Document xNXN8R649m2KD0mBn2dxQbEJ

G.J. Levinskas - A2SC August 29, 1975 PCBs memo WBP to GR Jr., 8/18/75 TO G. Roush, Jr A2SA . CC: D. R. /Bishop - BIND W. B/ Papageorge - B2SK R. G. Potter - B3SA W. W. Withers - B2SA The following/comments can beohade regarding the revised draft of t.hft ^PflB ^tntemrnt^ 1) End of 1st paragraph. Statement regarding discussion of findings with other scientists is meaningless if no subsequent reference is made to the outcome of those discussions. 2) 2nd paragraph. Lists 4 points of discussion. The truncated version of the amended statement has only 3 points. 3) The ending, starting with section (3) on page 2 has been rewritten. Since the statement opens with a reference to recent data on AROCLOR 1260 which has been brought to our attention, it is redundant to reintroduce that statement again. The suggested change restores the 4-point format referred to on page 1, but it doesn't really treat point 3 adequately. /bkp att. ^,Ge _ Levinskas DSW 318528 STLCOPCB4055667 PCBs Recently, we wei'e Informed that liver carcinomas were observed in female Sherman strain rats fed AROCLOR 1260 for 20-1/2 months. This prompted us' to re-examine livers from male .> and female rats of the Charles River strain which had been fed AROCLOR 1242, AROCLOR 12^4 or AROCLOR 1260 for 2 years in earlier studies conducted for Monsanto Company. In addition, we have discussed our findings and those reported to us with scientists working in the field of carcinogenicity. . There are 4 elements which are closely interwoven In this matter: (l) differences in test procedures, (2) differences in results obtained by various investigators, (3) definition of what is a cancer, and (4) evaluation of potential risks, if any, to man. These will be summarized briefly. (l) Several animal studies have been conducted with various brands of PCBs. In some studies, the test material has been identified by trade name (AROCLOR, KANECLOR). In others, there was just a general reference to PCB. Consequently, the quality of test material with respect to the amounts and nature of contaminating Impurities or by-products cannot be determined in all case. In addition, several strains of test animals were used, the duration of the experimental periods varied, and there was a wide range in the depth of detail with which the observa tions were reported. Consequently, it is difficult to make comparisons between these studies. .` SW 318529 STLCOPCB4055668 (2) In general, studies have shown mice to be more susceptible than rats and females to be more sensitive than males to the liver effects of PCBs. Beyond these generaliza tions, the results have not been consistent. Some investigators have reported liver carcinomas. -Others have observed only * benign tumors. Several have noted changes in liver tissue without detecting tumor formation. For -the reasons just cited, it is difficult to determine the bases for these different results. The most direct comparison can be made between the 2 studies on AROCLOR 1260 since the same high dosage level of the same lot of AROCLOR 1260 was employed in both experiments. In the studies reported to us, liver carcinomas occurred in approxi mately 8$ of female rats of the Sherman strain (the only sex used). In Monsanto's study, none of the liver lesions had progressed beyond the stage of benign tumors (hepatomas) despite a slightly longer duration of feeding of AROCLOR 1260 to rats of Sprague Dawley, Charles River strain. The Monsanto study employed rats of both sexes and lt.did confirm the previously noted greater sensitivity of female rats to liver effects of PCBs. sw 318530 (3) Recent data has shown AROCLOR 1260 to be a carcinogen in one strain of rat. A review of the liver alterations seen in all 3 AROCLORS in Monsanto's studies shows that the lesions were benign in character in the traditional pathologic sense. An evaluation of all information available to us, including the contradiction between the recent data showing AROCLOR 1260 to be a carcinogen and our earlier negative results on the same STLCOPCB4055669 product, leads to a conclusion that AROCLOR 1260 is not carcinogenic to all commonly used strains of laboratory test animals. (4) Since 197?, the sale of AR0CL0RS has been restricted to a single use, i.e.; as dielectric fluids. As such they are used in closed systems which will at least minimize additional environmental contamination. Considering the high degree of fire risk associated with this use, and recognizing that AROCLOR 1260 may have a weak carcinogenic potency which has not been fully proven and that AR0CL0RS 1242 and 1254 have not been shown to be carcinogens, it is concluded that the continued use of AR0CL0RS as dielectric fluids will not present an unreasonable human health hazard. DSW 318531 STLCOPCB4055670