In yet another study on mercury and autism, a team from the University of Texas has investigated blood mercury levels in children with autism spectrum disorders (ASDs). In Seafood Consumption and Blood Mercury Concentrations in Jamaican Children With and Without Autism Spectrum Disorders they report that “After controlling for the child’s frequency of seafood consumption, maternal age, and parental education, we did not find a significant difference (P = 0.61) between blood mercury concentrations and ASDs. ”
“we did not find a significant difference between blood mercury concentrations and ASDs”
Here is the abstract:
Mercury is a toxic metal shown to have harmful effects on human health. Several studies have reported high blood mercury concentrations as a risk factor for autism spectrum disorders (ASDs), while other studies have reported no such association. The goal of this study was to investigate the association between blood mercury concentrations in children and ASDs. Moreover, we investigated the role of seafood consumption in relation to blood mercury concentrations in Jamaican children. Based on data for 65 sex- and age-matched pairs (2-8 years), we used a General Linear Model to test whether there is an association between blood mercury concentrations and ASDs. After controlling for the child’s frequency of seafood consumption, maternal age, and parental education, we did not find a significant difference (P = 0.61) between blood mercury concentrations and ASDs. However, in both cases and control groups, children who ate certain types of seafood (i.e., salt water fish, sardine, or mackerel fish) had significantly higher (all P < 0.05) geometric means blood mercury concentration which were about 3.5 times that of children living in the US or Canada. Our findings also indicate that Jamaican children with parents who both had education up to high school are at a higher risk of exposure to mercury compared to children with at least one parent who had education beyond high school. Based on our findings, we recommend additional education to Jamaican parents regarding potential hazards of elevated blood mercury concentrations, and its association with seafood consumption and type of seafood.
Members of this team have other work on autism in Jamaica. Last year they presented Paternal and Maternal Age Are Jointly Related to Autism Spectrum Disorders In Jamaican Children at IMFAR. which had goals of:
This study’s primary objectives were to investigate whether environmental exposures to mercury, lead, arsenic and cadmium play a role in autism. Additionally, we investigated other potential risk factors for autism, including maternal and paternal age
So we see that the recently released paper is part of the conclusion of that study, which was incomplete at the time of abstract submission for IMFAR. I believe this team is reporting again at IMFAR 2012.
Why bring this up? It’s a relatively small study on a topic that has been well covered in the past: autism risk and mercury exposure. Besides, do even supporters of the autism/mercury hypothesis think that blood levels of mercury are a good indicator to track? The answer is “yes” when blood levels might implicate mercury and “no” when blood levels do not (as is this case).
The mercury/autism hypothesis has a long history, but it is worth noting that there was a great deal of excitement a few years ago when a researcher claimed that by re-analyzing an existing dataset she could show a correlation between blood mercury levels and autism. Porf. DeSoto’s 2007 paper was Blood Levels of Mercury Are Related to Diagnosis of Autism: A Reanalysis of an Important Data Set. The re-analysis was criticized (e.g. Autism Street’s A Tale Of Two Tails and A Photon in the Darkness’ Winter Potpourri). As noted, the re-analysis was also welcomed in some circles, including an article by Age of Autism’s Mark Blaxill: When Smart Scientists Make Stupid Mistakes:
This is an important and unexpected finding. It supports one of the central hypotheses at the heart of the autism-mercury controversy and suggests that the excretion deficit in autistic children might persist longer than anyone had guessed.
The idea that correlations between blood levels in autistics could be “an important…finding” was downplayed a great deal a few years later after Prof. Hertz-Picciotto’s team at the U.C. Davis MIND Institute came out with a study, Blood mercury concentrations in CHARGE Study children with and without autism. The MIND team concluded, “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”. Key in that conclusion–“after accounting for dietary and other differences in Hg exposures”. This is something that was not done in the dataset that Prof. DeSoto re-analyzed.
Which led to a press release from Mr. Blaxill’s organization, SafeMinds: New California Study on Children’s Blood Mercury Levels Leaves Unanswered Questions About Mercury’s Role in Autism which downplayed any impact of the MIND study while somewhat ironically using DeSoto’s re-analysis for support. In other words, new research on blood-levels of mercury are not so important because we have older, uncontrolled, data which does say blood-levels are important.
