RENO, Nev. (AP) - Nearly a year after the discovery of a radioactive isotope in some wells prompted two dairies to dump milk, federal officials have announced plans to conduct a study to determine the extent of the contamination around Fallon.
The study also will try to pinpoint why radioactive polonium-210 turned up in elevated levels in drinking water wells around the agricultural and military town 60 miles east of Reno, said Ralph Seiler, research hydrologist for the U.S. Geological Survey.
The three-year, $400,000 study, which will be funded jointly by the agency and Churchill County, is expected to start this fall.
"We need a better definition of what areas are likely to have high polonium levels so residents can decide whether to use bottled water" or to purify their drinking water, Seiler said.
Seiler said elevated levels of polonium-210 stem entirely from natural geologic causes, and there's no indication any human activity is responsible.
Last August, the release of a USGS report prompted officials from Sorensen's Dairy and Oasis Dairy near Fallon to dump milk and stop sales pending the outcome of more tests.
The study found polonium-210 in 17 of 25 wells tested. The naturally occurring isotope is known to cause cancer and can damage tissues and organs at high doses.
Concentrations of polonium-210 found in the wells ranged from less than 0.1 to 76 picocuries per liter. Thirteen of the wells had amounts greater than 15, which is the maximum allowed by the Environmental Protection Agency for public wells. The EPA does not regulate private wells.
Subsequent tests by the U.S. Food and Drug Administration found that it is safe to drink milk from dairies located near the wells.
County Manager Brad Goetsch stressed that no polonium-210 has
turned up in any municipal water system in the county.
"The elevated levels of polonium have only turned up in a small percentage of wells in southern Lahontan Valley," he said.
County commissioners reluctantly agreed Thursday to help fund the study, with some saying the results could harm the county's real estate and agricultural industries, the Lahontan Valley News and Fallon Eagle Standard newspaper reported.
"I see a potential to misuse the data," Commissioner Lynn Pearce said.
Elevated levels of the isotope, which derives from uranium in granite, also have turned up in water in California, Florida, Louisiana and Maryland.
The Lahontan Valley around Fallon is filled with sediments washed down from the Sierra Nevada, a range composed mostly of granite.
USGS researchers conducted the earlier well tests as part of a University of Nevada, Reno study investigating a possible link between groundwater contamination and 17 childhood leukemia cases around Fallon since 1997. Health officials say about one leukemia case in five years would be expected.
(Copyright 2008 by The Associated Press. All Rights Reserved.)