Investigation of the Relationship Between Multiple Environmental Exposures and Pediatric Obesity in a National Cross-Sectional Study of Canadian Children

BACKGROUND AND AIM: Pediatric obesity rates in Canada have nearly tripled in the last 30 years, leading to increased rates of morbidity. While environmental exposures are suspected to be obesogenic, data are lacking and mostly employ a single-exposure approach. We aimed to evaluate the potential associations between multiple environmental factors and pediatric obesity. METHODS: We used nationally-representative biomonitoring and health data for children aged 3-11 from the cross-sectional Canadian Health Measures Survey. Chemicals of interest, monitored in blood or urine, were polyaromatic hydrocarbons (PAH), bisphenol A (BPA), parabens, perfluorinated compounds, phthalates and metals. Obesity was characterized by WHO sex-specific body mass index (BMI) for age z-scores. Central obesity was defined using international waist circumference percentile cutoffs. Using generalized additive models, we examined the impact of multiple environmental characteristics, including proximity to greenspace, fine particulate matter (PM 2.5), nighttime light brightness and walkability (active living environment), on associations between single-chemical exposures and obesity. Using quantile-based G computational analysis, we quantified the combined effects of chemicals captured in all cycles, where feasible. Models were adjusted for confounders identified in a directed acyclic graph. Results are adjusted odd ratios with 95% confidence intervals (95% CI). RESULTS: Overall, 9,147 children were included. In single-exposure models, several PAH compounds, BPA, cadmium and total phthalates were linked to increased obesity and central obesity. Per interquartile range increase in total PAHs, risks of obesity and central obesity were elevated to 1.09 (95%CI 1.01, 1.18) and 1.14 (95%CI 1.01, 1.30), respectively. In combined-effects models for PAHs and BPA, risks of obesity and central obesity were strengthened to 1.46 (95%CI 1.20, 1.78) and 1.29 (95%CI 1.10, 1.56), respectively. CONCLUSIONS: Our findings support the role of early chemical exposure in pediatric obesity, particularly PAHs. The combined effects of chemicals strengthened the observed associations. KEYWORDS: Pediatric; Chemicals; Obesity; Public Health; Environment