the more toxic PCBs. 



For aquatic life, water concentrations of less than 0.014 ug total PCBs/1 

 (ppb) appear to afford a satisfactory degree of protection, although 

 concentrations as low as 0.006 ug/1 resulted in measurable accumulation by 

 various species of filter-feeding shellfish. Among sensitive species of 

 teleosts, total PCB residues (in ug/kg fresh weight) in excess of 500 in 

 diets, 400 in whole body, and 300 in eggs were demonstrably harmful, and 

 should be considered as presumptive evidence of significant PCB 

 contamination. Among small mammals, the mink ( Mustela vison ) is one of the 

 most susceptible species tested; dietary levels as low as 100 ug PCBs/kg fresh 

 weight caused death and reproductive toxicity. A tolerable daily limit for 

 mink has been estimated at less than 1.5 ug total PCBs/kg body weight. 

 Tolerable daily PCB levels for rhesus monkey ( Macaca mulatta ), dog ( Canis 

 sp.), and rat ( Rattus spp.) were 1.0, 2.5, and 5.0 ug/kg body weight, 

 respectively. For birds, total PCB levels (in ug/kg fresh weight) in excess 

 of 3,000 in diet, 16,000 in egg, or 54,000 in brain were frequently associated 

 with PCB poisoning. 



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