vermiculite and Respiratory-Tract-Diseases

To describe asbestos-related mortality among manufacturing workers who expanded and processed Libby vermiculite that contained amphibole fiber.. Standardized mortality ratio was calculated for 465 white male workers 31 years after last Libby vermiculite exposure.. Two workers died from mesothelioma, resulting in a significantly increased standardized mortality ratio of 10.5 (95% confidence interval, 1.3 to 38.0). These workers were in the upper 10th percentile of cumulative fiber exposure, that is, 43.80 and 47.23 fiber-years/cm, respectively. One additional worker with cumulative fiber exposure of 5.73 fiber-years/cm developed mesothelioma but is not deceased. There were no other significantly increased standardized mortality ratios.. Workers expanding and processing Libby vermiculite in a manufacturing setting demonstrated an increased risk for the development of mesothelioma following exposure to the amphibole fiber contained within this vermiculite ore source.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aluminum Silicates; Cause of Death; Cohort Studies; Confidence Intervals; Extraction and Processing Industry; Female; Humans; Inhalation Exposure; Lung Neoplasms; Male; Mesothelioma; Middle Aged; Occupational Exposure; Respiratory Tract Diseases; Young Adult

We reanalyzed the Libby vermiculite miners' cohort assembled by Sullivan to estimate potency factors for lung cancer, mesothelioma, nonmalignant respiratory disease (NMRD), and all-cause mortality associated with exposure to Libby fibers. Our principal statistical tool for analyses of lung cancer, NMRD, and total mortality in the cohort was the time-dependent proportional hazards model. For mesothelioma, we used an extension of the Peto formula. For a cumulative exposure to Libby fiber of 100 f/mL-yr, our estimates of relative risk (RR) are as follows: lung cancer, RR = 1.12, 95% confidence interval (CI) =[1.06, 1.17]; NMRD, RR = 1.14, 95% CI =[1.09, 1.18]; total mortality, RR = 1.06, 95% CI =[1.04, 1.08]. These estimates were virtually identical when analyses were restricted to the subcohort of workers who were employed for at least one year. For mesothelioma, our estimate of potency is K(M) = 0.5 x 10(-8), 95% CI =[0.3 x 10(-8), 0.8 x 10(-8)]. Finally, we estimated the mortality ratios standardized against the U.S. population for lung cancer, NMRD, and total mortality and obtained estimates that were in good agreement with those reported by Sullivan. The estimated potency factors form the basis for a quantitative risk assessment at Libby.

Topics: Adult; Aged; Aluminum Silicates; Cohort Studies; Environmental Exposure; Humans; Lung Neoplasms; Male; Mesothelioma; Middle Aged; Mining; Montana; Occupational Diseases; Occupational Exposure; Proportional Hazards Models; Respiratory Tract Diseases; Risk Assessment

Western Mineral Products/W. R. Grace operated a vermiculite plant in a mixed industrial/residential area of northeast Minneapolis from 1936 to 1989. The plant processed vermiculite ore contaminated with amphibole asbestos from a mine in Libby, MT. Air monitoring in the early 1970s found fiber concentrations in excess of 10 fibers per cubic centimeter of air (f/cc), indicating that worker exposure to asbestos was occasionally 100 times the current occupational standard. Residents of the surrounding community also had direct contact with vermiculite processing wastes (containing up to 10% amphibole asbestos) that were made freely available. Children played on waste piles and neighborhood residents hauled the wastes away for home use. In total, 259 contaminated residential properties have been found to date. Reported emission factors and plant process data were used as inputs to model airborne emissions from the plant over several operating scenarios using the U.S. Environmental Protection Agency (EPA) ISC-Prime model. Results estimate short-term air concentrations of asbestos fibers in residential areas nearest the plant may have at times exceeded current occupational standards. Exposure estimates for other pathways were derived primarily from assessments done in Libby by the U.S. EPA. The Northeast Minneapolis Community Vermiculite Investigation (NMCVI) was conducted by the Minnesota Department of Health to identify and characterize the exposures of a cohort of over 6000 people who live or lived in Northeast Minneapolis and may have been exposed to asbestos. This cohort is now being investigated in a respiratory health screening study conducted by the University of Minnesota and the Minnesota Department of Health.

Topics: Aluminum Silicates; Asbestos; Environmental Exposure; Environmental Monitoring; Epidemiological Monitoring; Hazardous Waste; Humans; Mass Screening; Mining; Minnesota; Public Health; Respiratory Tract Diseases

Topics: Adult; Aluminum Silicates; Calcium Hydroxide; Health Education; Health Promotion; Humans; Magnesium; Magnesium Compounds; Male; Middle Aged; National Institutes of Health (U.S.); Occupational Diseases; Research; Respiratory Tract Diseases; Risk; Silicon; Silicon Compounds; Smoking; United States; Workers' Compensation

A cohort of 406 men employed before 1963 for at least one year in a vermiculite mine in Montana was followed up until July 1983. The vermiculite ore as fed to the mill contained 4-6% of amphibole fibre in the tremolite series. Vital status was established in all but one of the 406 and death certificates were obtained and coded for 163 of the 165 men who died. Compared with white men in the United States, the cohort experienced excess mortality from all causes (SMR 1.17), respiratory cancer (SMR 2.45), non-malignant respiratory disease (SMR 2.55), and accidents (SMR 2.14). Four deaths were from malignant mesothelioma (proportional mortality 2.4%). Compared with Montana death rates, the SMR for respiratory cancer was somewhat higher (3.03). Man-year analyses of respiratory cancer and estimated cumulative exposure gave a relation that did not depart significantly from linearity. The results of this and case-referent analyses indicate an increased risk of mortality from respiratory cancer in this cohort of about 1% for each fibre year of exposure. In relation to estimated exposure the mortality experienced by the cohort from both lung cancer and mesothelial tumours was higher than in chrysotile mining.

Topics: Aluminum Silicates; Asbestos, Amphibole; Follow-Up Studies; Humans; Male; Mining; Montana; Occupational Diseases; Respiratory Tract Diseases; Respiratory Tract Neoplasms; Silicic Acid; Silicon Dioxide