Document mxY7bDdyOK1jNqq4DeZ5b4Bd

APR.15'2002 14:39 2148210977 KAESKE REEVES #5112 P.002/003 MOUNT SINAI SCHOOL OF MEDICINE oJThrCfty Uuiutnily oJNrv Yiirk MffH tvi^ut ^11 IMTH aratfT.wr* tok, n.T. frr Srpan*"* / CtmmMlf THtflflPr July 31, 1973 Mrs, ,Mart EMroann Ubrtruw-ln^cbargo Research Center Wbrary United States Gypsum Company" XOOO East Northwest Highway Dee Plaines, Illinois 90016 Dear Mrs. O^-nonm There Is a vast literature reporting reault# of Investigation* Into the comparative, toxicity pt chry.at,ile-otoee, lb T<lUa t otpex. fiber?, in summary,.po significant difference ws`found; al> 'varieties show important flbrogealc and carcinogenic activity. At your request, we will provide aomc of the nest pertinent reference a. Insofar as human effects are concerned, it is conceivable that tbe animal model* do not reflect a difference which night exist among the fiber varieties; this possible difference is the subject of investiga tion in e number of weye. Dr, McDonald considers that.his studies in the cbrysotlle nines In Quebec have shown less lung cancer and mesothelioma thoa other aebostos-exposed groups. V<ry worrisoae is his observation that more heavily exposed cbrysotlle miners bad five times s much lung cancer at thoaa more lightly expoeed(l), This would provide olear evidence of rbe cardoogenic effect of cbrysotlle asbestos, Since the individual* concerned bad-been exposed only to this fiber variety. Too, revlev gt x-rny* among these men has sham: numerous esses of asbsstoeie, demonstrating tbe fibrogenlc effect. In eddition to nine sod mill employees, studies have also been uodertaken of factory populations thought to be exposed only to ehrysottle. This is nore complicated, since it is difficult to be absolutely sure that the populations concerned never h<d any exposure, however small, to other fiber varieties, One such study" was reported by Dr. Thomas Maneuao in 1963, and an important esnar risk of the population in vestigated ws fowedC2). Another study hn been reported at scientific meetings by Dr. Joseph X. Wagoner of ne National Institute for Occupa tional Safety and Health, While thte has net yet appeared In the acie/v title press, t on sure that you will !je able to obtain a copy of tbe manuscript from Dr, Wagoner, 4. SCF-ALLF-04680