Has Thimerosal Actually Been Removed From Vaccines? If Not, Of What Value Are the Epidemiological Studies?

Are the epidemiological studies relied upon by public authorities to refute assertions that the mercury based vaccine preservative thimerosal is responsible for some or all autism cases reliable?

These studies tend to show that autism rates did not decline after removal of thimerosal from vaccines. This past year the epidemiological defense of vaccines took a hit with the Poling case and with assertions by Dr. Bernardine Healy, a former director of the American Red Cross and the US National Institutes of Health, that the necessary clinical research to refute such a connection had not been done, particularly into subsets of children who might be genetically vulnerable or prediposed to develop when autism triggered by mercury or other toxins? Dr. Healy stated in Fighting the Autism-Vaccine War, US News & World Report, April 10, 2008, that:

“vaccine experts tend to look at the population as a whole, not at individual patients. And population studies are not granular enough to detect individual metabolic, genetic, or immunological variation that might make some children under certain circumstances susceptible to neurological complications after vaccination.

She also stated, amongst other points, that:

thimerosal crosses the placenta, and pregnant women are advised to get flu shots, which often contain it.

I find that last statement very troubling. If the epidemiological studies are based on the premise that thimerosal has been removed from vaccines and in fact they have not then what is the probative value, if any, of the epidemiological studies? Particularly given the pregnancy context cited by Dr. Healy.

I am only a humble small town lawyer in Fredericton, New Brunswick, Canada but my concern is prompted in significant part by the information provided by a prominent and accomplished member of the US medical establishment. Other credible sources also lead me to the same concern about whether thimerosal has, or has not, been removed from vaccines as claimed in the public health authorities' refutations of vaccine-autism connections.

As of this posting the web site of the US Food and Drug Administration states: Over the past several years, because of an increasing awareness of the theoretical potential for neurotoxicity of even low levels of organomercurials and because of the increased number of thimerosal containing vaccines that had been added to the infant immunization schedule, concerns about the use of thimerosal in vaccines and other products have been raised. Indeed, because of these concerns, the Food and Drug Administration has worked with, and continues to work with, vaccine manufacturers to reduce or eliminate thimerosal from vaccines.

Thimerosal has been removed from or reduced to trace amounts in all vaccines routinely recommended for children 6 years of age and younger, with the exception of inactivated influenza vaccine (see Table 1). A preservative-free version of the inactivated influenza vaccine (contains trace amounts of thimerosal) is available in limited supply at this time for use in infants, children and pregnant women. Some vaccines such as Td, which is indicated for older children (≥ 7 years of age) and adults, are also now available in formulations that are free of thimerosal or contain only trace amounts. Vaccines with trace amounts of thimerosal contain 1 microgram or less of mercury per dose.

The above, current statements from the US FDA, raise several concerns for me:

1) Theoretical potential for neurotoxicity of even low levels of organomercurials

The use of the term "theoretical potential for neurotoxicity" tells me that potential toxcity of organomercurials has NOT been definitively ruled out by the FDA. I appreciate that the expression is used in an historical context to explain the decision to remove mercury based preservatives from vaccines but surely the FDA web site would have immediately stated after that comment that there was no longer even a theoretical potential if such were the case.

2) continues to work with, vaccine manufacturers to reduce or eliminate thimerosal from vaccines.

Again, this information is taken from the web site of the US FDA as it exists today. Why are they continuing to reduce or eliminate thimerosal from vaccines if the epidemiological studies were based on the premise that thimerosal had already been removed? I appreciate that some of the studies are from other countries but have those countries all completely removed thimerosal from vaccines? If so, why were those other countries able to completely remove thimerosal when the US can not?

In the United States a study by the California Department of Health released in February 2008 found that autism rates remained steady after the removal of thimerosal from vaccines. That study conclusion was qualified though by Dr. Robert Schechter, a health officer with the California health department and lead author on the report of the study as reported in the Lexington-Herald, February 5, 2008:

As for Haley's argument that some children still might be getting some mercury from vaccines, Schechter said that could be true. But he said the general removal of thimerosal from vaccines still should have caused autism rates to fall -- if mercury were the culprit in the disease. "I would not claim that children are getting no mercury from vaccines," Schechter said. "But the average exposure for the population has been substantially decreased over the past decade. If mercury from vaccinations was a primary cause of autism, you would expect rates to be dropping substantially."

Substantial decrease is not the same as total removal of mercury from vaccines. The California epidemiological study, at least, is not based on removal of mercury from vaccines.

3) Trace amounts

The FDA site, as quoted above, states that vaccines with trace amounts of thimerosal contain 1 microgram or less of mercury per dose. That certainly sounds like a very small amount and the implication appears to be that the amount is too small to have any effect. But the FDA also referred to the theoretical potential for neurotoxicity of even low levels of organomercurials.

It seems dubious to claim that epidemiological studies show no autism increase after removal of mercury-thimerosal if all elements of the material have not in fact been removed when the potential for neurotoxicity is recognized even in small amounts. Partcularly since the FDA, as stated above, considers vaccines with trace amounts to be vaccines with the mercury removed:

A preservative-free version of the inactivated influenza vaccine (contains trace amounts of thimerosal) is available in limited supply at this time for use in infants, children and pregnant women.

Why leave trace amounts in the vaccines to begin with? If trace amounts of thimerosal can still have a preservative effect on bacteria in the vaccines then why can't they also have a neurotoxic effect on children receiving the vaccines? And some of the flu vaccines, the ones not considered thimerosal free, contain more than trace amounts of thimerosal.

I am not a medical authority and do not pretend to be. Nor do I claim that vaccines or thimerosal cause autism. As some one who does earn his living by some degree of critical thinking and analysis I find the statements of public health authorities about epidemiological studies refuting a vaccine-autism link open to question.

Their own statements appear to contradict their claims that the studies refuting a vaccine-autism link are based on periods when thimerosal was removed from vaccines.

autism