The longitudinal effects of ambient air pollution exposure on obesity and risk factors for type 2 diabetes in Los Angeles Latino children

Abstract

Introduction: Studies suggest that ambient (AAP: NO2, PM2.5, and O3) contributes to risk for obesity and type 2 diabetes. The objective of this study was to examine relationships between residential AAP, adiposity, and risk factors for type 2 diabetes over 13 years of follow-up. Methods: Overweight and obese Latino children (8-15 years) were enrolled between 2001–2013 from urban Los Angeles, California (n=317). Yearly data include body mass index (BMI), body fat percent, and abdominal adiposity. Metabolic testing provided fasting insulin and glucose, insulin sensitivity (SI), acute insulin response to glucose (AIRg), and disposition index (DI, an estimate of β-cell function). Individual residential AAP exposure was estimated from central site monitors. Linear mixed models were used to assess associations between AAP and longitudinal outcomes. Effects are reported for each SD increase in exposure. Results: NO2 and PM2.5 exposure was positively associated with BMI growth (p=0.04 and p=0.007, respectively) and an increase of approximately 1.7 and 2.6 BMI units at age 18 (p<0.01 for both). NO2 and PM2.5 exposure was inversely associated with SI over follow-up (p=0.02 for both) and a 13.6% and 21% lower SI at age 18 (p=0.04 and p=0.01). PM2.5 exposure was positively associated with a 27.2% higher AIRg at age 18 (p=0.03). NO2 exposure was inversely associated with DI over follow-up (p=0.02) and a 13.7% lower DI at age 18 (p=0.04). Conclusions: This analysis provides the first longitudinal evidence of significant effects of NO2 and PM2.5 exposures on adiposity, glucose metabolism, and β-cell function in Latino children. These results identify AAP as a risk factor for obesity and type 2 diabetes-related pathophysiology in children.