Association between long-term exposure to particulate matter and childhood cancer: Retrospective cohort study

Abstract

BACKGROUND AND AIM: Particulate matter is known carcinogen, but its association with childhood cancer is inconsistent. The aim of the present study was to examine the association between air pollution and childhood cancer. METHODS: A retrospective cohort was constructed from claims database of the Korea National Health Insurance Service. Children who had been born in 7 metropolitan cities in Korea (Seoul, Incheon, Daejeon, Gwangju, Daegu, Busan, and Ulsan) from 2002 to 2012 were recruited and half of them were randomly selected. Children who were diagnosed with cancer within 5 years of birth were excluded. Monthly mean concentrations of particulate matter with aerodynamic diameter 10 μm (PM10) and other air pollutants (NO2, SO2, CO and O3) was calculated from AirKorea. Monthly mean concentrations of particulate matter with aerodynamic diameter 2.5 μm (PM2.5) was estimated with a concentration prediction model. The cumulative exposure was calculated by averaging monthly concentrations according to the subject's residential information. We constructed Cox proportional hazard model adjusting for potential confounders and O3 concentration. RESULTS:A total of 1,261,855 children (boys 641,704, girls 610,151) were included in the analysis. During the study period, 1,725 were newly diagnosed with cancer. Exposures to higher mean ambient PM2.5 and PM10 concentration increased the risk of childhood cancer. The hazard ratio of all cancers was 3.02 (95% confidence interval [CI]: 1.63, 5.59) and 1.04 (95% CI: 0.71, 1.45) for an increment of 10 μg/m3 of annual mean concentrations of PM2.5 and PM10, respectively. CONCLUSIONS:We observed significant positive association between particulate matter exposure and childhood cancer in a retrospective cohort of 1.2 million children. KEYWORDS: Particulate matter, Cancer, Children, Retrospective cohort