US EPA

Information on the potential carcinogenicity of lead and lead compounds is summarized and evaluated under EPA's Guidelines for Carcinogen Risk Assessment. The human studies provide suggestive evidence of carcinogenicity, but, because of confounding exposures o 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 stimated for lead. Many factors influence lead-induced cancer, creating difficulties in selecting an appropriate measure of dose. Cross-species pharamcokinetic 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 under EPA's Methodology for Evaluating Potential Carcinogenicity in Support of Reportable Quantity Adjustments Pursuant to CERCLA Section 102.

U.S. EPA, AND D. 20460. EVALUATION OF THE POTENTIAL CARCINOGENICITY OF LEAD AND LEAD COMPOUNDS: IN SUPPORT OF REPORTABLE QUANTITY ADJUSTMENTS PURSUANT TO CERCLA SECTION 102. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/8-89/045A (NTIS PB89181366).

Project Officer Jim Cogliano, FTS 382-2575