| Assessing the Cancer Risk from Environmental PCBs Vincent James Cogliano U.S. Environmental Protection Agency, National Center for Environmental Assessment, Washington, D.C. 20460 USA Abstract
A new approach to assessing the cancer risk from environmental polychlorinated biphenyls (PCBs) considers both toxicity and environmental processes to make distinctions among environmental mixtures. New toxicity information from a 1996 cancer study of four commercial mixtures strengthens the case that all PCB mixtures can cause cancer, although different mixtures have different potencies. Environmental processes alter PCB mixtures through partitioning, chemical transformation, and preferential bioaccumulation ; these processes can increase or decrease toxicity considerably. Bioaccumulated PCBs are of greatest concern because they appear to be more toxic than commercial PCBs and more persistent in the body. The new approach uses toxicity studies of commercial mixtures to develop a range of cancer potency estimates and then considers the effect of environmental processes to choose appropriate values for representative classes of environmental mixtures. Guidance is given for assessing risks from different exposure pathways, less-than-lifetime and early-life exposures, and mixtures containing dioxinlike compounds. Key words: bioaccumulation, cancer, mixtures, partitioning, PCBs, persistence, polychlorinated biphenyls, risk assessment. Environ Health Perspect 106:317-323 (1998) . [Online 13 May 1998] http://ehpnet1.niehs.nih.gov/docs/1998/106p317-323cogliano/ abstract.html Address correspondence to V.J. Cogliano, U.S. Environmental Protection Agency, 401 M Street, SW (8623-D) , Washington, DC 20460 USA. The author gratefully acknowledges the contributions of all who commented on the EPA's assessment, including the peer review panel and many scientists in the EPA's program, regional, and research organizations. Their efforts truly improved the final product. The views expressed in this paper are those of the author and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency. Received 22 May 1997 ; accepted 9 February 1998.
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