MONDAY, Dec. 17 (HealthDay News) -- A United Nations proposal to
ban the vaccine preservative thimerosal -- which contains a form of
mercury -- should not go through, says a leading group of U.S.
The American Academy of Pediatrics (AAP) joins the World Health
Organization (WHO) in urging the U.N. to drop the proposal from an
international treaty seeking to cut down on mercury exposures in a
variety of ways. Both the WHO and AAP say a thimerosal ban could
keep children in poor nations from getting needed vaccines.
The AAP, which announced its stance to members in June,
reiterates its position and provides three commentaries on the
issue in the January print edition of
Pediatrics, published online Dec. 17.
Thimerosal contains a form of mercury called ethyl mercury. For
years it was used in certain vaccines, but U.S. health officials
decided in 1999 that thimerosal should be removed from most
vaccines given to young children. (The exception is some flu
That was done as a precautionary measure until researchers could
learn more about how the ethyl mercury in thimerosal might affect
children's development. Ethyl mercury is different from methyl
mercury -- the form found in the environment that can harm young
children's developing brains.
"Back then, there were no guidelines on ethyl mercury exposure," said Dr. Paul Offit, chief of infectious diseases at Children's Hospital of Philadelphia.
"So the thinking at the time was, let's exercise the precautionary principle," Offit said.
Numerous international studies since have uncovered no evidence
of harm -- including no link between thimerosal and autism, which
had been a concern. The U.S. Centers for Disease Control and
Prevention says there is "no convincing evidence of harm caused by
the low doses of thimerosal in vaccines."
Given that, banning thimerosal globally could erode the already
low vaccination rates in developing countries for no potential
benefit, said Dr. Walter Orenstein, a member of the AAP Committee
on Infectious Diseases and co-author of one of the three new
Developing nations rely on vaccines containing thimerosal,
Orenstein said. The preservative is used in vials that contain more
than one dose of a vaccine, to prevent contamination, which can
happen when a syringe needle is inserted into the vial.
Rich countries such as the United States can get around the need
for thimerosal by using single-dose vials. But for poor countries,
multi-dose vials make vaccination programs more feasible, Orenstein
Switching to single-dose vials would pose practical problems.
For instance, local clinics would need much more refrigeration
space to house the same number of vaccine doses, Orenstein
Offit agreed. "These countries have limited resources," he said.
"Children there are already under-vaccinated. If there's a ban,
we'll be under-vaccinating them even more."
The AAP and WHO statements are in response to an international
treaty being hammered out by the U.N. Environmental Program. The
treaty would try to reduce mercury exposure from a variety of
sources -- from consumer products to medical equipment to emissions
from coal-fired power plants. The UN is considering including
thimerosal on that list.
Dr. Michael Smith, a pediatric infectious disease specialist at
the University of Louisville in Kentucky, said he agreed with the
"Since 1999, there have been multiple studies that have not found any link between thimerosal and autism, but at the time this information did not exist," Smith said, so the United States decided to be cautious and remove the preservative.
"It turns out this was not necessary," Smith said.
Offit used stronger terms. "We made a mistake in our country,"
he said. "To make the same mistake now, with the information we
have now, it could result in thousands of deaths."
Not everyone is convinced thimerosal is risk-free, though. Among
them is Barbara Loe Fisher, president of the National Vaccine
Information Center, a Virginia-based advocacy group
"If unused vials of thimerosal-containing vaccines must be disposed of as hazardous waste because of the mercury content, then why is the American Academy of Pediatrics strongly advocating that thimerosal-containing vaccines continue to be injected into children's bodies?" Fisher asked.
She added that U.S. health officials have not changed their
stance regarding children here. "The Environmental Protection
Agency and the Food and Drug Administration have not rescinded the
1999 directive to the pharmaceutical industry to take thimerosal
out of childhood vaccines," she said.
And it's unlikely that the agencies will, Orenstein said. "I
don't see any reason that the U.S. would add thimerosal back into
childhood vaccines," he said.
So whatever happens with the U.N. treaty, it probably won't
affect routine childhood vaccinations in the United States. But,
Orenstein noted, a global ban on thimerosal could conceivably be a
problem in the event of an emergency, such as a flu pandemic. If
Americans were suddenly clamoring for the flu vaccine, multi-dose
vials would be the best way to get it out quickly.
The U.S. Centers for Disease Control and Prevention has more
thimerosal in vaccines.
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