Determining a new federal standard for acceptable levels of arsenic in drinking water was no easy task. Now new research adds to the list of ills caused by exposure to the element. According to a study published in Circulation: Journal of the American Heart Association, long-term exposure to arsenic in drinking water is directly related to the development of atherosclerosis in the arteries leading to the brain.

Chih-Hao Wang of the National Taiwan University and colleagues studied 463 people living in an area of Taiwan with high rates of arseniasis, or chronic arsenic poisoning. Scientists have tracked the amount of arsenic in well water in the region for more than four decades. Combining these records with detailed residential and medical histories allowed the team to determine the amount of arsenic exposure for each participant. The researchers then used ultrasound to measure the amount of atherosclerotic plaque in subjects' carotid arteries, which carry blood to the brain.

The team found that three indices of long-term exposure to arsenic correlated directly with the amount of atherosclerosis present in the carotid arteries. People with the highest arsenic exposure, they report, had three times the risk of atherosclerosis as seen in those who were not exposed to the element. "Our results indicate that long-term arsenic exposure may lead to the progression or acceleration of carotid artery disease and most likely generalized artery disease in humans," Wang notes. Because this study occurred in a region characterized by extremely high levels of arsenic in drinking water, the lowest level of contamination examined was 50 micrograms per liter. The authors note that further research is required to assess the arterial risks associated with arsenic levels between five and 50 micrograms per liter.