WASHINGTON, Aug. 31 (UPI) -- Nearly 20 percent of untreated water taken from public and private wells in the United States contains risky levels of arsenic or uranium, the USGS discovered.
The U.S. Geological Survey in findings based on more than 5,000 samples taken from public and private wells across the country found so-called trace elements like arsenic and uranium in 20 percent of the samples.
The USGS survey noted these elements, which were found at levels that pose a threat to human health, occurred far greater than other groundwater contaminants like pesticides.
The report attributed some of the findings to human activities like mining and waste disposal. Drier parts of the country had more contamination than did humid regions. The same relationship was found when comparing agricultural areas with urban areas.
Exposure to arsenic leads to a variety of cancers, while high levels of uranium are linked to kidney disease.
Joe Ayotte, a hydrologist at the USGS and lead author of the study, said most of the time these contaminants are removed from water before people drink it.
"However, trace elements could be present in water from private wells at levels that are considered to pose a risk to human health, because they aren't subject to regulations," he said. "In many cases people might not even know that they have an issue."
Some of the trace elements encountered, the USGS adds, get into the water through natural processes.
