Study Says Toxic Substance Is Contaminating Drinking Water, But It's Not Linked To Coal Ash

A new study has found surprising information about the source of a toxin contaminating well water throughout North Carolina, and this particular substance isn't coming from coal ash ponds.

Duke University researchers found that the carcinogen hexavalent chromium is coming from natural sources. Specifically, the chemical is leaching into the water from volcanic rocks and not coal ash ponds, as originally suspected.

A team of scientists sampled 376 wells in the Piedmont region of central North Carolina for the substance. About 90 percent of the wells sampled had detectable levels of hexavalent chromium, and in many cases, the contamination is well above recommended levels for safe drinking water.

Avner Vengosh is a geochemist and professor at Duke University. He says they used technology similar to DNA testing to identify where the hexavalent chromium came from.

“The fact that it is naturally occurring doesn't mean it's good for you and the risk on health is the same, it doesn't matter what's the source,” says Vengosh. “I think the risk in this case is much wider because this type of geology is spread out all the way from the Piedmont area, all the way from Georgia to Virginia, so we have potentially millions of people [who] could be affected by that.”

In 2015, water quality officials in North Carolina issued temporary “do not drink” recommendations to residents living near coal-burning plants after tests detected potentially harmful levels of hexavalent chromium in their well water samples. Scientists say because elevated levels of the substance typically occur in coal ash, many people assumed the contamination was linked to the coal ash ponds.

Vengosh says his team's study is the first to show otherwise.

He hopes the information will encourage states to establish their own health standards for hexavalent chromium. Right now, there is no federal drinking water standard for the substance.

Despite the findings, Vengosh says coal ash is responsible for many other toxic substances found in drinking water. He's studied the issue for the past decade and says leaking coal ash ponds are contaminating ground and surface water with harmful contaminants such as arsenic and selenium.

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