Obesogens: An Environmental Link to Obesity

Obesity has risen steadily in the United States over the past 150 years, with a marked uptick in recent decades. Many attribute this trend solely to poor diet and lack of exercise, but a growing body of evidence suggests environmental exposures to chemical “obesogens” may also play a role.

Environmental Lead Levels after Hurricane Katrina

One of the environmental health concerns that emerged after Hurricane Katrina was the possible widespread contamination of soils and sediments. Rabito et al. assessed the distribution of residential soil and dust lead 2 years after the storm, and they also compared soil lead before and after the hurricane. Households were selected by stratified random sampling in a cross-sectional study conducted in New Orleans, Louisiana. Residents were given a standard residential questionnaire, and both the interior and exterior of homes were tested for lead. The authors used logistic regression to identify risk factors for lead levels that exceeded federal standards. Of the 109 households that were enrolled, 61% had at least one lead measurement above allowable levels. Of the homes with bare soil, 47% had elevated lead, and 27% had lead levels exceeding 1,200 ppm. Housing age was associated with soil lead, whereas housing age and soil lead were associated with interior lead. The median soil lead level (560 ppm) was significantly higher than the median level of samples collected before Hurricane Katrina. The authors note that the high prevalence of lead above recommended levels in soil and dust samples in and around residences raises concerns about potential health risks to the New Orleans population, most notably children. They recommend that steps be taken to mitigate the risk of exposure to lead-contaminated soil and dust.

Health Risks of Limited-Contact Water Recreation

Contaminated waters where swimming is not allowed are often used for other recreational purposes; however, little is known about the potential health risks associated with activities involving limited contact with the contaminated water. Dorevitch et al. evaluated the incidence of illness, severity of illness, associations between water exposure and illness, and risk of illness attributable to limited contact on waters dominated by wastewater effluent and waters approved for general-use recreation such as swimming. The authors analyzed data from the Chicago Health, Environmental Exposure, and Recreation Study to evaluate five health outcomes among three groups of people, including those who engaged in limited-contact water recreation on effluent-dominated waters, those who engaged in limited-contact recreation on general-use waters, and those who engaged in non–water recreation. With non–water recreation as the reference group, limited-contact water recreation was associated with the development of acute gastrointestinal illness in the first 3 days after water recreation at both effluent-dominated waters and general-use waters. For every 1,000 users, 13.7 and 15.1 cases of gastrointestinal illness were attributable to limited-contact recreation at effluent-dominated waters and general-use waters, respectively. Eye symptoms were associated only with effluent-dominated waters. Among water recreators, illness was associated with the amount of water exposure. These results suggest that limited-contact recreation, both on contaminant-dominated waters and waters designated for general use, is associated with an elevated risk of gastrointestinal illness.

Related News Article: In the Same Boat? Health Risks of Water Recreation Are Not Limited to Full-Contact Activities

Air Pollution, Temperature, and Blood Pressure in People with Type 2 Diabetes

Diabetes increases the risk of hypertension and orthostatic hypotension, and also raises the risk of cardiovascular death during heat waves and during episodes of high pollution. However, little is known about the association of short-term exposures to air pollutants and heat on blood pressure (BP) regulation in people with type 2 diabetes mellitus (T2DM). In a panel study of 70 persons with T2DM, Hoffmann et al. measured BP and performed pulse wave analysis every 2 weeks on up to five occasions (355 repeated measures). Concentrations of air pollutants and temperature were measured hourly at a central site. The authors applied linear-mixed models with random participant intercepts to investigate the association of air pollutants and temperature with systolic BP, diastolic BP, and mean arterial pressure. In subjects with T2DM, particulate matter was associated with increased BP; ozone was associated with decreased BP; and higher temperatures were associated with a marginal decrease in BP. These estimated effects appeared to be independent of each other and were of a magnitude that could result in clinically significant hemodynamic consequences for this vulnerable population.

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Health Impacts of the Built Environment

The built environment may influence exposures to physical inactivity and exposure to air pollution in different ways and thus may differentially influence the health of people living in urban areas. Hankey et al. examined the association of the built environment with air pollution and physical inactivity and estimated potential health risks. They used a regional travel survey to estimate within-urban variability in physical inactivity and home-based air pollution exposure to particulate matter (PM2.5), nitrogen oxides (NOx), and ozone (O3) for 30,007 individuals in Southern California. The resulting risk for ischemic heart disease (IHD) was then estimated using literature-derived dose–response values. A cross-sectional approach was used to compare estimated IHD mortality risks among neighborhoods based on “walkability” scores. The proportion of physically active individuals was higher in high- versus low-walkability neighborhoods, but the between-neighborhood variability in estimated IHD mortality attributable to physical inactivity was modest (7 fewer IHD deaths/100,000/year in high- vs. low-walkability neighborhoods). Between-neighborhood differences in estimated IHD mortality from air pollution were comparable in magnitude (9 more IHD deaths/100,000/year for PM2.5 and 3 fewer IHD deaths for O3 in high- vs. low-walkability neighborhoods). These findings suggest that the health benefits from increased physical activity in high-walkability neighborhoods may be offset by adverse effects of exposure to air pollution, and that differences in population health impacts between neighborhoods are similar for air pollution and physical activity. The authors note that both physical activity and exposure to air pollution are critical aspects of planning for cleaner, health-promoting cities.

Related News Article: Heart Disease Tradeoffs: The Built Environment, Air Pollution, and Activity