I know that some people are concerned that aluminum is linked to Alzheimer's and brain cancer, though whether or not that has anything to do with the safety rating is purely speculation. From what I recall reading, though, aluminum toxicity is mainly a concern when you're inhaling it or if you have severe kidney disease. I mean, I use it pretty frequently in cooking and it's even in deodorant and stuff (which is why people actually made a huge stink about it to begin with).