POSITION PAPER OF THE AMERICAN-COUNCIL-ON-SCIENCE-AND-HEALTH - PUBLIC-HEALTH CONCERNS ABOUT ENVIRONMENTAL POLYCHLORINATED-BIPHENYLS (PCB)

Polychlorinated biphenyls, or PCBs, were widely used in various indust rial applications for their insulating and fire retardant properties, In the 1960s, PCBs were found in soil and water, and research confirme d that some PCB congeners degrade very slowly in the environment and c an build up in the food chain, Two widespread poisoning episodes in Ja pan and Taiwan were initially attributed to the consumption of rice br an oil contaminated with PCBs, Although subsequent analysis suggested that toxic thermal degradation products of PCBs in the oil, rather tha n the PCBs, were responsible for the observed health effects, commerci al production of PCBs in the United States was discontinued in 1979. S everal regulatory and advisory agencies have categorized PCBs as anima l carcinogens; however, studies of workers exposed to high doses of PC Bs over long periods of time have not demonstrated an increased cancer risk, In fact, the only health effects that could be attributed to PC Bs were skin and eye irritation. Recent studies of the possible effect s of prenatal exposure to PCBs on neurodevelopment in infants and chil dren have been criticized for methodological deficiencies, There is no conclusive evidence that PCB levels in the general population are cau sing intellectual deterioration in children exposed in utero. Some inv estigators have also suggested that PCBs and other chemicals in the en vironment can interfere with the body's endocrine system, leading to i nfertility, certain types of cancer, and other hormone-related disorde rs. Evidence for estrogenic effects of environmental PCBs remains weak and circumstantial, The following actions are recommended: developmen t of innovative, cost-effective remediation techniques, particularly f or sites that are difficult to remediate (e.g., river sediments); and scientifically based improvements to risk assessment, to reduce the co nsiderable uncertainty associated with PCB exposure and health effects in humans. (C) 1997 Academic Press.