Welding Fumes and Three Medications Listed as Carcinogens Under Prop 65, With Warning Requirements Effective July 17, 2027

Effective July 17, 2026, OEHHA listed the following four chemicals under Prop 65 for the cancer end point:

• Welding fumes
• Hydrochlorothiazide (a synthetic chemical used to treat hypertension)
• Voriconazole (a synthetic chemical used to treat serious fungal infections)
• Tacrolimus (an immunosuppressant produced by fermentation and mainly used after transplants to reduce the risk of organ rejection)

These chemicals were listed pursuant to the Labor Code mechanism. As provided by Prop 65, the warning provision for these chemicals will not take effect until one year after listing, on July 17, 2027.

Further information on the listing of welding fumes is available here, and further information on the listing of hydrochlorothiazide, voriconazole, and tacrolimus is available here.