EPA Report Assesses Dioxins' Health Risks

Dioxins are carcinogens and can cause other health effects, EPA concludes in a long-awaited draft report released on May 21. There is no threshold below which dioxins pose no cancer risk, says the agency’s draft. To protect against noncancerous effects, the draft would, for the first time, set a safe daily dose of 7 × 10^–10 mg per kg of body weight per day for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic form of dioxin. Once finalized, the reassessment will influence a host of regulatory decisions affecting the group of compounds collectively called dioxins, including TCDD, polychlorinated biphenyls, and polychlorinated dibenzofurans. Most notable will be the degree of cleanup needed for contaminated river sediments. The reassessment could also impact rules governing air and water pollution, as well as waste disposal. The draft report updates the agency’s first official risk estimates for dioxins set in 1984 and based solely on cancer concerns. The agency has been reassessing dioxins’ risks since 1991. EPA Administrator Lisa P. Jackson has directed the agency to finalize its dioxin reassessment by the end of 2010.