LOS ANGELES — California regulators voted Wednesday to establish a drinking water limit on hexavalent chromium, a toxic chemical compound made infamous by the movie “Erin Brockovich.”

The rule is the first in the nation to specifically target the heavy metal, known as chromium-6, and is expected to reduce the number of cancer and kidney disease cases from long-term ingestion, state officials say.

The proposal was unanimously passed by the State Water Resources Control Board, though it needs approval from the Office of Administrative Law to take effect.

The standard could inspire other states to adopt their own. More than 200 million Americans are estimated to have the chemical compound in their drinking water, according to an analysis of federal water testing data by the Environmental Working Group, a nonprofit research and advocacy organization.

Until now, California combined its drinking water standard for chromium-6 with the less toxic trivalent chromium, an essential nutrient. California’s new limit on chromium-6 is 10 parts per billion — about 10 drops of water in a swimming pool.

“I know there’s mixed feelings about this decision today… that we should be at a lower standard,” board member Sean Maguire said before the vote. “But I do want to take a step back and look at California as compared to the rest of the nation, and I think here we are actually leading the way.”

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Public Health Concerns

Community members and health advocates worry California’s limit doesn’t do enough to protect public health from the metal. They want the state to adopt a drinking water limit closer to the public health goal of 0.02 parts per billion, the level scientists have said does not pose significant health risks.

“This really leaves a lot of California communities unprotected from that really potent carcinogen,” said Tasha Stoiber, senior scientist with the Environmental Working Group.

The board is required by law to set a limit as close to the public health goal as is economically and technologically feasible.

Some public water providers warned that with the new standard customers will pay more for water and the financial burden will disproportionately fall on disadvantaged communities. And some chemical industry groups have said the limit is not based on the most recent science.

The new limit will cost public water systems $483,446 to $172.6 million annually to monitor and treat water exceeding the standard, according to state water board estimates.

Cástulo Estrada, board vice president of the Coachella Valley Water District and utilities manager for Coachella city, said the limit would have “unprecedented” impacts on residents and customers. He said all six of the city of Coachella’s wells have chromium-6 above 10 parts per billion and that installing technology to lower levels to the limit would cost an estimated $90 million. “That would increase monthly bills.”

Ana Maria Perez, a Monterey County resident, urged the board to set a lower limit that would protect communities with chronic water contamination. “We have been waiting for a chromium-6 limit that protects our health,” she said in Spanish. “It’s not fair that many people must get sick.”

Testing and Compliance

Water providers will need to start testing for chromium-6, which is naturally occurring and produced in industrial processes, within six months of the effective date, anticipated in October. If water tests above the limit, they will need to submit a compliance plan within 90 days and comply within two to four years, depending on how many customers are served.

Chromium is naturally occurring in soil, plants, animals, rocks and more, and can leach from soil into groundwater. It comes in various forms, including chromium-6, and is used in electroplating, stainless steel production, leather tanning, textile manufacturing and wood preservation, which all can contribute to drinking water contamination, according to the California Office of Environmental Health Hazard Assessment.

While scientists have known for decades that inhaling chromium-6 can cause lung cancer, it was uncertain for a long time whether ingestion could cause cancer, too.

Studies by the National Toxicology Program changed that. Rodents that drank water with high levels of chromium–6 over two years developed intestinal and oral cancer, results showed.

Some researchers have criticized the studies, saying the chemical concentrations the rodents were given were thousands of times higher than what U.S. drinking water supplies would have.

The California environmental health hazard agency is updating its public health goal for hexavalent chromium, which was finalized in 2011 at 0.02 parts per billion. At that level, the lifetime risk for cancer is one-in-one-million, an amount generally accepted by health experts.

Some health advocates urged the board to wait to establish a limit until an updated public health goal is released. But some environmental justice nonprofits that favor a lower limit said the board should not wait longer.

With California’s new limit, the risk of cancer is 500 times greater than the public health goal. One person out of 2,000 exposed for 70 years to drinking water with 10 parts per billion of chromium-6 may experience cancer, according to a state water staff report.

Studies on the health impacts of ingesting chromium-6 through drinking water are limited, said Maria-Nefeli Georgaki, an environmental health specialist who has studied the health effects of ingesting chromium-6. But, she added, a maximum of 10 parts per billion is an important start that should then be “adjusted according to both the public health issues that arise, and the new research data, at specific regular intervals.”

Water staff must review standards every five years. But during Wednesday’s meeting, Darrin Polhemus, deputy director for the water board’s drinking water division, said they are constantly reviewing standards.

In 2014, the state adopted a limit of 10 parts per billion but it was overturned in 2017 for failing to consider whether the rule would be economically feasible.

The standard is the latest chapter in a decades-long fight to regulate the chemical that gained notoriety with the 2000 movie “Erin Brockovich,” which won Julia Roberts the Best Actress Oscar. In the 1990s, Brockovich helped investigate groundwater contaminated with chromium-6 that was sickening a Southern California community. Residents eventually won a $333 million settlement with Pacific Gas & Electric Co. for contaminating their water.