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<br /> GLt
<br /> 7. REGULATIONS AND ADVISORIES
<br /> The international, national, and state regulations and guidelines regarding lead in air, water, and other
<br /> ,Media are summarized in Table 7-1.
<br /> pTSDR has not derived an MRL for lead. Neither a reference concentration (RfC) nor`a reference dose
<br /> 1.fFf)) exist for lead and its inorganic compounds because it was decided that no thresholds have been
<br /> ldernonstrated for the most sensitive effects in humans. However, EPA (1990a) has determined that the
<br /> ;ritical effect for lead is central nervous system effects. EPA (1990a) has derived a chronic oral RfD for
<br /> tlkyl leads of 1 x10-7 mg/kg/day based on liver and neuronal damage in rats (Schepers 1964). A subchronic
<br /> 4value of 1 x 10-6 mg/kg/day for the same effect of concern has also been derived, based on the same studv.
<br /> The RfDs based on these chronic and subchronic studies were assigned uncertainty factors of 10,000 and
<br /> 31,000, respectively.
<br /> CEPA (IRIS 1990) has assigned lead a weight-of-evidence carcinogen classification of B2, which indicates
<br /> .hat lead is a probable human carcinogen. A quantitative estimate of lead carcinogenic risk from oral and
<br /> inhalation exposure has not been recommended by the Carcinogen Assessment Group. Quantifying lead's
<br /> `xncer risk involves many uncertainties, some of which may be unique to lead. Age, health, nutritional
<br /> ' Estate, body burden, and exposure duration influence the absorption, release, and excretion of lead.
<br /> kdditionally, current knowledge of lead pharmacokinetics indicates that an estimate derived by standard
<br /> 'procedures would not truly describe lead's potential risk (IRIS 1990).
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<br /> The CDC determined in 1991 that blood lead levels of >10 µg/dL were to be considered elevated (CDC
<br /> )991).
<br /> in an effort to protect human health by reducing the lead levels at consumers' taps to as close to the
<br /> XLG (zero) as is feasible, EPA (1989f, 1991a) requires water system authorities to: (1) install or
<br /> ,improve corrosion control to minimize lead levels at the tap while ensuring that treatment does not cause
<br /> the water system to violate any national primary drinking water regulation; (2) install treatment to reduce
<br /> dead in source water entering the distribution system; (3) replace lead service lines when more than 10%
<br /> of targeted tap samples exceed 0.015 mg/L lead in drinking water if corrosion control and/or source water
<br /> treatment does not bring lead levels below the lead action level; and (4) conduct public education programs
<br /> J lead levels are above the action level.
<br /> Lead is regulated by the Clean Water Effluent Guidelines for the following industrial point sources:
<br /> 'electroplating, organic and inorganic chemicals, iron and steel manufacturing, nonferrous metals
<br /> manufacturing, steam electricity, glass manufacturing, asbestos, rubber, timber products processing, metal
<br /> finishing, mineral mining, ore mining, paving and roofing, paint and ink formulating, gum and wood, carbon
<br /> black, battery manufacturing, metal molding and casting, porcelain enameling, copper forming, electrical
<br /> and electronic components, and nonferrous metal forming (EPA 1988b).
<br /> 11te Lead Contamination Control Act of 1988 mandates that the Consumer Product Safety Commission
<br /> (1) require the repair or recall of drinking water coolers containing lead in parts that come in contact with
<br /> drinking water, (2) prohibit the sale of drinking water coolers that are not lead-free, (3) require that states
<br /> 'Stablish programs to assist educational agencies in testing and remediating lead contamination of drinking
<br /> water in schools, and (4) require that EPA certify testing laboratories and provide for coordination by the
<br /> SDC of grants for additional lead screening and referral programs for children and infants (Congressional
<br /> Record 1988a, 1988b).
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