The historical bladder-cancer concern came from high-dose (>=3% of diet) studies in rats, where tumors arise via a rat-specific mechanism (urinary pH, osmolality and silicate microcrystal formation damaging the urothelium) that does not occur in humans. Human epidemiology has found no clear association with bladder cancer, leading the U.S. NTP to delist saccharin (2000) and IARC to assign Group 3 (not classifiable as to carcinogenicity). EFSA's 2024 review concluded saccharin does not cause DNA damage and that consumption is unlikely to be associated with cancer. Residual debate centers on metabolic signals: the Suez 2014 Nature study reported saccharin-driven glucose intolerance via gut-microbiota changes in mice and a small human subset, though a later controlled human/mouse study (Serrano 2021) found no such effect at supraphysiologic doses — so this signal remains unresolved. WHO (2023) advises against using non-sugar sweeteners for weight control, as they confer no long-term benefit for body-fat reduction (a recommendation that does not apply to people with pre-existing diabetes). No specific subgroup is required to avoid saccharin at normal intakes. Educational only — always check with your doctor or pharmacist before combining Saccharin with any medicine.