WEDNESDAY, Sept. 2, 2015 (HealthDay News) -- Two major aquifers in the Great Plains and California are contaminated with natural uranium that's been mobilized by farm-related pollution, a new study reveals.
Nearly 2 million people live above these aquifers, which provide drinking water and irrigation for crops in numerous states, the researchers said.
"Uranium is a widespread contaminant. And we are creating this problem by producing a primary contaminant that leads to a secondary one," study author Karrie Weber, an assistant professor of biological, earth and atmospheric sciences at the University of Nebraska-Lincoln, said in a university news release.
"These two aquifers are economically important -- they play a significant role in feeding the nation -- but they're also important for health. What's the point of having water if you can't drink it or use it for irrigation?" Weber said.
The study team took about 275,000 groundwater samples from the aquifers. They found that 78 percent of the uranium-contaminated sites were associated with the presence of nitrate, a common contaminant that comes mainly from chemical fertilizers and farm animal waste.
Through a series of bacterial and chemical reactions, nitrate releases naturally occurring uranium, making it soluble. This allows uranium to seep into the groundwater, the researchers explained.
The High Plains aquifer contains uranium concentrations up to 89 times the U.S. Environmental Protection Agency (EPA) standard. And, nitrate concentrations were up to 189 times greater than the EPA standards, the researchers reported. This aquifer provides water to eight states, the researchers said.
California's Central Valley aquifer contains uranium concentrations up to 180 times the EPA threshold. Nitrate concentrations were up to 34 times greater than the EPA threshold, the study revealed.
The study was published in the August issue of the journal Environmental Science and Technology Letters.
Previous studies have suggested that long-term consumption of uranium-contaminated water may be associated with increased risk of kidney damage and high blood pressure. Research has also shown that food crops can accumulate uranium when irrigated with water that contains high concentrations of the substance, the study authors said.
"We hope that this study serves as a catalyst to get other people interested in this issue," Weber said. The researchers added they were limited by the data that had been collected, and because uranium isn't often monitored.
The U.S. Centers for Disease Control and Prevention has more about drinking water.