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203 <br /> 5. POTENTIAL FOR HUMAN EXPOSURE <br /> The federal government regulates the release and disposal of lead. EPA has established national ambient <br /> with the air quality standards for lead. Under the Safe Drinking Water Act, EPA limits the level of lead in <br /> drinking water. Industrial emissions are regulated by the Clean Water Act. Lead and certain of its <br /> adequate compounds are designated hazardous substances; CERCLA requires that the person in charge of a vessel <br /> available, or facility notify the National Response Center immediately when there is a release of a hazardous <br /> designed substance in an amount equal to or greater than the reportable quantity for that substance. <br /> h effects) <br /> According to the Emergency Planning and Community Right-to-Know Act of 1986, 42 U.S.C. Section <br /> .ists from 11023, industries are required to submit chemical release and off-site transfer information to the EPA. <br /> The Toxics Release Inventory, which contains this information for 1988, became available in May of 1990 <br /> yet would (TRI88 1990). This database is updated yearly and provides a list of industrial production facilities and <br /> J not be emissions. <br /> tune, the <br /> a will be Environmental Fate. Lead released to the atmosphere partitions to surface water, soil, and sediment <br /> (Getz et al. 1977; EPA 19(S6a; Mundell et al. 1989; NAS 1980; NSF 1977; Nielsen 1984). Lead is <br /> transported in the atmosphere and in surface water. Organolead compounds are transformed in the <br /> atmosphere by photodegradation (DeJonghe and Adams 1986); however, the atmospheric transformation <br /> ounds are of inorganic lead compounds is not completely understood (EPA 1986a). Organolead compounds are <br /> ldavari et transformed in surface waters by hydrolysis and photolysis (EPA 1979d). Inorganic lead compounds may <br /> ies of the be strongly sorbed to organic matter in soils and sediments (EPA 1986a). Lead is a naturally occurring <br /> element and as such is persistent in the environment. Additional information on the atmospheric <br /> transformations of organic and inorganic lead compounds in the atmosphere would provide a basis for <br /> )orted for determining the lead compounds to which humans are most likely to be exposed. Modeling the availability <br /> place, the of lead compounds needs to be accomplished. <br /> Bioavailability from Environmental Media. Available pharmacokinetic data indicate that lead is absorbed <br /> by humans following inhalation of particulate lead in ambient air and ingestion of contaminated foods, <br /> :) sources, drinking water, and soil (Chamberlain et al. 1978; EPA 1986a; Morrow et al. 1980). In addition, children <br /> urce <br /> and was may ingest paint chips that contain lead. Absorption following dermal exposure is much more limited, <br /> :9although absorption of organolead compounds through the skin has been reported following accidental <br /> leeadad was exposures (Kehoe and Thamann 1931; Laug and Kunze 1949; Moore et al., 1980). The bioavailability of <br /> 1986, 70% lead on the hand after mouthing activity needs to be modeled. <br /> -istruction, <br /> was used Food Chain Bioaccumulation. Lead is bioaccumulated by terrestrial and aquatic plants and animals <br /> )r 1987b). <br /> products, (Eisler 1988). However, lead is not hiomagnified in terrestrial or aquatic food chains (Eisler 1988). No <br /> fluctuated additional information is needed. <br /> ons below AExposure Levels in Environmental Media. Environmental monitoring data are available for lead in <br /> in the use ambient air, indoor air, surface water, groundwater, drinking water, sediments, soils, and foodstuffs (Eckel <br /> assessing "and Jacob 1988; EPA 1982a, 1986a, 1988b, 1988f, 1989f, 1989h, 1990c; Lee et al. 1989; Maenhaut et al. <br /> {:1979; Mielke 1992; Mielke et al. 1983, 1985, 1989); however, these data are not current and additional <br /> monitoring data on lead levels in all environmental media, particularly data gathered after EPA lowered <br /> ited States ' the lead content of gasoline, would be helpful in determining current exposure levels. Estimates of human <br /> cling lead intake from inhalation of ambient air and ingestion of contaminated foods and drinking water are available <br /> containing <br /> unts being (Dabeka et al. 1987; EPA 1986a, 1991d; Gartrell et al. 1986b; Gunderson 1988). Estimates are also <br /> available for intake by children through ingestion of contaminated soils, dust, and paint chips (EPA 1989c). <br /> However, some of these estimates also are not current. Additional information on the concentrations of <br />