Fine particulate air pollution and adverse birth outcomes: Effect modification by oxidative potential

Abstract

Introduction: Oxidative stress has been identified as one of the toxic effects of fine particulate air pollution (PM2.5) that is most relevant for adverse birth outcomes. The aim of this study was to evaluate the association between PM2.5 oxidative burden and adverse birth outcomes. Methods: Data on 191,539 singleton births that occurred in the province of Ontario, Canada from 2003 to 2011 were obtained from a birth registry. Daily air pollution data were collected from ground monitors and regional PM2.5 oxidative potential was measured using a synthetic respiratory tract lining fluid containing the anti-oxidants glutathione and ascorbate. We used logistic regression models to examine the associations between air pollution concentrations and preterm birth (gestational age < 37 weeks) birth weight, term low birth weight (<2500 g) and small for gestational age (SGA, <10th percentile of birth weight for gestational age) adjusting for individual covariates and neighbourhood socioeconomic status (SES). Results: We observed that a 10 μg/m3 increase in PM2.5 over the entire pregnancy was associated with term low birth weight (OR = 1.22, 95% CI 1.02, 1.47) and SGA (OR = 1.04, 95% CI 1.01, 1.07). Regional differences in ascorbate-related oxidative potential modified the impact of PM2.5 on term low birth weight (p for interaction = 0.02). Glutathione-related oxidative potential did not modify the impact of PM2.5 on birth outcomes. Conclusions: Ascorbate-related oxidative potential may modify the impact of PM2.5 on term low birth weight. These findings may have implications in assessing regional differences in PM2.5 related health impacts.