Splenda is used in a variety of products from dessert mixes to syrups. It is also used as a direct sugar substitute, meaning you can use it in place of sugar in coffee and recipes that call for sugar.
The Food and Drug Administration has approved the use of sucralose, brand name Splenda, to be on the consumer market. This safety of the product is based on the review of more than 110 studies involving animals and humans. The FDA looked for carcinogenic, reproductive and neurological effects of usage and found none.
The bottom line is that the FDA has found no cancer causing properties in the usage of Splenda.
The cancer stigma that surrounds artificial sweeteners is believed to stem from the 1970s when lab rats developed bladder cancer during a saccharin trial. Although no case of cancer in a human has been reportedly linked to saccharin, the stigma still remains.
Sources: National Cancer Institute. Artificial Sweeteners Q&A
FDA. FDA APPROVES NEW HIGH-INTENSITY SWEETENER SUCRALOSE