Infectious disease chief: Thimerosal debate might affect flu vaccinations

How much mercury is too much mercury?

Dr. Paul Offit, the chief of the section of infectious diseases at the Children's Hospital of Philadelphia spoke to reporters in a national conference call Wednesday to address the safety of vaccines containing thi-merosal, a mercury-containing preservative.

Offit said the clinical research to date suggests no link between thimerosal and autism. He is fearful that parents are carelessly taking chances by not immunizing infants against influenza.

"What we've got to do is ask ourselves where do the real risks lie," he said. "We know every year 75 to 150 children die of influenza, we also know that thousands are infected, and we know an influenza vaccine will induce a protective antibody level that will protect a child from infection. So a choice not to vaccinate is a choice that has serious health risks associated with it."

The Environmental Protection Agency says mercury ingestion of more than 0.1 micrograms of mercury per kilograms of bodyweight is unsafe. The Centers for Disease Control currently recommends annual influenza shots for children older than six months.

Mercury is a naturally occurring substance found in the earth's crust. Offit said it is normal in the bloodstream at low levels and is deadly at high levels. Offit said when an infant breast feeds, he or she naturally ingests 360 micrograms of ethylmercury in the first six months of life. This figure dwarfs the 25 micrograms contained in vaccinations, he said.

The FDA, however, warns that pregnant women should eat no more than 12 ounces of fish weekly because of mercury content.

Offit cited an incident in the early 1970s when wheat dressed with ethylmercury was used for bread in an Iraqi town. The resulting mercury poisoning was one of the worst in history resulting in an estimated 10,000 deaths. Pregnant women and infants ingested the bread making it a tragic case study in the effects of mercury. The result: cases of mental retardation and epilepsy, but no autism.

"There are differences between the symptoms for mercury poisoning and those for autism, and the differences are clear and constant," said Offit.

A 2000 study by Safe Minds, an autism awareness organization, found 34 symptoms common to autism and mercury poisoning.

Offit has been an outspoken supporter of thimerosal's safety. He has appeared on programs such as CBS's "60 Minutes" and written editorials published in national newspapers including the Wall Street Journal. His critics, however, believe he has close ties to the pharmaceutical industry including a shared patent on a rotavirus vaccine and a research grant from Merck & Co.

New Study Makes Waves

A study published in the March 10 issue of The Journal of American Physicians by father and son research team David and Dr. Mark Geier indicates a drop of 22 percent in the occurrences of autism when thimerosal was removed from childhood vaccinations.

The Geier study used a joint CDC and FDA database and a California study from the state's Department of Developmental Services as the pool from which to draw data.

Offit said the study is unreliable and called it "a hypothesis generating mechanism." Offit also said spikes in autism rates may be attributable to "broadened diagnosis," where more high functioning autistic children are treated than in previous years.

David Geier, reached by telephone, said his study controlled for that potentiality. "In the case of the California data they don't accept people with the Asperger or pervasive developmental delay syndrome. Those people in California can't get into the program, so we didn't look at those people," he said. "And the facts remain that the instances in California went from 1 in 2,000 in the late '80s to 1 in 300 children born in late 90s."

Offit, however, worried that bad information provided by the Geiers would cause parents of autistic children to choose dangerous medical alternatives with the hope of curing autism. He cited chelation therapy used to flush out heavy metals and Lupron used for chemical castration as dangerous and unproven "cures" backed by parents and doctors.

The Geiers were at the forefront of using Lupron which they believe helps treat excessive testosterone levels in autistic patients. Geier defended its use as "following the scientific framework," and "the way medicine works."

Bird flu worries

With bird flu stoking global fears, Offit said he hopes that science trumps pseudoscience when it comes to vaccinations. "The mercury is much less than what you're exposed to during your daily routine, but we're going to move away from it in the interest of political correctness," he said. "Just wait, the government when they make a pandemic vaccine they will make it with thimerosal, because there is not a chance in hell they would spend the money for that many single-dose vowels."

Geier said that would be a scary proposition.

He sees a trend in the government's stance on thimerosal. "The preference has gone from in 1999 of 'let's get it out of vaccines' to 2004 when they said 'we should show no preference,' and now in 2006 the preference we're hearing from them is 'let's use thimerosal whenever possible.' It's very disturbing," he said.

tgreaney@semissourian.com

335-6611, extension 245