Autism and Mercury Revisited: DeSoto and Hitlan (2007) FAQ Site Updated

The FAQ site for the DeSoto and Hitlan (2007) reanalysis of the Ip et al (2004) data has been
updated. This FAQ site dispels some of the misinformation being circulated by bloggers about their 2007 reanalysis. Autism Street in particular has attempted to diminish the results and significance of the DeSoto and Hitlan reanalysis which:

"documents a research finding that has been said to show there is "no connection between mercury and autism" was wrong; thus, some may have written off any connection too hastily. Certainly, if persons concluded that mercury and autism could not be linked based on Ip 2004 stated results, they would want to reconsider."

If you have a non-faith based interest in this important autism issue, and your source of understanding of the DeSoto and Hitlan article is Autism Street, or other blog sites, you may want to visit the DeSoto and Hitlan updated FAQ site. The authors ask people to communicate with them directly if they have questions about their article and the conclusions they reached on this important subject.

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DeSoto and Hitlan Rebut (Crush?) Autism Street Critique of Autism-Mercury Data Reanalysis Article

Catherine DeSoto and Robert Hitlan have published an FAQ site Frequently Asked Questions about DeSoto and Hitlan (2007) to answer questions and refute some inaccurate, misleading and even erroneous critiques of their important article published in the November 2007 article of the Journal of Child Neurology Blood levels of mercury are related to diagnosis of autism: A reanalysis of an important data set. Most of the FAQ deals with questions raised on Autism Street in A Tale of Two Tails by bloggers Interverbal and Do'C. The two bloggers published a critical review of he DeSoto and Hitlan paper on Autism Street. The Desoto-Hitlan FAQ site exposes many information gaps in the Interval-Do'C critique.

DeSoto and Hitlan responded very politely to the critique and the FAQ site is important reading for anyone with a serious interest in autism, although it will undoubtedly be difficult for many of the 87 Autism Street cheerleaders who published their gloating sarcastic commentaries to read with an open mind. Interverbal posted an interesting comment:

Comment by Interverbal — 18 November, 2007 @ 4:06 pm At this time I don’t think we have any plans to write a letter to the editor. Speaking only for myself, I am anxious to see how Ip et al respond to DeSoto & Hitlan.

As one who does not share Interval's and Do'C's knowledge of statistical methodologies I might have been confused in saying that I too look forward to any reply by Ip et al. As I read DeSoto and Hitlan's FAQ it appears to me that they are saying that Ip et al already acknowledged their errors by the time the DeSoto article was published in November:


Q. Why did you take the time to write about a mistake that had already been corrected by the authors?

A. We didn’t. The mistake had not been found until we found it. We are the correctors. Again, some blog sites have unfortunately served to confuse this issue.

Q. What was really so wrong with the Ip 2004 article?


A. Based on their retraction which appeared in the same issue issue as our article, the mean for the autistic group was wrong, the standard deviations were wrong for both groups, the stated statistical significance in 2004 was way off. The means as they reported them in 2004 result in a significant t test by any standard…meaning that the autistic group had significantly more mercury in their blood than the control group. This is indisputable (or should be). It would not matter if a one tailed or a two tailed test was used. All interested parties should use their original data from the 2004 article and calculate the t value and p value (or put the numbers into an online t test calculator-- see "how can I check the original numbers myself?"). Their original stated level of statistical probability was off by almost 10 fold.


The data set they provided in 2007 misses conventional significance by a hair using their original statistical technique. Some blog sites such as Age of Autism have also pointed out that Ip et al overstated their findings in 2004. This means that the conclusions they made reached way beyond their findings. This is less serious compared to flubbing your stats, but I will note it for completeness.


If I am right in my reading of the DeSoto and Hitlan FAQ site commentary then I assume that Interval and Do'C will publish a retraction of their analysis on Autism Street. I will hold my breath until then. No, no ... on second thought ... I better not. I don't know if Interval and Do'C have the integrity to admit error. My lungs could explode, or I could implode, waiting for the retraction.

Too bad Interval didn't write that letter to the editor.

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Autism and Mercury Data Reanalyzed - DeSoto and Hitlan

The issue of whether autism is caused in whole or in part by mercury or mercury based preservatives (Thimerosal) in vaccines has been one of the most intense of the many divisive issues associated with autism disorders. I personally have never accepted that the available evidence, as interpreted by professional authority, demonstrated such a connection but I try to keep an open mind in the event that new evidence emerges, or new studies are done which demonstrate a mercury-autism connection.

Failure to keep an open mind is essentially a failure to think, to reassess conclusions in light of new evidence. In some ways a closed mind is also a worship of the past when a person did think through the issues based on the evidence available at that time and a lack of confidence in one's current analytic abilities. It is important for children with autism, now and those yet to be born, that any new relevant data which might help us understand causal factors giving rise to autism be understood and if possible preventions, treatments and cures developed. If mercury is a factor then we would be grossly negligent to ignore evidence of that factor solely because we had examined the issue in the past and failed to find the connection.

In a new article published in the November 2007 issue of the Journal Of Child Neurology M. Catherine DeSoto Ph D and Robert T. Hitlan Ph D, both of the Department of Psychology at the University of Northern Iowa, have gone back and reanalyzed previous data from an important previous study and concluded that contrary to the original study the data it reported did in fact support a connection between mercury and autism.

In Blood Levels of Mercury Are Related to Diagnosis of Autism: A Reanalysis of an Important Data Set DeSoto and Hitlan conclude that a significant relation does exist between the blood levels of mercury and diagnosis of an autism spectrum disorder:

The question of what is leading to the apparent increase in autism is of great importance. Like the link between aspirin and heart attack, even a small effect can have major health implications. If there is any link between autism and mercury, it is absolutely crucial that the first reports of the question are not falsely stating that no link occurs. We have reanalyzed the data set originally reported by Ip et al. in 2004 and have found that the original p value was in error and that a significant relation does exist between the blood levels of mercury and diagnosis of an autism spectrum disorder. Moreover, the hair sample analysis results offer some support for the idea that persons with autism may be less efficient and more variable at eliminating mercury from the blood.

Undoubtedly the DeSoto and Hitlan article will give rise to a response, hopefully from Patrick Ip and his colleagues who authored the 2004 study Mercury Exposure in Children With Autistic Spectrum Disorder: Case-Control Study. There is a good possibility of calm objective discussion of this article and its conclusions amongst scholars. Amongst internet bloggers and to some extent mainstream media commentators, emotional, ideologically based criticism will be the more likely result. As one who sits in neither camp in the great autism mercury war I agree with the statement in the DeSoto and Hitlan abstract that if there is any link between autism and mercury, it is absolutely crucial that the first reports of the question are not falsely stating that no link occurs.

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