Position paper of the American Council on Science and Health: public health concerns about environmental polychlorinated biphenyls (PCBs).

Polychlorinated biphenyls, or PCBs, were widely used in various industrial applications for their insulating and fire retardant properties. In the 1960s, PCBs were found in soil and water, and research confirmed that some PCB congeners degrade very slowly in the environment and can build up in the food chain. Two widespread poisoning episodes in Japan and Taiwan were initially attributed to the consumption of rice bran oil contaminated with PCBs. Although subsequent analysis suggested that toxic thermal degradation products of PCBs in the oil, rather than the PCBs, were responsible for the observed health effects, commercial production of PCBs in the United States was discontinued in 1979. Several regulatory and advisory agencies have categorized PCBs as animal carcinogens; however, studies of workers exposed to high doses of PCBs over long periods of time have not demonstrated an increased cancer risk. In fact, the only health effects that could be attributed to PCBs were skin and eye irritation. Recent studies of the possible effects of prenatal exposure to PCBs on neurodevelopment in infants and children have been criticized for methodological deficiencies. There is no conclusive evidence that PCB levels in the general population are causing intellectual deterioration in children exposed in utero. Some investigators have also suggested that PCBs and other chemicals in the environment can interfere with the body's endocrine system, leading to infertility, certain types of cancer, and other hormone-related disorders. Evidence for estrogenic effects of environmental PCBs remains weak and circumstantial. The following actions are recommended: development of innovative, cost-effective remediation techniques, particularly for sites that are difficult to remediate (e.g., river sediments); and scientifically based improvements to risk assessment, to reduce the considerable uncertainty associated with PCB exposure to health effects in humans.