Experts Argue to Keep Thimerosal in Some Vaccines

The mercury component was removed from most childhood vaccines but doctors say an international ban would put more youngsters at risk of infectious diseases.

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The mercury component was removed from most childhood vaccines, but doctors say an international ban would put more youngsters at risk of infectious diseases.

The U.N. Environment Program is discussing ways to lower environmental exposure to mercury, a chemical linked to developmental problems. Part of the proposal involves removing thimerosal, a mercury-based compound used as a preservative to maintain vaccine quality, from immunizations given to children around the world.

The proposed ban could potentially create a situation in which thimerosal-containing immunizations, with their potential but still unknown health risks, are concentrated in lower-resource countries while developed nations rely on thimerosal-free shots, owing primarily to more robust health systems that allow better storage and preservation of the immunizations.

Adding to the growing controversy over the proposed policy, the American Academy of Pediatrics (AAP) endorsed a World Health Organization (WHO) recommendation to continue the use of thimerosal in vaccines. Since the 1930s, thimerosal has been used to prevent bacteria contamination of multidose vaccines like those against pertussis (whooping cough). In 1999, the AAP and the U.S. Public Health Service (USPHS) called for the removal of thimerosal amid concerns the compound was associated with higher rates of autism or other neurodevelopmental disorders. Flu vaccines are among the only shots given to children that still contain the mercury-based compound.

(MORE: How Safe Are Vaccines?)

However, in three papers published in the journal Pediatrics, a group of experts, including a former member of the AAP board of directors back in 1999, say there is now a lack of evidence that thimerosal causes these problems, and that the benefits of keeping thimerosal in vaccines to maintain their quality outweigh any potential health problems associated with exposure to small amount of mercury used. In the past 15 years, studies have found no significant harms linked to thimerosal, and in 2002 the AAP retired its original recommendation against it.

In the new statement, the AAP experts argue thimerosal should not be banned, noting that the preservative is critical for developing countries that rely on the chemical as an inexpensive method to preserve vaccines. Many vaccines are shipped in vials that contain more than one dose, to save on packaging costs. While these can be used to vaccinate more than one child at a time, multidose containers are also more prone to contamination, which is why they are often treated with thimerosal. In the U.S. and Europe, thimerosal has not been used for over 10 years because single-dose vials, which are more expensive to manufacture and which are disposed after they are opened, can be stored in refrigerators until they are needed. That’s not always possible in lower-resource countries, say experts, where many children remain unvaccinated against preventable diseases. Dr. Walter Orenstein of the Emory Vaccine Center at Emory University, an author of one of the papers, told NPR that without thimerosal, diseases like whooping cough could resurge in developing countries.

In addition, in assessing the benefits and risks of retaining thimerosal in vaccines, the WHO’s Strategic Advisory Group of Experts notes that there are no viable alternatives for the preservative and countries currently relying on thimerosal will simply lose their supplies of vaccines if a ban were approved. More children could contract the infections, putting their health at risk. “Global removal of thimerosal has the potential to adversely affect the worldwide vaccine supply,” the authors of one of the Pediatrics papers write.

Making vaccines without the compound could greatly hinder transportation and storage as well as create a spike in manufacturing costs. The WHO estimates it could cost two to five times more to produce vaccines without the mercury-based preservative.

(MORE: Vaccine Safety: New Report Finds Few Adverse Events Linked to Immunizations)

“The World Health Organization recommendation to delete the ban on thimerosal must be heeded or it will cause tremendous damage to current programs to protect all children from death and disability caused by vaccine-preventable diseases,” write two pediatric experts in one of the editorials.

They point out that the removal of thimerosal a decade ago was more out of an abundance of caution than based on any hard evidence of the compound’s health harms. “We made a mistake in our country,” Dr. Paul Offit, chief of infectious diseases at the Children’s Hospital of Philadelphia and co-creator of the rotavirus vaccine said to HealthDay of the removal of thimerosal. “To make the same mistake now, with the information we have now, it could result in thousands of deaths.” They also say that not all forms of mercury have the same effect on the body, and that the U.S. Environmental Protection Agency’s warnings of health harms apply primarily to methyl mercury, which builds up in fish and can remain in the bodies of people who consume fish for long periods of time, causing damage to the central nervous system. Ethyl mercury, the form of mercury found in thimerosal, may be less toxic to people.

