Silica dust and lung cancer in the German stone quarrying andceramics industries: results of a case-control study

摘要

BACKGROUND—A work force based case-control study of lung cancer was performed in non-silicotic subjects exposed to crystalline silica to investigate the association between silica dust and lung cancer excluding the influence of silicosis.
METHODS—Two hundred and forty seven patients with lung cancer and 795 control subjects were enrolled, all of whom had been employed in the German stone, quarrying, or ceramics industries. Smoking was used as a matching criterion. Exposure to silica was quantified by measurements, if available, or otherwise by industrial hygienists. Several indices (peak, average and cumulative exposure) were used to analyse the relationship between the level of exposure and risk of lung cancer as odds ratios (OR).
RESULTS—The risk of lung cancer is associated with the year of and age at first exposure to silica, duration of exposure, and latency. All odds ratios were adjusted for these factors. Considering the peak exposure, the OR for workers exposed to high levels (⩾0.15 mg/m³ respirable silica dust which is the current occupational threshold value forGermany) compared with those exposed to low levels(<0.15 mg/m³) was 0.85 (95% CI 0.58 to 1.25). For thetime weighted average exposure the OR was 0.91 (95% CI 0.57 to 1.46).The OR for the cumulative exposure was 1.02 (95% CI 0.67 to 1.55). Noincrease in risk was evident with increasing exposure.
CONCLUSIONS—This studyshows no association between exposure to crystalline silica and lungcancer. The exclusion of subjects with silicosis may have led todilution with respect to the level of exposure and therefore reducedthe power to detect a small risk. Alternatively, the risk of gettinglung cancer may be restricted to subjects with silicosis and is notdirectly linked to silica dust.