Arsenic in drinking water tied to stroke risk
People who live in areas with moderately elevated levels of arsenic in the drinking-water supply may have a somewhat increased risk of stroke, a study of Michigan residents suggests.
The findings, published in the journal Stroke, do not prove that drinking-water arsenic is responsible for the elevated risk. Nor do they suggest that water with arsenic levels that meet guidelines from the U.S. Environmental Protection Agency (EPA) — which most U.S. drinking-water supplies do — are a stroke hazard, the study's lead researcher expressed.
However, the study does call for more in-depth research to determine whether arsenic in the water supply is contributing to some strokes.
Arsenic is an element found naturally in rock, soil, water, the air and the food supply. It is also released into the environment through industrial activities; for instance, arsenic is used as a wood preservative and in some paints, dyes and fertilisers.
High arsenic exposure can lead to cancer, and chronic exposure to even moderately elevated levels has been linked to high blood pressure and type 2 diabetes. But the possible health effects of such modestly increased exposures are not yet fully clear.
The EPA has set the maximum allowable level of arsenic in drinking water at 10 micrograms per liter (or 10 parts per billion). According to the Centers for Disease Control and Prevention, about 80 percent of U.S. drinking-water supplies have an arsenic level below 2 parts per billion (ppb), but 2 percent exceed 20 ppb.
It's also possible, she said, that chronic, low-level arsenic exposure could accelerate atherosclerosis, a hardening and narrowing of the arteries that can lead to heart attacks and stroke.
The findings, Lisabeth said, suggest an association between drinking-water arsenic and stroke risk, but do not prove cause-and-effect.
While most public drinking water in the U.S. meets the EPA standard, high arsenic levels are a bigger threat in other parts of the world. Researchers have estimated that about 140 million people worldwide drink water with arsenic levels above 10 ppb; Bangladesh has been hardest hit, with millions being exposed to high levels of naturally occurring arsenic in well water.