In the first study of its kind, researchers in Sweden have linked exposure to environmental toxins to an increased risk of atherosclerosis, or hardening of the arteries — a major risk factor for heart attack and stroke.
In recent years, studies have increasingly associated exposure to environmental pollutants like PCBs, dioxin and pesticides to cardiovascular problems, including high blood pressure and heart attack. Now, the new study clearly links such exposure to a key underlying cause of heart disease — atherosclerosis. (Previous research also shows that children born to mothers who were exposed to pesticides during pregnancy may have lower I.Q.)
Researchers from Uppsala University studied 1,016 adults age 70 or older in the small, industrial city of Uppsala, Sweden. The participants were tested for 23 environmental toxins, including many that have been banned. “In Sweden, and in many countries in the world, many of these substances are forbidden today, but since they are so long-lived they’re still out there in our environment. We ingest these environmental toxicants with the food we eat, and since they are stored in our bodies, the levels grow higher the older we get,” said Monica Lind, associate professor in environmental medicine at Uppsala University, in a statement.
Researchers then compared participants’ levels of environmental exposure to the health of their arteries, gauged by the amount of plaque build-up in the carotid artery. When fatty plaques accumulate on the inner walls of coronary arteries — known as atherosclerosis — it hardens and narrows the blood vessels, reducing the flow of blood to the heart; if an area of plaque ruptures, blocking blood flow completely, it can cause heart attack.
The researchers found a strong association between seven of the 23 environmental pollutants tested and plaque build-up in the carotid artery. Even after controlling for other cardiovascular risk factors like gender, obesity, high blood pressure, high cholesterol and smoking, the association remained significant.
Since heart attack and stroke, which are both associated with atherosclerosis, are leading causes of death in industrialized countries, investigating potential environmental contributors to disease may help reduce risks on a population level. The researchers are now following the study participants to see whether exposure to toxins increases their actual risk of heart attack or stroke.
The study was published online on Tuesday, in advance of publication in the journal Environmental Health Perspectives.
Meredith Melnick is a reporter at TIME. Find her on Twitter at @MeredithCM. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.