Ambient air pollution and incidence of early-onset paediatric type 1 diabetes: a retrospective population-based cohort study
Elten M, Donelle J, Lima I, Burnett RT, Weichenthal S, Stieb DM, Hystad P, van Donkelaar A, Chen H, Paul LA, Crighton E, Martin RV, Decou ML, Luo W, Lavigne É. Environ Res. 2020; 184:109291. Epub 2020 Feb 22. DOI: https://doi.org/10.1016/j.envres.2020.109291
Background — Studies have reported increasing incidence rates of paediatric diabetes, especially among those aged 0-5 years. Epidemiological evidence linking ambient air pollution to paediatric diabetes remains mixed.
Objective — This study investigated the association between maternal and early-life exposures to common air pollutants (NO2, PM2.5, O3, and oxidant capacity [Ox; the redox-weighted average of O3 and NO2]) and the incidence of paediatric diabetes in children up to 6 years of age.
Methods — All registered singleton births in Ontario, Canada occurring between April 1st, 2006 and March 31st, 2012 were included through linkage from health administrative data. Monthly exposures to NO2, PM2.5, O3, and Ox were estimated across trimesters, the entire pregnancy period and during childhood. Random effects Cox proportional hazards models were used to assess the relationships with paediatric diabetes incidence while controlling for important covariates. We also modelled the shape of concentration-response (CR) relationships.
Results — There were 1094 children out of a cohort of 754,698 diagnosed with diabetes before the age of six. O3 exposures during the first trimester of pregnancy were associated with paediatric diabetes incidence (hazard ratio (HR) per interquartile (IQR) increase = 2.00, 95% CI: 1.04-3.86). The CR relationship between O3 during the first trimester and paediatric diabetes incidence appeared to have a risk threshold, in which there was little-to-no risk below 25 ppb of O3, while above this level risk increased sigmoidally. No other associations were observed.
Conclusion — O3 exposures during a critical period of development were associated with an increased risk of paediatric diabetes incidence.
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