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 SO(2), NO(2), ozone (O(3)), SO(4), and particulate matter < 10 micro m in diameter (PM(10)). 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 O(3) exposure was significantly higher in children with type 1 diabetes than in healthy controls. Prediagnosis PM(10) exposure was significantly higher in children diagnosed before 5 yr of age, when compared with healthy controls. SO(2) exposure was significantly higher in children with later-onset diabetes compared with those with early-onset diabetes (EOD). NO(2), SO(2) and SO(4) exposure was significantly lower in children diagnosed after 5 yr of age, when compared with healthy controls. O(3), NO(2), SO(4) and PM(10) 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. PM(10) may be a specific contributory factor to the development of type 1 diabetes before 5 yr of age.