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Normal concentrations of heavy metals in autistic spectrum disorders.

Posted Feb 27 2012 1:42am

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 .
Albizzati A, Morè L, Di Candia D, Saccani M, Lenti C.
Operative Unit Child Neuropsychiatry A.O. San Paolo Hospital, University of Milan, Milan, Italy –
AIM Autism is a neurological-psychiatric disease. In the last 20 years we witnessed a strong increase of autism diagnoses. To explain this increase, some scientists put forward the hypothesis that heavy metal intoxication may be one of the causes of autism. The origin of such an intoxication was hypothesised to be vaccines containing thimerosal as antimicrobic preservative. This preservative is mainly made up of mercury. The aim of our research was to investigate the correlation between autism and high biological concentrations of heavy metals.
METHODS Seventeen autistic patients, between 6 and 16 years old (average: 11.52 DS: 3.20) (15 males and 2 females), were investigated, as well as 20 non autistic subjects from neuropsychiatric service between 6 and 16 years (average: 10.41 DS: 3.20) (15 males and 2 females). In both groups blood, urine and hair samples were analysed trough means of a semiquantitative analysis of heavy metal dosing. The metals analysed were Lead, mercury, cadmium and aluminium, since their build-up may give both neurological and psychiatric symptoms.
RESULTS The comparison of the mean values of the concentrations between the groups, performed with ANOVA test, has shown no statistically relevant differences.
CONCLUSION There wasn’t correlation between autism and heavy metal concentration.

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]

Lack of Correlation Between Metallic Elements Analyzed in Hair by ICP-MS and Autism.

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.

Blood mercury concentrations in CHARGE Study children with and without autism.

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.
Conclusions: Based on preliminary results, concentrations of heavy metals do not seem to be higher in children with ASD. The type of biomarker used may be important, and it is also possible that prenatal and early postnatal exposure to heavy metals contributes to the development of ASD in some children, but not others.


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.


Fifteen autistic children and four typically developing children completed the study. Three autistic subjects excreted one metal in greater quantity during the provoked excretion than baseline. Two of these were very close to the limit of detection. In the third case, the provoked excretion of mercury was between the upper limit of normal and lower limit of the potentially toxic reference range. Fish was removed from this child’s diet for greater than one month, and the provoked excretion test repeated. The repeat excretion of mercury was within the normal range.

In the absence a proven novel mode of heavy metal toxicity, the proportion of autistic participants in this study whose DMSA provoked excretion results demonstrate an excess chelatable body burden of As, Cd, Pb, or Hg is zero. The confidence interval for this proportion is 0-22%.

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:

[Lack of association between thimerosal-containing vaccines and autism].

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.

  1. Autism Blog – Normal concentrations of heavy metals in autistic … | My Autism Site | All About Autism:
    [...] See the original post here: Autism Blog – Normal concentrations of heavy metals in autistic … [...]
  2. MikeMa:
    I see folks with shovels coming to dig up and move the goalposts. Any chance of replicating this work on a larger scale to settle it more definitively?
  3. Oh come on:
    What does that metaphor even mean? They tested for correlation and no correlation between autism and heavy metals were found. Seems like someone is using flowery wording to escape admitting to a delusion.
  4. Science Mom:
    What does that metaphor even mean? They tested for correlation and no correlation between autism and heavy metals were found.
    What metaphor are you referring to? I don't understand your complaint.
  5. MikeMa:
    @Oh come on, If the metaphor you are referring to is my goalposts one, I am anticipating the heavy metal fans on the anti-vax sites looking for reasons to ignore or ridicule the study. One way would be to point out that it was, as Sullivan said, rather small. Another might be the Pharma conspiracy gambit where the loons will discount the results because big pharma paid for some or all of it. Otherwise I am as confused as Science Mom.

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