Millers and miners (299 workers) from Montana (MT), Texas (TX), and North Carolina (NC) were examined for abnormal respiratory behavior following talc (14807966) exposure. Average exposure time was between 7, 6, and 10 years and average exposure concentrations 1.2, 2.6, and 0.3 milligrams per cubic meter for MT, TX, and NC workers, respectively. TX workers were all males while 20 percent of MT and NC workers were females. Blue collar and potash workers were used as comparisons. New York (NY) talc workers were also used for comparison. Dust samples were collected from all work sites. Maximum forced expiratory volume (FEV) and maximum forced vital capacity (FVC) were measured. Tremolite (14567738) and antigorite (12135863), acicular particles, and tremolite and anthophyllite (16829439) were found in the TX, NC, and NY talc workers, respectively. No correlation was found between symptoms (cough, phlegm, dyspnea) or reduced lung function and cumulative exposure, years worked or smoking. Prevalence of symptoms were similar in MT, TX, and NC groups and the values did not differ significantly from those of the blue collar or potash workers. The incidence of bilateral pleural thickening (BPT) was higher among talc workers aged 40 or more (7, 16, and 14 for MT, TX, and NC, respectively) than those below 40 years (0, 0, and 10 percent). The incidence was highest among smokers. No nonsmoker had BPT and there was a tendency for prevalence to increase with exposure. There was no difference in prevalence between MT, TX, and NC populations and NY population. After adjusting for age and smoking, FEV and FVC were similar between the talc exposed and blue collar and potash workers. However, the flow rates at low lung volumes were reduced 4 to 19 percent in the talc group (MT, TX, and NC). The three groups were similar regarding age coefficient for FEV and FVC and flow rates by smoking category. The authors conclude that association of BPT with talc exposure is weak and further studies are required concerning the prognostic significance of this observation.
National Institute for Occupational Safety and Health, Appalachian Laboratory for Occupational Safety and Health, 944 Chestnut Ridge Road, Morgantown, WV 26505, U.S.A.