Incidence of lung cancer among subway drivers in Stockholm

Background Very high levels of airborne particles have been detected in the subway system in Stockholm. Subway particles are more toxic to DNA in cultured human lung cells than particles from ambient air. Methods This cohort comprised all men in Stockholm County who were gainfully employed in 1970. They were followed for cancer incidence until 1989. Lung cancer cases were identified from the national cancer register Subway drivers were identified from the census in 1970. The reference cohort comprised all transport and communication workers in Stockholm. Results There were nine cases of lung cancer among the subway drivers, giving a SIR of 0.82 (95% confidence interval 0.38-1.56). Conclusion The lung cancer incidence was not increased among the subway drivers. The study gives some evidence against the hypothesis that subway particles would be more potent in inducing lung cancer than particles in ambient air.