A cross-sectional study of U.S. attapulgite workers.
Gamble-J; Sieber-WK; Wheeler-RW; Reger-R; Hall-B
Ann Occup Hyg, Inhaled Particles VI 1988 Dec; 32(Suppl 1):475-481
Attapulgite clay is a hydrated magnesium-aluminium silicate and is similar in crystalline structure and chemical formula to palygorskite, but differs in morphology and biological activity. Reported here is a cross-sectional morbidity study of U.S. workers mining and milling U.S. attapulgite. The current U.S. work force in two companies comprises the study cohort of 717 males. The mean age was about 38 years, and tenure was about 11 years. Dust levels were highest in crushing/screening, Raymond mill, and shipping/loading areas; dust levels were among the lowest in mining. Attapulgite particles are micro-fibrous, 0.02-0.1 microm in diameter and 0.5-3.0 microm in length and clumped together in large agglomerates 15-70 microm in diameter with little separation of individual particles. The prevalences of symptoms in companies A and B were respectively 5.1 % and 3% for cough, 3.5% and 9.2% for dyspnea, and 12.2% and 3.4% for wheezing. There was no consistent association of symptoms and exposure as measured by tenure and cumulative dust exposure. Forced vital capacity and forced expiratory volume in one second were generally lower in the medium and high exposure groups, but the differences were not statistically significant. The overall prevalences of category I pneumoconiosis were 6.4% and 0.9% for category 2. About two thirds were rounded opacities and one third irregular opacities. Pneumoconiosis increased with age and exposure (tenure, cumulative respirable and total dust) but the trends were not statistically significant. There was no apparent association of reduced FEY, and FVC with pneumoconiosis category. Overall, these data exhibit no consistent association of respiratory morbidity with exposure.
Silicate-miners; Silicates; Mineral-processing; Minerals; Humans; Epidemiology; Statistical-analysis
National Institute of Occupational Safety and Health, Division of Respiratory Disease Studies, 944 Chestnut Ridge Road, Morgantown, West Virginia 26505
Dodgson-J; McCallum-RI; Bailey-MR; Fisher-DR
Annals of Occupational Hygiene, Inhaled Particles VI