Dioxin-type carcinogens pose additive risks

Pollutants known as dioxins and furans, and at least some polychlorinated biphenyls (PCBs), have additive cancer-causing effects when mixed together, a new toxicology study indicates. That finding lends validity to a previously unconfirmed assumption that researchers and regulatory agencies in many countries use to calculate the risks posed by dioxins and dioxinlike chemicals, which include furans and some PCBs.