Study finds probable carcinogen in tap water of 31 U.S. cities

By Lyndsey Layton
Washington Post Staff Writer
Monday, December 20, 2010; 7:47 PM

A new analysis showing the presence of a probable carcinogen in the tap water of 31 cities across the country has raised questions about possible risks posed to consumers in those communities and how they can reduce their exposure.

The chemical, hexavalent chromium, got public attention in the 2000 film "Erin Brockovich" and has been found to cause cancer in laboratory animals by the National Toxicology Program, part of the National Institutes of Health.

Although basic water filters such as those made by Brita and PUR do not remove hexavalent chromium, several reverse-osmosis systems designed for home use can take the chemical out of water. Such systems are available for purchase online and at hardware stores.

Bottled water is not necessarily an alternative because it is often drawn from municipal water systems and can still contain hexavalent chromium or other contaminants.

The analysis, released Monday by the Environmental Working Group, is the first nationwide look at hexavalent chromium in drinking water to be made public. The advocacy group sampled tap water from 35 cities and detected hexavalent chromium in 31 of those communities. Of those, 25 had levels that were higher than a health goal proposed last year by the state of California.

Locally, Bethesda and Washington had levels of .19 parts per billion, more than three times the California goal.

The federal government has not set a limit for hexavalent chromium in drinking water but is reexamining the chemical to decide whether it should impose such restrictions.

"This definitely raises the issue about a national drinking water standard for hexavalent chromium and why we don't have one," said Lynn Goldman, an epidemiologist and former top official at the Environmental Protection Agency who now serves as dean of the School of Public Health at George Washington University.

Goldman said the new study demands deeper investigation. "This is the very first signal that there might be a problem," she said. "But it's premature to say we know really what the level (of contamination) is, whether it's there all the time or just intermittently and what the source is."

Illinois senators Richard Durbin (D) and Mark Kirk (R) planned to meet Tuesday with EPA Administrator Lisa Jackson to discuss the report, which found hexavalent chromium in Chicago drinking water at about the same levels as in Bethesda and Washington.

Last year, California released a draft of a "public health goal" for a safe level of hexavalent chromium in drinking water: 0.06 parts per billion. If the state sets a limit, it would be the first in the nation.

Hexavalent chromium was a commonly used industrial chemical until the early 1990s. It is still used in some industries, such as chrome plating and the manufacturing of plastics and dyes. The chemical can also leach into groundwater from natural ores.

It has long been known that hexavalent chromium causes cancer in humans if it is inhaled. But in the past several years, researchers have found it causes cancer in animals when it is ingested.

In 2007, the National Toxicology Program documented significant increases in tumors in rats and mice in the oral cavity and small intestine, places where cancer is rarely seen in laboratory animals.

Public awareness about the possible health effects of hexavalent chromium was heightened when residents of Hinkley, Calif., accused Pacific Gas & Electric of leaking the chemical into groundwater for more than 30 years. The company paid $333 million in damages in 1996 and pledged to clean up the contamination. The case was the basis for the movie "Erin Brockovich," which starred Julia Roberts.

But a recent California study found that cancer levels in Hinkley are not elevated. The California Cancer Registry's third study on the town, released this month, found that cancer rates remained unremarkable from 1988 to 2008.

"People have been left with the impression from lawsuits and the movie that there is an excess of cancer in the community, but there is not," said John W. Morgan, the epidemiologist conducting the cancer studies.

Still, Morgan said, no one should draw a conclusion from the Hinkley studies that hexavalent chromium poses no health risk. "That's not a question that our data can answer," he said.

Other experts, including Goldman, say because Hinkley's population is so small and exposure among residents to hexavalent chromium so varied, it is not unusual that Hinkley's cancer rate is comparable to other California towns.

The American Chemistry Council, which represents the chemical industry, says the California goal is unrealistic because some water supplies have naturally occurring hexavalent chromium that is higher than .06 parts per billion.

In a written statement, the group's senior director, Ann Mason, said that "even the most sophisticated analytical methods used by EPA are not able to detect the extremely low levels that California wants to establish."

In her statement, she said that "given that hexavalent chromium exists naturally in groundwater, it is not surprising that it was found in 31 of the 35 sites selectively targeted, which had previously reported the existence of chromium."

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