Vaccination part 13
In the 1930s, concern was raised over potential contamination of vaccines dispensed in multi-dose vials, and the possibility of introducing contaminating bacterial & fungal pathogens during vaccination. Preservatives were introduced to minimize this risk; the most notorious of these being the organomercurial compound thimerosal (thiomersal, sodium ethylmercurithiosalicylate, Merthiolate®).
Other preservatives - the antibiotics neomycin, kanamycin, chlortetracycline, amphotericin B, polymyxin B, gentamicin, & streptomycin - are employed in the manufacture of some vaccines, with trace amounts potentially remaining in the final product. These pose a hypothetical risk of allergy to those sensitive to these compounds.
If you grew up in the 1950s, you were likely familiar with tincture of Merthiolate® (Mercurochrome®), which was slathered on every cut & scrape encountered as a topical antiseptic. (In the mid-1950s, the popular trade name was reapplied to market the non-mercurial antiseptics chlorhexidine digluconate and benzalkonium chloride, still available under the trade names Merthiolate® or Mercurochrome®, which include dyes to mimic the well-known neon-pink color of the original mercurial compound).
In the body, thimerosal is metabolized or degraded to ethylmercury (C2H5Hg+) and thiosalicylate, and may release inorganic mercury by the dealkalinization of ethylmercury. Thimerosal is perhaps best regarded as a means of biological delivery of ethylmercury. Ethylmercury, methylmercury, and elemental mercury are highly neurotoxic and cytotoxic in general.
Methylmercury has been used as a reference for ethylmercury toxicity based on the assumption that the two compounds share comparable toxicokinetic profiles; however studies in non-human primates suggest significant differences in their toxicokinetics.
The CDC suggests
The human body eliminates thimerosal easily.
Thimerosal does not stay in the body a long time so it does not build up and reach harmful levels. When thimerosal enters the body, it breaks down to ethylmercury and thiosalicylate, which are readily eliminated.
Which is overly simplistic to the point of being insulting.
Ethylmercury, like methylmercury, distributes to all body tissues, crossing the blood–brain barrier and the placental barrier. Estimates have suggested that ethylmercury clears from the circulation with a half-life of 3-7 days in adults. However this does not account for its uptake and persistence in tissues, particularly in the central nervous system. In newborn monkeys, ethylmercury readily enters central nervous tissues, and clears the brain with a half-life of 24.2 days (versus 59.5 days for methylmercury), but leaves behind more inorganic mercury in CNS tissues than does methylmercury.
… and “less toxic than methylmercury” hardly exonerates thimerosal as “safe.”
The CDC gaslights on the toxicity of mercury in general:
Mercury is a naturally occurring element found in the earth’s crust, air, soil, and water.
Mercury is a naturally occurring element; so is Plutonium. Many naturally occurring substances are highly toxic. To the CDC’s credit, I suspect they honestly believe in the safety of their products, and paternalistically oversimplify such descriptions to allay public concern.
Concerns based on extrapolations of the effect of methylmercury (the organomercurial of concern as an industrial contaminant in fish) in a statement issued by the American Academy of Pediatrics and the US Public Health Service resulted in the removal of thimerosal from most childhood vaccines manufactured for use in the U.S. in 1999, with thimerosal-containing lots expiring in 2003 , but it remains in use in appreciable quantity in multidose vials (MDV) of the influenza vaccines Afluria MDV, FluLaval, Fluuviron MDV, & Fluzone MDV, in multi dose vials of the DT (diphtheria/tetanus) , the TT (tetanus toxoid) vaccine, the Td (tetanus/diphtheria) vaccine, and the Meningococcal vaccine Menomune, with trace amounts remaining from manufacturing (but not added as preservative to the final product) in the DTaP, DT single dose, and Hepatitis A/B vaccine. Notably, the MMR vaccine has never contained thimerosal.
The removal of an ingredient claimed to be “safe” in order to render vaccines “more safe” has engendered confusion in the medical community, and both confusion & distrust in the general public.
Defense of the continued use of thimerosal in some vaccines rests on the unqualified presumption that it has proven to be safe in 70 years of use in vaccines. From the CDC:
Thimerosal has been shown to be safe when used in vaccines.
Thimerosal use in medical products has a record of being very safe. Data from many studies show no evidence of harm caused by the low doses of thimerosal in vaccines.
, and that it is cleared from the circulation more rapidly than is the highly toxic methylmercury.
We don’t really understand the potential impact of thimerosal in vaccines on the human body. Mercury, in elemental form and as methyl- & ethylmercury, is highly cytotoxic in general (hence its effectiveness as a disinfectant & preservative), with particular neurotoxicity. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8276940/.
A statistical correlation between mercury exposure in vaccines with the rate of reported autism
…together with the known neurotoxicity of mercury and the demonstrated neuroinflammatory nature of autism has implicated thimerosal in the possible etiology of autism. The continued rise of the reported incidence of autism since the removal of thimerosal from childhood vaccinations in 1999/2003 would argue against this hypothesis.
Again, be very cautious of assuming causation from correlation; we could draw similar correlation of the reported incidence of autism with the rising cost of home ownership or the prevalence of reality TV shows.
Mercury is also implicated in altering the gut microbial community, which is implicated in many human illnesses, including autism and autoimmune disease.
Somewhere between the source of a naturally occurring element cleared from the circulation more rapidly than is the highly toxic methylmercury with a “proven track record of being safe,” necessary for the preservation of vaccines distributed in multi-dose vials from bacterial & fungal contamination, and an intensely neurotoxic poster child of widespread vaccine injury, thimerosal continues to be used as a preservative in some vaccines, tho is currently present in vaccines intended for use in children in only trace amounts as remnants from the manufacturing process.
