I'm just guessing but I don't think it's anything like EDTA. I've also seen vitamin C used but not for autism. Before I have my children, I'm going to do my research on vaccines and PRAY I don't get an asshat for a pediatrician. You know some think they know what's better for your baby than you the parent.
I have a new child and have researched the vaccine mercury issue. Go here: http://www.fda.gov/cber/vaccine/thimerosal.htm#t1. Personally, I believe that this whole mercury vaccine thing is just another trial lawyer grab.