Traffic noise in relation to markers of obesity in nine Nordic cohorts

Abstract

Background and aims: Evidence suggests that transportation noise may increase the risk of obesity. However, there are uncertainties regarding e.g. exposure-response relations, potential threshold effects and interactions, in particular with air pollution. In this study, we aim to assess the exposure-response associations between residential exposure to road traffic noise and Body Mass Index (BMI), overweight and obesity, as well as to investigate interaction with air pollution (PM₂.₅). Methods: The study was based on pooled analyses of nine cohorts from Denmark and Sweden, including 128 000 subjects, recruited 1990–2004. Road traffic noise was calculated as time-weighted average Lden exposure five years prior to the baseline of each cohort. Linear and logistic regression models were used to assess associations with BMI and overweight (BMI ≥25 kg/m²) and obesity (BMI ≥30 kg/m²), respectively, adjusting for individual and area-based demographic, socio-economic, lifestyle and environmental factors. Exposure-response relationships were assessed using restricted cubic splines. Results: In the fully adjusted model, exposure to road traffic noise was associated with an increased BMI of 0.07 kg/m² (95% confidence interval, 95% CI, 0.03–0.10) per 10 dB Lden, as well as with an excess risk of being overweight, odds ratio (OR) 1.03 (95% CI 1.01–1.05), or obese, OR 1.06 (95% CI 1.03–1.09). There appeared to be a threshold around 50–55 dB Lden in the exposure-response relationship for BMI. Furthermore, stronger associations were suggested at levels above the mean PM2.5 (15 µg/m³): 3rd quartile 0.11 kg/m² (95% CI 0.04–0.17) and 4th quartile 0.22 kg/m² (95% CI 0.16–0.28). Conclusions: Preliminary findings from this study indicate positive associations between road traffic noise and BMI as well as with overweight and obesity. Stronger associations appeared at noise levels above 50–55 dB Lden and at higher PM₂.₅ levels. Keywords: Road traffic noise, BMI, overweight, obesity, exposure-response function, interaction