[A stable, colorless, combustible liquid that emits toxic fumes of sulfoxide when heated to decomposition. Methyl methanesulfonate is used for laboratory purposes as a catalyst in chemical synthesis and has been tested clinically as a cancer chemotherapeutic agent. This substance is an alkylating agent and acts as a mutagen by altering and damaging DNA and is reasonably anticipated to be a human carcinogen. (NCI05) ( NCI )] (UMLS (NCI) C0025706) =Organic Chemical; Pharmacologic Substance; Hazardous or Poisonous Substance