Chromium-6, known as the “Erin Brockovich” chemical, is “likely to be carcinogenic” if consumed in drinking water, an EPA draft review of the metal’s toxicity concludes.
The Environmental Protection Agency on Thursday released its draft Integrated Risk Information System toxicological review of hexavalent chromium, or chromium-6. The draft is open for public comment through Dec. 19 in advance of an EPA Science Advisory Board hearing on the metal.
Hexavalent chromium already had been known to be carcinogenic if inhaled, but the effects of swallowing it previously had been less clear in humans.
Chromium-6 is used in pigment manufacturing, metal finishing and other industrial processes, and is emitted into the air by burning fossil fuels. It can easily contaminate drinking water and “is likely to be carcinogenic to the human GI tract,” the EPA concluded in its review.
The EPA’s current standard is a maximum contaminant level of 100 parts per billion for chromium-6. But the upper limit of lifetime exposure for chromium-6 in drinking water is 0.5 milligrams per kilogram of body weight per day, for a lifetime oral slope factor of 0.5 (per mg/kg-d), the EPA said in the review.
The draft review, once finalized, will be the scientific underpinnings of EPA’s assessment of risks associated with exposure to chromium-6.
The EPA didn’t immediately respond to a request for comment.
The American Chemistry Council, the chemical industry’s trade group, said Thursday it is reviewing the EPA’s draft but says it believes the existing standard for drinking water is safe.
“The draft IRIS assessment is at odds with the findings of over 30 peer-reviewed studies supporting non-mutagenic, threshold mode of action, and we will be engaging with EPA to understand why its assessment is not consistent with the best available science,” the council said in a statement.
But the Environmental Working Group, which advocates against chemical contamination in drinking water, in March found chromium-6 exceeding safe levels in tap water nationwide, affecting 251 million people.
“After reviewing the science in detail, the EPA found that ingestion through drinking water is likely carcinogenic,” EWG scientist David Andrews said. “After a decade of delay caused by the polluters, it is encouraging that EPA is finally moving forward on publishing a safe exposure value for chromium-6.”
The chemical was made famous by Brockovich, who discovered that Pacific Gas and Electric Co. (PG&E Corp.) in the 1950s and 1960s dumped wastewater laced with chromium into ponds that polluted groundwater around Hinkley, Calif. A 2000 movie starring Julia Roberts chronicled the story and a class action lawsuit.
A standard limiting chromium-6 in drinking water was passed by the House in 2021 and included in the INVEST in America Act (H.R. 3684). It was not included in the final infrastructure law passed later that year, however.
Chromium is listed among the critical minerals that qualify for electric vehicle tax credits in the Inflation Reduction Act, which became law this summer.