Document dY48gby15OB1X84krk06xybme

10/16^90 10:52 W&ftftSN A, COOK fit *M6AY MIVC OMACU MILL- N.C. 17814 ,April 9 1986 Dr. Thcass ?. Matvcuso Professor Snecltus Depsrtasnt of Industrial and Snvixonntncal Sciences Graduate School of Public Health University of Pittsburgh Pittsburgh, PA 13261 * u/******* i j*. 'f T t- *-- j ****** Yu (\<A* # Dear tost In response co jour specific questions, copies of ay reports oa surveys of brake lining and ochar planes Involving aabeetoa verm kept on file ae the Connecticut State Department of Health during ay eaaoclaton there, 1923*1937 at the Zurich Insurance Companies in Chicago while there in 1937-1953. X would fully expect thee these would have long since been discarded. I had never made it a practice to retain copies of reports in ay personal files prior to my June 30, 1971 retirement from The University of Michigan* Sines that time my occasional consultation has not involved survey# of asbestos exposures. <m W* t was interested in reviewing the copy of the Healon raport of June 1967 for the Industrial Hygiene foundations of Aaerlea, prepared during John McMahon's managing directorship, a report chat X had not been aware of even though X wee rather close to the Foundation la those year*, l.did find in ay file of reprints of papers on ei beetoe your paper (vitlTsl-ACCar) on Cancerogeoic Risk end Duration of Employment, preeuaably of your study of tha Rsybeatoe Manhattan plant In Pennsylvania* ' . ' \ -"t The book to which X referred over the phone would have been ay aonogreph on occupational exposure Halts--`worldwide. X really doubt that I will svar put together ay experience* in industrial hygiene in a book* la our telephone chat, you wished ae to write you concerning ay understanding of the inclusion of all dust particles, asbestos and others, in the results of dust counts in the 1930's end on up to the W when fiber counts of ovr 5 aicrone in length replaced the dust count of all particles less than 10 microns in disaster. , My training in dust counting was according to the technique published by Leonard Oreenburg and JJ* Bloomfield in Public Health Reports, Vol, 67, Mo* 12, March 12, 1932 and also In the subsequent publication by JJ* Bloomfield and J*M, Dallavslle in Public Health Bulletin, Ho* 217, April 1935. This training was conducted personally by Jaek Bloomfield at tha Tala University Station of tha ASPHS in Haw Haven in 1929 while X was first associated with tha Connecticut Bureau of Occupational Diseases, This technique called for counts of all dust particles smeller than 10 slerons In diameter on the basis that larger particles did not reach the alveoli* ^ 10/is^e 10:53 -2- 003 la my duet counting of asbestos exposure* in the I930's, X continued to count end report t&e numbed ofi all particles smeller then 10 microns-* The biweekly Public Health Repotree regularly came across my desk, at the Connecticut State Department of Health and X aunt have seen the report of the asbestos study of 1929 - January 1931 by tha Metropolitan Life Insurance Company group in P*S. Report# of January 4, 1935* Even though Bill fehaal started to count dusc particles of all slats,afttr their initial survey in viev of the report that asbestos particles of much larger slats had bean found in lung tissue, it is probable chat X continued to 'follow the published 0SPHS procedure and Bloomfield's direction with Inclusion of only particlss smaller than 10 mieroos in my counts* da stated in the Metropolitan Life report, tha difference between counts of only < 10 micron particles and counts of all particles vas not significant a# they reported chat 971 of the particles mere smaller chan 10 microns* . At was the practice *e that time, the dust counts rsportsd included both asbestos particles and those of other composition following the procedures of the two above cited publications* This was 'ey practice also* Thee it was the practice of the Metropolitan Life group is evidenced by their statement that with asbestos being only 231 of the material in the textile operations, the actual exposure to asbestos is considerably lass chan indicated by their dust counts* In the P.a. Bull* Ho* 241, 1936 report of the Dreesen-Deilevells asbestos study, the reference to dust counting technique used Is that of pB* Bulletin 217 of 1933 by Bloomfield end Dallevallm* This procedure, as did the 1932 publication in Public Haalth Reports, states that "in general, only particles lesa than 10 microns in diameter are counted* with no suggestion that the counts should be limited to any given mineral of special interest. Sincerely, /<? Warren A* Cook Professor Emeritus, Tha University of Michigan Adjunct Professor The University of forth Carolina WAC/cr