Risk factors for lung cancer among nonsmoking Illinois residents

The purpose of this study was to examine possible risk factors for lung cancer among nonsmokers. The Illinois State Cancer Registry was used to identify all nonsmoking lung cancer cases diagnosed between 1985 and 1987. Subjects were classified as nonsmokers only if their medical record specifically stated that they had never smoked during their lifetime. These cases were compared with nonsmoking colon cancer cases. White male nonsmoking lung cancer cases were more likely to have worked in the construction industry than controls [odds ratio (OR) = 1.6, 95% confidence interval (CI) = 1.2-2.3] and to have worked in the bus service and urban transit industry (OR = 2.6, 95% CI = 1.0-6.9), in the trucking service industry (OR = 2.1, 95% CI = 1.3-3.6), and in blast furnaces, steelworks, and rolling and finishing mills (OR = 1.9, 95% CI = 1.0-3.6). White female cases were more likely to have worked as registered nurses than were the controls (OR = 1.9, 95% CI = 1.0-3.5). Negative associations between lung cancer and farming were found in both white males (OR = 0.6, 95% CI = 0.5-0.7) and white females (OR = 0.1, 95% CI = 0.01-0.6). Several other less plausible associations between employment and lung cancer were also found. To determine whether urban residence and associated air pollution increased the risk of lung cancer for nonsmokers, rates among nonsmokers in Cook County were compared with those in the remainder of Illinois. Cook County rates of nonsmoking lung cancer were elevated among white females and nonwhite females, but not among males. Residences of the white female and nonwhite female lung cancer cases were mapped to determine whether clustering within Chicago had occurred. The absence of observable clustering suggests that the excess of female lung cancer cases in Cook County is not attributable to pollution.