A mercury-containing preservative known as thimerosal, occasionally used in the United States, should not be eliminated as an ingredient in vaccines, according to a disputable American Academy of Pediatrics (AAP) announcement that came yesterday and was published in the journal Pediatrics.

In their statement, the AAP backed recommendations from a World Health Organization (WHO) committee stating that the preservative thimerosal should not be named as a harmful source of mercury and should not be forbidden by the United Nations.

In 1999, the AAP asked for the elimination of thimerosal from vaccines in the United States due to a worry that children receiving several shots containing it might be exposed to a large dose of mercury. They believed this could result in autism or other neurodevelopmental problems, regardless of little concrete evidence available at that time.

Dr. Louis Cooper, from Columbia University in New York, who served on the organization’s board of directors, said:

“It was absolutely a matter of precaution because of the absence of more information. Subsequently an awful lot of effort has been put into trying to sort out whether thimerosal causes any harm to kids, and the bottom line is basically, it doesn’t look as if it does.”

The U.S. Institute of Medicine found in a 2004 safety analysis that there was no evidence thimerosal-containing vaccines result in autism.

A study also published in Pediatrics in 2010 reported that infant exposure to thimerosal does not increase the risk of autism spectrum disorder.

Also, a study done by the CDC in 2007 suggested that there is no link between childhood vaccines and mercury toxicity with neurological development issues.

Besides certain types of flu shots, thimerosal is not used in single-dose vial vaccines in the United States. In less developed nations, where many kids continue to die from vaccine-preventable diseases, it is inexpensive and simpler to use multi-dose vials of vaccines against diseases like tetanus and diphtheria.

Thimerosal stops the remainder of the a multi-dose vial from becoming contaminated with fungi or bacteria every time a dose is used.

Investigators approximate that it may cost two to five times as much to produce vaccines for developing nations without thimerosal, and moving these vaccines and keeping them cold would be more difficult.

Dr. Cooper added, “We’re having a hard time completing the task of getting every kid immunized now. That would add a tremendous burden.” This could result in more preventable child deaths.

Thimerosal includes a kind of mercury known as ethyl mercury. Its toxic effects are linked to its cousin, methyl mercury, which remains inside the body for a long period of time.

A few months back, the WHO pointed out that replacing thimerosal with an alternative preservative could affect the safety of vaccines and also make them less available.

Mercury is on the list of international health hazards to be eliminated in a draft treaty from the United Nations Environment Program, implying a ban on thimerosal.

However, an exception is crucial because thimerosal is important for protecting kids.

Written by Kelly Fitzgerald