Easy to read summary of the Desoto & Hitlan metals and autism study

DeSoto M.C., Hitlan R.T.Sorting out the spinning of autism: heavy metals and the question of incidence (pp: 165-176)

The main points of the Desoto and Hitlan article:

1. The paper is a critical appraisal of the body of research purporting to show that the rise in autism prevalence is not associated with exposure to heavy metals and to mercury in particular. The main conclusion is “scientific research does not support rejecting the link between neurodevelopmental disorder of autism and toxic exposure.” In fact, the authors write that “the weight of evidence favor[s] a connection that is not well understood.”

2. Research on the recent increased prevalence of autism was reviewed and arguments made confirming that a sizable portion of the rise in rates is real and not simply an artifact of better awareness and changes in diagnostic practices.

3. The paper then reanalyzes the data from a 2007 paper by Sarah Soden and colleagues on mercury excretion among autistic children that has been widely cited to refute a mercury-autism link. Desoto and Hitlan convincingly show that the data actually supports a link, with the autism children excreting statistically significant more mercury than normal controls.

4. Desoto and Hitlan review their previous reanalysis of another study from 2004 by P. Ip and colleagues. The reanalysis shows that the blood levels of autistic children had statistically significant higher levels of mercury than normally developing controls.

5. Overall, the authors review of the relevant peer reviewed scientific literature showed that "of the 58 empirical reports on autism and heavy metal toxins, 43 suggest some link may be present, while 13 reports found no link...- in sum, the evidence favors a link".