IS INGESTED INORGANIC ARSENIC A THRESHOLD CARCINOGEN

Ingested inorganic arsenic (As) is known to be a human carcinogen. An intriguing question is whether there is a threshold for the carcinogen ic effects of As, i.e., is there a level below which it does not induc e the development of cancer(s)? This Roundtable will discuss the Unite d States Environmental Protection Agency's As risk assessment using th e Taiwan data from different viewpoints. It will also consider the hyp othesis that there is a threshold for As and data for or against this hypothesis. For example, some scientists believe that epidemiological data cannot answer this question, while others feel that different stu dy designs and larger sampling will provide adequate data. Reasons for each position are given. This Roundtable discussion demonstrates the controversy surrounding the use of the Taiwan data for risk assessment . (C) 1996 Society of Toxicology