air pollutionsHigher exposure to one measure of traffic-related air pollution is associated with higher levels of a hormone linked to increased rates of obesity, heart disease and diabetes, reports a study in the September Journal of Occupational and Environmental Medicine, official publication of the American College of Occupational and Environmental Medicine (ACOEM).

Gregory A. Wellenius, ScD, of Brown University and colleagues analyzed the relationship between measures of traffic-related air pollution and blood leptin levels in 765 Boston-area older adults. Leptin, an “inflammatory cytokine,” is an obesity-related hormone.

The results showed a significant association between exposure to black carbon — a measure of fine-particle air pollution from traffic sources — and leptin levels. Participants with higher exposure to black carbon were less likely to be white, had lower incomes, and had higher rates of high blood pressure and diabetes.

But even after adjustment for these differences, average leptin levels were 27 percent higher for older adults in the highest category of black carbon exposure. An alternative measure of exposure to traffic-related pollution — residential distance to the nearest major roadway — was unrelated to leptin levels. The estimates of black carbon exposure “likely reflect contributions from traffic on a wider range of roadways in the immediate vicinity of each participant's home,” the researchers write.

While the study can’t prove any causal link, the link between black carbon exposure and leptin levels may help to explain observed increases in cardiovascular disease risk associated with air pollution — especially from traffic. Dr. Wellenius and colleagues conclude, “If confirmed, these findings support the emerging evidence suggesting that certain sources of traffic pollution may be associated with adverse cardiometabolic effects.”

Citation — Wang Y, Eliot MN, Kuchel GA, et al. Long-term exposure to ambient air pollution and serum leptin in older adults: results from the MOBILIZE Boston Study. J Occup Environ Med. 2014;56(9):e73-7.