Toxics on tap

Chromium-6 in water has cancer risks

There is something in the water. Rather than something with a fin or teeth, this menace is a cancer-causing chemical. But the good news is there are simple things that can be done to avoid it, and efforts are underway to increase its regulation.

The carcinogen—hexavalent chromium, or chromium-6—is found in tap water. Originally believed to be benign, studies in the last 20 years have determined the chemical causes cancer in laboratory animals, especially stomach cancer.

As a result of these findings, in December, the nonprofit Environmental Working Group released a study of chromium-6 in 35 cities in the United States. The study, the first public national survey, found that 31 cities had some levels of chromium-6. Twenty-five cities, including Sacramento, had levels above the state of California Department of Public Health’s suggested limit of 0.02 parts per billion. Sacramento’s level registered 0.16 parts per billion, well above the state’s benchmark.

“We wanted to know [how] high the levels were in tap water,” Rebecca Sutton, an EWG senior scientist and author of the report EWG, said. “We consider this a mandatory first step toward a safety standard for chromium-6.”

The EWG study is also part of broader efforts to regulate chromium-6—a chemical produced in industrial manufacturing (and most famously depicted in the movie Erin Brockovich) that is also found naturally in ore.

For years, chromium-6, a heavy metal, had been lumped in with chromium-3, which is not harmful and a vitamin. Scientists also believed that certain factors, including chlorine in the water and stomach acid, could neutralize the harmful effects of chromium-6.

But 20 years of studies have proved this is not the case, despite some industry pushback (in one case in California, a consulting firm hired by PG&E attempted to distort the findings of a medical study conducted in China).

California, with four cities testing high in the EWG study—particularly San Jose and Riverside—has been at the forefront of efforts to better regulate chromium-6. California’s Department of Public Health, for instance, maintains databases for chromium-6 levels in individual communities. In the Sacramento area, Davis scores high, with 0.22 parts per billion. California is also the only state to require water districts to test for chromium-6, and has also established the public health goal 0.02 ppb. That level was revised at the end of December from 0.06, reflecting the still-fluid level of understanding about how chromium-6 works.

“The change reflects new guidelines that sensitive populations, particularly infants, may be more vulnerable,” Sam Delson, a spokesman for California’s Office of Environmental Health Hazard Assessment, told SN&R. He added that the public health goal is nonbinding, but the first step toward establishing regulatory restrictions and a statewide drinking standard.

The U.S. Environmental Protection Agency is also paying increasing attention to chromium-6. Although the EPA does not require its water districts to test for it, it does classify the chromium-6 as “likely to be carcinogenic to humans when consumed in drinking water.” This is week the federal agency also issued guidelines to help public water districts monitor and evaluate chromium-6.

Sutton shares the EPA’s concerns about ingesting the chemical.

“We have known chromium-6 can be acquired through inhalation,” she said. “But there is a growing body of evidence that chromium-6 can be ingested through water when you drink it, which is why we conducted our study.”

As part of the study, the EWG also said up to 74 million people drink tap water contaminated by chromium-6.

Still, Sutton says people can help reduce their exposure by simply visiting a store.

“We are exposed to a lot of chemicals in our water, and the best suggestion is to apply a reverse-osmosis filter to your water faucet,” Sutton said. “I also don’t recommend bottled water, because it may be from the tap.”