Occupational exposure to air pollution and cancer risk among Danish urban mail carriers.

OBJECTIVES

Our objective was to study the risk of cancer associated with exposure to air pollution among mail carriers.

METHODS

We carried out a retrospective cohort study of 17,233 persons who had been mail carriers during the period 1898-1996. Data on employment was obtained from company files. Data on cancer was obtained from the Danish Cancer Registry.

RESULTS

Male mail carriers employed for more than 3 months had a low incidence of cancer, standardised incidence ratio (SIR) 0.92. For cancers related to air pollution the risk estimates were 0.96 for lung cancer, 0.91 for laryngeal cancer and 0.98 for bladder cancer. A significant low risk for cancer of the oesophagus (SIR 0.50), kidney (SIR 0.73), prostate (SIR 0.81) and skin (melanoma) (SIR 0.87) was seen. Among female mail carriers the risk pattern showed a significant excess of cancer of the cervix uteri (SIR 2.24).

CONCLUSION

In our study of mail carriers who had spent most of their day doing physical hard work outside in the general air pollution we saw no excess in cancers related to air pollution compared with the general population of Copenhagen. This might be due to the protective effect of physical activity.