Review of Dioxin Reassessment Begins

On Nov. 22, a National Academies panel met to begin a review of EPA's 2003 draft reassessment of the risks of TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) and dioxin-like compounds. The review will focus on a number of topics, including the scientific basis for classifying TCDD as a human carcinogen and the validity of using a non-threshold linear dose-response model to calculate dioxin risks. At the meeting, William H. Farland, acting deputy assistant administrator for science in EPA's Office of Research & Development, upheld the agency's contention that TCDD is a human carcinogen and that dioxin-like compounds are likely carcinogens. He pointed out that, although industrial releases of dioxins have declined greatly in recent years, average body burdens of dioxins are within a factor of 10 of the equivalent levels that cause noncancer adverse effects, such as reproductive effects, in animals and humans. Representatives of chemical and food industries, however, said EPA's conclusions conflict with recent dioxin assessments by the European Commission and the World Health Organization, which consider dioxins less of a risk.