Thimerosal: Time to move on

"The lady doth protest too much, methinks." (Hamlet III, ii, 239)

What does this have to do with thimerosal, the mercury-based preservative?

The "lady" in our case today is not Queen Gertrude but the venerable grande dame of medical journals, the New England Journal of Medicine.  Tomorrow’s edition of the NEJM will include an article titled, "Early Thimerosal Exposure and Neuropsychological Outcomes at 7 to 10 Years."  The mainstream media across the world will pick the story up and run with it, announcing the authors’ conclusion that the study "does not support a causal association between early exposure to mercury from thimerosal-containing vaccines and immune globulins and neuropsychological functioning at the age of 7 to 10 years."  The study basics: over 1000 kids ages 7-10 were administered a battery of cognitive tests and researchers compared retrospective histories of thimerosal exposure.  Autism spectrum disorders and other diagnosed neurodevelopmental disorders were not assessed for.  No remarkable differences in testing based on thimerosal exposure were reported; notably, only 30% of recruited subjects completed the study.

What’s the big deal?  Another large epidemiological study showing no ill effects of thimerosal (50% ethyl mercury by weight), published in a well-respected medical journal?  Been there, done that.  The problem is, folks are reaching the right conclusion – that the story’s over – for the wrong reasons.  Why, if we’re so sure there’s no harm from thimerosal – used to preserve childhood vaccines for decades and still used in over 90% of the current injectable flu vaccine supply – is the conventional medical establishment still defending it?

Could it be that the conclusions are based on less than stellar data collection and analysis? This has been well documented elsewhere and the current study’s limitations are reviewed by A-CHAMP in detail here. Furthermore, the limits of epidemiological studies are also hotly debated – both the NY Times and LA Times covered this issue recently, as I posted last week.  To me, the only logical conclusion is that, yes, the story’s over.  Why?  Not because thimerosal is proven to be safe – quite the opposite. Thimerosal is mercury, and mercury is not good for you.  In fact, it’s quite bad for you.  All the epidemiological studies in the world will not prove that mercury is safe in products we inject into our kids.  Can and should we design a prospective randomized trial comparing thimerosal to placebo in infants? No, of course not.  If thimerosal came up for approval to the FDA today, it would be rejected.  Enough said.  The CDC and AAP both agreed we should phase it out of vaccines in 1999.  Why are we still debating this?

Enough already.  Time to move on.