There is quite a bit of evidence people with autism have a propensity to have a more difficult time eliminating heavy metals. So what might be safe for someone with a good detoxification system could cause autism in someone else. One study on hair analysis showed lower levels of mercury in the hair of kids with autism and more mercury in the hair of normal children. This is an example of the type of cover-ups on this topic:
http://www.rollingstone.com/politics...adly_immunity/