More telling of the shift in support for blood mercury concentrations is this 2010 comment from Katie Wright at the Age of Autism:
Measuring random blood levels is a fruitless exercise, like testing ASD kids for grass allergies in the wintertime.
Don’t assume the door was closed on blood levels of mercury. In 2011 a paper was published, Theoretical aspects of autism: Causes—A review, which stated that there was evidence for a “metal metabolism disorder” in autistics and Supporting this relationship are reports documenting that heavy metals are increased in the blood and urine of autistic subjects”. This review was not surprisingly welcomed by groups promoting the idea that vaccines and/or mercury cause autism as well as criticized by many (for example)
So while, yes, these groups do welcome research indicating that blood levels of mercury are important in discussing autism research, they are also quite prepared to downplay using on blood-levels of mercury in studies which don’t support the mercury-causation idea.
Which is why one will not be surprised that research such as this new paper from Jamaica will have little impact on the mercury-causes-autism movement. Well, that and the fact that it is evidence against causation.
For those who claim that mercury testing should be done earlier–that testing autistic children is too late (“like testing ASD kids for grass allergies in the wintertime”) there is another study in process, one that was presented at IMFAR 2011. Prenatal and Neonatal Peripheral Blood Mercury Levels and Autism Spectrum Disorders which I don’t believe has been published yet. The conclusion from that study: “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.”
Mercury levels in pregnant women aren’t correlated to whether their children have autism. Mercury levels in newborns aren’t associated with autism risk. Blood levels in autistics are not correlated with their diagnosis. Add to this the fact that autism risk is not correlated to levels of mercury exposure from vaccines or immunoglobulins (e.g. Prenatal and Infant Exposure to Thimerosal From Vaccines and Immunoglobulins and Risk of Autism). And the fact that autism does not look like mercury intoxication. And that autism prevalence estimates continue to rise even after mercury was removed from vaccines. Why is there still support for this idea?
Left Brain Right Brain 
Rigid thinking?
“Why is there still support for this idea?”
-because it was one of the “original ideas” about the cause of autism?
-because there are still “practitioners” who are subjecting children with autism to undergo mercury chelation?
-because “other ideas”, such as “too many, too soon vaccines”, haven’t taken hold?
-because the aluminum-adjuvants-in-vaccines “idea” and the latex-in-vaccine-vials-ports and latex-in-syringes-plungers-and syringe-packing “idea”, have been thoroughly debunked?
-because some credulous parents of children diagnosed with ASDs, need to assign blame to something or someone?
I probably should have stressed:
These are big reasons why so few people give this credibility any more.
Why indeed?
Of all the rants and raves that I have read from the anti-vax crowd, I’m yet to read what their endgame is. They haven’t said, “When we have X, Y, and/or Z, we’ll stop.”
Alright. Alright. Some nut-jobs (my opinion) have said and written that they’ll stop when vaccines are 100% safe, which, as we all know, is an impossibility.
It is unfortunate that this site, and visiting commentators, like Liz Ditz, can not simply present the study with any relevant analysis without using it as a pretext to attack “yet again” what you call the “anti-vax” crowd.
I have never claimed or thought that my son’s autistic disorder was caused by vaccines but I don’t see why there is a need to attack those who believe the contrary based on direct observation of regression following their children’s vaccinations.
Mercury is a toxic substance. It makes sense to study it carefully including multiple studies to confirm or refute previous studies. Your cheap “anti-anti-vax” rhetoric does nothing but generate hostility.
@Ren
The goalposts will never stop moving. For whatever reason, guilt or desire for control or a need to blame something/someone, the anti-vaxxers will never give up the fight. Accepting their new reality (dealing with ASD) and dealing with it rationally is not going to happen any time soon.
More than a moving of goalposts, it is like playing ‘Whack-A-Mole’ where after you beat down mercury, aluminum pops up. You beat down aluminum and toxins pop up. The worst part is that after a while, mercury pops up again. Anti-science, pro-conspiracy groups are always recruiting.
@Harold
It is the repeated blame on mercury or aluminum or whatever the toxin du jour is in spite of studies showing no causal link that generates the exasperation by commenters. The implicit eye rolling is a common reaction to repeated ignorance and lies by the anti-vax crowd.
