Even Minute Levels of Arsenic Could Cause Cancer, Study Says

New evidence suggests that arsenic in drinking water could be more hazardous than earlier thought--a finding that could shape new standards for drinking water in California and nationwide.

Even minute amounts of arsenic in drinking water could lead to higher rates of lung and bladder cancer than initial research showed, according to a study released this week by the National Academy of Sciences.

The study provides new ammunition for those opposed to the controversial Bush administration decision in March to delay a more stringent drinking water standard for arsenic, pending further study. Since then, administration officials have tried to find a way out of the public relations disaster caused by that announcement.

The new report “absolutely raised more concern” when U.S. Environmental Protection Agency chief Christine Todd Whitman was briefed on it this week, a spokesman said.

The findings could have an effect in California and other arid Western states where high concentrations of arsenic occur naturally in some ground water.

“They’re certainly of great interest to us,” said Allan Hirsch, spokesman for the state Office of Environmental Health Hazard Assessment, part of the California Environmental Protection Agency. California is conducting its risk assessment of arsenic and could set a tougher standard for drinking water than that of the federal government.

The study released this week found that people consuming water daily with 3 parts per billion of arsenic have an increased risk of developing bladder or lung cancer. Specifically, 1 in 1,000 such people could be expected to develop one of those cancers in their lifetime because of the arsenic.

The added lifetime risk at 10 parts per billion--the level in the Clinton rule--is greater than 3 in 1,000 people, the study states. It also notes that some studies overseas have linked arsenic exposure to diabetes, respiratory and cardiovascular problems and birth defects. The committee conducting the study recommends more research on arsenic’s potential ties to illnesses other than cancer.

Federal EPA standards seek to limit increased lifetime cancer risk to 1 in at least 10,000 people.

California and federal regulations allow arsenic at no more than 50 parts per billion in tap water. After a 1999 National Academy study, the EPA proposed tightening that level to 5 parts per billion, later changing the level to 10 parts per billion, the level adopted by the Clinton administration in its final days.

That level provoked sharp criticism from several Western states, utilities and the mining industry, which questioned the science used by the EPA and cited the high costs of compliance.

So Whitman rescinded the Clinton rule in March, infuriating environmentalists and some scientists.

After the March announcement of the delay, the EPA asked the National Academy’s National Research Council to independently review the most recent findings about arsenic risk. The EPA asked for an evaluation of the cancer risk of consuming water daily with arsenic levels of 3, 5, 10 and 20 parts per billion.

One environmental group, the Natural Resources Defense Council, said the study illustrates the fallacy of the Bush administration postponing the Clinton era standard.

“The National Academy made it very clear that the scientific consensus is that low levels . . . present very high cancer risks,” Erik D. Olson, senior attorney with the council. His group believes the standard should be set at 3 parts per billion.

In California, arsenic levels in ground water used for drinking vary widely, and that water is treated to the 50-parts-per-billion standard, said David P. Spath, chief of the division of drinking water and environmental management for the state Department of Health Services.

Ground water in the Central Valley, for instance, can have arsenic levels of 20, 30 or 50 parts per billion. Some wells in arid areas in San Bernardino and Riverside counties have levels above 100 parts per billion before treatment, state figures show.

If a 10-parts-per-billion level were adopted statewide, about 500 water companies would have to treat water more stringently. If a 3-parts level were chosen, 40% to 50% of the water companies could be affected statewide. Many of those water systems are quite small, said Spath, chairman of the National Drinking Water Advisory Council.

“We’re probably talking about a couple of thousand companies,” he said. “As a result, the cost would be borne by a small number of people, and they would generally be very high.”