CURRENT RECOMMENDATIONS 



At present, there are no criteria or standards promulgated for any of the 

 75 PCDD isomers, by any regulatory agency, for the protection of sensitive 

 species of wildlife and aquatic organisms. Data are scarce or missing on the 

 distribution and upper limits of background levels of PCDDs in natural 

 resources, on the identification of fish and wildlife resources potentially at 

 risk, on the relative importance of PCDD sources, and on the comparative 

 toxicities of various PCDDs to fish and wildlife, especially reproductive and 

 immunosuppressive toxicities (NRCC 1981). A similar situation exists for 

 human health protection, except for the 2,3,7,8-TCDD isomer. 



For protection of human health, concentrations of 2,3,7,8-TCDD (in ppt 

 fresh weight) in fish muscle (and presumably other food items) considered 

 acceptable are 10 in New York State (Kleopfer and Zirschky 1983), 20 in Canada 

 (Kleopfer and Zirschky 1983), and 25 in other States within the U.S., 

 according to the U.S. Food and Drug Administration (Stolzenburg and Sullivan 

 1983). Food items containing more than 50 ppt are considered unsafe for human 

 consumption, but fish fillets containing between 25 and 50 ppt of 2,3,7,8-TCOn 

 may be eaten once weekly by occasional consumers of fish, and twice monthly 

 for those who eat contaminated fish year round (Stolzenburg and Sullivan 

 1983). It is not known at this time whether residues of 10 to 50 ppt (or 

 higher) of 2,3,7,8-TCDD in fish flesh represents an unacceptable risk to the 

 growth, survival, reproduction, metabolism, or behavior of the teleost, or to 

 its predators; clearly, this is a high priority research topic. 



For protection of aquatic life, it is conservatively estimated that water 

 levels of 2,3,7,8-TCDD should not exceed 0.01 ppt as judged by laboratory 

 studies with freshwater teleosts. The highest 2,3,7,8-TCDD concentration 

 tested to date which has no measurable adverse effect on freshwater fish is 

 0.01 ppt (Miller et al . 1979). The next highest concentration tested, 0.1 

 ppt, was associated with fin disease in guppies (Miller et al . 1979) and 

 reduced growth of northern pike (Helder 1980) and rainbow trout (Helder 

 1981). 



Diets containing up to 10 or 12 ppt of 2,3,7,8-TCDD may prove to be non- 

 hazardous to birds and other wildlife, as judged by the results of laboratory 

 studies with rats, monkeys, and chickens, and by the recommendations of New 

 York State for human health protection. Higher dietary levels of 12 to 30 ppt 

 of 2,3,7,8-TCDD (equivalent to about 1.0 ng/kg body weight daily) are not 



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