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Mercury in Childhood Vaccination

Posted by medconsumers on January 1, 2004

Study Finds No Autism Link to Mercury in Childhood Vaccinnations—Findings are Challenged

A new study, which had been designed to detect a link between the rise in autism and the mercury in vaccines, found no such danger to children born in the 1990s when the greatest number of mercury-containing vaccinations was administered. The feel-good results, from the U.S. Centers for Disease Control and Prevention (CDC), were immediately challenged by an advocacy organization armed with documents obtained through the Freedom of Information Act.

Thimerosal is a mercury-based preservative added to vaccines in order to prevent bacterial contamination. Even at low levels, mercury has long been known to be a potent toxin with adverse effects on the brains and nervous systems of fetuses and young children.

Thimerosal has been in vaccines since the 1930s, but the amount in each vaccine is so minute that safety was never an issue until the standard vaccination regimen expanded and tripled the dose of mercury administered to infants in the first months of life. A baby born in the 1990s received as many as 17 vaccinations for up to ten different diseases in the first 18 months of life. The regimen typically began within hours of birth and continued every two months thereafter. (A baby born in the 1940s would have received one vaccination around age five.)

The cumulative effect of a known toxin in the small body of an infant or toddler led the Food and Drug Administration (FDA), in 1999, to ask manufacturers to voluntarily remove thimerosal from the vaccines routinely administered to children. The FDA action was based on the belated realization among public health officials that the mercury exposure from vaccines had become higher than the safe threshold set by the federal guidelines for food sources of mercury (e.g., large fish).

As things stand now, the schedule of vaccines administered to babies under 18 months has expanded to include the pneumonia and flu vaccines, but thimerosal has been removed from most of the products*. Mercury-related concerns center upon the children born in the era when the mercury burden was highest. There is a growing suspicion that mercury is implicated in the dramatic increase in the number of children diagnosed with a neurological disorder called autism. This possibility got a boost from a 2001 Institute of Medicine report that concluded, it was “biologically plausible,” though not proven, that thimerosal could be related to neurodevelopmental delays in some children.

The prevalence of autism is estimated by the CDC to be ten times higher today than it was in the studies conducted in the U.S. during the 1980s and early 1990s. The rate now is approximately one in 300. The incidence of autism is four times more common in boys. The potential for lawsuits is extremely high should the link between autism and thimerosal ever be confirmed.

The Centers for Disease Control (CDC) may not be the most objective group to settle the question of thimerosal safety, as it is the federal agency that mandates the number and type of childhood vaccinations. The new study was led by the CDC’s Thomas Verstraeten, MD, and published in the November issue of Pediatrics, the journal of the American Academy of Pediatrics. Dr. Verstraeten now works for GlaxoSmithKline, one of the world’s largest vaccine manufacturers.

The new CDC study looked at more than 140,000 infants who were born in the 1990s and were in the care of three large HMOs. An increase in tics and language delay was found to be associated with cumulative exposure to mercury in the first 3-7 months of life. “No consistent significant associations were found between thimerosal-containing vaccines and neurodevelopmental outcomes,” concluded the CDC study.

But Dr. Verstraeten and colleagues did initially find a statistically significant link between thimerosal and autism. This is evident from documents obtained through the Freedom of Information Act by Safe Minds, an organization funded primarily by parents of autistic children. Included in these documents are the original study and the changes made thereafter. The most interesting document contains “highlights” of the discussions from a closed meeting in 2000 when CDC and other officials gathered to decide what to do next—after the first phase of the study indicated an increase in autism among children subjected to the highest level of mercury exposure.

In the transcript of the meeting, the physicians, scientists and vaccine company executives come across less as truth seekers than as people exploring ways to change the methodology for the next phase of the study in order to come up with a more favorable conclusion. Several spoke as if they wished the study had never have been initiated in the first place. One physician at the meeting said that he did not want his newborn grandson to get a thimerosal-containing vaccine “until we know better what is going on.” Two weeks later, the same physician, who is a member of the CDC’s Advisory Committee on Immunization Practices, voted against a policy of telling parents to request thimerosal-free vaccines for their babies, according to Safe Minds.

The documents show that the CDC study went through major changes on the way to publication. According to an analysis of these documents conducted by Safe Minds, the HMO databases used for the subsequent phase of the study appear to have been selected to “skew the results” and find “inconsistencies” in the data.

According to the Safe Minds spokesperson Sallie Bernard, Dr. Verstraeten, who is the lead author of the study, should not have been listed as a CDC employee when the study was published in November 2003. “Dr. Verstraeten left the CDC in 2001 to work for GlaxoSmithKline,” she said in a telephone interview. “The study went through many major changes since then, and as the lead author, Dr. Verstraeten was responsible for overseeing these alterations, which were done while he was an employee of the vaccine company.”

For More Information:
The documents retrieved from the CDC through the Freedom of Information Act are available at Safe Minds describes itself as an organization that encourages research efforts to understand scientifically how mercury may be causing health problems and to identify effective treatments. The organization is working to have mercury removed from all medical products. It provides lists of currently used thimerosal-containing medical products (by brand) for children and adults, as well as information about environmental and food sources of mercury.

*There are a few exceptions, such as some of brands of the flu vaccine currently advised for babies over age six months.

Maryann Napoli, January 2004

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