Ban on all mercury-based products would risk global immunization efforts, says AAP, WHO

doi:10.1542/aapnews.20120601-1

The Academy has endorsed a recommendation by the World Health Organization’s Strategic Advisory Group of Experts (SAGE) on Immunization that the preservative thimerosal be retained for use in the global vaccine supply.

The announcement is in response to a United Nations Environment Programme (UNEP) proposal to completely eliminate mercury in all products and processes. Such a ban would mean thimerosal, which contains ethylmercury, could not be used in any vaccine products worldwide.

“As many as 84 million children globally are dependent on vaccines whose safe distribution requires availability of thimerosal as a preservative,” said Louis Z. Cooper, M.D., FAAP, an AAP past president (2001-’02) who works closely with the International Pediatric Association.

Thimerosal is included in various vaccines in resource-poor countries that rely on the more affordable multi-use vials. In the United States, thimerosal is found in only one childhood influenza vaccine and in trace amounts in a few others as part of the manufacturing process.

Despite claims of anti-vaccine proponents who have erroneously linked thimerosal to autism, studies over the past 15 years have not shown evidence of harm. Some of those activists confused ethylmercury with the dangerous neurotoxin methylmercury.

“You’re going to have some people who feel that any amount of mercury in the environment is not a good thing,” said Michael Brady, M.D., FAAP, chair of the AAP Committee on Infectious Diseases.

“Thimerosal does contain mercury, and it is reasonable to try and reduce the amount of mercury that exists in the environment,” Dr. Brady said. “However, the portion of mercury in the environment that is resulting from thimerosal in vaccines is infinitesimally small. And its current use has allowed us to safely provide vaccines to millions of children around the world.”

Reporting on recommendations from SAGE, the WHO’s May 26 Weekly Epidemiological Record states that replacing thimerosal with an alternative preservative may affect the quality, safety and efficacy of vaccines. SAGE proposed — and the Academy concurs — that this portion of the ban should be dropped from the UNEP plan.

“There is insufficient existing manufacturing capacity to remove thimerosal and switch to single-use vials,” WHO noted in the May 26 article, adding there would be significant cold-chain, storage and waste management implications. The report predicted some vaccine products would become unavailable, especially the tetanus toxoid, diphtheria-tetanus-whole cell pertussis, and hepatitis B vaccines. There could be serious disruption to routine immunization programs and mass immunization campaigns with a sizable increase in mortality, for “exceedingly limited environmental benefit.”

In 1999, a joint statement from the Academy and others sought to move toward thimerosal-free vaccines as a precautionary measure, though no evidence of harm existed. At that time, the Academy and other groups erred on the side of caution, Dr. Brady said.

UNEP has been working to reduce mercury use since 2003. In 2009, the group’s governing council requested a committee prepare a “global legally binding instrument” or treaty on mercury, to be completed in 2013. As part of the process before ratification, outside parties are allowed to submit comments.

The health community “has an obligation, country by country” to make sure that accurate information is being disseminated, Dr. Cooper said. Among other groups endorsing the SAGE recommendation is the Pediatric Infectious Diseases Society.

WHO had provided independent health information to the UNEP committee in fall 2011. At that time, a group of 40 professional associations and research programs including the Academy sent a letter to UNEP commending efforts to recognize the harms of some types of mercury but expressing concern about limiting availability of vaccines containing mercury-added products.

“There is no evidence that suggests the amount of ethylmercury found in thimerosal-containing vaccines is harmful to human health,” the letter read.

The UNEP committee will take up the matter again at a meeting June 27-July 2 and again in January 2013.

For more information, read the UNEP document at www.unep.org/hazardoussubstances/Portals/9/Mercury/Documents/INC3/3_6_health_advance.pdf. The WHO report can be found at www.who.int/wer/2012/wer8721.pdf. Read frequently asked questions about thimerosal at www.cdc.gov/vaccinesafety/Concerns/thimerosal/thimerosal_faqs.html.