California Needs a Stricter Limit for Hexavalent Chromium In Drinking Water

Gina-Marie Cheeseman

A naturally occurring element also used for industrial processes, Hexavalent chromium is considered carcinogenic and much too prevalent in California's drinking water.

Not all of the drinking water in the golden state is all that golden. Hexavalent chromium (chrome-6) is in the drinking water in many parts of California. A naturally occurring element, chrome-6 is also associated with industrial sites because it is widely used in chrome plating, paints and dyes, leather tanning, and as a corrosion inhibitor. The U.S. is one of the leading producers of chromium compounds in the world.Chrome-6 is a known carcinogen when inhaled. Workers can be exposed to high levels of chrome-6 who work in industries that use or process chromium compounds. Chrome-6 can cause nasal and sinus cancer, kidney and liver damage, eye irritation and damage and nasal and skin irritation and ulceration. Exposure to chrome-6 through inhalation affects a small part of the population since it mainly occurs through occupational exposures.

But what happens when chrome-6 is ingested? It is designated by the California Environmental Protection Agency as a potential oral carcinogen. The National Toxicology Program (NTP) conducted a two-year study that found that chrome-6 to be carcinogenic in rats and mice. A study in the Oinofita region of Greece, where drinking is contaminated with chrome-6, found an elevated cancer mortality rate which “supports the hypothesis of hexavalent chromium carcinogenicity via the oral ingestion pathway of exposure.”

The prevalence of chrome-6 in California drinking water

Chrome-6 from industrial sources has been found in groundwater in California, including in alluvial aquifers in the Los Angeles metropolitan area. However, industrial sources are not the only source of chrome-6 contamination in drinking water. Chrome-3 is another naturally occurring chromium compound that can be oxidized to chrome-6 when certain geochemical conditions happen. Two areas where this occurs is the west side of the Central Valley and the Coastal Ranges. A 2018 study of California groundwater found that naturally occurring sources of chrome-6 affect more areas and a larger population than industrial sources. Although the highest concentrations of chrome-6 in any one well are from industrial sources, more wells are contaminated from naturally occurring chrome-6. “As we continue to push the need to use and manage groundwater, understanding how these naturally occurring contaminants can jeopardize water becomes really, really important,” said co-author of the study Scott Fendorf.

A stricter limit in the state for chrome-6 in drinking water was tossed out in 2017 after a judge ruled the limit, set in 2014, invalid because the California Department of Health “failed to properly consider the economic feasibility of complying with the maximum contaminant level was economically feasible.”

What you can do

The State Water Resources Control Board plans to reestablish a drinking water standard for chrome-6. However, that has been delayed by Governor Gavin Newsom who has yet to approve the release of a white paper about how the Board performs economic analyses of drinking water standards. Send a message to Governor Newsom by signing a petition urging him to take action to protect the drinking water of California communities.

Regardless of how chrome-6 contaminated groundwater, there needs to be a stricter limit. Californians deserve to have safe drinking water, which is not a privilege but a basic human right. The UN General Assembly acknowledged clean drinking water is essential to the realization of all human rights

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