Ozone (O3) exposure during the first trimester of pregnancy is associated with pediatric diabetes incidence, according to results from a retrospective study published in Environmental Research.
Studies have reported increasing rates of pediatric diabetes in children 0 to 5 years of age, but the evidence linking air pollution to pediatric diabetes has been inconclusive.
To examine the association between maternal and early-life exposures to common air pollutants and the incidence of pediatric diabetes, a retrospective analysis of population data from 754,698 pregnancies between April 1, 2006 and March 31, 2012 was performed. Individuals with missing data, inconsistent birthdays across databases, or postal codes that were missing or outside of Ontario, Canada, were excluded. Women with pregnancies of 2 or more fetuses were also excluded.
The incidence of pediatric diabetes was established through an algorithm applied to physician claims. This algorithm was not able to distinguish between type 1 and type 2 diabetes, although diagnosis of type 2 diabetes in children <10 years of age is rare. Postal codes of mother and child were used to determine ambient air pollutant exposure levels during pregnancy and early childhood.
Of the 754,698 children included in the analysis, 1094 (0.14%) were identified as incident cases of diabetes before age 6 years, which was similar to prevalence estimates in Canada overall in the years 2002 to 2013 (approximately 0.15%). Children who developed diabetes before age 6 years had similar birth weight and gestational length as children who did not develop pediatric diabetes, but were twice as likely to be born to mothers with a history of diabetes (3.6% vs 1.8%).
O3 concentrations during the first trimester of pregnancy were positively associated with pediatric diabetes incidence (hazard ratio, 2.00; 95% CI, 1.04-3.86 per interquartile range [10.31 ppb] increase in O3), whereas associations for other time periods were not statistically significant. Exposure below approximately 25 ppb of O3 was associated with little to no risk for pediatric diabetes incidence, whereas exposure above this level was associated with risk that increased in sigmoidal fashion.
Overall, this study found O3 exposure in the first trimester of pregnancy was the only major ambient air pollutant assessed that was positively associated with pediatric diabetes incidence.
A limitation of this study was that exposure to various pollutants was considered only at the child’s reported place of residence and did not take into account other relevant locations, such as the child’s school.
According to the study authors, future research should use mutually adjusted models and investigate potential sources of oxidative stress during the early prenatal period in relation to type 1 diabetes development.
Elten M, Donelle J, Lima I, et al. Ambient air pollution and incidence of early-onset paediatric type 1 diabetes: A retrospective population-based cohort study. Environ Res. 2020;184:109291.