Occupational exposure to asbestos and lung cancer in men: evidence from a population-based case-control study in eight Canadian provinces

BMC Cancer. 2012 Dec 13;12:595. doi: 10.1186/1471-2407-12-595.

Abstract

Background: Asbestos is classified as a human carcinogen, and studies have consistently demonstrated that workplace exposure to it increases the risk of developing lung cancer. Few studies have evaluated risks in population-based settings where there is a greater variety in the types of occupations, and exposures.

Methods: This was a population based case-control study with 1,681 incident cases of lung cancer, and 2,053 controls recruited from 8 Canadian provinces between 1994 and 1997. Self-reported questionnaires were used to elicit a lifetime occupational history, including general tasks, and information for other risk factors. Occupational hygienists, who were blinded to case-control status, assigned asbestos exposures to each job on the basis of (i) concentration (low, medium, high), (ii) frequency (<5%, 5-30%, and >30% of the time in a normal work week), and (iii) reliability (possible, probable, definite). Logistic regression was used to estimate odds ratios (ORs) and their corresponding 95% confidence intervals (CI).

Results: Those occupationally exposed to (i) low, and (ii) medium or high concentrations of asbestos had ORs for lung cancer of 1.17 (95% CI=0.92 - 1.50) and 2.16 (95% CI=1.21-3.88), respectively, relative to those who were unexposed. Medium or high exposure to asbestos roughly doubled the risk for lung cancer across all three smoking pack-year categories. The joint relationship between smoking and asbestos was consistent with a multiplicative risk model.

Conclusions: Our findings provide further evidence that exposure to asbestos has contributed to an increased risk of lung cancer in Canadian workplaces, and suggests that nearly 3% of lung cancers among Canadian men are caused by occupational exposure to asbestos.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asbestos / adverse effects*
  • Canada / epidemiology
  • Case-Control Studies
  • Humans
  • Lung Neoplasms / epidemiology
  • Lung Neoplasms / etiology*
  • Male
  • Occupational Diseases / epidemiology
  • Occupational Diseases / etiology*
  • Occupational Exposure / adverse effects*
  • Odds Ratio
  • Surveys and Questionnaires

Substances

  • Asbestos