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 5yr 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 5yr 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 5yr 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 5yr of age.