Several people have asked me about an article that appeared in the Newark Star Ledger which quoted me as saying that thimerosal was no longer the “smoking gun" in autism.
The article, about the recent vaccine forum sponsored by Deirdre Imus in New Jersey, went on to say that, “Several national studies have found no connection, and a California study found that, even after thimerosal was removed from vaccines, diagnoses of autism continued to rise.”
The term “smoking gun” comes from Sherlock Holmes and it refers, of course, to the person found holding a still-warm firearm at the scene of a murder. To this writer’s mind (though interpretations may vary, I am sure) the term means the “one and only cause,” since only one person can pull a trigger.
I do not believe that thimerosal is the one and only cause of autism. I wish it were, because I think the whole world would be much better off dealing with such a simple, and removable, etiology.
Does that exonerate thimerosal as a suspect on the list of possible perpetrators (to continue the Holmes motif) that might conspire in different ways to cause, trigger or somehow exacerbate the symptoms of autism in at least one subset of susceptible children?
Not in my mind, and I said so at the forum.
Allow me to place my “smoking gun” comment firmly in context, (and perhaps in more context than some readers will appreciate).
In my opening remarks, before the slide presentation, I stated that:
“It’s possible that something has gone wrong with our vaccine program, whether it is individual ingredients, such as MERCURY, such as live viruses, such as aluminum, and/or the larger vaccine program, the schedule itself. Are there some children with genetic susceptibilities who simply cannot handle the schedule as it is now? It may be a small percentage, but we need to identify them and vaccinate them separately.”
And a bit later, this:
“There has been so much debate over ‘What is THE cause?’ And for a long time in this country, we were fixated on thimerosal, the vaccine preservative, and I share some of the blame for that because my book focused mostly on thimerosal. In the UK, they have been focused mostly on MMR. But you can’t make the model work. You can’t make every case of autism be caused by thimerosal. You can’t make every autism case be caused by MMR. So I think what we need to do is, step back and look at the bigger picture, by starting with the children who got sick, examining them, and work our way backwards. If we see common symptoms, in these very different cases of autism, well, what types of things might cause those symptoms? What types of environmental triggers might combine with what types of genetic susceptibilities, to cause the different outcomes that we see in autism?”
At this point, I turned and referred to my very first slide, titled “MAIN POINTS,” which included the following bullets:
● Look at genetic susceptibilities: immune, metabolic, mitochondrial, metal metabolism. What percentage of the population is born “at risk?”
● No single type of autism and no single cause – Look at many different combinations of genes and environmental “triggers.”
● Possible triggers include mercury & other heavy metals in food, air and water, thimerosal, multiple vaccines, pesticides, viruses, etc.
And this is what I said:
“There is no single type of autism and there is no single cause. We have to look at the combinations of genes and triggers. The triggers, as I mentioned, might include, unfortunately, everything, and when I wrote my book I was hopeful that maybe thimerosal was the smoking gun. And if we just got mercury out of vaccines, autism would rapidly reduce. And we haven’t seen that happen yet. But I did say if that does not happen then that’s bad news; now we’re back to square one. It would have been so much nicer, and easier, and cleaner to say, gosh, it was the mercury in the vaccines and now we can take it out and the case is closed. That didn’t happen, and we need to look at everything. And as I said, not only the individual vaccine ingredients, but also the cumulative effects of so many vaccines at once.”
More than one-third of my slides made reference to thimerosal, and I hardly think I exonerated the neurotoxin as a possible contributing factor to some cases of autism in my discussion.
As for the California study, that particular exoneration of thimerosal appears to be based largely, though not entirely, on one year’s data, from a single year’s birth cohort.
Why? The last thimerosal (preservative) containing vaccines on the childhood schedule reportedly expired in early 2003, though parents have also reported that their children received thimerosal-preserved vaccines, sold in multi-dose vials, after that time.
The most important cohorts to look at, then, would be children born in 2003 (when the last mercury-containing vaccines, except for the flu shot, were expiring) and those born in 2004 (when all mercury preservative, except for the flu shot, was out).
