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

Abstract: 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.