Experts address N.C. radon hazard

Residents in three Western North Carolina counties who have private wells containing high levels of radon are likely adding radioactive gas to their house when they turn on the shower or sink faucet.

What the added health risks are for those households is still a topic of scientific debate.

Radon, an odorless gas that naturally occurs in soil and rock, primarily seeps into houses from the ground through cracks in the foundation and remains trapped there. Breathing radon over a period of years causes lung cancer and, in fact, is the second leading cause of lung cancer, the surgeon general says.

The issue of added risk posed by radon in groundwater will bring national and state experts to Duke University today.

"During the past decade, a lot of attention has been paid to educating the public about the risks on radon in indoor air spaces, but much less attention has been focused on determining the health risks and so-called 'safe' levels of radon in household water," said Avner Vengosh, an associate professor at Duke University's Nicholas School of the Environment and Earth Sciences.

Nearly one out of every 15 homes in the United States is estimated to have elevated radon levels, the U.S. Environmental Protection Agency says.

The agency recommends that homeowners take steps to reduce radon in their houses if the levels exceed 4 picoCuries per liter of air.

Of 103 private wells tested in Buncombe, Henderson and Transylvania counties last year, 98 percent had levels of radon in well water that exceeded EPA's proposed federal standard, a newly released state study indicated.

Surprisingly, most of the risk to people with well water containing radon comes not from drinking the water but from breathing the gas that rises off the water.

"The risk of ingesting radon-rich water is far lower than risks from inhalation of radon in the air," said Ted Campbell, a hydrogeologist with the Division of Water Quality, who wrote the state's study.

The state is testing wells in four additional western counties this year and plans to do more testing next year to map the extent of radon in groundwater, Campbell said.

The source of the radioactive gas is the underlying granite and gneiss rock, which are rich in uranium. Such types of rock are common in North Carolina's Piedmont and mountains.

People who have radon gas in their wells would primarily be exposed through showers and running water to wash dishes.

Scientists from Duke measured the levels of radon in the air in bathrooms at 18 houses in Western North Carolina that had radon in well water.

"Most of them we found levels that far exceed the 4 picoCuries in the air," Vengosh said. "If it exceeds 4 picoCuries in the air, you should do something about that."