Arsenic Exposure in Drinking Water Increases Risk of Stroke, Infant Mortality
Arsenic, an odorless and tasteless metal, enters drinking water supplies from natural deposits in the earth or from agricultural and industrial practices. The element has been linked to several health concerns, including new research that indicates that elevated levels in the drinking supply may have an increased risk of stroke and infant mortality.
Chronic Arsenic Exposure Can Lead to Atherosclerosis, Hypertension, and Diabetes
A study of Michigan residents, where it is estimated that 230,000 in the southeastern portion of the state are exposed regularly to drinking water that exceeds the EPA standard for arsenic (10 micrograms per liter or ten parts per billion), used state government data on water samples collected between 1983 and 2002 to estimate residents’ exposure in all 83 counties. Data from hospital databases collected information on stroke between 1994 and 2006.
In most counties, the average arsenic level in drinking water was below the EPA cutoff (median 1.8 micrograms per liter). However, in counties where drinking-water arsenic levels are higher – between 19 and 22 micrograms per liter - stroke rates were twice as high, reports lead researcher Dr. Lynda D. Lisabeth from the University of Michigan in Ann Arbor.
The findings do not prove cause-and-effect, but Dr. Lisabeth notes that chronic, low-level exposure could accelerate atherosclerosis that can lead to heart attacks and stroke. Arsenic exposure is also linked to high blood pressure and diabetes as well as several types of cancer.
A separate study, conducted in Bangladesh by researchers at the Uppsala University Hospital in Sweden, found a link between arsenic exposure in pregnancy and an increased risk of infant mortality. Public health experts estimate that as many as 77 million people in Bangladesh have been poisoned by arsenic from the drinking water supply.
The scientists followed almost 3,000 pregnant women who provided urine samples for arsenic testing when they were eight weeks along. Eighty-six percent of the women had live births, but women with the most arsenic exposure during pregnancy (249-1253 micrograms per liter) significantly increased the risk that the infant would not reach his or her first birthday.
As a reference, 0 to 35 micrograms per liter is considered normal.
The Centers for Disease Control and Prevention notes that most of the US drinking-water supply meets the EPA guidelines. About 80% has an arsenic level below 2 parts per billion, but about 2 percent exceed 20 ppb.
Those concerned about water safety should have their water tested for arsenic, particularly those with private wells. If levels exceed 10 micrograms per liter, reverse osmosis filters are recommended for removing the element.
Stroke (journal), October 2010
Epidemiology (journal), November 2010