Heart Disease In The Air? Women With Diabetes May Be More Susceptible To Pollution-Related Health Risks

Air pollution
In China, air pollution and tobacco consumption are the main causes of lung cancer, an extensive study finds. Pixabay

Researchers continue to investigate the burden of disease from air pollution, only this time they're focused on cardiovascular disease (CVD).

Using data collected from the Nurses' Health Study, a prospective cohort study that began in 1976, researchers analyzed questionnaires completed by 114,537 women ages 30 and older. Women were asked questions that would provide detailed information on their respective demographics, lifestyle characteristics, and prevalence of a number of diseases. This included the occurrence of physician diagnosed CVD, specifically any incidence of coronary heart disease and ischemic stroke. The NHS study followed up with women every two years so they could update risk factor and disease status, with a consistent response rate of 90 percent.

Exposure to particulate matter (PM) pollution — a complex mixture of extremely small particles and liquid droplets, the Environmental Protection Agency reported — was assessed using certain prediction models for all months between January 1988 and June 2006 for each residential address in the United States. These models relied on monthly averages of PM or PM monitoring data from the EPA's Air Quality System, called the IMPROVE network, as well as calculated for different PM size: PM 2.5 and PM 2.5-10.

PM 2.5, for example, is created from car combustion and power plants, and is reportedly 2.5 thousandths of a millimeter in diameter — that’s smaller than a speck of dust.

All women experienced "small, but non-statistically significant elevations in incidence of CVD, CHD, and stroke," but the risk for each 10 micrograms per cubic meter of air was 44 percent for CVD for the smallest PM size; 17 percent for CVD for road dust-size PM; and 19 percent for CVD from exposure to both PM size fractions.

Overall, among 114,437 NHS participants eligible for analysis, 6,767 women developed CVD during study follow-up, while 3,878 and 3,295 respective cases of CHD and stroke were reported. However, researchers found "statistically significant elevations in risk for almost all PM size fractions and outcomes among women with diabetes."

The risk was also higher for women aged 70 and older, obese women, plus women who lived in the Northeast or South.

"Although studies have shown that people with diabetes are particularly vulnerable to the cardiovascular effects of acute exposures to air pollution, our study is one of the first to demonstrate high risks of cardiovascular disease among individuals with diabetes with long-term exposures to particulate matter," said lead study author Jaime E. Hart, an assistant professor at Brigham and Women's Hospital and Harvard Medical School in Boston, in a press release.

Hart and her team also note the study's limitations; the data they chose was comprised mostly of middle-aged and elderly white women who at one time were nurses. Therefore, these results "may not be generalizable to men or to more racially or socioeconomically diverse populations." And though researchers used a sophisticated PM model, measurement error may still be present.

Researchers concluded that overall, the study "adds to the literature on chronic exposures to air pollution with cardiovascular outcomes, and adds to the limited body of knowledge identifying especially susceptible populations."

Source: Hart JE, et al. Effect Modification of Long-Term Air Pollution Exposures and the Risk of Incident Cardiovascular Disease in US Women. Journal of the American Heart Association. 2015.

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