Keep Thimerosal in Vaccines, Says AAP

Preventing ban on thimerosal in vaccines urged by pediatricians and WHO

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) Vaccines contain different ingredients besides the ones that create an immunity against disease in our bodies. One of the most debated ingredients is called thimerosal.

The American Academy of Pediatricians (AAP) is pressuring the United Nations not to ban thimerosal from vaccines in their international treaty related to mercury safety.

"There is no credible scientific evidence that the use of thimerosal in vaccines presents any risk to human health," wrote Katherine King, PhD, MSc, in Pediatrics today. Dr. King is from St. Michael's Hospital in Toronto.

The AAP argues that removing thimerosal from vaccines is unjust and will endanger children across the world who may lose access to vaccines for deadly diseases.

"Vaccinate your children."

Thimerosal is made from inorganic mercury, called ethylmercury. It is used as a preservative in flu vaccines in the U.S. and in childhood vaccines across the world.

In 1999, the U.S. removed thimerosal from all childhood vaccines except certain flu vaccines because of concerns about the effects of mercury.

It was possible that getting multiple vaccines would lead a child to receive more thimerosal than the upper limit of methylmercury recommended by the Environmental Protection Agency.

However, thimerosal is made from ethylmercury, which is very different from the neurotoxin methylmercury. The body processes and disposes of ethylmercury much more quickly than methylmercury, and ethylmercury does not pose the same dangers to the brain and development that too much methylmercury can cause.

In 1999, doctors and researchers did not have enough information about ethylmercury to be certain beyond any doubt that it was safe, so it was removed from vaccines in the U.S. and in other high-income countries that could afford to remove it.

However, today much more is known about the safety of ethylmercury, and over 120 countries continue to use thimerosal in their vaccines. Approximately 84 million children are immunized with vaccines that contain thimerosal every year, the AAP reports, preventing approximately 1.4 million deaths.

As a preservative, the thimerosal allows the vaccines to be made more cheaply and to be stored more easily and cheaply. Getting rid of thimerosal would cost over $300 million for vaccines given by UNICEF and the Pan American Health Organization, according to Dr. King, of the Ethical, Social, and Cultural Program for Global Health at St. Michael’s Hospital.

If an international treaty containing a ban on thimerosal in vaccines is passed by the United Nations, doctors at the AAP and officials at the World Health Organization argue that this could endanger the lives of those children if it restricts their access to the vaccines.

"In the absence of risk to human health, the use of thimerosal in vaccination programs in lower- and middle-income countries presents no threat of injustice," Dr. King writes. "Rather, it is banning thimerosal that would cause an injustice to those living in lower- and middle-income countries and relying on these vaccines for effective protection against many harmful infectious diseases."

A total of three articles in Pediatrics argue the same point. One of the articles, written by Louis Cooper, MD, a pediatrician at Columbia University, and Samuel Katz, MD, a pediatrician at Duke University School of Medicine, reviews the history of thimerosal in vaccines.

Both Dr. Cooper and Dr. Katz were involved in the decision to remove thimerosal from vaccines. One side issue was concern about the now-debunked study linking autism to certain vaccines.

Now that study has been debunked and researchers know there is no link between vaccines and autism or between thimerosal and any health conditions.

Therefore, write Dr. Cooper and Dr. Katz, "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."

Reviewed by: 
Review Date: 
December 15, 2012
Last Updated:
December 21, 2012