THE BLOG
09/30/2007 08:02 pm ET Updated May 25, 2011

Congress Finds Nothing Underhanded About CDC's Thimerosal Work

A Senate committee commissioned 18 months ago to investigate whether federal agencies had cooked the books on their thimerosal research found no evidence to support these claims in a report it issued Friday.

Several members of Congress, spurred by groups like SafeMinds and the National Autism Association, have alleged that the Centers for Disease Control and other public health agencies covered up evidence that the measles vaccine and shots containing thimerosal, a preservative, caused what they described as a nationwide epidemic of autism and other diseases.

David Kirby's 2005 book Evidence of Harm, told from the perspective of SafeMinds and other parents of autistic children, alleged that the CDC and the Institute of Medicine had covered up secret documents and meetings where evidence of harm from thimerosal was discussed. This theory has spread widely on the Internet and has been picked up by celebrities, alternative medical practitioners and a few scientists involved in the thousands of legal claims filed by the parents of autistic children.

In response to the claims, in 2005 the Health, Education, Labor and Pensions Committee began an inquiry. It reviewed thousands of relevant documents and interviewed 80 witnesses to pursue the allegations, which included claims that the IOM's Immunization Safety Review Committee was compromised by CDC influence, that the CDC held a June 2000 conference to cover up evidence that thimerosal causes autism, and that the CDC investigation's lead author was pressured into changing his research position alleging a link to autism.

Each of these allegations was "not substantiated" by the investigation. While there were "injudicious remarks" by participants at the CDC-organized 2000 conference at the Simpsonwood resort in Georgia, "allegations of a coverup are not substantiated" because the CDC freely distributed all the data at the meeting and made the transcript available to the public. The 52 participants at the conference agreed that the dataset that initially suggested a link to neurological problems was too weak to rely upon.

Thomas Verstraeten, lead author of the initial CDC research, left CDC to work for a drug company in his native Belgium about a year after that conference, and conspiracists cited this as evidence of a tit-for-tat agreement to cover up evidence from the study. That isn't true, the committee found. Verstraeten's temporary job at CDC ended and he went home.

The report also concluded that the IOM's vaccine safety committee, which issued a 2004 report clearing thimerosal as a cause of autism, was acting independently of the CDC in making that judgment.

Nothing in the Senate report is news to those who have closely followed the subject. But groups who alleged a coverup had been counting upon Congress for a political stamp of approval.
Interestingly, the one allegation confirmed by the committee was that the Food and Drug Administration had "inappropriately" utilized Environmental Protection Agency guidelines regarding the toxicity of mercury in vaccines containing thimerosal.

The FDA's decision, during its 1999 risk assessment of thimerosal, to use the EPA guidelines -- which were stricter than its own at the time -- were a key element in unleashing the entire controversy. The risk assessment indicated that thimerosal levels in vaccines might be higher than EPA-established threshholds. But the EPA limits were based on studies of methyl mercury, a compound often found in sea animals that is similar but not identical to the ethyl mercury in thimerosal. The committee said that it understood the FDA had little data on which to make its assessment, but still described it as inappropriate.

The committee declined to comment directly on allegations that thimerosal causes autism. It said it would leave that up to the scientific community to decide. But its report appears to conclude Congress' pursuit of the CDC over this matter.