Vermiculite, respiratory disease, and asbestos exposure in Libby, Montana: update of a cohort mortality study.
BACKGROUND
Vermiculite from the mine near Libby, Montana, is contaminated with tremolite asbestos and other amphibole fibers (winchite and richterite). Asbestos-contaminated Libby vermiculite was used in loose-fill attic insulation that remains in millions of homes in the United States, Canada, and other countries.


OBJECTIVE
This report describes asbestos-related occupational respiratory disease mortality among workers who mined, milled, and processed the Libby vermiculite.


METHODS
This historical cohort mortality study uses life table analysis methods to compare the age-adjusted mortality experience through 2001 of 1,672 Libby workers to that of white men in the U.S. population.


RESULTS
Libby workers were significantly more likely to die from asbestosis [standardized mortality ratio (SMR) = 165.8; 95% confidence interval (CI), 103.9-251.1], lung cancer (SMR = 1.7; 95% CI, 1.4-2.1), cancer of the pleura (SMR = 23.3; 95% CI, 6.3-59.5), and mesothelioma. Mortality from asbestosis and lung cancer increased with increasing duration and cumulative exposure to airborne tremolite asbestos and other amphibole fibers.


CONCLUSIONS
The observed dose-related increases in asbestosis and lung cancer mortality highlight the need for better understanding and control of exposures that may occur when homeowners or construction workers (including plumbers, cable installers, electricians, telephone repair personnel, and insulators) disturb loose-fill attic insulation made with asbestos-contaminated vermiculite from Libby, Montana.
Sullivan
Patricia A
PA
Field Studies Branch, Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA. PSullivan@cdc.gov
D000368:Aged; D000538:Aluminum Silicates / Q000009:adverse effects*; D017636:Asbestos, Amphibole / Q000009:adverse effects*; D001195:Asbestosis / Q000401:mortality*; D015331:Cohort Studies; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality*; D008297:Male; D008654:Mesothelioma / Q000401:mortality; D008875:Middle Aged; D008906:Mining; D009009:Montana / Q000453:epidemiology; D016273:Occupational Exposure; D010997:Pleural Neoplasms / Q000401:mortality; D012189:Retrospective Studies
D000538:Aluminum Silicates; D017636:Asbestos, Amphibole; C003760:vermiculite; C005846:tremolite