Role of exposure to air pollutants in the development of type 1 diabetes before and after 5 yr of age.

: Objective:  To assess the role of ambient air pollutants in type 1 diabetes in children. Design and methods:  Prediagnosis exposure to five air pollutants was studied in two subgroups with onset of type 1 diabetes before and after 5 yr of age, and two matched subgroups of healthy children. Zip codes and dates of residence from birth to diagnosis were used to obtain geographic- and time-specific air concentrations of SO2, NO2, ozone (O3), SO4, and particulate matter < 10 µm in diameter (PM10). Prediagnosis time-adjusted pollutant exposure levels were created by summing up zip code-specific pollution data and dividing by months of exposure from birth to diagnosis. Two-tailed t-test and logistic regression were used to evaluate relative effects and test data between cases and controls. Results: Prediagnosis average O3 exposure was significantly higher in children with type 1 diabetes than in healthy controls. Prediagnosis PM10 exposure was significantly higher in children diagnosed before 5 yr of age, when compared with healthy controls. SO2 exposure was significantly higher in children with later-onset diabetes compared with those with early-onset diabetes (EOD). NO2, SO2 and SO4 exposure was significantly lower in children diagnosed after 5 yr of age, when compared with healthy controls. O3, NO2, SO4 and PM10 levels did not significantly differ between the two diabetic subgroups. Conclusion: Increased ozone exposure may be a contributory factor to the increased incidence of type 1 diabetes. PM10 may be a specific contributory factor to the development of type 1 diabetes before 5 yr of age.