There’s been a lot of buzz in the last month or so concerning this latest study by Michael Pichichero et al. from the University of Rochester which was purportedly published in the February issue of the medical journal Pediatrics a month ahead of schedule in order to combat what was thought to be unscientific autism-is-caused-by-vaccines rhetoric in a fictional television courtroom drama called Eli Stone.

And the media didn’t disappoint, there were lots of reports that latched right onto the “findings” of the study. Here are some examples from The Washington Post, Science Daily and Reuters.

You can begin to understand why the hubbub erupted after you look at the misleading abstract:

“The blood half-life of intramuscular ethyl mercury from thimerosal in vaccines in infants is substantially shorter that that of oral methyl mercury in adults.”

This sounds like great news, telling us that the mercury preservative in vaccines (still currently in most of the recommended children’s flu shots) is cleared from the blood of children much more quickly than the mercury found in seafood eaten by adults is cleared from their blood. “Maybe thimerosal IS safe,” you might think, if you didn’t actually bother to read the study, “and those people who were worried about injecting mercury into the bloodstream were alarmists.”

Of course, there are some relevant bits of information that were omitted from the abstract, such as where all the mercury cleared from the vaccinated children’s blood WENT. Pichichero doesn’t actually know, as his stated aim was to evaluate the similarity of methyl (fish) and ethyl (vaxes) mercury in order to determine whether current EPA guidelines that suggest maximum exposure to methyl mercury found in fish is suitable for application to ethyl mercury in some vaccinations. He analyzed urine, blood and feces, and so therefore can only report those findings; some inorganic mercury was excreted via a one-time fecal sample from the study subjects, which seems to indicate that at least some of mercury contained in the shots was excreted in this manner, but he doesn’t know how much of the mercury that was injected was excreted via feces. There was no significant excretion of mercury via urine.

Fortunately, Thomas Burbacher, et al. can make a good guess as to where some of the mercury from the injected infants went: their brains. Burbacher’s study reached a very similar result as Pichichero’s in that the half-life of ethyl mercury in the blood was significantly shorter than that of the methyl mercury. The difference is that Burbacher also examined the amount of mercury in the brains of infant macaques that had received either ethyl or methyl mercury, and found that blood mercury levels were not good indicators of brain mercury levels. Furthermore, while Burbacher’s results are similar to those of Pichichero’s in that there does not seem to be any accumulation of mercury in the blood after thimerosal exposure, there are concerns about the accumulation of mercury in the brain.

Burbacher found that absolute inorganic mercury concentrations in the brain were approximately twice as high in the thimerosal-exposed macaques than those exposed to methyl mercury in the diet. Inorganic mercury has a very long half-life in the brain, between 227 to 540 days, depending on which region of the brain in which the mercury is deposited.

When I read the Pichichero study, I couldn’t help but wonder why he so strenuously avoided any reference to the work Burbacher et al. had done; he had, in fact, cited that same study when he noted that “…ethyl mercury readily transports to all tissues but that it has a shorter half-life.” But then when interviewed by reporters concerning his recent study, as in the Reuters article linked above, he made claims such as “Now it’s obvious that ethyl mercury’s short half-life prevents toxic build-up from occurring. It’s just gone too fast.” Burbacher didn’t find it was gone too fast. He found it was going to the brain, and there was nothing in the Pichichero study that demonstrated that he knows where the mercury went when it left the blood. He knows it did not appear in the random urine sample, and that some of it appeared in a random fecal sample, but as far as he knows, a whole bunch of it might be sitting in some tissue in the body. So it is difficult to see his statement as anything more than pure conjecture, and unrelated to anything he knows to be true, in the usual scientific understanding of the word true, and certainly unrelated to anything he demonstrated in his study.

Burbacher and Pichichero did agree that the EPA guidelines for maximum exposure to methyl mercury should not be applicable to ethyl mercury, because both substances seem to be handled differently by the body. But they seem to be parting company on what this means. Burbacher recalls that inorganic mercury in the brain is associated with an increase in microglia and notes that a study has shown an increase in brain inflammatory processes including a large proliferation of microglia in the brains of autistic patients. Whereas Pichichero seems to be holding out hope when in the conclusion of the recent study he states: “Our results suggest that a new risk assessment regarding exposure to thimerosal…should be conducted in light of the demonstrated short half-life of ethyl mercury following vaccination.”

As always, I would gently suggest that you are as informed as possible before you inject substances into your children or yourself. And I further advocate the exercise of caution and extreme critical analysis when a person whose interests might be contrary to yours advocates that you do something based on purported research findings, particularly when the findings are actually outside the purview of the study. (It is interesting to have a look at the “Research Focus” heading here).

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