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California Proposition 65 adds 4 new carcinogens to its list, totaling 879 substances!
Time：
2026-07-22
The California Proposition 65 list of carcinogens officially includes four substances: hydrochlorothiazide, voriconazole, tacrolimus, and welding fumes, with a total of 879 substances on the list.
On July 17, 2026, the California Office of Environmental Health Hazard Assessment (OEHHA) officially added four substances—hydrochlorothiazide, voriconazole, tacrolimus, and welding fumes—to the Proposition 65 list of carcinogens. Currently, the Proposition 65 list contains a total of 879 substances.
The regulatory process began with the Notice of Intent to List published in the California Regulatory Notice Register on May 8, 2026. The public comment period ran from May 8 to June 8, 2026, during which OEHHA received no comments.
It is worth noting that, apart from "welding fumes" classified as posing a process-generated risk, the other three drug components each have specific CAS numbers corresponding to their chemical structures. These components include hydrochlorothiazide (CAS RN 58-93-5), voriconazole (CAS RN 137234-62-9), and tacrolimus (CAS RN 104987-11-3). However, in the latest official Prop 65 list update, none of these four substances have been assigned specific CAS numbers.
It is not uncommon for substances to be listed on the California 65 List using generic names or broad categories instead of specific CAS numbers. This strict regulatory strategy aims to expand the scope of legal application and prevent companies from evading warning requirements through minor chemical modifications, such as changing the salt or hydration state. This category based listing method has a mature precedent in Proposal No. 65, commonly used for substances such as heavy metals, PFOS/PFNA, and phthalates.
It is recommended that affected entities, including manufacturers, distributors, and retailers involved in the aforementioned chemical products, must review their compliance obligations. According to Proposition 65, businesses are typically required to provide clear and reasonable warnings before knowingly and intentionally exposing Californians to listed chemicals.
As a professional third-party testing and certification service organization, Jiayu Testing has qualifications such as CMA, CNAS, CBTL, CPSC, CCC, etc. It has also obtained laboratory accreditation from multiple authoritative certification agencies at home and abroad. The laboratory is strictly built and managed according to standards, equipped with advanced instruments and equipment, and has a skilled professional technical team with rich industry service experience and strong testing technology capabilities. It is proficient in various regulatory standards. Jiayu Testing provides California 65 testing services to assist enterprises in actively responding to regulatory requirements, helping them achieve hazardous substance risk control, and effectively improve product compliance. Welcome to contact us at 400-9269-886 ！
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