Diet soft drink
The first artificial sweeteners used in diet soda were cyclamates (often synergistically with saccharin).  While many say these cyclamate-sweetened soda had a better taste than the diet soda that came after them, in 1970 the Food and Drug Administration banned cyclamates in the United States because there was proof that they caused cancer in lab rats.  Cyclamates are still used in many countries around the world, including for diet soda.