Crystalline Silica Exposure, Radiological Silicosis, and Lung Cancer Mortality in Diatomaceous Earth Industry Workers

Details

• Personal Author:
  Checkoway, Harvey ; Demers PA ; Hughes JM ; Seixas, Noah S. ; Weill H
• Description:
  The role of silicosis as either a necessary or incidental condition in silica associated lung cancer remains unresolved. To address this issue a cohort analysis of dose-response relations for crystalline silica and lung cancer mortality was conducted among diatomaceous earth workers classified according to the presence or absence of radiological silicosis. Radiological silicosis was determined by median 1980 International Labour Organisation system readings of a panel of three "B" readers for 1809 of 2342 white male workers in a diatomaceous earth facility in California. Standardised mortality ratios (SMR) for lung cancer, based on United States rates for 1942-94, were calculated separately for workers with and without radiological silicosis according to cumulative exposures to respirable crystalline silica (milligrams per cubic meter x years; mg/m3-years) lagged 15 years. Eighty one cases of silicosis were identified, including 77 with small opacities of > or = 1/0 and four with large opacities. A slightly larger excess of lung cancer was found among the subjects with silicosis (SMR 1.57, 95% confidence interval (CI) 0.43 to 4.03) than in workers without silicosis (SMR 1.19, 95% CI 0.87 to 1.57). An association between silica exposure and lung cancer risk was detected among those without silicosis; a statistically significant (p = 0.02) increasing trend of lung cancer risk was seen with cumulative exposure, with SMR reaching 2.40 (95% CI 1.24 to 4.20) at the highest exposure level (> or = 5.0 mg/m3-years). A similar statistically significant (p = 0.02) dose-response gradient was observed among non-silicotic subjects when follow up was truncated at 15 years after the final negative radiograph (SMR 2.96, 95% CI 1.19 to 6.08 at > or = 5.0 mg/m3-years), indicating that the association among non-silicotic subjects was unlikely to be accounted for by undetected radiological silicosis. The dose-response relation observed between cumulative exposure to respirable crystalline silica and lung cancer mortality among workers without radiological silicosis suggests that silicosis is not a necessary co-condition for silica related lung carcinogenesis. However, the relatively small number of silicosis cases in the cohort and the absence of radiographic data after employment limit interpretations. [Description provided by NIOSH]
• Subjects:
  Aluminum Silicates Biomarkers Epidemiology Lung Lung Diseases Mortality Neoplasms Occupational Exposure Occupational Health Respiratory System Respiratory Tract Diseases Risk Assessment Risk Factors Safety Silicon Dioxide Workplace

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• Keywords:
  Exposure-levels Lung-cancer Mortality-data Mortality-rates Occupational-exposure Pulmonary-system-disorders Respiratory-system-disorders Risk-factors Silica-dusts Silicates Silicosis Work-environment Workers

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• ISSN:
  0040-6376
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 10 ; Washington
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  56-59
• Volume:
  54
• Issue:
  1
• NIOSHTIC Number:
  nn:20024511
• Citation:
  Thorax 1999 Jan; 54(1):56-59
• Contact Point Address:
  Dr H Checkoway, University of Washington, Department of Environmental Health, Box 357234, Seattle, Washington 98195-7234, USA
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  1999
• Performing Organization:
  University of Washington, Seattle, Washington
• Peer Reviewed:
  True
• Start Date:
  19940401
• Source Full Name:
  Thorax
• End Date:
  19960331
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:a83759b04210bf6e1a9c0e56e6c6482978b89ec96e841d638c230c7c63ce89f0be1b973832df42b68e32b175b1e17e9e853125676c6a3bdfcb2913074f765a18
• Download URL:
  https://stacks.cdc.gov/view/cdc/196281/cdc_196281_DS1.pdf
• File Type:
  [PDF - 110.82 KB ]