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Thimerosal: No Smoking Gun

CDC: No Evidence of Child Brain Damage Due to Vaccine Preservative

Thimerosal and Tics continued...

WebMD asked pediatric neurologist Jonathan W. Mink, MD, PhD, to comment on the CDC study. Mink is chief of child neurology at the University of Rochester, N.Y., and co-chairman of the scientific advisory board for the Tourette Syndrome Association. He was not involved in the CDC study.

"Tics are seen quite commonly in kids with autism. But most kids with tics don't have autism," Mink tells WebMD. "The bottom line is that the rate of tics here is well within the rate we would expect to see in 7- to 10-year-old kids. Some of them have transient tics, which would go away, and some have tics that will never be a problem."

The bottom line, Mink says, is that the study gives "no reason to think that thimerosal or vaccination causes tics."

No Proof of Thimerosal Safety

The CDC asked more than a dozen outside consultants to comment on the study prior to publication of the final manuscript. One was Sallie Bernard, the parent of a child with autism and executive director of Safe Minds. Safe Minds is one of the groups working to convince parents that medical use of mercury causes autism and other child health problems.

Bernard formally dissents with the CDC's conclusion that the study "does not support a causal association between early exposure to mercury from thimerosal-containing vaccines and immune globulins and deficits in neuropsychological functioning at the age of 7 to 10 years."

In a news release, Bernard points out that lack of evidence of thimerosal harm is not proof of thimerosal safety.

"The [CDC's] conclusion misleads the public, implying without qualification that a relationship has been disproved," Bernard says. "In fact, the study was unable to prove either the presence or absence of a causal relationship."

Bernard points to flaws in the study -- such as the inclusion of a relatively small number of children exposed to very high or very low amounts of thimerosal.

While definitive proof of thimerosal safety remains elusive, so is definitive proof that thimerosal-containing vaccines caused harm. Schuchat says the study findings are "consistent with previous research."

"The findings are very reassuring that exposure to vaccines during the 1990s was not associated with significant problems in children 7-10 years old," she says.

(Do you think the MMR vaccine causes autism? WebMD’s Rod Moser, PA, PhD, says, “No!” Find out why on his blog.)


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