On July 17, 2026, the Office of Environmental Health Hazard Assessment (OEHHA), under the California Environmental Protection Agency (CalEPA), issued a notice adding four substances—hydrochlorothiazide, voriconazole, tacrolimus, and welding fumes—to the list of carcinogens under the Safe Drinking Water and Toxic Enforcement Act of 1986, commonly known as Proposition 65.

Under Proposition 65, any business operating in California must provide a clear and reasonable warning if its products, premises, or emissions contain a listed chemical and the exposure level exceeds the safe harbor threshold, informing consumers or workers that the substance is known to cause cancer or reproductive harm. The warning requirement takes effect one year after the chemical is added to the list.

Furthermore, the Act strictly prohibits any business from knowingly and intentionally discharging listed chemicals into sources of drinking water during operations within California. Upon a chemical's listing, businesses have twenty months to implement discharge control measures to ensure full compliance with this prohibition.

4 substances were added to the U.S. California The Proposition 65 List

Recently, the California Office of Environmental Health Hazard Assessment (OEHHA) announced the addition of N-methyl-N-formylhydrazine to the Proposition 65 list as a carcinogen. On the same day, OEHHA also announced that it is adding the developmental toxicity endpoint to the listing for bisphenol S (BPS). Both amendments took effect on December 8, 2025.

California’s Proposition 65, officially known as the Safe Drinking Water and Toxic Enforcement Act of 1986, was enacted through a ballot initiative in November 1986. The law is designed to protect the state’s drinking water sources from contamination by chemicals known to cause cancer, birth defects, or other reproductive harm, and it requires businesses to inform Californians about exposures to such chemicals.

2 substances were added to the U.S. California The Proposition 65 List

The latest version of Proposition 65 List in California is available.

Bisphenol S (CAS no.80-09-1) was added to the Proposition 65 List in California.

Bisphenol S (CAS no.80-09-1) was added to the Proposition 65 List in California

The latest version of Proposition 65 List in California is available

3 substances were added to the Proposition 65 List in California.

3 substances were added to the Proposition 65 List in California

1,1,1-Trichloroethane (CAS no.71-55-6) and leucomalachite green (CAS no.129-73-7) were added to the Proposition 65 List in California (as of April 25, 2023)

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