Mercury studies have been done. The most common response I’ve read from science is that mercury poisoning and autism present very differently. What studies would you like to see performed?
@ Mike Ma:
About those goal posts:
Anti-vaxxers like our friends @ AoA, Thinking Moms’ Revolution, Safe Minds, the Canary Party et al, have included Al and other toxins beyond those that they imagine to be in vaccines to include toxins encountered in daily life ( see Deirdre Imus’ website) AND
they have also expanded the size of the field ( because I’m talking about 2 dimensions: goalposts is only one) to include other conditions like Alzheimer’s, MS, asthma et al.
In effect, they’re saying: All kinds of toxins- including those in vaccines and vaccines themselves- cause all kinds of conditions- including autism. This links them up nicely with natural health / health freedom advocates.
These people will never stop and they will recruit others via internet alt med- alt media sites like those which I survey.
In order to avoid having viewpoints projected onto me, let me clarify:
I’m glad this team is doing this work. They are working in a community which does not have a great deal of previous work focused upon it (Jamaica). Reports on under-studied populations as well as under-served populations is extremely important.
If in the process of doing this work they collect data on the (failed) mercury hypothesis, that’s great. They published the work. While this does little to change the body of knowledge already in print (i.e. that blood levels of mercury are not correlated with autism), it may help to bolster that point with people who question the science.
And that is the problem–people who, through poor science or manipulated messages, are left unclear on the fact that there was no mercury-induced autism epidemic.
Would I like to see the researcher time and funding applied to other aspects of autism research? Absolutely. But, as a side-project to their work in Jamaica, I’m glad to see this work.
If one wishes to promote the idea
Readers will note that Mr. Doherty provides no instance of me using the term anti-vax. I rarely if ever use that term. I have on rare occasions used the term anti-vaccine.
How, exactly does one characterize statements such as this?
Rather than use the term “anti-vaccine”, how about irresponsible? How about dangerous?
One reason is that the use of these terms gives people the opportunity to avoid the conversation at hand (as exemplified above). Conversations involving the term “anti-vax” tend to center around individuals or groups saying, “but I don’t have anit-vaccine *sentiments*” while avoiding the fact that most often the another group is pointing out the anti-vaccine *actions* of the individual or group.
@Denice:
“All kinds of toxins- including those in vaccines and vaccines themselves- cause all kinds of conditions- including autism.”
Don’t forget (in the case of aluminum “toxins”) those in the most common minerals of the Earth’s crust, including mud.
David N. Brown
Mesa, Arizona
@DNB: “…including mud.”
a lotta kids i know play in mud and get autism…sorry but couldnt resist.
Carey Sullivan (Irish background ? you big goon)…. still banging on with this same old nonsense (who are you really working for I’d love to know) ….Right Foot … My left foot . mercury in the blood rubbish…….just remember the lot of you on here …..keep your vaccinations fully up to date . can we get a thread going on the latest “obese mothers” .The cutting edge of science – dont make me laugh . Scientists with starving brains more like ! Or maybe we can talk about Donald Trump ? Come on numbnuts ?
Jamaica study , Danish study , Faroe Islands – anywhere but in the USUK where any dodgy results can be challenged in courts , yeah ?
“Fiona Godless”
I’ll ask that you stick to a single pseudonym.
“who are you really working for I’d love to know”
That’s pretty easy to find out, but has nothing to do with this website. No one pays me to write here. Never has. Participation in this website has cost me money over time. Is that what “you’d love to know”? Somehow it’s a bit more mundane than I suspect you would “love to know” and more mundane than you were trying to imply.
@Fiona Godless: nice word salad. What kind of dressing would you like on it?
Studies have been done. I’m sorry you don’t like the results. That’s the breaks when it comes to science.
Some people will just never get the simple fact,that correlation does not equal causation.
Ms. Godless, perhaps you would like to express to Finn of the Dublin Skeptics your learned opinion on both the Irish and autism. I am sure she would love your racist alt-med word salad.
>“who are you really working for I’d love to know”
>That’s pretty easy to find out, but has nothing to do with this
>website. No one pays me to write here. Never has. Participation in
>this website has cost me money over time. Is that what “you’d love
>to know”?
Some people find it hard to imagine that _anyone_ would work for a good cause (such the health and welfare of children) without some ulterior motive – because they themselves would never do such a thing.