Effect of occupational air pollutants on various histological types of lung cancer: a population based case-control study.

A population based case-control study was performed in Cracow, Poland, to determine the effect of occupational air pollutants on various histological types of lung cancer. Male cases and controls were identified from the Cracow Death Register. Information was obtained by mailed questionnaire from next of kin on smoking, occupational branch, occupational exposures, and other pertinent variables. Response rates were 73.5% in cases and 72.0% in controls. For cases that underwent a bronchial biopsy or surgical excision the histological diagnosis of the tumour was obtained from clinical records. The case group contained 343 subjects with squamous cell carcinomas, 151 with small cell carcinomas, and 106 with adenocarcinomas. Twenty seven cases showed other histological types (large cell carcinoma and not classifiable). Analysis was performed separately by histological type for occupational exposure variables adjusted for smoking. Long term exposure to mineral dust and metal dust (20 years or more) was found to be a significant risk factor for small cell and squamous cell carcinoma. The effect was more pronounced if the analysis was restricted to those aged less than 70 years. The highest relative risk (RR) due to occupational exposures was found for squamous cell carcinoma and exposure to mineral dust for more than 20 years (RR = 2.45, 95% CI 1.43-4.19). The estimated effect of mineral dust on small cell carcinoma and adenocarcinoma was smaller (RR = 2.29, 95% CI 1.16-4.53 and RR = 2.04, 95% CI 0.89-4.64 respectively). The effect of metal dust and fumes seemed about the same for squamous and small cell carcinoma. No specific agent could be identified as particularly important for a specific histological type; it rather seemed that the effects of the substances considered were similar for lung cancers in general.