On 17 July 2026, the California Office of Environmental Health Hazard Assessment (OEHHA) added four new carcinogenic substances to the California Proposition 65 list. The newly listed substances are: Welding Fumes Hydrochlorothiazide Voriconazole Tacrolimus The addition of these substances requires manufacturers, importers, distributors, and retailers to review their products and supply chains to determine whether products sold in California may expose consumers or workers to these listed chemicals. Where exposures exceed the applicable safe harbor levels (or where no safe harbor level exists and exposures require assessment), businesses may be required to provide Proposition 65 warnings.