The Washington Post reported yesterday on the vaccine court proceeding that starts today. Almost 5000 families will make the case that vaccines caused their children to develop autism. I don’t think the families have a good case. To start off, the large majority of findings would suggest that there is not link. There are, however, some very good reasons why these studies could be wrong and that’s what’s keeping the theory alive. Let’s look at a couple of arguments that people like to make and what I think about them.
Con – The IOM said that overall there was no link. While this is true, the IOM (Institute of Medicine) did note possibility that some children may be genetically susceptible to thimerosal, which is a logical assumption since almost all diseseases are a combination of genetics and environment. In this case, which I see as the only possibility, the number of effected children would only be a sliver of the children who were vaccinated.
Pro – Thimerosal is mercury! Sort of, it’s ethyl-mercury which isn’t as toxic as methyl mercury, the mercury in polluted waters and in fish.
Con – Thimerosal is ethyl-mercury which isn’t very toxic. Wrong. Although not as bad as methyl-mercury, the ethyl version still gets into the brain and does damage after reverting back to elemental mercury, just like methyl.
Con – Autism advocates are crazy. Hmmm…very scientific. Let me note that citizen advocates for almost anything can seem a bit, um…enthusiastic, but it doesn’t mean they’re wrong, it just means they don’t have a PR firm. Some are probably a bit nuts, but let me ask you, how many organizations, even professional ones, don’t have a few nuts? Heck, even the Senate has some.
Pro – Mercury poisoning looks like autism. In many ways it does, although autism usually develops in a different way than mercury poisoning does.
Con – It takes tons more mercury to create mercury poisoning than the amount of mercury present in the vaccines. This is a very strong con-point. It is possible that the timing of the mercury exposure or the co-administration of the rest of the vaccine may effect the child in a different way that mercury poisoning does, but the size of the dose doesn’t support a link.
Con – When we took mercury out of most vaccines, there wasn’t a sharp drop in autism, so they couldn’t be related. This is the one I hear the most from other scientists and I think it’s premature if not wrong. Why? Most autistic kids are diagnosed between 3-7 yrs old but there’s a lot of diagnoses out side of that range too. The thimerosal phase out began in 1999. That means that we are just getting near the end of when the majority of kids would be diagnosed from this period. So if you don’t get diagnosed until 3-7 yrs after your exposure then there would be no sharp drop off, only a gradual one. We are just getting there so we won’t be able to tell for a couple years whether there will be a drop off or not. (Update: there are reasons why we simply shouldn’t use most of this data anyway, pro or con)
Con – The increase is mostly due to increased awareness and diagnosis. There are a couple of well reasoned papers on why the increase is unlikely to be due to increased diagnosis alone (it certainly is part of the increase). This doesn’t mean it’s vaccines, though; it could be another type of exposure.
Pro – Many autism patients seem to have decreased ability to get rid of metals such as mercury. This is too complicated to go into for this post (perhaps some other time), but suffice it to say that there are a lot of chicken and egg problems with this line of thinking but it does offer one of the better insights into how some of the children might be treated.
Pro and Con – Anecdotes. Stop using them. I ate some Cheerios the day I broke my arm when I was 6. My brother ate them every day and never broke his arm. Think this says anything about the role of Cheerios in arm fractures? The WP does a nice job of juxtaposing two conflicting ones.
The Angry Toxicologist’s Conclusion: The case for thimerosal is plausible but I see no hard evidence that would make me conclude that it’s real. I do know this though: Putting mercury in vaccines was a very stupid thing to do. The public health community should say so in a clear way. They are afraid to do so, thinking that people won’t trust the vaccine program anymore and not get vaccinated. What really hurts the vaccine program are the directors of these programs not being straight with the public. Medical professionals that think autism advocates are crazy and the advocates that think there is a vaccine maker/government cover-up conspiracy aren’t helping matters either. This problem needs to be researched with open minds but both sides are so bull-headed I fear that we may never come to understand what’s really going on.
AT’s Tip: Thimerosal is still used in multi-dose vials of flu-vaccine. If you’d rather not get one of those in the fall, just ask if it is preservative-free (most are now).
Update:Â As with the vegan post, people seem to be mis-reading the point of the post which is the majority of the work out there supports no link but there are major problems with the work that make it, as I see it, still an open question that can be debated. From practical standpoint (a legal and/or public health question that I had to act on), I’d say there is no link. No one has threatened to eat my kids yet so we’re off to a better start.
Update 2: To make this absolutely clear: Everyone should follow the vaccination schedules that are currently recommended for infants. There are still serious risks out there to serious diseases. My kids are vaccinated and I wouldn’t recommend otherwise, professionally or personally.
Update 3 for Science Blogs readers: Please seethe original post for the many back and forths in the comment section.