Prenatal thimerosal and autism: evidence opposing the mercury hypothesis

An interesting study that I look forward to reading when it becomes available. Due to some weird University-Publisher interaction, I can’t get my hands on this article yet. From the abstract and the news it seems that Rh- mothers who receive Rh immune globulin via vaccine pre-partum did not have any higher incidence of autistic outcomes than the normal population. Good news for Rh- women wanting to have children, but I still have concerns about thimerosal in general.

The authors state in their abstract:

These findings support the consensus that exposure to ethylmercury in thimerosal is not the cause of the increased prevalence of autism. These data are important not only for parents in this country but also for the international health community where thimerosal continues to be used to preserve multi-dose vials which in turn makes vaccines affordable.

I think the authors hastily and unfairly generalized their results in this instance, though I intend to read the document and report more thoroughly when it is available.

A few points to think about.

1.)Vaccinations were given to mothers pre-partum. The concentration of thimerosal to a fetus in a vaccination given to a 135 lb. woman is going to be less than that given to a post-partum baby. I’d have to read the article and wrap my head around the literature to determine the average amount of thimerosal exposure in each case. Most likely, it is a much lower exposure in the prenatal Rh vaccination.

2.)Multiple rounds of multi-dose vials exceeded FDA approved levels of mercury exposure. Period. The authors are comparing apples to oranges here. Any one pre-2001 vaccination did not exceed FDA levels of mercury exposure, but the combination of multiple vaccinations in a short span did exceed FDA approved levels. This report is not the nail in the coffin of the thimerosal hypothesis that the authors suggest.

3.)Johnson and Johnson funded the study. Good science is often funded by private companies, but it should be noted that although the original report cites this funding, the news media do not. I love Johnson and Johnson, and most all pharm companies. Really, they do great work. But these possible conflicts of interest must be highlighted in every study.

In conclusion, Rh- women have some reassurance that Rh vaccination won’t have adverse developmental effects on their baby. For the rest of us concerned about multiple exposures to flu and other vaccines on infants, there is little to gain from this study, despite the smug confidence of the authors.

Pubmed abstract


Thimerosal update

A good article on what we know now about thimerosal and autism (i.e. not much)

Thimerosal has been withdrawn from many pediatric vaccines since 1999 as a result of concerns over the neurodevelopmental toxicity of organic mercury although it is still used in influenza, diphtheria, and pertussis vaccinations (Goth et al, 2006).

In the United States autism, once a rare condition (Goodman & Koduru, 2000), has increased from 4 – 5 per 10,000 children in the 1980’s to 30 – 60 per 10,000 children in the 1990’s, an increase of more than ten times, and the diagnosis of ADHD increased 250% between 1990 and 1998 (Szpir, 2006). The cause of these diseases is largely unknown at this time though some researchers are looking to phthalates, PCB’s, and other chemicals for which use has increased about the same time (Booker, 2001). A 2006 study concluded that there is a potential association between autism and estimated metal concentrations in the air (Windham et al, 2006). Another study postulates that thimerosal may be a potential triggering mechanism contributing to autism in susceptible individuals (Walker et al, 2006).

To date no studies have been performed to compare human populations vaccinated and populations unvaccinated. In the past the Centers for Disease Control (CC) has purported vaccines and autism to be unrelated or casually related (Institute of Medicine, 2004) though the CDC has recently announced the funding of a multi-agency study to determine the potential for environmental and genetic causes of autism which includes thimerosal (Centers for Disease Control and Prevention, 2006).

It’s a long article, and I’m not sure if I buy it all, but it is something to keep in mind.

Mercury and autism…nothing to see here folks.

Good article on the subject linked above Hat tip to Developing Intelligence

Wellman collected cabbage seeds infected with a common fungus and dunked some of them in a solution of mercury salts and hot water. “The lots treated with mercuric [chloride] were shaken vigorously at first to get thorough contact with the solution,” he wrote. His faculty adviser at the time was concerned about an epidemic of cabbage fungus that was wrecking havoc on Wisconsin farms, and he enlisted his student Wellman’s help in researching solutions.

By the time his son was born 14 years later, in 1936, Wellman had graduated to advanced plant pathology work at the U.S. Agriculture Department’s main research center in Beltsville, in Prince George’s County, just outside Washington.

In a résumé, he wrote at length about his experience there with fungicides. On cabbage seeds, he reported, “organic mercury compounds were found to be most satisfactory disinfecting agents.” For tomatoes, “proprietary organic mercury dusts also gave good results.” All three of the fungicide sales brochures in his archive were for organic mercury compounds–two of them containing ethyl mercury, which was introduced in commercial products just a few years earlier.

Ethyl mercury is also the active ingredient in a vaccine preservative called thimerosal. A maverick minority of scientists and a larger percentage of parents blame thimerosal–which is 49.6 percent ethyl mercury by weight–for the rising autism rate, up tenfold in 20 years to one in 150 8-year-old U.S. children, according to a report this month by the Centers for Disease Control and Prevention. Some parents say they watched their children become physically ill and regress into autism soon after they got shots that contained the chemical–a link public-health officials call coincidence, not cause and effect.


All forms of mercury are toxic, but organic mercury–which can cross the body’s blood-brain barrier and the placenta–is especially dangerous.

One kind of organic mercury, methyl, “bioaccumulates” or builds up in some large fish. Pregnant women are advised not to eat too much of certain fish for fear of causing neurological damage to their offspring.

Ethyl is a sister compound from the same alkyl subgroup of organic mercury; it has one more carbon and two more hydrogen atoms than methyl. But ethyl mercury is man-made–it was not present in the environment, and humans were not exposed to it, until a Ukrainian immigrant named Morris S. Kharasch created the first commercial formulations just before Kanner’s earliest autism cases were born.

“A light bulb went off for me at a conference in Portland [Ore.] in 2001 where I met a mother of five children, all on the spectrum, all unvaccinated,” King recalls in an interview. “She was from eastern Washington, she came from a family of farmers, and her husband was a farmer as well. All five of her children had regressive autism. Meeting her changed the way I look at autism, and prompted me to explore the connection.”

King says her “jaw literally dropped” when presented with the idea that mercury in fungicides could link Kanner’s early cases. “It would be hard to convince me that there isn’t a connection,” she says.