Traffic-related air pollution and risk for leukaemia of an adult population

Abstract

Air pollution causes lung cancer, but associations with other cancers have not been established. We investigated whether long-term exposure to traffic-related air pollution is associated with the risk of the general population for leukaemia. We identified 1,967 people in whom leukaemia was diagnosed in 1992-2010 from a nation-wide cancer registry and selected 3,381 control people at random, matched on sex and year of birth, from the entire Danish population. Residential addresses since 1971 were traced in a population registry, and outdoor concentrations of NOx and NO2, as indicators of traffic-related air pollution, were calculated at each address in a dispersion model. We used conditional logistic regression to estimate the risk for leukaemia after adjustment for income, educational level, cohabitation status and co-morbidity. In linear analyses, we found odds ratios for acute myeloid leukaemia of 1.20 (95% confidence interval: 1.04-1.38) per 20 μg/m3 increase in NOx and 1.31 (1.02-1.68) per 10 μg/m3 increase in NO2, calculated as time-weighted average exposure at all addresses since 1971. We found no association with chronic myeloid or lymphocytic leukaemia. This study indicates an association between long-term exposure to traffic-related air pollution and acute myeloid leukaemia in the general population, but not for other subtypes of leukaemia. What's new? Outdoor air pollution is classified by the International Agency for Research on Cancer (IARC) as a human lung carcinogen. Further, several known and suspected leukaemogens are present in outdoor air at low concentrations. It is, however, uncertain whether outdoor air pollution detectably increases the risk of general populations for leukaemia. In this large population-wide case-control study, we found an association between long-term exposure to traffic-related air pollution outside the residence and risk for acute myeloid leukaemia but not for other subtypes of leukaemia.