CURRENT RECOMMENPATIONS 



Effective July 1979, under Section 6e of the Toxic Substances Control 

 Act, and unless specifically exempted by the U.S. Environmental Protection 

 Agency, the manufacturing, processing, commercial distribution, and use of 

 PCBs (except in a totally enclosed system) were prohibited (Rremer 1983). 

 Similar actions had been initiated by Michigan, Wisconsin, and Minnesota in 

 1977 (Bremer 1983). However, PCBs remain universally distributed in the 

 environment, and releases still include those from manufacturing, leaks from 

 supposedly closed systems, and disposal of PCBs manufactured prior to 1971 

 (Ayer 1976). PCB burdens in waters, sediments, soils, disposal sites, and in 

 deployed transformers and other containers of PCB is estimated at 82 million 

 kg (D'ltri and Kamrin 1983). At this time, total PCB residues in organisms 

 appear to be a more reliable measure of environmental PCB levels than 

 measurements of any commercial mixtures (Schmitt et al. 1985). In light of 

 the demonstrated differential toxicities within the array of PCB congeners, 

 existing standards and criteria may need to be modified in order to reflect 

 the more toxic PCBs (Brown et al. 1985). 



PCB tolerance levels have been recommended for protection of various 

 environmental resources and human health (Table 7). The recommended 

 freshwater aquatic life protection criterion of 0.014 ug/1 (24-hour average) 

 is lower than 0.1 ug/1, a concentration known to adversely affect the growth 

 of freshwater algae and fish (EPA 1980). This criterion would probably afford 

 a satisfactory degree of protection to freshwater life if it were changed from 

 0.014 ug/1 (24-hour average) to 0.014 ug/1 (maximum). Criteria based on 

 average daily concentrations usually indicate that high doses of toxicants may 

 occur within a short period. Unfortunately, data bases existing for PCBs are 

 inadequate to predict long-term effects on growth, uptake, and other variables 

 when repeated high doses occur in short intervals. 



The criterion of 0.03 ug/1 (24-hour average) recommended for saltwater 

 aquatic life protection is unsatisfactory. Concentrations of 0.1 ug/1 of 

 Aroclor 1254 are fatal to sheepshead minnows in 21 days, and concentrations as 

 low as 0.006 ug/1 result in significant uptake by oysters over a period of 65 

 days (Ernst 1984). Until additional data become available, the saltwater 

 aquatic life protection criterion should not differ from the freshwater 

 criterion (0.014 ug/1, maximum). 



Fish diets containing 1.0 mg of Aroclor 1254 per kg fresh weight produced 

 pathological changes in the kidney of rainbow trout after 11 months, and diets 



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