Documenting temporal trends of polychlorinated biphenyls in the environment.

In the 15 years since the regulation of polychlorinated biphenyls (PCBs) in the United States, numerous studies have been undertaken to assess PCB levels in the environment. This report reviews the available data from published literature and government agency reports on temporal trends of PCB levels in various environmental compartments. Adequate data were identified to discuss PCB trends in foods for human consumption, human adipose tissue, human blood sera, various fish species, and shellfish. The review found that PCB levels in the human diet currently are less than 1% of the levels detected in the early 1970s as measured by the nationwide Total Diet Study of the FDA. Similarly, EPA data indicate a decrease in the percentage of persons with over 1 ppm of PCBs in adipose tissue from 62% in 1972 to 2% in 1984 when the study was terminated. Studies by the National Oceanic and Atmospheric Administration (NOAA) and other groups have shown a 2- to 10-fold decline in PCB contamination in fish and shellfish from the early 1970s to the late 1980s. The most dramatic declines across all environmental compartments appear in the late 1970s to the mid-1980s which corresponds to the time frame when regulatory controls were imposed by the Toxic Substances Control Act (TSCA). These declines are expected to continue but at slower rates.