A technical panel of the USEPA's Risk Assessment Forum has studied three special issues regarding certain health effects, particularly skin cancer, associated with arsenic ingestion: (1) the validity of the Taiwan study and its use for dose-response assessment in the U.S. population (2) the interpretation and use of skin lesions reported as arsenic-induced skin cancers, and (3) the role of arsenic as an 'essential' nutritional requirement in the human diet. The Technical Panel also reviewed auxiliary information on genotoxicity, metabolism, and other factors that might suggest the most appropriate approach to dose-response assessment. In brief summary, the analysis shows a causal relationship between ingestion exposure to arsenic and an increased risk of skin cancer. However, there is not sufficient information to evaluate a dose-response according to any specific mechanism that one may postulate. In the absence of fully persuasive evidence for any of the possible mechanisms, a generalized multistate model that is linear at low doses was used to place an upper bound on the expected human cancer dose-response. The report summarizes the Technical Panel's review and analysis of relevant data.

Includes bibliographical references. Cover title. "Prepared for the Risk Assessment Forum, U.S. Environmental Protection Agency." "November 1987." "EPA/625-3-87-013a."