consumed as food on a daily basis (16.4 to 11.2.), and by a safety factor of 

 100 applied to a dietary level of 0.64 mg PCBs/kg fresh weight of diet. Since 

 safety factors are usually applied to the no observed effect levels, a 

 tolerable level of PCBs for mink may be less than 1.0 ug/kg body weight 

 daily. Other species of mammalian wildlife tested were more resistant to PCBs 

 than mink, and tolerance levels for livestock (Table 7) may also afford a 

 reasonable degree of protection for wildlife, except mink. 



Sound management of fishery and wildlife resources--including those 

 resources that are artificially propagated and released--requires 

 noninterference with desired uses such as health and well being of humans and 

 other organisms at various trophic levels. Prior to the legislative 

 restrictions on PCB use, substantial losses to the atmosphere resulted from 

 evaporation of plasticizers and from improper incineration, directly impacting 

 occupational workers (EPA 1980), as well as aquatic ecosystems (Ayer 1976). 

 In recent years, PCB levels have significantly declined in all human food 

 items, with the possible exception of fish; most samples of fish containing 

 more than 5.0 mg PCBs/kg fresh weight originated from the Great Lakes area 

 (Hoeting 1983). In Michigan, all of a sample of 1,057 mothers had measurable 

 PCBs in their breast milk at an average level of 2.3 mg/kg. Nursing infants 

 from Michigan mothers might consume 10 to 25X the maximum daily dose i-ate of 

 1.0 ug PCBs/kg body weight that is currently recommended by the U.S. Food and 

 Drug Administration for human adult intake (Swain 1983). The Michigan 

 Department of Public Health has since established a Public Health Advisory 

 related to fish consumption. They recommend that children, pregnant women, 

 nursing mothers, and women who expect to bear children should not consume fish 

 from the Great Lakes area (Swain 1983). Canadian PCB tolerance levels in food 

 items for human health protection are markedly lower than those of the United 

 States (Table 7). In one case, the current USA health tolerance level of 5.0 

 mg/kg fresh weight in fish and shellfish presents a distinct hazard to 

 piscivorous teleosts and to fish-eating birds and mammals. A lowering from 

 5.0 to 2.0 mg PCBs/kg fresh weight in fish and shellfish has been proposed by 

 FDA, but the tolerance level has not yet been changed; the delay appears to be 

 based on economic reasons (Hoeting 1983). In the Great Lakes, for example, 

 55% of the domestic fish samples collected in 1979-1980 exceeded 2.0 mg 

 PCBs/kg fresh weight; in 1980-1981, this was 17%; and in 1981-1982, 10% of the 

 samples exceeded 2 mg/kg, including chinook salmon and their eggs, and lake 

 trout (Hoeting 1983). In every collection year, measurable PCB residues were 

 recorded in at least 28% of the Great Lakes fish samples collected (Hoeting 

 1983). At present, three courses of action appear warranted: continuation of 

 the Nationwide monitoring program of fish and wildlife for PCBs and other 

 environmental pollutants (O'Shea and Ludke 1979), additional investigations on 

 the fate of PCBs under conditions prevailing in the natural environment, and 

 controlled studies on the toxicological significance of chlorinated 

 dibenzofurans and other trace impurities found in commercial PCB mixtures and 

 used PCB containing fluids. 



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