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"Thimerosal and the Occurrence of Autism: Negative Ecological Evidence from Danish Population-Based Data"
Pediatrics, Kreesten M. Madsen, MD (September 2003)


Written by a Danish vaccine company, the study made a mockery of the data, a problem the authors themselves warned of. And, the CDC engineered the entire study. This one goes beyond useless, it was fraudulent to run the numbers this way, and they knew it.

Actual Question This Study Asked & Answered:

Q: Did the discontinuation of thimerosal use in vaccines in Denmark lead to a decrease in autism?

A: No, autism cases actually rose.

Did the study look at unvaccinated children?


Conflict of Interest (from the study itself):

"The activities of the Danish Epidemiology Science Centre and the National Centre for Register-Based Research are funded by a grant from the Danish National Research Foundation. This study was supported by the Stanley Medical Research Institute." [Two of the seven authors were employees of Denmark’s largest vaccine manufacturer, Statens Serum Institute]

While not mentioned in the study, the study was initiated by the U.S. Centers for Disease Control.

Ability to Generalize:

The study only considered 956 children with autism. Worse, a material change in how autism data is obtained happened right around the time the numbers of autism cases seemed to grow, rendering the data meaningless. From

The study looked at data between 1970-2000. In 1995, the Danish registry added "Outpatient Clinics" to their count of autism cases. It turns out that Outpatient Clinics are where 93% of Danish children are diagnosed with autism, so the number of autism cases before 1995 did not include the clinics. More surprising, the authors even note this in the study: "since 1995 outpatient activities were registered as well...the proportion of outpatient to inpatient activities was about 4 to 6 times as many outpatients as inpatients...this may exaggerate the incidence rates."

Exaggerate the incidence rates? It is the equivalent of doing a study on "Divorce Rates in North America" and counting Mexico and Canada only for the first few years, then adding in the United States, and noting that divorce rates went up. As a SafeMinds critique of the study noted, "Therefore, their purported increase after 1994 can be explained entirely by the registration of an existing autism population that did not require hospitalization." To compound the problem, Denmark also changed the diagnostic code they used, to the more universal ICD10 code, beginning in 1993, which would have further raised the rates.

Post-Publication Criticism:

Significant. The study’s "fatal flaw" was evident to all who read the study, and it was largely dismissed by the autism community as having no merit whatsoever. But, the media and people like Amanda Peet still talk about it.

Scoring (Out of 40 possible points):

Asked the Right Question: 1

Ability to Generalize: 0

Conflict of Interest: 0

Post-Publication Criticism: 0

Total Score: 1

Choice Excerpt from the Study:

"Also, outpatient activities were included in the Danish Psychiatric Central Research Register in 1995 and because many patients with autism in former years have been treated as outpatients this may exaggerate the incidence rates, simply because a number of patients attending the child psychiatric treatment system before 1995 were recorded for the first time, and thereby counted as new cases in the incidence rates."

Meaning: we didn’t count 93% of the kids diagnosed with autism in Denmark during the time mercury was in vaccines, then we did once it was removed.

Guest Critic: Mark Blaxill, SafeMinds Click on link for complete document.

Danish Thimerosal-Autism Study in Pediatrics: Misleading and Uninformative on Autism-Mercury Link


"A report by Madsen et al. published by the American Academy of Pediatrics in their journal Pediatrics1 claims to provide evidence against a link between autism rates and the mercury in thimerosal, a preservative used in childhood vaccines. Unfortunately, the study analysis is full of flaws and inaccuracies, invalidating the conclusions regarding thimerosal. The study adds little of value to the scientific literature on autism and mercury.

The report provides information on autism rates in Denmark that is distorted and misleading. These distortions allow the authors to make assertions about a rising trend in autism "incidence" in the 1990s that has no basis in fact."