Document v1k7Qq2zKVOeaykKrN8B1X638

`A ; \ ! I II Research on Health Effects of Asbestos LEWIS J. CRALLEY. Ph D. W. CLAKK 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 of potential industrial applications. It was not until the end of the last century, how ever. that it gained importance as on industrial resource. The study of the use of asbestos in a number of technological area* and its contribu tion to new products is the precursor of the spe cial science of industrial mineral fiber technology. Tlie rrcommi'Hilaimsf in this report remlted from a mi**--I mi rpofiiorrd by iht OecHpofioHot Haaitk Program '.< lb- P'lOlir Health Srrricf'* Halinnof Center for Urbnn rji ifoliuirmf Health, on December 1 and I. J365. under ;!,e Cl,,iimoH*hrji iif Afurroy C. Bniuiii, M.D. Copies of this ;<t|(..r may l.e I.uinmed irnm the Ompaiiuhct Health Promum. iVsnonal Cniur /or Urban and Industrial Health, I'.iTHS. UHr\V. Cincinnati. Oh.o. Ltu-it J Crolley. PhD. it Associate Chief. Occupational Health prnijnm. tlSPHtl. Cincinnati; W. Clerk Cooper, M 0. is Hr.,lemur m Itesidenee. Occnpationoi Health, Unirernnt *,f Colifnrnie. Berkeley; William S. Loinhort. MJ). s Assistant t.'hie/. Picld Studies. Occupational Hsallh Proyrem. HUPIIC. Cincinnati; and Murray C. Brown, MD, Chief. Orruiiaitoual Heoith Program, USPHS, C.ncinnati, OWi. 38 Asbestos is essential in today's industrial lech, nology including national defense, aerospace. ,,nd to civilian consumer use. COP 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 < cial importance. Each differs somewhat from e .., others in chemical composition, physical pro % ties such as ability to withstand heat and chcm ,| erosion, crystalline structure, fiber dimension | pre ch< to sad sui evi of of degree of fiber harshness and brittleness. The worldwide production of asbestn.*. u ;* greatly expanded since the turn of the cent the over-all consumption in this country Jevt. ^ , ; off for the period 1958 to 1963 at around 7-Vi :, short tons annually. Of this tonnage, appruxmi.. .... ^ ly 93'I was chrysotile. 3,Sr.' crocidolite, 2 V,. * amosite, and Y' anthophylite and tremolile. ; Even though asbestos has been in industrial u** - j for well over 50 years, much is unknown regard- j 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 !\ ax> ec as tM W tb tb IT- u p c6 v "asbestosis." More recently, evidence has been de- ' veloped that the incidence of respiratory tract -r and other malignancies in asbestos workers is ex 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 1 i of disease. Also in the mid-nineteen thirties and earlier, there was little dust control and the work- i ers were often exposed to massive levels of dust from asbestos and other associated materials in ; the manufacture of asbestos products. Thus, the i' causative agents of the resultant disease are es- 1 a s \ < i c 1 1 i j sentially unknown. Included in theae 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, tare and pitches, and concomitant external ex posures to tobacco smoke or other air pollutan CO o A salient point is that in subsequent years ivh -a heavy dust exposures were reduced, disease al.o diminished. This definitely indicates that w: !t o o eU to sufficient knowledge of the agentfs) responsil.a for the disease, along with dose-response da,a. 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 .N'o. 1 HFM -011703 SCF-FA-6050