California’s MCL for Hexavalent Chromium Is Based on a Flawed Process and Outdated Science that Will Undermine State and Local Water Affordability Initiatives

WASHINGTON (April 18, 2024) — Today, the American Chemistry Council, the California Chamber of Commerce, the California League of Food Producers, the California Manufacturers & Technology Association, the Partnership for Sound Science in Environmental Policy, and Western Wood Preservers Institute issued the following statement on the State Water Resources Control Board’s action to adopt a final rule to lower the maximum contaminant level for hexavalent chromium:

“The State Water Resources Control Board’s (SWRCB) maximum contaminant level (MCL) of 10 parts per billion (ppb) for hexavalent chromium was not developed in the manner intended, and required, by the California Safe Drinking Water Act (SDWA). Among the fundamental requirements of the SDWA is that a drinking water standard be adopted through a transparent, multi-step process that starts with a risk assessment based on the best available science, includes external peer review of the scientific portions of the proposed standard, meaningfully engages the public, and results in a drinking water standard that is protective of public health without imposing unnecessary costs on water system operators or rate payers.

“The 10 ppb MCL for hexavalent chromium is based on the public health goal (PHG) adopted by the Office of Environmental Health Hazard Assessment (OEHHA) in 2011, before the publication of a large body of high-quality scientific research designed to better understand how exposure to hexavalent chromium in drinking water can affect the risk of adverse health effects like cancer. The SDWA requires OEHHA to review a PHG at least once every 5 years, and the hexavalent chromium PHG should have been reviewed in 2016 and again in 2021 based on the availability of newly published research. OEHHA started the PHG-update process with a data call-in on October 28, 2016, and issued a second data call-in on March 27, 2023. At that time, and consistent with past practice, the SWRCB should have suspended the MCL-rulemaking process pending completion of the PHG update to allow the SWRCB to fully evaluate the impact of the new PHG on the estimated health benefits, economic feasibility, and affordability of the proposed MCL.

“Instead, less than three months after OEHHA’s announcement that it was reviewing the PHG, the SWRCB released a proposed MCL for hexavalent chromium. The MCL adopted by the SWRCB today is unchanged from that proposal, even though the PHG review process is still ongoing at OEHHA and is not anticipated to be completed until after the SWRCB’s adoption of the MCL.

“In the last 13 years since OEHHA’s public health goal was adopted, over 30 studies have been published in the peer-reviewed literature that investigated not only what levels of hexavalent chromium in drinking water can result in adverse health effects, but also the biological processes by which hexavalent chromium causes those effects. This body of research shows no observed toxicity in rodents exposed to concentrations equivalent to the current U.S. EPA total chromium MCL of 100 ppb and supports the conclusion that the current California total chromium MCL of 50 ppb is health protective. In addition, based on this research, other authoritative bodies, including Health Canada and the World Health Organization, have set health protective drinking water guidelines at 50 ppb total chromium. These standards are designed to protect against exposures to hexavalent chromium.

“Based on the SWRCB analysis for the proposed regulation, setting the MCL for hexavalent chromium at 10 ppb will have significant impacts on affected water providers and rate payers, including making water less affordable in economically disadvantaged communities. The SWRCB estimated in 2021 that it would cost nearly $10.3 billion over a five-year period to implement interim and long-term water quality solutions for systems that are failing or at risk of failing to meet existing MCLs. These costs are in addition to future costs expected to be incurred by public water systems and passed down to rate payers for anticipated MCLs for other contaminants. Given drinking water funding constraints and challenges, the state cannot afford to increase that burden, especially if the best available science indicates that the additional cost will not produce meaningful improvements in public health.”