CHARLOTTE, NC (WBTV) - A new independent study by Duke University has concluded that a cancer causing chemical called hexavalent chromium is not linked to coal ash ponds.
The study concludes instead that the chemical is naturally occurring and that it remains a health concern.
"The contamination doesn't, however, stem from leaking coal ash ponds as many people feared after state officials tested wells near coal plants last year and detected potentially harmful levels of hexavalent chromium in the water," the study states. "Instead, it's caused by the natural leaching of mostly volcanic rocks in aquifers across the Piedmont region."
"About 90 percent of the wells we sampled had detectable levels of hexavalent chromium, and in many cases the contamination is well above recommended levels for safe drinking water. But our analysis clearly shows it is derived from natural sources, not coal ash," said Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School of the Environment.
"This doesn't mean it poses less of a threat," Vengosh stressed. "If anything, because the contamination stems from water-rock interactions that are common across the Piedmont region, people in a much larger geographic area may be at risk. This is not limited only to wells near coal ash ponds."
"The bottom line is that we need to protect the health of North Carolinians from the naturally occurring threat of hexavalent chromium, while also protecting them from harmful contaminants such as arsenic and selenium, which our previous research has shown do derive from leaking coal ash ponds," Vengosh said. "The impact of leaking coal ash ponds on water resources is still a major environmental issue."
For this study, researchers collected groundwater samples from 376 wells located both close to and far from coal ash ponds across the Piedmont region of central North Carolina.
Representatives from Duke Energy told WBTV that this study validates the company's longstanding position that it was not contaminating groundwater near wells.
"When combined with previous research, there is overwhelming evidence that coal ash basins are not impacting water quality in neighbor wells," said Harry Sideris, senior vice president of environmental, health and safety. "This study is an extraordinary development, particularly for hundreds of plant neighbors who have been needlessly concerned that ash basins contributed hexavalent chromium or other substances to their wells."
Catawba Riverkeeper Sam Perkins says he would like to see more of the research of the study, and stressed that it doesn't change the fact that there is a health concern.
"It still concluded that with other contaminants Duke's unlined coal ash ponds are still polluting groundwater....it doesn't change the health concern," Perkins said. "It doesn't change the fact that there is contamination of groundwater and that the sites need to be removed. These people (neighbors) also want to see the coal ash removed, they want it cleaned up."
The Duke team published its findings October 26 in the peer-reviewed journal Environmental Science and Technology Letters.
Last year water-quality officials in North Carolina issued temporary "do not drink" recommendations to residents living near coal-burning plants, including the Buck plant in Rowan County and the Allen Steam Station in Gaston County, after tests detected potentially harmful levels of hexavalent chromium in their well water samples.
"I received a letter from the state of North Carolina saying that my water was not safe to drink, so I had to go out and get water," Deborah Graham told WBTV at the time. "I was just scared, nervous and scared, you know, you use your water everyday."
Because elevated levels of chromium typically occur in coal ash, many people assumed the contamination was linked to the coal ash ponds.
Vengosh's team's study is the first to show otherwise, according to the study's summary.
The current drinking water standard for chromium in the United States is 100 parts per billion. This is based on an assumption that most chromium contained in drinking water is composed of a less toxic form known as trivalent chromium. Only California has set a statewide standard of 10 parts per billion for the much more toxic hexavalent form.