INTRODUCTION 



As a result of human activity, polychlorinated biphenyls (PCBs) are now 

 distributed worldwide, with measurable concentrations reported in polar bears 

 ( Ursus martinus ) from the Canadian Arctic, birds and fish from the Great 

 Lakes, wildlife in Europe, Scandinavia, and the United Kingdom, marine 

 organisms of the Atlantic and Pacific Oceans, and up to 91% of the adult human 

 population in the United States. Their presence in the organisms has been 

 shown to cause reproductive failure, birth defects, skin lesions, tumors, 

 liver disorders, and, among sensitive species, death. PCB toxicity is further 

 enhanced by their ability to bioaccumulate and to biomagnify within the food 

 chain due to extremely high 1 iposolubi lity. These, and other, biological 

 effects of PCBs have been extensively reviewed by Ayer (1976), Roberts et al . 

 (1978), NAS (1979), EPA (1980), Pal et al . (1980), D'ltri and Kamrin (1983), 

 Fleming et al . (1983), Ernst (1984), Stickel et al . (1984), Safe (1984), 

 Simmons (1984), and Lucier and Hook (1985a, b). 



PCBs, a group of synthetic halogenated aromatic hydrocarbons, were first 

 prepared in 1881, and since 1930 have been in general use in products that 

 include heat transfer agents, lubricants, dielectric agents, flame retardants, 

 plasticizers, and waterproofing materials (Roberts et al. 1978). After 1971, 

 they were used almost exclusively as insulating or cooling agents in closed 

 electrical systems, such as transformers and capacitors (NAS 1979). 

 Environmental contamination resulted from industrial discharges, from leaks of 

 supposedly closed systems, from disposal of PCB wastes to municipal sewage 

 treatment plants, landfills, and equipment dumps, and especially through 

 atmospheric transport of incompletely incinerated PCBs. Long-range 

 atmospheric transport of PCBs by wind, rain, and snow is now well documented 

 (NAS 1979). PCBs tend to bond tightly to particulate matter, notably soils 

 and sediments of lakes, estuaries, and rivers, where they may remain available 

 for resuspension for at least 8 to 15 years (Swain 1983). The North Atlantic 

 Ocean seems to be the dominant sink for PCBs, accounting for 50 to 80% of the 

 PCBs in the environment, while freshwater sediment is a major continental 

 reservoir (NAS 1979). Other significant reservoirs of mobile PCBs still exist 

 along with even larger, currently immobile, pools. The latter includes those 

 materials containing PCBs that are still in service, and those deposited in 

 landfills and dumps. 



Between 1930 and 1975, more than 630 million kg of PCBs were manufactured 

 domestically (Safe 1984). At present, PCBs are not produced in the United 

 States. PCB legislation under the Toxic Substances Control Act, effective 



