Document Z8LNVNNDa6ZeNDwzjDv7JjMDO

LaSrariyVRi.oZPorbeesli,deMntD MPR 0dMedical Dirctor 3M Medical Deparment S3tM. CPeanut,erM,NBu5i8ld1i4n4g10020200-06-W-08 63511773333 55118512FOafxfice am June 27,2005 Sue Shallal, Ph.D. Designated Federal Officer US. EPA Science Advisory Board Via e-mail: shallal.suhair@epa. gov Re: PFOA Review Panel SubmissionofPathology Working Group Report on Mammary Tumors in ChronicStudy ofPFOA DearDr. Shallal: We are submitting for the PFOA Panel's consideration a copy ofa recently-completed Pathology Working Group (PWG) reportexamining the mammary findings from the 3M (Sibinski et al. 1983) chronic study onPFOA. (Experimental Pathology Laboratories, Inc., "Pathology Peer Review and Pathology working Group Review ofMammary Glands from a Chronic Feeding Study in Rats with PFOA," June 17,2005.) The pathology review was a joint projectofthe 3M Medical Department and DuPont Haskell Laboratory. `The report concludes (p. 12): The PWG concluded thatthe incidence ofmammary gland neoplasms in the study was not affected by chronicdietary administrationofPFOA. The morphologic appearance, overall incidence and distributionofthe neoplasms observed in treated and control animals were similar. Dr. Subair Shallal June 27,2005 Page20f2 `The primary difference betweenthe original reported findings and the PWG results involved findings initially reported as lobular hyperplasia which the PWG classified as fibroadenoma. `There were minor differences in classification ofother findings. Dr. David Gaylor performed statistical analyses on the findings for the PWG. The PWG report states: There were no statistically significant differences in the incidence of fibroadenoma, adenocarcinoma, total benign neoplasms or total malignant neoplasms between control and treated animals using Fisher's Exact Test for pairwise comparison. Combining benign and malignant neoplasms is not recommended. However, even if combined in this study, there was no significant difference between control and treated groups. (p. 11) None ofthe tumor types or combinationsof tumor types exhibited statistically significant survival-adjusted dose-response trends. (p. 20) There was no increase in tumor multiplicity or incidence with dose between control and treated groups. (p. 11) The morphologic appearance ofneoplasms in treated groups was similar to those. observed in the control group, indicating tht treatment did not affect the phenotype ofthe neoplasms in the study. (p. 11) The incidenceofmammary gland neoplasms in the study is similar to historical control data for untreated Crl:CD female Sprague Dawley rats in 104-week studies, as reported in the literature. (pp. 11-12) Respectfully submigted,