Document vV3OEowyLw2gvqL1dOxOOyYqw

POTENTIAL HEALTH EFFECTS FROM ASBESTOS EXPOSURE The human toxicological significance for the inhalation of chrysotile as bestos fibers is well documented; and instances of mesothelioma in auto r"e" pair workers have been identified. 16*17318 In a detailed examination of 90 union vehicular maintenance workers in New York City,1 with 10 or more years of shop work, 29$ had decreased vital capability; the percentage in creased with age and most markedly after 20 years from the outset of auto work. Many of the workers examined showed signs consistent with aisbestosis, with observed changes noted in chest x-rays and indication of restrictive pulmonary function. The prevalence of these changes was significantly higher after 20 years exposure, a result expected after occupational exposure to asbestos. ^ Unlike chrysotile,, the health effects of exposure to forsterite, or transi tion series fibers (chrysotile/forsterite) with altered crystalline structures are not well documented. In studies by Davis and Coniam, 20 and Koshi 21 in which fibers of chrysotile, chrysotile/forsterite, and forster ite were injected into the pleural and peritoneal cavities of mice, the results suggested varying degrees of toxic effects. Fiber implantation ani- mal studies conducted by Pott, et. al. ' J and Davis, et. al. suggest that the morphology and size of a fiber, regardless of fiber type, are re- sponsible for its carcinogenicity. Likewise, Stanton, et. al. suggests that fibers <1.5 vm in diameter and >8 um in length pose the greatest risk in producing pleural sarcomas. These studies tend to suggest that the phy sical morphology (size dimensions) and to a lesser degree chemical and sur-/ ' ... / face characteristics of a fiber are the determining factors for inducing 23