Preservatives in Vaccines

by on March 18, 2013

in News

Q: I have decided not to vaccinate my children, because I am concerned that some vaccines contain mercury. When will all vaccines be mercury-free?

A: In order for vaccines to be free of contamination, experts decided as far back as the 1930s to use ethyl mercury as a preservative. This avoids the risk of vaccines getting contaminated by bacteria and fungi when multidose vials are used. (A multidose vial is where the vial containing the vaccine is punctured each time the vaccine is given, thus running the risk of getting contaminated) Vaccines are one of the most effective ways to prevent infectious diseases and deaths globally. (The Canadian Pediatric Society published a book intended for parents, “Your Child’s Best Shot: a parent’s guide to immunization”) However, the safety of vaccines has also become extremely controversial—especially over the past 2 decades.

A growing number of parents remain concerned about the use of thimerosal in vaccines–even though this preservative, which contains ethyl mercury, has been around for over 60 years and even though it has been studied extensively for its safety. The unsubstantiated suspicion that it could be neurotoxic may be one reason for lower vaccine rates in some parts of North America.

During the mid 1990s some researchers speculated that there is a link between exposure to ethyl mercury and autism. In the USA it set off a political storm which became quite inflamed by a famous actress and a Congressman who had relatives with autism. This forced the hand of influential pediatric organizations such as the American Academy of Pediatrics to come out with a position statement.

In 1999 a landmark position paper was published by the AAP indicating that the research at the time did not confirm any dangers associated with vaccines containing a thimerosal preservative. Nevertheless, the AAP felt that given the political and social pressures by influential people—even when 60 years of scientific data, did not identify any dangers—that all vaccines should be free of ethyl mercury.

One must point out that methyl mercury on the other hand is indeed neurotoxic because it has the potential to accumulate in the body over time. This type of mercury is not found in any vaccine. It is therefore critically important not to confuse methyl mercury with ethyl mercury.

This whole controversy has now intensified more than ever before. The World Health Organizations Environmental Program (UNEP) is developing an international treaty to eliminate all mercury exposure—-including removing mercury from thermometers, blood pressure measurement tools and possibly all vaccines.

This has sparked a massive dilemma, which birthed three back—to—back articles in the January 2013 copy of the journal Pediatrics. The first article, authored by a heavyweight expert in the field of vaccinations, Dr. Walter Orenstein, pleads for the UNEP to exempt ethyl mercury from their goal of eliminating all exposures to mercury, including multidose vial vaccines.

The second article authored by Drs Louis Cooper and Samuel Katz—both influential doctors who served on the board of the AAP or wrote the 1999 position paper calling for the elimination of mercury from vaccines— explains why the AAP now reversed their 1999 position regarding thimerosal in vaccines. The AAP feels that since 1999 enough studies have shown the safety of the thimerosal. The authors end their article with saying “Had the AAP known what research between 1999 and 2012 has revealed about the safety of thimerosal, it is inconceivable to us that the AAP would have made their 1999 statement” In the third paper, authors from the University of Toronto point out that currently multidose vaccines containing thimerosal are used in over 120 countries to immunize close to 84 million children every year. Switching over to single dose vials with no ethyl mercury in it will lead to more waste of vaccines, require more storage space and increase the cost of vaccines by an estimated $300 million. They also appeal to the UNEP to go ahead and eliminate all mercury exposure worldwide, except for ethyl mercury because it has been proven to be safe.

What about the use of alternative preservatives, which, potentially can work just as well as thimerosal? Thus far there are none that satisfy safety standards and robust scientific research. However, the search for alternative preservatives continues and the recent advice given to the WHO can be found HERE

My own opinion is that this controversy regarding preservatives in vaccines is a bit like confetti, pollution and toothpaste: once it is out there it is hard to get it back. In other words, no matter how many millions of studies show ethyl mercury to be safe, the perception that it is unsafe will remain in the minds of some who vehemently oppose its use. Perception has indeed trumped reality.

For more information on vaccine safety in general, see the website of the Johns Hopkins Bloomberg School of Public Health

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