A recent study once again looks for metals in autistic children. Once again fails to find significant differences between lead, mercury, cadmium and aluminum levels in autistic and non-autistic children. The study is relatively small (17 autistic children, 20 non-autistic). This group tested hair, blood and urine.
Here is the abstract
Normal concentrations of heavy metals in autistic spectrum disorders .
This follows on the heels of a recent study published in the Public Library of Science, A Comparison of Urinary Mercury between Children with Autism. , which found no differences in urine concentrations of mercury. This study was discussed here at Left Brain/Right Brain.
Looking back, what other studies have there been?
The current findings challenge the notion that perinatal heavy metal exposure is a major contributor to the development of ASDs and HDB [highly disruptive behaviors]
A cross-sectional case-control study was carried out to evaluate the concentrations of metallic elements in the hair of 44 children with diagnosis of autism and 61 age-balanced controls. Unadjusted comparisons showed higher concentrations of molybdenum, lithium and selenium in autistic children. Logistic regression analysis confirmed the role of risk factor for male gender and showed a slight association with molybdenum concentrations. Unconventional chelation and vitamin-mineral supplementation were ineffective on elemental hair concentrations. A meta-analysis including the present and previous similar studies excluded any association of autism with hair concentrations of mercury, cadmium, selenium, lithium and copper. A slight association was found for lead only, but it was very weak, as strictly dependent on the worst data from one study.
After accounting for dietary and other differences in Hg exposures, total Hg in blood was neither elevated nor reduced in CHARGE Study preschoolers with AU/ASD compared with unaffected controls, and resembled those of nationally representative samples.
IMFAR (unpublished) abstracts:
Conclusions: Levels of total mercury in serum collected from mothers during mid-pregnancy and in blood collected from infants at birth were not associated with risk of ASD.
Results: Initial analyses do not indicate higher concentrations of lead, manganese, or mercury in either prenatal or postnatal regions of the teeth among children with ASD as compared to matched controls. The presentation will include final analyses and interpretations on the full sample and on other elements.
Conclusion: There is no evidence that children with PDD have elevated levels of mercury or that they have deficiencies in mercury excretion. The findings do not support the use of chelation therapies as a treatment of autism.
Analysis of hair sample data by t-tests for equality of means and equal variance yielded no significant difference in mercury levels for the two groups. Despite the small sample size, results raise questions about the usefulness of evaluation for mercury exposure using hair samples, and about claims of mercury toxicity in children with autism.
Conclusion: Autism appears to not exist amongst Inuits from Northern Quebec. If confirmed, it would have significant implications for the genetic understanding of autism. In addition, as Inuits are exposed through their fish-eating practices to high pre- and post-natal levels of mercury, it would also suggest that high mercury exposure in itself does not increase the risk of autism.
Yes, you can find papers claiming there are differences in hair, blood or urine concentrations of mercury. Many by father-son team Mark and David Geier. I won’t take the time to go into the lengthy discussion of why I don’t trust anything they do without corroboration. There is the old Amy Holmes “baby haircut” study that was taken apart at the autism omnibus proceeding (amongst other places). Plus a couple papers by James Adams. Yes, and a poorly done reanalysis of an existing dataset. Just not a strong body of evidence to support the idea that “autism is a novel form of mercury poisoning”.
In the end all of this evidence comes in a far second to the fact that multiple studies have shown no increased risk for mercury exposure from vaccines. For example:
Our study revealed no evidence of an association between TCVs and autism.
So much time spent. So much money spent. And it is still going on. It’s long past time to move on. The vast majority of the research community already has. Most parents have.