Evaluation of the Potential Carcinogenicity of Lead and Lead Compounds: In Support of Reportable Quantity Adjustments Pursuant to CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) Section 102

摘要

Information on the potential carcinogenicity of lead and lead compounds is summarized and evaluated. The human studies provide suggestive evidence of carcinogenicity, but, because of confounding exposures to other carcinogens and the lack of measurements of lead exposure, are inadequate to prove or disprove carcinogenicity. Numerous long-term animal studies, using several different forms of lead and routes of exposure, provide sufficient evidence. This combination of evidence, together with information from short-term tests, other toxic effects, and pharmacokinetic properties, yields a classification of lead and lead compounds as probably human carcinogen, Group B2. No specific cancer potency has been estimated for lead. Many factors influence lead-induced cancer, creating difficulties in selecting an appropriate measure of dose. Cross-species pharmacokinetic models are needed before the animal studies can be used to estimate a human cancer potency. Because it has been relatively high concentrations of lead that have increased the incidence of cancer in animals, it seems appropriate to characterize the cancer potency of lead as low, placing lead in potency Group 3.