Thimerosal in vaccines: Opposition to Mercury Ban Waning

The state chapters of the American Academy of Pediatrics and the American Academy of Family Physicians had opposed the bill on various grounds — warning mainly that it could lead to vaccine shortages.

On Tuesday, the pediatrics group said it had switched to a neutral stance, based on Pavley's acceptance of modest amendments. Tom Riley, a lobbyist for the family physicians group, said Tuesday that it also was reassessing its stand.

The state Department of Finance is on record in opposition to the bill, on grounds it will cost the state extra to purchase thimerosal-free vaccine.

According to state health officials, the added cost would be about $40,000 per year.

Closely watched by federal health officials and the vaccine industry, the bill is advancing at a time of mounting concern over environmental exposures to mercury, a potent neurotoxin. It also comes amid scientific debate and legal battles over whether thimerosal in children's shots has contributed to a sharp rise in reported cases of autism and other neurological disorders.

Last month, experts from the Institute of Medicine, a branch of the National Academy of Sciences, declared that the evidence does not support a causal link between thimerosal and autism.

But a few studies have suggested there is a link. And Marie C. McCormick, a professor at the Harvard School of Public Health who led the Institute of Medicine panel, said regardless of its findings it was wise "to reduce as much as possible exposure to mercury from all causes."

Proposed thimerosal bans are also pending in a few other states, and a weaker version of the Pavley bill was adopted in Iowa earlier this year. Legislation pending in Congress to eliminate thimerosal from vaccines has 13 Democratic and 10 Republican co-sponsors.

The academy of pediatrics five years ago joined federal officials in urging the pharmaceutical industry to eliminate thimerosal from routinely administered pediatric vaccines. Parent activists said the group's opposition to the California bill represented a reversal of that stand.

That the nation's leading organization of pediatricians had opposed "a ban on mercury in vaccines does not speak well for its leadership," said Barbara Loe Fisher, co-founder of the National Vaccine Information Center, a group that promotes safer vaccines.

"Pediatricians across the country should be joining with parents in seeking a ban on exposing children to mercury in any form," she said.

Rick Rollens, a co-founder of the MIND Institute at UC Davis and parent of an autistic son, said fear of a vaccine shortage was a "bogus" issue. He argued that the real concern is avoiding any step that could "erode confidence in the overall immunization program."

Thimerosal is 49.6% ethyl mercury, a different form than the methyl mercury in power plant emissions and fish. Ethyl mercury has been less well-studied, but some research suggests it is more easily eliminated from the body.

Thimerosal is regarded as the most effective of several preservatives used to prevent the growth of bacteria and fungus during production of vaccines. It is diluted to trace concentrations in vaccines sold in single-dose vials or syringes. But producers add extra preservative to vaccine packed in 10-dose vials to resist contamination when needles puncture the seal. Over the years, doctors and clinics favored the 10-dose vials because they were cheaper and easier to store.

But things began to change in 1999, when the U.S. Public Health Service and academy of pediatrics called on the industry, as a precaution, to eliminate thimerosal by switching to single-dose vials.

In doing so, they acknowledged a major oversight: Under the country's increasingly aggressive policy of childhood immunizations during the 1990s, they had failed to grasp that many infants were being exposed to mercury in doses exceeding Environmental Protection Agency guidelines.

Now, thimerosal is being reintroduced in one type of pediatric vaccine, after a decision earlier this year to add flu shots to the list of fully recommended childhood immunizations.

That's because Aventis Pasteur Inc., the only maker of flu vaccines for infants 6 months through 23 months old, is marketing them in both single-dose thimerosal-free and multi-dose thimerosal-laced containers.

According to some estimates, making thimerosal-free vaccine results in the loss of as much as one-third of the vaccine volume, mainly because of spillage from filling single-dose containers. And while vaccine makers haven't publicly warned of supply problems, the academies of pediatrics and family physicians had raised the issue of shortages.

Eliminating thimerosal "would save everybody a big headache" by encouraging parents to have their children vaccinated, said Dr. Dean Blumberg, an associate professor of pediatrics at UC Davis, and chairman of the academy of pediatrics' committee on infectious disease in California.

But if there is not enough thimerosal-free vaccine, "California's children are going to be left out in the cold and unprotected from a potentially deadly disease," Blumberg said.

Pavley said that while doctors were raising the shortage issue, vaccine manufacturers "have not been involved in this at all."

Indeed, Aventis Pasteur is not opposing the bill or saying it won't be able to produce enough thimerosal-free vaccine by 2006.

"Aventis Pasteur has not taken a position on this specific bill," the company said in a statement. "However, in general, we oppose any legislation that would interfere with the public availability of FDA-approved vaccines and unnecessarily undermines public confidence in national vaccine policy."

On Tuesday, the academy of pediatrics said it would withdraw its opposition because Pavley had agreed to two changes — a six-month delay in the start of the ban, from January to July 2006, and a provision for temporary waiver of the ban in case of a public health emergency.