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Chrysotile, tremolite and fibrogenicity
J C McDonald1, A D McDonald, J M Hughes
1Department of Occupational & Environmental Medicine, Imperial College of Science, Technology & Medicine, London, UK.
The Annals of Occupational Hygiene
|December 3, 1999
Summary
Fibrous tremolite in Thetford Mines was linked to higher rates of lung disease in miners. This amphibole fiber appears more fibrogenic than chrysotile asbestos.
Area of Science:
- Occupational Health
- Mineralogy
- Pulmonary Medicine
Background:
- Previous studies linked mesothelioma and lung cancer risks in Quebec chrysotile miners to fibrous tremolite exposure.
- The fibrogenicity of different asbestos types remains a critical area of research in occupational lung disease.
Purpose of the Study:
- To investigate radiographic changes indicative of lung disease in Thetford Mines workers based on mine location and presumed tremolite content.
- To assess the fibrogenicity of amphibole fibers, specifically tremolite, in comparison to chrysotile.
Main Methods:
- Analysis of chest radiographs from 294 former miners employed in 1965, categorized by work location in central (high tremolite) or peripheral (low tremolite) mines.
- Radiographs were read by six readers for small parenchymal opacities; logistic regression adjusted for smoking, age, and cumulative exposure.
Main Results:
- Higher prevalence of small parenchymal opacities was observed in men employed in central mines (13.6%) compared to those not employed there (7.4%), despite lower mean cumulative exposure.
- Adjusted odds ratio for central mine employment was 2.44 (95% CI: 1.06), indicating a significantly increased risk of radiographic changes.
Conclusions:
- Amphibole fibers, including tremolite, appear to be more fibrogenic than chrysotile asbestos.
- Findings support the hypothesis that tremolite contributes significantly to lung parenchymal changes in asbestos-exposed populations.