“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.
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).
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: 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:
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 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.”
"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.
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.
Harold L Doherty:
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.