ABSTRACT
Polychlorinated biphenyls (PCBs) belong to a broad family of man-made organic chemicals that due to their non-flammability, chemical stability, high boiling point, and electrical insulating properties, were used in hundreds of industrial applications. The same qualities make many individual chlorobiphenyls slow to degrade upon their release to the environment. As a consequence, PCBs are widespread and persistent environmental contaminants found in air, water, sediments, and soils. Moreover, they can accumulate through the trophic chain to the aquatic organism, to fish and humans. As PCBs move through the environment, the concentrations of individual chlorobiphenyls change over time and from one environmental medium to another because of physical and chemical processes and selective bioaccumulation and biotransformation by living organisms. These processes result in mixtures that are substantially different from the original mixtures that were released to the environment. The identification, quantification, and risk assessments are complicated by these changes in the composition of the PCB mixtures.
