Overall, the Panel concluded, on the basis of all the evidence currently available from this ERF study and previous evaluations, that there is no indication of any genotoxic or carcinogenic potential of aspartame and that there is no reason to revise the previously established ADI for aspartame of 40 mg/kg bw.
Opinion on a request from the European Commission related to the 2nd ERF carcinogenicity study on aspartame | European Food Safety Authority
Considering results from the large number of studies on aspartame's safety, including five previously conducted negative chronic carcinogenicity studies, a recently reported large epidemiology study with negative associations between the use of aspartame and the occurrence of tumors, and negative findings from a series of three transgenic mouse assays, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food.
FDA Statement on European Aspartame Study
Following these studies, the US National Cancer Institute conducted a study of nearly half a million people, comparing those who consumed drinks containing aspartame with those who did not. Results of the
2006 study (PDF, 87kb) found aspartame did not increase the risk of leukaemia, lymphoma or brain cancer.
The truth about aspartame - Live Well - NHS Choices