Morbidity and Mortality of Vermiculite Miners and Millers Exposed to Tremolite-Actinolite

摘要

A morbidity and mortality study on vermiculite workers was conducted. In the mortality study, the cohort consisted of 581 workers, 569 males, who were hired at a vermiculite mill and mine in Montana before 1970 and worked for longer than 1 year. Vital status of the cohort as of December 31, 1981 was determined. Death certificates were obtained and reviewed. Exposures were estimated from previously obtained air sampling data. In the morbidity study, the cohort consisted of 191 males employed for at least 5 years from 1975 to 1982. Chest X-rays were examined. A questionnaire on occupational and smoking history and respiratory symptoms was administered. In the mortality study, the average cumulative exposure for the entire cohort was 196.3 fiber years (fy), range less than 30 to over 2,000fy. Excessive lung cancer and non respiratory disease mortality occurred. This was associated with cumulative exposure. In the morbidity study, cumulative exposure was associated with parenchymal and pleural X-ray abnormalities and increased dyspnea. The author concludes that cumulative fiber exposures above 400fy are associated with increased risks of lung cancer mortality. Smoking must be considered as a possible confounding factor as the data was not controlled for the effects of smoking.