Waste products that contain lead include storage batteries, ammunition waste, solder, pipes, and other metal products; consumer electronic products; solid waste and tailings from lead mining; items covered with lead-based paint; and solid wastes generated by mineral ore processing, iron and steel production, and copper and zinc smelting. The general population can be exposed to lead in ambient air, foods, drinking water, soil, and dust (ATSDR 1997b). Table 4-4 presents estimates of environmental lead concentrations in remote, rural, and urban areas.
Metals processing is the major source of lead emissions to the atmosphere. The arithmetic mean concentration of lead in ambient air in 1997 is estimated by EPA to have been 0.04 µg/m3. EPA's estimate of the 95th percentile concentration is 0.12 µg/m3 and of the 5th percentile concentration is 0.01 µg/m3 (EPA 1998b,c). By comparison, the National Ambient Air Quality Standard (NAAQS) for this pollutant is 1.5 µg/m3 as an annual average. The highest ambient air concentrations of lead are found in the vicinity of ferrous and nonferrous smelters, battery manufacturers and other stationary sources of lead emissions (EPA 1998b,c). EPA estimates that less than 1% of the public water systems in the United Sates have water entering the distribution system with lead levels above 5 µg/L. Those systems are estimated to serve less than 3% of the population that receives drinking water from public systems (EPA 1991a). EPA also estimates that lead levels between 10 and 30 µg/L can be found in drinking water as a result of plumbing corrosion and subsequent leaching of lead (EPA 1989).
Atmospheric deposition is an important source of lead found in soils. The strong absorption of lead to organic matter in soil tends to limit the bioavailability of lead and thus it tends not to bioaccumulate in aquatic and terrestrial food chains. Lead can be added to food crops through uptake from soil, direct deposition onto crop surfaces from the atmosphere, during transport to market, food processing, and kitchen preparation.
ATSDR (1997b) reports that data from Phase 2 of the National Health and Nutrition Examination Surveys (NHANES) III (conducted during October 1991 to September 1994) indicate that the overall geometric-mean blood-lead level of the population aged 1 year or younger was 0.11 µmol/L (2.3 µg/dL). Among those aged 1-5 years, approximately 4.4% had blood-lead levels of 10 µg/dL, representing an estimated 930,000 children with levels high enough to be of concern.
Dioxins and furans refers collectively to polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Those chemical compounds are generally classified as halogenated aromatic hydrocarbons (HAHs).