A case-control study of lung cancer with special reference to the effect of air pollution in Poland.

The aim of the study was to assess the affect of inhaled pollutants on lung cancer risk. The study was a retrospective case-control survey of lung cancer deaths over a six year period (1980-1985). Information on occupation, smoking habits, and residency was collected from next of kin. Classification of exposure to community air pollution was based on measured levels of total suspended particular matter and sulphur dioxide. Cases and controls had been resident in the city of Cracow, Poland. Cases were male (n = 901, questionnaire response rate 70.7%) and female (n = 198, response rate 65.1%) lung cancer deaths; controls were deaths from other causes, excluding other respiratory diseases, and frequency matched by age and sex (males n = 875, response rate 73.5%; females n = 198, response rate 64.0%). Lung cancer risk was found to depend strongly on total cigarette consumption, on age at starting to smoke, and on time since stopping smoking. Relative risk estimates for occupational exposure in iron and steel foundries or in other industries were significantly increased in males. Relative risk in men for highest air pollution level was 1.48 (95% confidence interval 1.08-2.01), while in women the increase was not significant. The joint action of the risk facts of smoking, occupational exposure, and air pollution was found to fit almost perfectly into a multiplicative model. Under conditions found in Cracow, air pollution may increase lung cancer risk, acting multiplicatively with known risk factors such as smoking and industrial exposure.