Erin Brockovich may have made this cancer-causing chemical famous, but data from nationwide tests show it’s still in our water — and at potentially dangerous levels. The US Environmental Protection Agency should have enforced stricter standards on the chemical years ago, advocates say.

The chemical, called chromium-6 or hexavalent chromium, was featured in the movie Erin Brockovich, in which Julia Roberts plays an activist leading a lawsuit against Pacific Gas & Electric for contaminating water with it. Chromium-6 can be produced from industrial activities like producing stainless steel or manufacturing textiles.

The EPA still has no guideline for chromium-6 specifically

Today’s report, published by the Environmental Working Group, analyzes data from 60,000 water samples collected by the EPA itself. It concludes that 218 million people are drinking tap water at levels higher than those recommended by some scientists. The highest concentrations were in Phoenix, St. Louis County, and Houston. And, over time, this could lead to 12,000 additional cases of cancer, the group claims.

In 2008, the National Toxicology Program confirmed that chromium-6 causes cancerous tumors in mice, and the chemical is included in the 13th Report on Carcinogens. Despite this, the EPA only has a single guideline for total chromium that combines chromium-6 and a safe version called chromium-3, according to David Andrews, a senior scientist with the Environmental Working Group.

At the state level, California has the strictest safety recommendation for chromium-6. Its “public health goal” of 0.02 parts per billion is based off the 2008 study, according to Elaine Khan, a senior toxicologist at California’s Office of Environmental Health Hazard Assessment.

This is the baseline that the EWG report uses for water to be considered “safe”; the 218 million number is the number of people across the country who are drinking water above that level. (California’s public health goal is now due for a required five-year update. The team is going through new research to see if there’s anything significant enough to warrant an adjustment.)

To understand the true risk, let’s look at the numbers: at California’s recommended level of chromium-6, one out of 1 million people is likely to get cancer after drinking that water for 70 years. But this is not legally enforced, says Sam Delson, deputy director for external and legislative affairs for OEHHA. “We consider only health in making these goals and other organizations have to factor in feasibility, which includes cost prohibitions,” he added.

In fact, California’s legal standard — which isn’t strict enough, the EWG argues — is 10 parts per billion. At this level, about 500 people out of a million will get cancer if they drink the water for 70 years. The EPA’s legal standard for total chromium is looser still. The federal number is 100 parts per billion. This applies whether it’s 90 parts of dangerous chromium-6 and 10 parts of safe chromium-3, or 10 parts of chromium-6 and 90 parts of chromium-3.

Fewer than 2 percent of the water systems reported chromium-6 levels higher than California’s legal limit, the EPA said in a statement. The agency added that ensuring safe drinking water “is a top priority” and that it is working on a risk assessment of chromium-6 specifically. It hopes to release a draft for public comment next year.

That risk report would have been released years ago if it weren’t for pressures from the chemical industry, according to EWG managing editor Bill Walker. According to Walker, the EPA was taking steps to regulate the chemical after the 2008 report. But then, the American Chemistry Council objected to the NTP study and instead funded outside studies by a consulting firm named ToxStrategies.

This raises a red flag about public drinking water

The ACC argued in a statement that chromium-6 is found “at low levels” that are not only below the EPA’s legal guideline but can be attributed to “geologic formations, such as rocks.” Accordingly, the group hired an outside organization “because of the limited scientific data available” to show how low environmental levels of chromium could impact human health. (ToxStrategies could not be reached for comment.)

Some reports suggest that higher chromium-6 limits are okay because our stomachs process some chromium-6 into its harmless cousin, chromium-3. More research needs to be done, but Khan notes that the amount left over could still be enough to cause cancer. She added that since stomach acidity affects how much chromium-6 can be converted, people with lower acidity — like newborns or those taking gastric reflux medications — would be especially vulnerable to higher limits.

In the meanwhile, there are ways to remove chromium-6 from water. This can be done with special filters out of water at home, or it can be done at the water utilities site. Still, says Andrews, the EWG senior scientist, this is an issue that requires a national drinking water standard and further investigation. “This raises a red flag in terms of questioning how adequate are our public drinking water,“ he added.

Correction: People with lower stomach acidity would be especially vulnerable to higher chromium-6 limits. An earlier version of this post stated that people with higher acidity would be especially vulnerable.