One interesting study is called, “Radiological abnormalities and asbestos exposure among custodians of the New York City Board of Education” by Levin, S.M. ; Selikoff, I.J. - Annals of the New York Academy of Sciences; (United States); Journal Volume: 643. Here is an excerpt: “Six hundred sixty custodians employed by the New York City Board of Education underwent examination from 1985 through 1987 for asbestos-related disease and other general medical conditions by the clinical staff of the Division of Environmental and Occupational Medicine of the Mount Sinai School of Medicine of the City University of New York. Two-thirds of the men (no women were examined) were 20 or more years from onset of any custodial work, with 44% having had at least 20 years of employment as custodial workers in New York City Board of Education schools. Twenty-four percent had begun custodial work in buildings 30 or more years earlier. Findings among them were of particular interest since asbestos-related disease might forecast what might be expected among school custodians with less seniority. Since the Board of Education, in selecting custodians for examination, had chosen only custodians currently employed, the study group comprised men still working in the school system. These, then, represented a survivor population'. Although a considerable amount of clinical information was obtained, abnormalities on chest X-ray consistent with asbestos-induced scarring were used as the key index of disease resulting from exposure to asbestos. Since scarring of the lung tissue may be present but undetectable on standard chest radiographs (a relatively insensitive diagnostic technique), the prevalence of abnormality on X-ray film represents a conservative estimate of the actual burden of scarring lung disease in the group. Such changes are indicative of previous asbestos exposure, however, and provide evidence of an increased risk of later asbestos-related malignancy. Overall, abnormalities on chest X-ray consistent with asbestos-related scarring were found in 28% of the men examined.”
Another study is called, “Magnetic lung measurements in relation to occupational exposure in asbestos miners and millers of Quebec” - Environmental Research Volume 26, Issue 2, December 1981, Pages 535-550 by David Cohen, Thomas S. Crowther1Graham W. Gibbs2 and Margaret R. Becklake. Here is an excerpt: “Abstract - Fe3O4 particles (ferrimagnetic) are usually attached to asbestos fibers (nonferrimagnetic) in the chrysotile asbestos mining and milling industries; therefore, a magnetic measurement of Fe3O4 in the lungs of workers in these industries could help determine the amount of asbestos which has been inhaled and retained in their lungs. As a first assessment of this method, magnetic measurements were made of Fe3O4 in the lungs of 115 miners and millers in Quebec. These measurements at an industrial site were found to be feasible and practical; however, the amount of Fe3O4 seen in the lungs of those with welding exposure was large enough to mask the Fe3O4 contributed by asbestos, and this subgroup was considered separately. For the remainder (nonwelders), the amount of Fe3O4 was plotted against a total dust exposure index (asbestos and other dust) estimated for each worker. Although the correlation between these quantities was not high, it was statistically significant at the 1% level. Because retained asbestos is likely to increase with increasing exposure to total dust, this correlation suggests that a magnetic lung measurement of a chrysotile miner or a miller does reflect, to some extent, the amount of asbestos in his lung. There was considerable scatter in the data, partly due to individual variations in deposition and clearance, to which this method is sensitive. When the data of only the nonsmokers were plotted, the amount of Fe3O4 was greater than for the total group of nonwelders. This is consistent with previous findings that less dust is deeply deposited in the lungs of smokers, due to constriction of small airways.”
Another study is called, “The histopathology and ultrastructure of pleural mesotheliomas produced in the rat by injections of crocidolite asbestos.” By Davis JM. - Br J Exp Pathol. 1979 Dec;60(6):642-52. Here is an excerpt: “Abstract - Primary tumours of the pleural cavity were produced in rats by the intrapleural injection of crocidolite asbestos. Their histological structure as seen with both light and electron microscopy was very variable and tumours frequently contained elements of both connective-tissue and epithelial type. In some instances the connective-tissue elements predominated from the start and the earliest tumour nodules consisted mainly of pleomorphic connective-tissue cells with only a few layers of cells more nearly epithelial in type on the surface. This pattern was largely retained when tumour nodules increased in size and coalesced, but in the deeper layers of advanced tumours the pleomorphic connective-tissue pattern was often replaced by a more uniform spindle-cell form. Other tumours were more predominantly epithelial in type, showing either a papillary pattern with rounded epithelial cells growing in solid columns, or a vesicular form in which large tissue spaces, often intracellular, were lined by very thin layers of extended cell cytoplasm. Whereas early tumours showed only one histological pattern, the more advanced stages often exhibited areas of all 3, so that there seemed to be some degree of histological mutability. The spindle-cell areas of advanced tumours frequently showed evidence of direct invasion of the surrounding tissue but this was never seen with the epithelial forms of rat mesothelioma.”
If you found any of these excerpts interesting, please read the studies in their entirety. We all owe a debt of gratitude to these fine researchers.
