Lung cancer among industrial sand workers exposed to crystalline silica.
In 1997, the International Agency for Research on Cancer determined that crystalline silica was a human carcinogen but noted inconsistencies in the epidemiology. There are few exposure-response analyses. The authors examined lung cancer mortality among 4,626 industrial sand workers, estimating exposure via a job-exposure matrix based on 4,269 industrial hygiene samples collected in 1974--1995. The average length of employment was 9 years, and estimated average exposure was 0.05 mg/m(3) (the National Institute of Occupational Safety and Health Recommended Exposure Limit). Results confirmed excess mortality from silicosis/pneumoconioses (standardized mortality ratio = 18.2, 95% confidence interval: 10.6, 29.1; 17 deaths). The lung cancer standardized mortality ratio was 1.60 (95% confidence interval: 1.31, 1.93; 109 deaths). Limited data suggested that smoking might account for 10--20% of the lung cancer excess. Exposure-response analyses by quartile of cumulative exposure (15-year lag) yielded standardized rate ratios of 1.00, 0.78, 1.51, and 1.57 (p for trend = 0.07). Nested case-control analyses after exclusion of short-term workers, who had high overall morality, yielded odds ratios by quartile of cumulative exposure (15-year lag) of 1.00, 1.35, 1.63, and 2.00 (p for trend = 0.08) and odds ratios by quartile of average exposure of 1.00, 0.92, 1.44, and 2.26 (p = 0.005). These data lend support to the labeling by the International Agency for Research on Cancer of silica as a human carcinogen. There are approximately 2 million US workers exposed to silica; 100,000 are exposed to more than 0.1 mg/m(3).
National Institute for Occupational Safety and Health, Cincinnati, OH 45226, USA. kns1@cdc.gov
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D000328:Adult; D017677:Age Distribution; D000368:Aged; D015331:Cohort Studies; D016001:Confidence Intervals; D019652:Extraction and Processing Industry; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D011336:Probability; D012307:Risk Factors; D012822:Silicon Dioxide / Q000009:adverse effects*; D012829:Silicosis / Q000453:epidemiology / Q000209:etiology; D016019:Survival Analysis; D013997:Time Factors; D014481:United States / Q000453:epidemiology
D012822:Silicon Dioxide