The 2003 birth cohort would have made up the three-year-olds inside California’s Department of Developmental Services (DDS) receiving services for autism (though not for milder spectrum disorders like PDD and Aspergers) in 2006, when the study was nearing completion.
There were more three-year-olds with autism enrolled in DDS in 2006 than there were in 2005. That is indeed a severe blow to the thimerosal-as-the-cause theory, as I predicted it would be. (The study ended in the 1st quarter of 2007; we have only limited data on the 2004 cohort).
When I made my prediction back in 2005, I was unaware of, or regretfully failed to take into account, several potential confounding factors that might – alone or in combination – have increased the number of three year olds with autism enrolling in DDS in 2006 (a number that rose by 327 cases in a rapidly growing state of 36.4 million people).
I believe that several legitimate questions about the imperfect “California experiment” need to be investigated and answered before we can give thimerosal a complete clean bill of health:
1) Could recent, aggressive early intervention programs in California and a falling age of diagnosis have increased the number of three year olds with autism entering the DDS system from 2005 to 2006?
The CDC waits until children have reached 8-years-old before doing autism prevalence studies in birth cohorts.
2) Could thimerosal in the flu shot be a confounding factor?
Mercury exposures from flu shots could include 25mcg prenatally (up to 70% of which – or 17.5 mcg - could have reached the highly susceptible fetus), 12.5 mcg at 6 months, 12.5 mcg at 7 months and another 25mcg at 18 months, for a total of .67.5 mcg. In the 2004-2005 flu season, nearly 60% of the infants enrolled in one huge California HMO were vaccinated for flu. I do not have data for 2003-2004.
3) Could rising immigration rates to California since 2001 be playing a role?
One-in-four California residents was born in a foreign country, (mostly in Asia and Latin America). High rates of autism among children of immigrants have been reported in Minneapolis, Montreal, Sweden, Ireland and elsewhere. According to California DDS data, since 2003, the rate of autism increased by more than 80% among Asian and Hispanic children, compared to about 50% among black and white children.
4) Could rising levels of background mercury in the environment be contributing to autism cases?
At least three peer-reviewed studies (including one funded by the CDC and published in an NIH journal) have shown an association between environmental mercury levels and an increased risk for autism. Recent Federal data show that the percentage of Americans with detectable levels of inorganic mercury in their blood increased eightfold between 2000 and 2004.
Does any of this incriminate thimerosal? Of course not. But it doesn’t fully exonerate the highly toxic preservative, which has the potential to cause “constriction of visual fields, impaired hearing, emotional disturbances, spastic movements, incontinence, groaning, shouting, dizziness, nausea, vomiting, diarrhea and constipation,” (HERE) (otherwise known as every afternoon at the Redwood house, circa 1998 in my book).
It’s tempting to write off thimerosal as a perpetrator in the autism epidemic, based on the California study. But it is just too early to do so.
According to Medical News Today, the authors of the study, “Cautioned that the evaluation of the trends needs to continue in order to confirm their findings for the children born more recently.” (HERE)
So, despite all the cries of innocence among mercury supporters, the California study authors insist that this trend has not been confirmed. Researchers need to go back and look at the 2004, 2005 and, soon, the 2006 cohorts, to see what happened to those kids. (They should also try to account for other sources of mercury, such as diet and air pollution, according to a panel of the National Institute of Environmental Health Sciences.). (HERE)
Ironically, sadly, incredibly, that will never happen.
As of January 1, 2008, entry criteria for receiving free autism services from DDS were expanded to include, “more current diagnostic standards and updated evaluation questions.” In other words, more children with ASD are now eligible for services - a wonderful thing for California families, indeed.
On the other hand, DDS autism data can no longer offer us a continuous window into autism epidemiology in California. Now that the standards have been altered, the department’s website (HERE) warns us: “Many data items are changed or new. Information from these items will not be comparable to prior information.”
Meanwhile, keep your eye on those immigrant kids in Montreal. Something interesting seems to be happening up there.
David Kirby is author of Evidence of Harm and a contributor to Age of Autism.