Radiographic evidence of silicosis risk in the diatomaceous earth industry.
Hughes JM; Weill H; Checkoway H; Jones RN; Henry MM; Heyer NJ; Seixas NS; Demers PA
Am J Respir Crit Care Med 1998 Sep; 158(3):807-814
There is limited and conflicting evidence regarding the exposure-response relationship between exposure to crystalline silica and silicosis; the level of risk to current workers remains uncertain. We conducted an epidemiologic investigation of 1,809 workers in the diatomaceous earth industry, where exposures to crystalline silica are primarily to the cristobalite form. On the basis of the median of three independent readings, 81 (4.5%) workers were judged to have opacities on chest radiographs (small opacities, profusion 1/0, and/or large opacities). Age-adjusted relative risk of opacities increased significantly with cumulative exposure to crystalline silica. The concentration of respirable crystalline silica to which workers were exposed (highly correlated with period of hire) was an important determinant of risk after accounting for cumulative exposure. For workers with an average exposure to crystalline silica of 0.50 mg/m3 (or hired 1950), the cumulative risk of opacities for a cumulative exposure to crystalline silica of 2.0 mg/m3-yr was approximately 1.1%; for an average exposure > 0.50 mg/m3 (or hired < 1950), the corresponding cumulative risk was 3.7%. These findings indicate an exposure-response relationship between cumulative exposure to crystalline silica and radiographic opacities; moreover, the relationship was substantially steeper among workers exposed at the highest average concentrations of crystalline silica.
Occupational-exposure; Exposure-levels; Workers; Work-environment; Epidemiology; Biomarkers; Silicosis; Risk-factors; Silicates; Silica-dusts
Dr. Janet M. Hughes, Department of Biostatistics and Epidemiology, SL18, Tulane University Medical Center, 1430 Tulane Avenue, New Orleans, LA 70112
American Journal of Respiratory and Critical Care Medicine
University of Washington, Seattle, Washington