This is a brilliant source of information from the European Food Safety Authority on aspartame, dated this year (they're currently re-evaluating all food additives):
http://www.efsa.europa.eu/en/faqs/faqaspartame.htmA specific point that I've taken from here is this:
"
19. What are the Panel’s conclusions regarding specific safety concerns?The Panel’s draft conclusions in relation to potential safety concerns in humans are as follows:
- Studies do not suggest an increased risk associated with aspartame consumption for pre-term delivery in pregnant women, leukaemia, brain tumours or a variety of cancers, including brain, lymphatic and haematopoietic (blood) cancers.
- The weight of evidence suggests that aspartame ingestion has no effect on behaviour or cognitive function.
- There is no evidence that consuming aspartame causes seizures.
- There is no convincing evidence that consuming aspartame causes headaches.
- The weight of evidence shows that aspartame is not associated with allergic type reactions.
- In addition, available data do not indicate a genotoxic concern for aspartame (i.e. it does not affect DNA, the genetic material of cells)."
Also:
to reach the ADI for aspartame (40 mg/kg body weight), an adult weighing 60kg would have to drink 12 (330ml) cans of a diet soft drink (containing aspartame at the maximum permitted levels of use), every day for the rest of his/her life. However, in reality, aspartame is used at lower levels and amounts found in soft drinks can be 3 to 6 times less than the maximum permitted levels; this would increase the number of cans required to meet the ADI to 36 or more.
Of course, it's up to you make up your own mind, but their findings are quite convincing and take into account a lot of external studies, theories and supporting information.
I personally enjoy many sugar-free drinks ranging from Coke to the no-added-sugar supermarket drinks and squashes. I also ensure I'm drinking less than 12 cans' worth per day (just to be on the safe side!).