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Anne M. Hurley, Mina Tadrous, Elizabeth Miller | The Journal of Pediatric Pharmacology and Therapeutics | (2010)
Primary Link Pubmed DOI Openalex Full text (OA)

Abstract

Although epidemiologic evidence has not supported the hypothesis of a causal relationship between thimerosal-containing vaccines and autism, concerns continue about pediatric exposure to mercury through vaccine administration. A statement issued by the American Academy of Pediatrics and the US Public Health Service in 1999 prompted the removal of thimerosal from many vaccines. In 2004, the Immunization Safety Review Committee of the Institute of Medicine rejected the hypothesis of a causal relationship between thimerosal-containing vaccines and autism.In a search of MEDLINE and EMBASE, we identified articles that address the potential association between thimerosal and neurodevelopmental disorders, specifically autism. In this article, we review recent pharmacokinetic and epidemiologic studies published between 2003 and 2008 regarding the proposed link between thimerosal and autism.

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Sample Definition And Size

The review covers pharmacokinetic and epidemiologic studies published between 2003 and 2008. It includes a pharmacokinetic pilot study (infants 3–28 days post-vaccination) and a follow-up study with 216 infants (72 newborns, 72 two-month-olds, 72 six-month-olds). Epidemiologic studies include: a prospective cohort of 12,956 children from the Avon Longitudinal Study; a retrospective cohort of 103,043 subjects (100,572 term infants, 2,471 preterm); and an ecologic study of 278,624 children in the Vaccine Safety Datalink project. Additional ecologic studies analyzed autism prevalence trends over birth cohorts.

Study Type

This is a narrative review article summarizing pharmacokinetic studies (pilot and follow-up) and epidemiologic studies (prospective cohort, retrospective cohort, and ecologic studies).

Conflicts Of Interest

No conflicts of interest are declared in the abstract or available metadata.

Results Summary

Pharmacokinetic studies found ethylmercury has a short half-life (pilot: ~7 days, 95% CI 4–10 days; follow-up: ~3.7 days) and does not accumulate in infants. Prospective cohort (Avon): among 12,956 children, no association between thimerosal exposure and neurodevelopmental outcomes, except a small association with poor prosocial behavior (adjusted OR 1.12; 95% CI 1.01–1.23; p=0.031), likely due to chance. Retrospective cohort (103,043 subjects): no significant association between thimerosal exposure and autism; hazard ratio for tics increased (HR 1.62; 95% CI 1.05–2.50), but no autism link. Ecologic study (278,624 children): observed increased risk of neurodevelopmental disorders including autism with ethylmercury exposure, but design limitations undermine causal inference. Other ecologic studies showed autism prevalence increased despite reduced thimerosal exposure. Overall, epidemiologic evidence does not support a causal link between thimerosal-containing vaccines and autism.

Referenced In

Lee Johnson
2 months ago
A Scientific Review of Claims made by RFK Jr.

Claim: The CDC Covered Up Data Proving a Link Between the Hepatitis Vaccine and Autism

Validity: False and misleading

“[I]n 1999, [the CDC] brought in a team of scientists under a Belgian researcher named Thomas Verstraeten, and they looked at the data, they looked at children who had received the hepatitis vaccine within the first 30 days of life and compared those children to children who had received the vaccine later or not at all. And they found an 1135% elevated risk of autism among the vaccinated children. And it shocked them. They kept the study secret and they manipulated it through five different iterations to try to bury the link.”

RFK, Jr., speaking on the Tucker Carlson Show last year

RFK Jr. Provides an Update on His Mission to End Skyrocketing Autism and Declassifying Kennedy FilesThis week, a federal court basically hit the “undo” button on RFK, Jr.’s hand-picked vaccine committee, including their recommendation to remove six vaccinations – including hepatitis A and B – from the childhood vaccine schedule earlier this year.

But why oppose these vaccines? Taking a single example – hepatitis – RFK Jr.’s comments on the Tucker Carlson Show from 2025 show his main opposition to the vaccine.

He claims that the CDC “buried” a link uncovered by a 1999 study from Thomas Verstraeten, which showed huge increases in autism among those exposed to the vaccine.

Did the CDC Cover Up the Data?

No.

RFK Jr. is referencing the first phase of a two-phase study, which was submitted to a conference. As with basically all conference papers, only the abstract is available. The paper looks at thimerosal-containing vaccines, comparing unexposed kids to those with the highest exposure at 1 month of age. It alleged an almost 8-fold increased risk of autism in this group.

However, the full, peer-reviewed publication from this study concluded that there were “no consistent significant associations” between thimerosal-containing vaccines and neurodevelopmental outcomes. This difference was, in part, because the second phase involved confirmation of diagnoses.

So it is completely false to claim this was covered up. In fact, the CDC approved the conference abstract RFK Jr. is referencing, and the paper was later published. 

Do Thimerosal-Containing Vaccines Cause Autism?

No. Epidemiological evidence has consistently shown that there is no link between thimerosal exposure and autism. And finally, thimerosal was removed from all childhood vaccines except certain flu vaccines from 1999 onwards.

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