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

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.