Document nmGVVy63Z4VvDrabv718yb1pw

to NEWS /Ju>n*7U SAff-iy '7C' X'C / Monsanto FOR RELEASE IMMEDIATELY 1975 ,v^ MONSANTO INDUSTRIAL CHEMICALS CO D. R. Bishop (314) 694-2891 PUBLIC RELATIONS DEPARTMENT 800 N. Llndburgh Boulevjud St. Louts. Missouri 83}46 CHICAGO, Nov. 19 -- Monsanto Company today^mnounced that a newly completed scientific review, 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^tfad been previously reached and widely reported by Dr. Renate/D. Kimbrough of the Center for Disease Control of the U.S.A ublic Health Service in Atlanta. / The Monsanto-sponsored r/port, a re-evaluation of Dr. Kimbrough's work, is titled./"Histopathological Re-evaluation of Tissues from Sherman Rats F^d Aroclor 1260," and is authored by Dr. Parviz 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) . -more- MCNS 0607,5 --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 PCB feeding studies conducted by Industrial Bio-Test Laboratories 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 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 ,jsueh organs, as the liver, with its marked tendency toward regeneration, it is, in my -more- HOMS 060796 --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. 63166. HONS 060797 Based on some animal tests, EPA considers PCB's to be suspect carcinogens. More extensive animal tests conducted by Monsanto several years ago concluded that PCB's did not cause cancer. The livers of experimental animals showed evi dence of some damage in both sets of tests, but pathologists do not agree that cancer was the result. We have examined available records of employees in our PCB department of the Wm. J. Krummrich Plant for the 1950mid 1975 period. No deaths involving liver malignancy (tumors) have been found. Several months ago a group from NIOSH visited the plant. They concluded that employee exposure to PCB in our operation was too low to be of concern. MONS 060798