[Article first published at New West]
Naturally occurring uranium and the radioactive products it forms as it breaks down over time cannot be seen, tasted, or smelled in water. This lesson hit home for some residents in southwest Montana recently, when laboratory testing showed their well water contained high concentrations of radioactive material.
In the first week of May the U.S. Geological Survey released the preliminary results of an analysis of 128 residential wells in seven counties in southwest Montana. The USGS sampled 40 of the wells in a 2007 study and tested the other 88 wells from November 2009 through September 2010. USGS scientists found concentrations of radioactive contaminants at levels greater than the Environmental Protection Agency’s safe drinking water standards in 29 percent of the wells. The water from each well had some level of radioactive material in it.
In response to the USGS study, Megan Bullock, sanitarian at the Environmental Health Department in Jefferson County, Montana, tested some reverse osmosis systems to see how effective they were at removing certain radionuclides. She hoped to better inform residents about filter systems to treat contaminated well water.
Bullock tested nine point-of-use systems, which attach to individual faucets or are installed beneath the sink, and can be bought from local home improvement stores or water treatment companies. The filter systems cost between $147 and $1,000. Bullock also tested a $3,000 whole-house system that treats water as it enters the home.
Most of the filter systems removed uranium, radium and gross alpha and beta particles (the radiation emitted at various stages during the uranium decay process) to below detectable levels, Bullock explained. The systems that didn’t remove the radioactive constituents to non-detectable limits reduced the levels to below the EPA’s drinking water standards, she said.
“We were basically just checking to see if a person could go to a home improvement store and buy one off the shelf and do a point-of-use application on their kitchen faucet,” said Bullock.
“The intent was to show people that they could go purchase a system for a couple hundred dollars and it was effective: it would do what they were wanting it to do,” she said.
Bullock’s study did not analyze the removal of radon, a radioactive gas that is a by-product of uranium decay, since the point-of-use devices she tested are not sufficient to curb radon contamination. In her report, Bullock recommends that people with high indoor radon levels should consider whole house, point-of-entry devices to remove radon from all water that enters the house.
Potential Health Effects
Some people who drink water that contains radionuclides in excess of the EPA’s maximum contamination levels over a lifetime may have an increased risk of cancer, according to the EPA. Because it is also a toxic heavy metal, uranium in drinking water may cause damage to the kidneys.
The way the EPA calculates the risk level for uranium consumption means that if 10,000 people drank two liters of water containing uranium at the EPA’s maximum contamination level each day for 70 years, about one of those people might be at risk of getting fatal cancer. This risk factor could be compared to the general risk of contracting cancer. American men have slightly less than a one in two chance of developing cancer in their lifetime, while for women the risk is a little more than one in three, according to the American Cancer Society.
Uranium Rich Rocks Increase Background Levels
It is not unusual to find uranium in groundwater, since uranium occurs at low levels in virtually all rock, soil, and water, according to the EPA. Likewise, radon exists in almost all rock and all soil and water. However, the Boulder batholith, a 2,300 square mile chunk of igneous rock that lies in Jefferson County and reaches into Silverbow, Lewis and Clark, and Powell counties, is known to have uranium deposits in some areas.
Fifty-eight of the wells draw their water from rocks that form part of the batholith.Thirty-eight of these wells had levels of radioactive constituents in excess of the drinking water standards, according to the USGS. However, the batholith did not account for all the contamination. Eleven of the 70 wells outside the batholith region had levels of radioactive material higher than at least one of the EPA’s drinking water standards.
The concentration of radioactive constituents in groundwater depends on how the water flows through fissures in underground rock and whether it comes into contact with zones that have elevated uranium minerals, said Rod Caldwell, a USGS scientist.
“It’s highly variable. We had wells side by side that one may have been above a drinking water standard and the next door neighbor may have been below,” he said.
Since private wells are unregulated it’s up to individuals to have their drinking water tested, Caldwell said. He recommended sampling a few times, at different times in the year, to ensure that contaminant levels don’t vary over time.
The Montana Department of Public Health and Human Services Environmental Laboratory does drinking water analyses. A list of certified private laboratories is available through the University of Montana.
While the reverse osmosis systems Bullock tested are effective at removing radionuclides, her report recommends that users test their treated water periodically to make sure the systems are working properly.
Reverse Osmosis Systems Tested in the Study
Bullock recommends NSF-approved treatment systems, but stressed she is not endorsing any of the brands tested.
GE Profile PXRQ15F, $279
Ideal Choice RO3500, $270
Whirlpool WHER25, $147
Challenger Conqueror, $672 (installation included)
Kinetico 2040S OD, $1,000
Watts Premier ZRO-4, $530
Challenger Conqueror 4, $400
Vitasalus Whole House Oxidation-Filtration System, $3,000 (installation included).