Occupational exposure to talc containing asbestos.

The National Institute for Ctcupational Safety and Health (NIOSH) conducted studies of mortality and morbidity patterns and occupational exposures among talc miners and millers in upper New York. The mortality study was based on 398 white male workers who began employment between January I, 1947 and December 31, 1959, and whose vital status was determined as of June 30, 1975. Observed cause specific mortality for the cohort as compared with that expected based on U.S. white male mortality rates indicated a significant increase in mortality due to bronchogenic cancer, nonmalignant respiratory disease (excluding influenza and pneumonia) and respiratory tuberculosis. The average latency period for bronchogenic cancer was 20 years. In the morbidity study current workers (156 male miners and mi 11 ers) from the same New York ta lc company were examined. ()le hundred twenty-one (121) workers were administered the MRC respiratory questionnaire (including smoking and work histories), lung function tests (FEVl, FVC, expired flow rates), and chest X-rays (PA and lateral). The results are similar for all 121 workers, and for a subset of 93 workers having talc exposure only at the facility under study. Lung function is expressed as percent predicted, with 9,347 coal miners and 1,005 potash miners matched on age, height, and smoking habits providing expected values for the prevalence of symptoms, X-ray findings, and lung function. Cumulative exposure is calculated by estimating the mean exposure level in a current job, times the time spent in that job summated for all jobs. Findings from the morbidity study included the following: Talc workers with less than 15 years work have a higher prevalence of cough and phlegm than coal and potash miners. Talc workers with more than 15 years work have a higher prevalence of cough, dyspnea, and irregular opacities than potash miners, but less phlegm and dyspnea than coal miners. Pleural thickening and calcification is significantly higher in talc workers than in coal and potash miners, and pleural thickening is significantly higher than in chrysotile asbestos workers in Canada. Mean pulmonary function of the talc workers is reduced compared to coal and potash workers: Reductions in FEVI and FVC are associated with the highly correlated variables of years worked, particulate, and fiber exposure. Talc workers with pleural thickening have reduced lung function compared to those workers without pleural thickening. iii The industrial hygiene study demonstrated that the major components of the tales mined and milled are talc, tremolite, anthophyllite, and serpentines with traces of dolomite, calcite, and quartz. These trace metals were found to be present only in very small quantities. Time-weighted average (TWA) exposures to asbestiform amphiboles (anthophyllite and tremolite) were found to be in excess of present U.S. Occupational Safety and Health (O~A) and Mine Safety and Health Administration (M~A) occupational exposure standards in many mine and mill operations with more than 90 percent of the total airborne fibers being less than 5-pm in length. Results of the present study are compared with those of other studies of workers exposed to the same or similar minerals, and it is concluded that exposures to such tales are associated with an increased risk of developing not only pleural thickening and pleural calcification, but also both bronchogenic cancer and nonmalignant respiratory disease.