A nested case-control study of 130 male
lung cancer cases and 627 controls was initiated from a cohort study of 7855 subjects employed at least 1 year between 1972 and 1974 in four
tin mines in China. Three of the
tin mines were in Dachang and one was in Limu. Cumulative total exposure to dust and cumulative exposure to
arsenic were calculated for each person based on industrial hygiene records. Measurements of
arsenic,
polycyclic aromatic hydrocarbons (PAHs), and
radon in the work sites were also evaluated. Odds ratios (
ORs), standard statistic analysis and logistic regression were used for analyses.
RESULTS: Increased risk of
lung cancer was related to cumulative exposure to dust, duration of exposure, cumulative exposure to
arsenic, and tobacco smoking. The risk ratios for low, medium, and high cumulative exposure to dust were 2.1 (95% confidence interval (95% CI) 1.1 to 3.8), 1.7 (95% CI 0.9 to 3.1), and 2.8 (95% CI 1.6 to 5.0) respectively after adjustment for smoking. The risk for
lung cancer among workers with short, medium, and long exposure to dust were 1.9 (95% CI 1.0 to 3.5), 2.3 (95% CI 1.3 to 4.1), and 2.3 (95% CI 1.2 to 4.2) respectively after adjusting for smoking. Several sets of risk factors for
lung cancer were compared, and the best predictive model included tobacco smoking (OR=1.6, 95% CI 1.1 to 2.4) and cumulative exposure to
arsenic (
ORs for different groups from low to high exposure were 2.1 (95% CI 1.1 to 3.9); 2.1 (95% CI 1.1 to 3.9); 1.8 (95% CI 1.0 to 3.6); and 3.6 (95% CI 1.8 5 to 7.3)). No excess of
lung cancer was found among silicotic subjects in the Limu
tin mine although there was a high prevalence of
silicosis. Exposures to
radon were low in the four
tin mines and no carcinogenic PAHs were detected.
CONCLUSIONS: