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-4 I l* It 3 Ii Research on Health Effects of Asbestos LEWIS J. CRAJ-LEV. Ph.D. W. CLARK COOPER. M.D. WILLIAM S. LAINHART. M.D. MURRAY C. BROWN. M.D. sbestos as a curious material was A known several centuries B.C.. especially for its ability to withstand flame. The physical and chemical properties of asbestos together with its fibrous structure made it a unique material with a wide range <>f potential industrial applications. It was not until the end of the last century, how ever. that it gained importance as an industrial resource. The study of the use of asbestos in a number of technological areas and its contribu tion to new products is the precursor of the spe cial science of industrial mineral fiber technology. Tlie rfrommcKilaimsf m this report remitted from a in.*-t no rpoiiiored hij tfie OecKpeiinnot Health Program it eii*. P'ltitir Health Srrrice'g National Center for Urban rM iiuiuuriat Health, on December 1 and I. J365, under the Chuinuan.hiji of Murray C. Bruton, M.D. Copies of this -tjcr may hr uiitninrd jrnm the Occupational Health Pror#>. iValmnal O-nier for l/riiau and Indnetnol Health, L'SrilS. UHF.W. Cincinnati, Oh.o. Ltu-It J t'rolley, PhD. it Aeeociate Chief. Occupational Health prngratn. VSPHCi. Cincinnati; Vtr. Clark Cooper, M D. :< Pr.,|rur in Armdetice, Occnpationol Health. C/nirernm Califumie. Berkeley; William $. Lainhort. MO. .itaei*coat Chief, Field Studies. Occupational Health Pro gram. I-'SPHC. Cincinnati; and Murray C. Broum, M.D., Chief. Occuiiaiinnal Health Program. VSPHS, Cincinnati, 38 Asbestos is essential in today's industrial tech, nology including national defense, aerospace, end to civilian consumer use. Asbestos is a general term applied to a group of fibrous crystalline hydrated silicate miner iis : Although a number of different types of asbe ; minerals exist, only four or five are of cornu ... > COP pre ch to saf cial importance. Each differs somewhat from e ... others in chemical composition, physical pm % ties such as ability to withstand heat and chon. ,| erosion, crystalline structure, fiber dimension | SUI evi of of degree of fiber harshness and brittleness. ' The worldwide production of asbestos j <* greatly expanded since the turn of the cent ; the over-all consumption in this country Jew. - off for the period 1956 to 1963 at around 7.Vi .'i short tons annually. Of this tonnage, appruxun.. ly 93'1 was chrysotile. S.S'V erocidolite, 2 Vi amosite, and V-f anthophylite and tremolile. Even though asbestos has been in industrial u< for well over 50 years, much is unknown regard ing its health effects and safe levels of exposure. It has been known since the early nineteen hundred's that excessive exposure to asbestos gives rise to the disabling pulmonary disease i.J ao ec as b W tb tb IT u p c6 v "asbestosis." More recently, evidence has been de veloped that the incidence of respiratory tract and other malignancies in asbestos workers is ex a t cessive. A major problem in studying the health effects of asbestos is the long latent period of 20 \ < or more years from initial exposure to the onset i of disease. Also in the mid-nineteen thirties and c earlier, there was little dust control and the work 1 ers were often exposed to massive levels of dust 1 from asbestos and other associated materials ia i the manufacture of asbestos products. Thus, the i causative agents of the resultant disease are es- \ sentially unknown. Included in these potential 1 sources of causative agents, either alone or in combination, are asbestos fibers themselves, ma- ' terials associated with the fibers in the ores such . as trace minerals and polycyclic aromatic oils, ma terials added during processing such as meta-s, tars and pitches, and concomitant external ex posures to tobacco smoke or other air pollutan 00 o A salient point is that in subsequent years \vh -a heavy dust exposures were reduced, disease al.o diminished. This definitely indicates that tv: a o .ou N> sufficient knowledge of the agentfs) responsil.e for the disease, along with dose-response da,.:, safe levels of exposure can be established. Research to elucidate the importance of the as bestos minerals os hazards to health fall into two broad categories: first, studies to provide answers cT January 1968 Volume 10 No. I HFM-011703 SCF-FA-6050