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Control of Silicosis in Vermont Granite Industry.

Hosey-AD; Trasko-VM; Ashe-HB;
NIOSH 1958 May:79 pages
This report presents the results of investigations and observations on progress made in the control of silicosis in the Vermont granite industry. A brief history of U.S. Public Health Service studies of the industry since 1920 is presented. An environmental resurvey of the industry in 1955 showed that dust concentrations were lower than those in previously published data. Average counts were within the Vermont limit of 10 million particles per cubic foot of air. The decrease in dustiness since the previous study was caused by more effective exhaust ventilation. Settled dust samples averaged 21.9% quartz and 6.8% silicon-carbide insoluble in hydrofluoric-acid (7664393). Toxic elements found included lead (7439921), beryllium, (7440417) and mercury (7439976). By determining the total silica (7631869) concentration in operators' breathing zones, it was found that stonecutters using dry processes were exposed to 1.4 milligrams per cubic meter as against 0.6 milligram for the other workers. Chest X-ray records were analyzed to determine the progress in the suppression of silicosis. Annual prevalence rates have been steadily decreasing. The rate in 1952 was 20.3% and in 1956 15.1%. The inquiry into the nature of the silicosis problem was based on the cumulative records of 2,246 men who were X-rayed one or more times or had died during 1950-1955. 2,001 men were employed in the sheds, 75 were either not working or working at other trades and appeared periodically for X-rays, and 170 were known dead. Silicosis in one stage or another was evident on the X-ray film in 535 of the study group. Silicosis was diagnosed in 534 of the 1,112 men employed prior to 1937. The average number of years employed for the men with silicosis was 32.4, and for those with no silicosis 26.3. Of the 1,134 men starting work in the industry in 1937 or later, under cost controlled conditions, one case of suspected silicosis was found. The average years of employment for this group was 7.4. Analysis of the occupational experiences shows that 73% of the 535 men with silicosis worked as pneumatic tool operators or at other dust making jobs. Based on serial chest X-rays records of 153 men with silicosis it was determined that it took, on the average, 23 years of dust exposure to produce silicosis among pneumatic tool operators and 29 years among polishers, lumpers, and other low dust operations. Mortality data indicate that silicotuberculosis as a cause of death is decreasing.
States; Mining-industry; Quarries; Pollution; Particulates; Respiration; Lung; Epidemiology;
7664-39-3; 7439-92-1; 7440-41-7; 7439-97-6; 7631-86-9;
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Occupational Health Program, Bureau of State Services, Public Health Service, U.S. Department of Health, Education, and Welfare, Report No. 557, 79 pages, 20 references