In the study, researchers took digital retinal photographs of blood vessels of participants aged 45-84 in the Multi-Ethnic Study of Atherosclerosis. They calculated the level of fine particulate matter in the air at each of the 4,607 participants' homes over the two years preceding the eye exam, and also used measured pollution levels on the day before the eye exam to calculate short-term exposure. Participants had no history of heart disease.
Even though pollution levels in the study were generally below the level that the EPA considers acceptable, these levels still appeared to negatively affect the tiny blood vessels, which are about the width of a human hair, Adar said. Though the vessels only narrow by about 1/100th the width of a human hair, this could have important health consequences if all of the microvasculature in the body is affected in the same way, she said.
In order to establish a causal relationship between air pollution and heart disease, scientists must demonstrate a plausible biological mechanism between exposure and heart disease, said Kaufman. This particular study provides compelling evidence in living people of the visible biological effect of air pollution in a pathway related to heart attack, stroke, or other vascular events.
Going forward, Adar said it's important to study the effects over time.
"Another exam, which is currently underway in these same people, will allow us to see if we can find changes in these vessel diameters over time as a function of air pollution," she said. "If we can, that will give us even more evidence that air pollution causes this vessel narrowing." Adar said that study could produce results in as little as two years.
|Contact: Laura Bailey|
University of Michigan