In my opinion, anything that is not natural, that is man made could be dangerous. Aspartame is a form of sugar, but not a natural sugar. People say not to give it to children because it is dangerous. Aspartame can cause headaches, belly aches, and other ailments. It is important to eat organic or natural foods.
I would expect that aspartame is bad for human health because it is a chemical additive, and even though sugar in excess is bad for your health, it is at least a natural product that is only harmful in excess. Even bugs won't eat aspartame, so that should give us some warning about our own intelligence in being willing to consume it.
Aspartame has been highly researched to determine if there are any dangers associated with consumption. After all the studies have been performed, researchers found there is no link to any health dangers, but anything can be dangerous in extreme causes. Salt, for instance, is necessary for your body, but having too much salt can be detrimental to your health. It could cause high blood pressure. The key to everything is moderation.
No, I don't believe aspartame is dangerous to one's health. The reason I take this stance is because I have personally experienced ingesting aspartame for over 5 years (via Diet Coke). As such a heavy drinker of Diet sodas, I thought it best to research the effects that aspartame might have on a body, and I've read the effects doctors have written about, and have personally experienced none, neither has anybody who I know that drinks Diet Coke regularly.