organic solvents and in biological lipids (EPA 1980). Monochlorobiphenyls are 

 comparatively soluble in water (1,190-5,900 ug/1), but this decreases rapidly 

 with increasing chlorination: dichlorobiphenyls, 80 to 1,880 ug/1; trichloro 

 BP, about 8 ug/1 ; and tetrachloro BP, 3 to 170 ug/1 (NAS 1979). The 

 solubilities of various PCB isomers in water also decreased with increasing 

 chlorine content: 2, 4'-dichloro BP was soluble to 637 ug/1; 2,2' ,5-trichloro 

 BP to 248 ug/1; 2,2' ,5,5'-tetrachloro BP to 26.5; 2,2' ,4,5,5'-pentachloro BP 

 to 10.3; and 2,2 ' ,4,4 ' ,5,5' -hexachloro BP to 0.95 ug/1 (Menzie 1978). Water 

 solubilities of various Aroclor formulations, in ug/1, were 240 for 1242, 50 

 for 1248, 10 for 1254, and 3 for 1260 (NAS 1979). PCB octanol /water partition 

 coefficients ranged between 10,000 and 20,000 for representative tri-, tetra-, 

 and pentachlorobi phenyls. High partition coefficients with this biphasic 

 solvent system correlate well with PCB biomagnification in fatty tissues of 

 aquatic organisms (EPA 1980), and with incorporation into sediments (Fox et 

 al. 1983). In fact, PCBs are strongly adsorbed on soils, sediments, and 

 particulates in the environment, with levels usually highest in aquatic 

 sediments containing microparticulates (EPA 1980; Duinker et al. 1983) and 

 high organic or clay content (NAS 1979). Uptake of PCBs from contaminated 

 marine sediments by benthic invertebrates is governed by processes that 

 include ingestion of contaminated sediment particles, and exchange of PCBs 

 directly from sediment particles (Larsson 1984). PCB-laden sediments of 

 Raritan Bay, New Jersey, and lower New York Harbor were effective in producing 

 population perturbations of benthic marine invertebrates when sediments 

 contained high silt and clay composition; low silt and clay sediments were 

 ineffective (Stainken 1984). 



The number and position of the chlorine atoms on the biphenyl rings 

 affects the biological properties of the compound. For example, PCBs with 

 hydrogen atoms on two adjacent carbon atoms in one or both rings are more 

 readily metabolized than those with hydrogen atoms adjacent only to chlorines, 

 due to metabolic reactions involving arene oxide intermediates (EPA 1980). 

 Furthermore, PCBs with chlorines in the 2 and 6 (ortho) positions are easily 

 metabolized by humans while those with chlorines in the 4 and 4' (para) 

 positions or 3, 4, or 3, 4, 5 positions on one or both rings tend to be 

 biologically active and well-retained in tissues (EPA 1980). 



In mammals, PCBs are readily absorbed through the gut, respiratory 

 system, and skin. Initally, PCBs concentrate in liver, blood, and muscle; 

 eventually, accumulations are highest in adipose tissue and skin. Phenolic 

 derivitives or dihydrodiols are the major metabol ities, but susceptibility of 

 individual PCB isomers to metabolism is a function of the number of chlorine 

 atoms present on the biphenyl rings and their arrangement. In general, most 

 readily metabolized PCBs are also rapidly excreted in urine and bile. The 

 highly chlorinated isomers are difficult to metabolize and accumulate almost 

 indefinitely. PCBs can be transferred to young mammals either 

 transplacentally or in brtast milk. Retention of PCBs is highly species 

 specific: nonhuman primates, for example, retained PCBs more efficiently than 

 rodents (EPA 1980). PCB patterns, especially in warm-blooded animals, only 

 vaguely resemble the mixture from which they originated (Hansen et al . 1983; 

 Ernst 1984). Subtle differences between chlorobiphenyls are further amplified 



