Food and Drug Administration s (FDA s) Total Diet Study data, lead intake from food for infants and toddlers is about 5 pg/day (Bolger et al. 1991). In some cases, a missing value can be estimated from a known value. For example, EPA (1986) has suggested that indoor air can be considered 0.03 x the level of outdoor air. Suggested default values are listed in Table 3. 

Inhalation is actually a less Important route of entry than assumed by CDC, if other data are considered. For example, the EPA has estimated that the average concentration of total suspended particulates (TSP) In Missouri Is about one-half the level assumed by CDC, or about 0.070 mg/m (32.33). Secondly, only a fraction (about 30%) of the total amount of airborne dust Is respirable (less than 10 pm aerodynamic diameter) (32). The percentage of TSP which Is respirable has been estimated by EPA to be no more than 50% (2). Also, the assumption that all of the airborne particles are derived from dioxin-contaminated soil Is overly conservative. Actually, about 50% of the Inhaleable particles are respirable and the remainder are between 10 and 50 pm. Further, about 83% of the non-respirable particles are from crustal material (e.g., soil) and only 47% of the respirable particles are from soil (32). Larger studies conducted by the U.S. EPA have suggested that the portion of Inhaleable dust due to soil can often be much less (34). 

The choice of dust sampling method depends on the purpose of the study. A number of publications compare various wipe and vacuum methods for Pb sampling (e.g., U.S. EPA, 1995 Sutton etal., 1995 Laxen et ah, 1988). Wipe methods have the advantage of being simple and inexpensive compared to vacuum techniques. However, vacuum methods have some distinct advantages over common wipe methods vacuum... 

Many studies report that the age of the home is a chief predictor of Pb concentration in household dust, largely due to the prevalence of Pb-based paint in older homes (Sutton etal., 1995 Rasmussen etal., 2001 Adgate etal., 1998 Davies etal., 1990 Thornton etal., 1994 Meyer etal., 1999). Older paints had concentrations of up to 50% Pb, while later paints had lower Pb concentrations but increased concentrations of Ti, Zn and Ba (U.S. EPA, 1986). Thus, indoor Pb levels tend to increase while houses are being renovated, particularly if the renovation involves electric sanding or burning with a blow lamp (Laxen etal., 1988 Davies etal., 1990). Galvanized iron roofing material, used commonly in Australia and New Zealand, con-... 

Nowadays, much of our interest in air is actually driven by concerns over the levels and effects of various pollutants. The U.S. Environmental Protection Agency (EPA) defines pollutants as unwanted chemicals or other materials found in the air. Although this definition does include a variety of small solid particles such as dust or soot, most air pollutants are gases. Thus an exploration of some of the issues surrounding the monitoring and control of air pollution will form the backdrop for our study of gases and their properties. 

Concentrations of lead in outside dusts vary with their location and inputs. A summary of studies in U.S. EPA (1986, Ch. 7) shows that in rural environments at a time when leaded gasoline was in use, rural roadside dusts were on the order of 80—130 ppm, and urban roadways had dust levels in the range of 1,000—20,000 ppm. Interior household dusts in the United States can present an upper range of 5,600—16,(X)0 depending on source inputs to these dusts such as deteriorating lead paint (Angle and Mclntire, 1979 Clark et al., 1985) or lead smelter emissions (Landrigan et al., 1975). 

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