Saccharin
An artificial sweetener which diluted in water is 300-500 times sweeter than the sugar sucrose.
(Saccharin is o-sulfobenzimide; 2,3-dihydro-3-oxobenzisosulfonazole.) The US government removed saccharin from its list of potential cancer-causing agents in 2000 because tests showing it causes tumors in rats proved not to apply to people.