Document gnoDY8DOmow21z40xV7Qkdy9

IMMEDIATELY 1975 MONSANTO INDUSTRIAL CHEMICALS CO. D. R. Bishop (314) 694-2891 PUBLIC RELATIONS DEPARTMENT 900 N. Lindbergh Boulevard St. Louie, Mieeouri S3166 CHICAGO, Nov. 19 -- Monsanto Company today announced that a newly completed scientific report, commissioned by the St. Louis-based company, does not confirm the presence of malignant liver tumors in experimental rats fed a commercial polychlorinated biphenyl (PCB) mixture...a conclusion that had been previously reached and widely reported by Dr. Renate D. Kimbrough of the Center for Disease Control of the U.S. Public Health Service in Atlanta. The Monsanto-sponsored report, a re-evaluation of Dr. Kimbrough's work, is titled, "Histopathological Re-evaluation of Tissues from Sherman Rats Fed Aroclor 1260," and is authored by Dr. Peter Pour, a pathologist with the renowned Eppley Institute for Research in Cancer of the University of Nebraska Medical Center at Omaha. Aroclor is a Monsanto trademark for a class of chlorinated hydrocarbon industrial chemicals it manufactures. In her study. Dr. Kimbrough reported that when Sherman strain female rats were fed 100 parts per million of PCB (Aroclor 1260) for about 21 months, 170 of the 184 experimental animals developed neoplastic lesions (precursors of malignant tumors). She further identified 26 of these lesions as hepatocellular carcinomas (malignant liver tumors) . M0NS 058036 2 During his re-evaluation. Dr. Pour saw the same alterations but identified them as being hyperplastic or non-tumorous lesions, further pointing out that it was his strong impression that many of the detectable alterations were a degenerative and reparative rather than a neoplastic process. Dr. Pour's re-evaluation is consistent with conclusions drawn from Monsanto's own PCB feeding studies which have never produced a carcinogenic response in experimental animals. In his discussion, Dr. Pour reported that he observed 20 cases of abnormal lesions which presented such structural criteria as to be considered possible precursors to tumors, although a most significant criteria for malignancy -- namely invasiveness - was missing, and the sign of ongoing toxic, degenerative and regenerative processes in the rest of the tissue was evident. "At present, the statement that these lesions may have metastasized (infiltrated adjacent tissue) if the treatment had been continued is as much as unreliable as the possibility that they might have been regressed if the animal would have been kept longer or for life," he stated. "In summary," the Eppley Institute pathologist reported, "it is difficult at present to conclude whether or not some of the examined lesions represent a malignant lesion, because of the lack of invasion and metastases. In the case of such organs, as the liver, with its marked tendency toward regeneration, it is, in my -more- HONS 058037 --3 opinion, difficult and sometimes impossible to distinguish between regeneration, hyperplasia and neoplasia, particularly when the tissue is continuously exposed to a toxic substance." Quoting further from Dr. Pour's report, he wrote, "in this context, Dr. Kimbrough's study seems of particular interest, in that polychlorinated compounds may be retained in the body, even in higher concentrations for several months after feeding has been stopped. This finding may explain the continuing degenerative and regenerative processes in the livers of most experimental rats, even two months after Aroclor was removed from the diet. "One should also bear in mind that some animal strains may react more specifically to a compound because of common endogenous diseases, as in the case of the Sherman rats used in this experiment which tend toward spontaneous liver lesions. "In my opinion," he concluded, "many of the lesions Induced were of a degenerative nature, and without further studies, the induced liver lesions could not be definitely designated as neoplasia (tumorous). -0O0- NOTE TO EDITORS: Copies of Dr. Pour's report are available on request, in writing, from Public Relations Department, Monsanto Industrial Chemicals Co., 800 N. Lindbergh Blvd., St. Louis, Mo. 63It MOMS 058038