The hypothesis of heavy metal poisoning as a cause of autism originates from the idea that mercury in vaccines cause autism. The vaccine/autism issue is discussed elsewhere on this site. Many speakers at AutismOne who promote chelation therapy have, themselves, been allegedly involved in some tragic deaths of patients undergoing unwarranted treatments. This treatment originated from the Autism Research Institute (ARI) and the Defeat Autism Now (DAN) protocol, which is discussed here, here and here.
The problems with chelation have been summed up here by Orac on Respectful Insolence:
Indeed, it is from that concept (that “autism is a misdiagnosis for mercury poisoning,”, which is not supported by epidemiological or preclinical evidence) that flows all sorts of dubious therapies to “remove” the mercury. Foremost among these questionable therapies is chelation therapy, using a chelating agent like EDTA or DMSA to bind to and remove this supposed mercury excess. This therapy is touted as being extremely effective in improving the behavioral abnormalities in autism, but, contrary to what its proponents say, it is neither efficacious nor safe. Indeed, six months ago it resulted in the death of an autistic boy named Abubakar Tariq Nadama at the hands of a quack named Dr. Roy Kerry in a clinic near Pittsburgh. There are many variations of chelation therapy, including Dr. Rashid Buttar‘s famous “transdermal” chelation. Despite the fact that Dr. Buttar has never been able to demonstrate scientifically that his DMSA-laced cream chelates anything or is even absorbed through the skin, parents line up to pay him big bucks to administer this therapy. Not long after Abubakar’s death, I learned of another variant that Dr. Buttar has come up with that involves intravenous minerals, intravenous ozone, and an unnamed “environmental detoxifier,” to treat autism. (One wonders if it’s because even Dr. Buttar is starting to realize that chelation therapy doesn’t do anything for autism.)