Radon Levels in 2 Wells Not ‘Astounding’

Radon, a colorless, odorless gas considered to be the second-greatest cause of lung cancer, has been found at two ground-water wells in San Diego County, but the levels are not “astounding,” a U.S. Environmental Protection Agency official said.

The naturally occurring gas is released when uranium ore in the ground decays. When the ore is below a water table, the gas percolates through rock and dissolves in the water, then escapes when a faucet is opened. If a home is airtight, the gas accumulates, and particles of radon can become lodged in the lungs.

It is prolonged exposure to radon that causes lung cancer, said Greg Helmes, an environmental specialist for the EPA.

In a six-month study, the Metropolitan Water District of Southern California tested 200 wells in Los Angeles, San Bernardino, Ventura, Orange and San Diego counties. Although the district supplies only surface water to its member agencies, the study was done on their behalf, said Jennifer Smith, a spokeswoman for the district. There are about 60 wells within the district’s boundaries in San Diego County, she said, adding that most of the water drawn from the wells is used for irrigation.

Maximum contamination levels have not been set by the EPA, but they are expected to be by the end of this year or early next year, Helmes said.

He said the maximum level of radiation could be set as low as 200 picocuries per liter, or as high as 2,000 picocuries. (Radiation is measured in curies, or the amount of material undergoing radioactive decay in one second. A picocurie is one-trillionth of a curie.) One of the two wells tested is managed by the city of San Diego and is near Lakeside between the El Cajon and El Monte-Santee basins. It averaged 215 picocuries per liter. The other is in the Helix water district near the San Pasqual Basin in northeastern San Diego County and averaged 298 picocuries per liter.

The risk of getting lung cancer after a lifetime of exposure at levels between 200 and 500 picocuries per liter is one in 10,000, Helmes said.

The levels found in San Diego County are “not astounding. I mean, it’s not something to make you run out of the house or anything,” he said.

Radon ranks second only to smoking as a cause of lung cancer. It largely dissipates when it comes in contact with air.