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Risk of silicosis in a Colorado mining community
Author(s) -
Kreiss Kathleen,
Zhen Boguang
Publication year - 1996
Publication title -
american journal of industrial medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.7
H-Index - 104
eISSN - 1097-0274
pISSN - 0271-3586
DOI - 10.1002/(sici)1097-0274(199611)30:5<529::aid-ajim2>3.0.co;2-o
Subject(s) - silicosis , medicine , exposure duration , logistic regression , occupational exposure , toxicology , environmental health , pathology , biology
We investigated exposure‐response relations for silicosis among 134 men over age 40 who had been identified in a previous community‐based random sample study in a mining town. Thirty‐two percent of the 100 dust‐exposed subjects had radiologic profusions of small opacities of 1/0 or greater at a mean time since first silica exposure of 36.1 years. Of miners with cumulative silica exposures of 2 mg/m 3 ‐years or less, 20% had silicosis; of miners accumulating > 2 mg/m 3 ‐years, 63% had silicosis. Average silica exposure was also strongly associated with silicosis prevalence rates, with 13% silicoties among those with average exposure of 0.025–0.05 mg/m 3 , 34% among those with exposures of > 0.05–0.1 mg/m 3 , and 75% among those with average exposures > 0.1 mg/m 3 . Logistic regression models demonstrated that time since last silica exposure and either cumulative silica exposure or a combination of average silica exposure and duration of exposure predicted silicosis risk. Exposure‐response relations were substantially higher using measured silica exposures than using estimated silica exposures based on measured dust exposures assuming a constant silica proportion of dust, consistent with less exposure misclassification. The risk of silicosis found in this study is higher than has been found in workforce studies having no follow‐up of those leaving the mining industry and in studies without job title‐specific silica measurements, but comparable to several recent studies of dust exposure‐response relationships which suggest that a permissible exposure limit of 0.1 mg/m 3 for silica does not protect against radiologic silicosis. © 1996 Wiley‐Liss, Inc.