Do Vaccines Cause Autism? Mercury Debate Intensifies


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Thimerosal Molecule: Image by Ben Mills

The “Danish Study”

The study in question, “Thimerosal and the Occurrence of Austism: Negative Ecological Evidence from Danish Population-Based Data,” published in the journal of Pediatrics on September 1, 2003, examined the possible link between thimerosal and autism. In this study, researchers in Denmark conducted an analysis of data from the Danish Psychiatric Central Research Register. Researchers recorded all psychiatric admissions since 1971, and all outpatient psychiatric departments in Denmark since 1995. The study included a total of 956 children between the ages of two and ten who were diagnosed with autism between 1971 and 2000. The conclusion of the study states,

“The discontinuation of thimerosal-containing vaccines in Denmark in 1992 was followed by an increase in the incidence of autism. Our ecological data do not support a correlation between thimerosal-containing vaccines and the incidence of autism.” 

Problems with the Danish Study

The problems with the Danish Study, one of many studies that have found no link between thimerosal in vaccinations and autism, include allegations of data errors and missing information, as well as the indictment of one of the study’s authors for financial crimes in connection with the study.

  • According to reports from 11 Alive, a Georgia news station, the study left out large amounts of data, such as changes in sample size, which may have affected the legitimacy of the study’s conclusions.
  • The Coalition for Mercury-free Drugs (CoMeD) headed by Dr. Mark Geier sent out a press-release  in late October, entitled, “Scandal Exposed in Major Study of Autism and Mercury.” According to the site’s research, including this email, obtained from a Freedom of Information Act request, the authors of the “Danish Study” found that autism rates actually fell when thimerosal was taken out of the vaccines, but did not include that information in the study’s conclusions.
  • According to the Atlanta Business Chronicle, Dr. Poul Thorsen, a co-author of the Danish Study, was indicted in April of 2011 for 13 accounts of wire fraud, and nine accounts of money laundering, which resulted in the alleged theft of $1 million from the CDC grant.

Decoded Science reached out to the CDC for comment on these developments, but has received no response as of publication.

Vaccination vs. Autism

Vaccinations save lives: Image courtesy of the CDC

Vaccination is a critical method of preventing illness, but many parents are concerned about the mercury content of vaccines, and avoid vaccination to prevent autism. There are a number of studies available that demonstrate the safety of vaccinations, and there are formulations available without thimerosal, so if you are concerned about your child’s vaccinations, talk to your doctor.


U.S Food and Drug Administration. “Thimersal in Vaccines.” March 31, 2010. Accessed on November 11, 2011.

Coalition for Mercury-Free Drugs. “Scandal Exposed in Major Study of Autism and Mercury.” October 25, 2011. Accessed on November 12, 2011.

11 Alive. “Vaccine Researcher Flees with $2 Million.” March 10, 2010. Accessed on November 11, 2011.

Atlanta Business Chronicle. “Dane indicted for defrauding CDC.” April 13, 2011. Accessed on November 10, 2011.

Madsen, Kreesten M., Marlene B. Lauritsen, Carsten B. Pedersen, Poul Thorsen, Anne-Marie Plesner, Peter H. Andersen, and Preben B. Mortensen. 2003. “Thimerosal and the Occurrence of Autism: Negative Ecological Evidence From Danish Population-Based Data.” Pediatrics 112 (3): 604 -606.

*This article does not constitute medical advice. Consult your physician for information about the safety of individual vaccines.*

Updated 11/12/2011

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