Contaminants: PCBs (Polychlorinated Biphenyls)
Polychlorinated biphenyls (PCBs) are synthetic organic chemicals comprising 209 individual chlorinated biphenyl compounds (known as congeners). Exposure to each of these compounds is associated with different levels of risk for harmful effects. There are no known natural sources of PCBs. Although PCBs are no longer manufactured in the United States, people can still be exposed to them. The two main sources of exposure to PCBs are the environment and the workplace. Due to resistance to degradation, PCBs persist in the environment for decades.
Recent studies conducted in the Great Lakes basin indicate that a) fish consumption remains the major route of exposure to PCBs and b) health consequences are associated with these exposures. The following summary identifies those groups at risk because of exposure to PCBs and summarizes recently published information on exposure, sociodemographics, and health findings for these groups.
Several occupational or epidemiologic studies have indicated or demonstrated other adverse health effects from exposure to PCBs, including cancer and effects on the cardiovascular, hepatic, immune, musculoskeletal, endocrine, gastrointestinal, and dermal systems. Kreiss et al. (1981) have reported a 30% increase over the national average incidence of borderline and definite hypertension observed in a population from Triana, Alabama. Increased serum PCB levels were significantly associated with increased systolic and diastolic blood pressure. The relationship between serum PCB levels and systolic blood pressure disappeared when serum cholesterol and triglyceride levels were considered, but the association between PCB and diastolic blood pressure remained significant. Consumption of contaminated fish was considered the primary source of PCB exposure.
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Recent findings indicate that susceptible populations (e.g., certain ethnic groups, sport anglers, the elderly, pregnant women, children, fetuses, and nursing infants) continue to be exposed to PCBs via fish and wildlife consumption. Human health studies discussed in this summary indicate that:
- reproductive function may be disrupted by exposure to PCBs;
- neurobehavioral and developmental deficits occur in newborns and continue through school-aged children who had in utero exposure to PCBs;
- other systemic effects (e.g., self-reported liver disease and diabetes, and effects on the thyroid and immune systems) are associated with elevated serum levels of PCBs; and,
- increased cancer risks, e.g., non-Hodgkin's lymphoma, are associated with PCB exposures.