(Schmitt et al . 1983, 1985). The ubiquity of PCB residues probably results 

 from the dispersal of contaminated sediments, from atmospheric transport, and 

 from patterns of continued use and disposal. Maximum concentrations in whole 

 fish did not change appreciably at most locations in recent years; 

 concentrations approaching 100 ppm fresh weight and 500 ppm in lipids were 

 measured as recently as 1978 (Schmitt et al . 1983). Residues of PCBs in fish 

 were more widely distributed than reported previously, but appeared to be 

 declining in some areas of high concentration, and the less chlorinated PCBs 

 (resembling Aroclor 1242) were disappearing. PCB concentrations in whole 

 fish, collected Nationwide between 1976 and 1979, tended to be highest in the 

 industrialized regions of the Northeast and the Midwest. Fish from the Hudson 

 River, near Poughkeepsie, New York, contained 4 to 6X more PCBs than any of 

 the other 108 stations analyzed; mean residue levels were 33.9 ppm fresh 

 weight in 1976-1977 and 44.1 in 1978-1979 (Schmitt et al. 1983). However, 

 data from 1982 (Brown et al. 1985) indicated a general decline in PCB content 

 of fish from the Hudson River (although levels in some species remained 

 substantally higher than the 5.0 ppm temporary tolerance level established by 

 the U.S. Food and Drug Administration); this was attributed primarily to 

 declines in the less chlorinated PCB congeners, especially Aroclor 1016. 

 Accumulations in excess of 1.0 ppm PCBs fresh weight were reported in fish 

 from stations in the Northeast, the Ohio River system, the Missouri River 

 system, the Great Lakes, portions of the Mississippi River in Wisconsin, and 

 from the Manoa Stream near Honolulu, Hawaii (Schmitt et al. 1983). In 

 general, frequency of detectable PCB residues and total PCB residue levels in 

 fish did not change significantly from 1974 to 1979. One exception to this 

 pattern was the decline in residues resembling Aroclor 1242 from 14% of all 

 samples in 1973, to 5% in 1974, to zero in 1976-1977; apparently, components 

 most prevalent in the 1242 mixture are rapidly degraded. Furthermore, the 

 continuing presence of residues resembling Aroclor 1248 suggest that 

 relatively unaltered PCBs continue to enter the environment (Schmitt et al . 

 1983). The most recent Nationwide monitoring survey (Schmitt et al. 1985) 

 demonstrated a significant downward trend in whole fish body burdens of PCBs 

 in 1981-1982, with no significant increases at any station, confirming that 

 residues were highest at stations in the industrialized regions of the 

 Northeast, the Great Lakes, the Upper Mississippi River System, the Ohio River 

 System, and the Cape Fear River in North Carolina. Schmitt et al. (1985) 

 suggested that total PCBs measure environmental PCB contamination more 

 reliably than do measurements of any commercial mixtures such as Aroclor 

 PCBs. 



About 10% of coho salmon ( Oncorhynchus kisutch ) and 58% of chinook salmon 

 (£. tshawytscha ) collected in 1980 from the Great Lakes exceeded the current 

 FDA action level of 5.0 ppm total PCBs on a fresh weight basis. All chinook 

 and about half the coho salmon exceeded the proposed FDA action level of 2.0 

 ppm total PCBs in fillets (Rohrer et al . 1982). PCBs detected in salmon from 

 the Great Lakes in 1980 most closely resembled Aroclor 1254, although higher 

 and lower chlorohomologues were present. PCBs resembling Aroclor 1260 were 

 detected in only 10% of coho salmon from Lake Huron and may be the result of 

 widespread historical use of Aroclor 1254 and more limited use of Aroclor 1260 

 (Rohrer et al. 1982). Marked variations in PCB content of selected tissues 



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