Traffic noise exposure may be a risk factor for central obesity

1. While obesity by BMI was not linked with traffic noise, obesity by waist circumference was associated with increase noise exposure.

2. Aircraft noise may increase risk for higher waist circumference more strongly than other types of traffic noise.

Evidence Rating Level: 3 (Average)       

Study Rundown: Chronic environmental stressors negatively affect health, with the cardiovascular and metabolic disease risk being particularly increased with these exposures. Traffic noise may affect health by impairing sleep, leading to increased stress hormone signaling and metabolic dysfunction. This Swedish cross-sectional study aimed to assess the effect of exposure to traffic noise in the form of road, aircraft, and railway traffic noise on obesity measured by BMI, central obesity, and waist-hip ratio. The analysis found a slight increase in the risk of higher waist circumferences in women and slight increased risk of higher waist-hip ratios in men associated with >45dB of traffic noise. No link was found with BMI. Aircraft noise in particular may have increased risk more than other types of traffic noise exposure. Further, exposure to all three sources of traffic noise as linked the highest risk of central obesity.

Despite the consistent methodology of measuring noise exposure and assessing patient health, this study had a number of limitations that make the results difficult to interpret. Traffic noise was assessed by geographic location instead of individualized measurements, making it difficult to know what actual exposure was like in the homes. In addition, a number of demographic differences were noticed between high and low traffic noise populations, including gender, age, residence of >10 years, marital status, job strain, noise annoyance and sensitivity, healthy versus unhealthy diet, and air pollution. The study population, which was originally recruited to study diabetes, was skewed towards assessing diabetes risk by balancing those with and without familial history of diabetes. Finally, while high variability as evidenced by the large confidence intervals suggests this study may lack the power to make valid conclusions, it does support the literature in linking factors that disturb sleep and increase the risk of obesity.

Click to read the study in Occupational & Environmental Medicine

Relevant Reading: Increased prevalence in hypertension in a population exposed to aircraft noise

In-Depth [cross-sectional study]: 2382 men and 3329 women were recruited for the Stockholm Diabetes Prevention Program, which was designed to study risk factors for diabetes after 8-10 years of follow-up (72% follow-up rate) from an almost evenly split population of those with high and low familial risk of diabetes type II. Road noise exposure assessment was compiled using a Nordic Prediction Method for road traffic and geographic data. Railway noise was assessed using the European Environmental Noise Directive, and aircraft noise was assessed using the Integrated Noise Model. There was a slight increase per 5dB increase in noise for waist circumference in women (0.21 cm; CI₉₅ 0.01 to 0.41), and a slight increase in the OR per 5dB increase in noise for waist/hip ratio in men (0.16cm; CI₉₅ 0.06 to 0.27). The risk for increased BMI was not significantly different. Overall, the odds ratio (OR) was 1.18 (CI₉₅ 1.03 to 1.34) for the central obesity and 1.29 (CI₉₅ 1.14 to 1.45) for the waist/hip ratio in those exposed to >45dB of noise compared to those exposed to <45dB of noise. Interestingly, exposure to all three types of traffic noise carried an OR of 1.95 (CI₉₅ 1.24 to 3.05) for obesity based on waist circumference.

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