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Crystalline silica exposure and lung cancer mortality in diatomaceous earth industry workers: a quantitative risk assessment.

Authors
Rice-FL; Park-R; Stayner-L; Smith-R; Gilbert-S; Checkoway-H
Source
Occup Environ Med 2001 Jan; 58(1):38-45
NIOSHTIC No.
20021850
Abstract
OBJECTIVE: To use various exposure-response models to estimate the risk of mortality from lung cancer due to occupational exposure to respirable crystalline silica dust. METHODS: Data from a cohort mortality study of 2342 white male California diatomaceous earth mining and processing workers exposed to crystalline silica dust (mainly cristobalite) were reanalyzed with Poisson regression and Cox's proportional hazards models. Internal and external adjustments were used to control for potential confounding from the effects of time since first observation, calendar time, age, and Hispanic ethnicity. Cubic smoothing spline models were used to assess the fit of the models. Exposures were lagged by 10 years. Evaluations of the fit of the models were performed by comparing their deviances. Lifetime risks of lung cancer were estimated up to age 85 with an actuarial approach that accounted for competing causes of death. RESULTS: Exposure to respirable crystalline silica dust was a significant predictor (p<0.05) in nearly all of the models evaluated and the linear relative rate model with a 10 year exposure lag seemed to give the best fit in the Poisson regression analysis. For those who died of lung cancer the linear relative rate model predicted rate ratios for mortality from lung cancer of about 1.6 for the mean cumulative exposure to respirable silica compared with no exposure. The excess lifetime risk (to age 85) of mortality from lung cancer for white men exposed for 45 years and with a 10 year lag period at the current Occupational Safety and Health Administration (OSHA) standard of about 0.05 mg/m3 for respirable cristobalite dust is 19/1000 (95% confidence interval (95% CI) 5/1000 to 46/1000). CONCLUSIONS: There was a significant risk of mortality from lung cancer that increased with cumulative exposure to respirable crystalline silica dust. The predicted number of deaths from lung cancer suggests that current occupational health standards may not be adequately protecting workers from the risk of lung cancer.
Keywords
Respiratory-system-disorders; Respirable-dust; Pulmonary-system-disorders; Lung-cancer; Lung-disorders; Silica-dusts; Dust-exposure; Dusts; Statistical-analysis; Humans; Risk-analysis
CODEN
OEMEEM
CAS No.
14808-60-7; 14464-46-1; 61790-53-2
Publication Date
20010101
Document Type
Journal Article
Email Address
frice@cdc.gov
Fiscal Year
2001
NTIS Accession No.
NTIS Price
Issue of Publication
1
ISSN
1351-0711
NIOSH Division
EID
Source Name
Occupational and Environmental Medicine
State
OH
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