Childhood leukemia development and correlation with traffic air pollution in Taiwan using nitrogen dioxide as an air pollutant marker.

To investigate the relationship between traffic air pollution and development of childhood leukemia (14 yr of age or younger), studies were conducted on a matched cancer case-control cohort using childhood deaths that occurred in Taiwan from 1995 through 2005. Data on all eligible childhood leukemia deaths were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. The control group consisted of children who died from causes other than neoplasms or from diseases that were not associated with respiratory complications. The controls were pair matched to the cases by gender, year of birth, and year of death. Each matched control was selected randomly from the set of possible controls for each case. Air quality data for recorded concentrations of nitrogen dioxide (NO2) from study municipalities for 1995-2005 were obtained as an indicator of a subject's exposure to air emissions from motor vehicles. The subjects were divided into tertiles according to the levels of NO2 in their residential municipality. The results showed that there was a significant exposure-response relationship between exposure to traffic exhaust pollutants and the risk of leukemia among young children after controlling for possible confounders. The findings of this study warrant further investigation of the role of traffic air pollution in the etiology of childhood leukemia.