Vaccines may pose mercury hazard for kids

By Kathleen Fackelmann, USA TODAY

Infants and children should not get vaccines with the mercury-containing preservative thimerosal, says an Institute of Medicine report that was issued Monday.

The report found no scientific proof that the small doses of thimerosal in vaccines caused any harm. "This should be reassuring news for parents," says Marie McCormick, chairwoman of the IOM panel that issued the report. Yet the panel couldn't dismiss possible problems related to thimerosal, a preservative added to vaccines. Thimerosal contains ethylmercury, a form of the heavy metal mercury that at high levels can lead to neurological problems.

Manufacturers routinely used thimerosal in vaccines starting in the 1930s, the report noted. In 1999, some scientists grew concerned that low levels of ethylmercury in vaccines might add up and cause neurological problems in some children. That concern fell short of proof, however.

To be on the safe side, the Food and Drug Administration asked manufacturers to take thimerosal out of their vaccines. They did so, and by mid-2000, thimerosal-free vaccines were widely available.

To get a bias-free analysis of the scientific evidence, the IOM, an independent scientific group that advises federal policymakers, appointed a panel of 15 experts. The panel spent a year reviewing the scientific evidence on thimerosal and neurodevelopmental disorders such as autism, attention deficit disorder, and speech and language delays.

The panel found that the scientific evidence was not conclusive, yet the group did find cause for concern about these vaccines.

The panel reviewed preliminary evidence from one study that found a link between thimerosal vaccines and language and speech delays in children. That study, which is not yet complete, did not find a link between the vaccine and autism, McCormick says.

In addition, the panel noted that some scientists had found a connection between very high doses of thimerosal (much higher than the amounts found in vaccines) and neurological problems in adults and children.

The report also notes that some of the thimerosal vaccines are still on the shelves in some clinics. The vaccines in question are those for hepatitis B, diphtheria, tetanus, whooping cough and haemophilus influenzae type B.

The IOM panel says parents should ask that their child receive thimerosal-free vaccines. But if unavailable, they should still get the vaccinations for their child.

Parents should insist on getting thimerosal-free vaccines for their kids, says Sallie Bernard, the executive director of the New Jersey-based Safe Minds, a group calling for the recall of all thimerosal vaccines.