Smaller Water Firms Periled by Limits on Radon

Nearly 60 water systems in California serving at least 56,000 customers could be forced to shut down, at least temporarily, if the U.S. Environmental Protection Agency adopts stringent new limits on radon concentrations in drinking water, state health officials said Monday.

The proposed standard, which could take effect in three years, is expected to mainly affect smaller water systems that draw from wells dug in radon-bearing granite rock like that found in communities located in the mountains and foothills, or in areas where geological faulting provides a pathway for radon to enter the underground drinking water aquifers.

Larger systems in highly populated areas like Los Angeles, which get their water from surface supplies like rivers and aqueducts, or from local wells, probably would not be affected since high radon concentrations from these sources are unlikely.

Radon is a naturally occurring radioactive gas that is estimated to cause 13,000 lung cancer deaths each year, second only to smoking. As radon gas decays, it throws off atoms of heavy metals called alpha particles or radon daughters. The radon daughters attach to smoke and dust particles that are inhaled and lodge in the lungs where they emit cell-damaging radiation.

The biggest threat from radon is from soil gas that seeps into houses through cracks and other openings. A small percentage of the radon threat, however, can be attributed to drinking water.

While drinking such water is not in itself believed to pose a serious health problem, there is a health risk when the gas, which is water soluble, escapes from the water into the air during washing, bathing and flushing of toilets. For that reason, the EPA is considering limiting radon in water to between 200 and 2,000 picocuries per liter. A picocurie is a standard unit of radiation measurement.

By comparison, radon in most water in Southern California is believed to be 400 to 500 picocuries. By contrast, a well serving the Bodfish Water Co. in eastern Fresno County had radon concentrations of 40,000 picocuries. Customers of the small system were informed several years ago.

Several state health officials on Monday questioned the need for such a strict standard and warned it would pose financial problems for smaller water companies while offering minimal health protection.

“If they (EPA) proceed with 2,000 picocuries or less, then there are some real potential problems in the state,” said David Spath of the state Department of Health Service’s public water supply branch. Water systems are divided into two categories--those with fewer than 200 connections and those with more than 200 connections.

He said the smaller companies within the large company category would be hit hardest. “And we don’t even know what the smaller system (with less than 200 connections) problem is,” he said.

Steven Hayward of the Health Service Department’s Air and Industrial Hygiene Laboratory said the proposed federal drinking water standard would be far stricter than the EPA’s own recommended limits for radon in air.

Comparison Made

Hayward said an EPA drinking water standard of 200 picocuries would be like an air standard of .02 picocuries. That is because 1 picocurie of radon in the air is estimated to have the same health impact as 10,000 picocuries of radon in water since not all the radon dissolved in water is liberated or becomes airborne when the tap is turned on. Moreover, while indoor air is breathed all the time, water is not always in use. The EPA’s recommended indoor air limit is 4 picocuries per liter, which is equivalent to 40,000 picocuries in water.

But, Joseph Cotruvo, director of the EPA’s drinking water standards office, said Monday that a tougher radon standard for water is mandated by the federal Safe Drinking Water Act, which requires contaminants to be reduced to levels that are “technologically and economically feasible.” He said there is no doubt that it is technically possible to reduce radon to levels in water through aeration or activated carbon filters far below levels that are tolerated in the air.

And, he said that while such radon levels would be far lower than those allowed in indoor air, radon in water still poses a more serious health threat than toxic chemicals.

Cotruvo noted, however, that communities of less than 1,500 could seek two-year exemptions from complying with whatever the new standard is if they meet certain conditions. The new regulation is expected to take effect sometime in 1992.