Arsenic in Environment & Heart Attack, Stroke Risk
Researchers suspect groundwater and certain foods raised levels of chemical in study of Native Americans
By Dennis Thompson
MONDAY, Sept. 23 (HealthDay News) -- People chronically exposed to low to moderate levels of arsenic in their environment may be more likely to suffer a heart attack, stroke or other cardiovascular disease, a study of American Indians suggests.
Previous research has linked exposure to high levels of arsenic in drinking water (more than 100 micrograms per liter) with coronary heart disease, stroke, peripheral artery disease and carotid atherosclerosis.
Environmental health researchers decided to explore whether exposure to the lower levels of arsenic more commonly found in drinking water or food also would increase the risk of heart disease.
"We didn't know what would happen at levels that occur regularly in the United States," said study author Dr. Ana Navas-Acien, a researcher in the department of environmental health sciences at the Johns Hopkins Bloomberg School of Public Health.
Regular exposure to more common levels of arsenic did indeed correlate to increased risk of fatal and nonfatal cardiovascular disease, even after adjusting for other risk factors such as smoking, obesity and cholesterol levels, according to the findings, which were published in the Sept. 24 issue of the journal Annals of Internal Medicine.
"It's a chronic long-term health effect," Navas-Acien said. "We need to understand that cardiovascular disease is a very complex illness, and there are many environmental risk factors like arsenic which can contribute."
Although the study found that relatively common levels of arsenic in drinking water were associated with a higher risk of heart disease, it did not prove a cause-and-effect relationship.
The researchers studied nearly 3,600 American Indian men and women living in Arizona, Oklahoma, North Dakota and South Dakota, beginning in 1989 and following up with them through 2008.
Groundwater likely provided the major source of arsenic exposure in Arizona and the Dakotas, researchers said. Private wells in those states often exceed the U.S. standard for arsenic in drinking water of 10 micrograms per liter, and are sometimes as high as 50 micrograms per liter.
Oklahomans likely were exposed to arsenic through their food, with potential sources including rice, flour and other grains, the researchers wrote.
Study participants provided urine samples that the research team used to estimate their exposure to inorganic arsenic.
Of the participants, nearly 450 died of cardiovascular disease and almost 1,200 developed either fatal or nonfatal cardiovascular disease. Researchers found that a person's risk of death from cardiovascular disease increased with their arsenic exposure.
The one-quarter of patients who showed the highest levels of arsenic in their urine had about a 50 percent increased risk of death by heart attack or stroke compared to those with the lowest levels of arsenic, Navas-Acien said.
Arsenic exposure also was associated with an increased risk of developing cardiovascular disease.