12/17/2012 04:38 pm ET

Thimerosal Should Not Be Banned From Vaccines Used Around The World, AAP Says

Thimerosal, a vaccine preservative that contains mercury, should not be banned from vaccines around the world, according to a statement put out by a major pediatricians group today.

The New York Times explained that the United Nations is planning to meet next month to talk about eliminating mercury-releasing factors that could pose health risks -- including the mercury-containing thimerosal. But in the new statement, the American Academy of Pediatrics endorsed the position of a World Health Organization committee against the banning of thimerosal.

"The preponderance of available evidence has failed to demonstrate serious harm associated with thimerosal in vaccines. As such, we extend our strongest support to the recent Strategic Advisory Group of Experts recommendations to retain the use of thimerosal in the global vaccine supply," according to the AAP statement.

The New York Times reported that thimerosal's purpose in vaccines is to stop bacteria and fungus from growing and contaminating multidose vials. Thimerosal had been used in vaccines since the 1930s, but it has slowly been phased out of many child vaccines in the U.S. The Centers of Disease Control and Prevention explains why:

Over the past several years, because of an increasing awareness of the theoretical potential for neurotoxicity of even low levels of organomercurials and because of the increased number of thimerosal containing vaccines that had been added to the infant immunization schedule, concerns about the use of thimerosal in vaccines and other products have been raised. Indeed, because of these concerns, the Food and Drug Administration has worked with, and continues to work with, vaccine manufacturers to reduce or eliminate thimerosal from vaccines.

Now, all vaccines recommended for kids ages 6 and younger do not contain thimerosal, and only some flu vaccines contain the preservative, according to the CDC.

However, in 1999, the FDA did a sweeping review of the evidence of potential health risks from thimerosal, and "found no evidence of harm from the use of thimerosal as a vaccine preservative, other than local hypersensitivity reactions," according to the AAP statement.

That same year, Reuters reported that the AAP endorsed the removal of thimerosal from vaccines because its health risks were uncertain (its role in autism -- though discounted now -- was especially of high concern, though in 2004, the Institute of Medicine released a statement saying it found no "causal relationship between thimerosal-containing vaccines and autism.")

Now, "the bottom line is basically, it doesn't look as if it does" cause any harm, Dr. Louis Cooper, on the board of directors of the AAP at the time of the 1999 decision, told Reuters.

The writers of the AAP position statement explained that while thimerosal is no longer used in many vaccines in the U.S., it "remains an important vaccine preservative in resource-poor countries," they wrote. "Thimerosal allows the use of multiuse vials, which reduce vaccine cost and the demand on already constrained cold-chain systems. Even in the United States, thimerosal could be critical for dealing with emergencies and the need to rapidly increase vaccine supply and delivery, such as during a serious pandemic of influenza."

Reuters reported that especially in developing countries -- where it's more feasible to use multidose vaccines instead of single-dose vaccines -- thimerosal could help to improve the ability to get kids vaccinated, while keeping costs down.

"If we had to take the thimerosal out of those multi-dose vials, we're having a hard time completing the task of getting every kid immunized now, that would add a tremendous burden," Cooper told Reuters.