A group of prominent doctors and public health experts warns in articles to be published Monday in the journal Pediatrics that banning thimerosal, a mercury compound used as a preservative in vaccines, would devastate public health efforts in developing countries.
Representatives from governments around the world will meet in Geneva next month in a session convened by the United Nations Environmental Program to prepare a global treaty to reduce health hazards by banning certain products and processes that release mercury into the environment.
But a proposal that the ban include thimerosal, which has been used since the 1930s to prevent bacterial and fungal contamination in multidose vials of vaccines, has drawn strong criticism from pediatricians.
They say that the ethyl-mercury compound is critical for vaccine use in the developing world, where multidose vials are a mainstay.
Banning it would require switching to single-dose vials for vaccines, which would cost far more and require new networks of cold storage facilities and additional capacity for waste disposal, the authors of the articles said.
“The result would be millions of people, predominantly in low- and middle-income countries, with significantly restricted access to lifesaving vaccines for many years,” they wrote.
In the United States, thimerosal has not been used in children’s vaccines since the early 2000s after the Food and Drug Administration and public health groups came under pressure from advocacy groups that believed there was an association between the compound and autism in children.
At the time, few, if any, studies had evaluated the compound’s safety, so the American Academy of Pediatrics called for its elimination in children’s vaccines, a recommendation that the authors argued was made under the principle of “do no harm.”
Since then, however, there has been a lot of research, and the evidence is overwhelming that thimerosal is not harmful, the authors said. Louis Z. Cooper, a former president of the academy and one of the authors, said that if the members had known then what they know now, they never would have recommended against using it. “Science clearly documented that we can’t find hazards from thimerosal in vaccines,” he said. “The preservative plays a critical role in distribution of vaccine to the global community. It was a no-brainer what our position needed to be.”
Advocacy groups have lobbied to include the substance in the ban, and some global health experts worry that because the government representatives due to vote next month are for the most part ministers of environment, not health, they may not appreciate the consequences of banning thimerosal in vaccines. The Pediatrics articles are timed to raise a warning before the meeting.
“If you don’t know about this, and you’re a minister of environment who doesn’t usually deal with health, it’s confusing,” said Heidi Larson, senior lecturer at the London School of Hygiene and Tropical Medicine, who runs the Vaccine Confidence Project.
In an open letter to the United Nations Environmental Program and the World Health Organization this year, the Coalition for Mercury-Free Drugs, a nonprofit group that supports the ban, disputed the assertion that scientific studies had offered proof that thimerosal is safe, and urged member states to include it in the ban.
That it is being used in developing countries, but not developed countries, is an “injustice,” the letter said.
The World Health Organization has also weighed in. In April, a group of experts on immunization wrote in a report that they were “gravely concerned that current global discussions may threaten access to thimerosal-containing vaccines without scientific justification.”
Dr. Larson said she believed that the efforts of pediatricians and global health experts, including the W.H.O., would influence the negotiations in Geneva and that the compound would most likely be left out of the final ban.
“You can’t just pull the plug on something without having a plan for an alternative,” she said.
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