Did you read the section under health concerns citing scientific studies? It's compelling enough that the FDA is taking another look and the companies are trying to do damage control.
Here's more info and you'll see that the companies are trying to reduce the amount of the chemical in their diet sodas:
All the health effects were found in animals at incredibly high doses. California added it to a list, so the soda companies are only changing their formulas to meet CA's regulations, not because of any health effects.
In consideration of tumor occurrence in the NTP rat studies, the NTP concluded that there was equivocal evidence of carcinogenicity in female rats based on the occurrence of mononuclear cell leukemia and no evidence of carcinogenicity in male rats. Section 25703(a)(3) states that “risk analysis shall be based on the most sensitive study deemed to be of sufficient quality.” The NTP studies in male and female rats were not sensitive and thus are not used for the dose response assessment. Thus, while the studies were considered, they were rejected for NSRL development due to lack of sensitivity.http://www.oehha.ca.gov/prop65/law/pdf_zip/100711_4MEIfindin... So California basically ignored some of the evidence.