The U.N. group will make its decision in January.

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I have concerns related to thimerosol.  Firstly, if there is no studies linking it to autism.  Why exactly were Hannah Polling and Bailey Banks families awarded multi million dollar settlements from the vaccine injury compensation program (VICP), citing vaccines caused their autism?  Secondly why do they even have to go to an administrative hearing instead of being able to utilize their constitutional right to due process of law and sue the manufacturer in a competent court of law?  Lastly, the FDA recommended thimerosol be removed from vaccines in 1999.  Ever since, it has been repeated over and over that thimerosol has been removed from vaccines.  Is there any evidence to show vaccine manufacturers actually did follow this recommendation or are they just saying its removed based soley on the recommendation?


Anne, It is absurd to imply that the collective opinion of American pediatricians has been influenced by the insignificant donations from vaccine manufacturers you cite. An individual pediatrician would receive zero personal benefit from a donation to a national association. Additionally, even supposing a donation or "perk" made directly to an individual pediatrician, do you really believe that an individual who has a passion for caring for children, and who has made numerous sacrifices just to be a pediatrician is going to put the health and well-being of children at risk so that drug companies can sell more vaccines. To believe that requires a belief that the majority of pediatricians are willing to conspire to bring potential harm to millions of children for a relatively tiny financial gain. Absurd. Really.


Thimerosal goes back 75 years. It was invented by Eli Lilly Pharmaceutical Company in 1930. The one “study” on thimerosal was done by Eli Lilly on 22 adult patients suffering from meningitis. There was no chance for follow-up to observe long-term effects, as all of the patients died. Even if follow-up had been possible, damage to the developing brains of very young children would have remained an unknown. Eli Lilly said it was safe and the medical community just accepted it. After the creation of the FDA, its use was simply continued. This unconscionable oversight failure should call any safety claim into question.Anne Dachel, Media editor: Age of Autism


Imagine the argument that banning a know neurotoxin would be bad for kids. In truth, this is egregious discrimination. We’re often told that American children haven’t been exposed to mercury in their vaccines since the early 2000s---except in “some” flu vaccines. Even though there was “no evidence of harm” from thimerosal (a product never tested or approved by the FDA), they removed it from kids’ shots. Then comes the argument that to totally ban it from all vaccines would mean that the poorest counties of South America, Africa, and Asia won’t be able to have their children vaccinated. It seems that the wealthy nations can afford to protect their children from this toxin while the poorest children on Earth will have to suffer the risks from getting cheap, mercury-laced vaccines. It seems that the only winners in this are the vaccine makers.Anne Dachel, Media editor: Age of Autism


On Jul 25, 2008, CBS News aired the story, How Independent Are the Vaccine Defenders? Sharyl Attkisson discussed the American Academy of Pediatrics and the “strong financial ties to the industry whose products they promote and defend.”Attkisson: “The vaccine industry gives millions to the Academy of Pediatrics for conferences, grants, medical education classes—even helped pay to build their new headquarters. The totals are kept secret, but public documents reveal bits and pieces.”Attkisson went on to list the drug companies and their contributions to the AAP:A $342,000 payment Wyeth, from inmaker of the pneumococcal vaccine - which makes $2 billion a year sales.A $433,000 from contribution vaccine -Merck, the same year the academy endorsed Merck's HPV which made $1.5 billion a year in sales.Another top donor: Sanofi Aventis, maker of 17 and a vaccinesnew five-in-one combo shot just added to the childhood vaccine schedule last month.One has to wonder if the AAP is most concerned about the health and safety of children or the interests of the drug industry.Dr. Offit and his ties to Merck were also a part of this CBS story.Anne Dachel, Media editor: Age of Autism