Thimerosal is a preservative commonly used to prevent bacterial and fungal growth in items such
as makeup, contact lens solutions, vaccines, and more [1]. Because of its antimicrobial abilities,
thimerosal is commonly used in multi-dose vials of vaccines, including flu vaccines, meaning that
the dose in the vial is enough to vaccinate more than one person [2]. When a new needle is
inserted into the multi-dose vial, it increases the chances of contamination of the vaccine contents
[2]. This is when thimerosal comes into play and prevents this contamination from happening
when each vaccine dose is drawn out.
as makeup, contact lens solutions, vaccines, and more [1]. Because of its antimicrobial abilities,
thimerosal is commonly used in multi-dose vials of vaccines, including flu vaccines, meaning that
the dose in the vial is enough to vaccinate more than one person [2]. When a new needle is
inserted into the multi-dose vial, it increases the chances of contamination of the vaccine contents
[2]. This is when thimerosal comes into play and prevents this contamination from happening
when each vaccine dose is drawn out.
Once thimerosal enters the body, it is quickly broken down to ethylmercury, which became the
root of the biggest controversy regarding vaccines; do they cause autism? [2]. Back in the late
1900’s, a researcher named Andrew Wakefield claimed to have found that exposure to
methylmercury, a highly toxic compound to humans and animals, from thimerosal in vaccines
was the underlying cause of autism in children [2]. This sparked debate, which led to the removal
of thimerosal as a preservative in vaccines [2]. Later on, it was found that Wakefield’s findings
and claims were false [2]. From this, it was clear that the terms methylmercury and
ethylmercury were being used interchangeably, when in reality, thimerosal only contains
ethylmercury, which is eliminated from the body much faster than methylmercury and is,
therefore, less likely to be harmful [2]. Further studies also showed that the amount of
thimerosal in vaccines was small enough to not have any major negative effects on children’s
health [2].
root of the biggest controversy regarding vaccines; do they cause autism? [2]. Back in the late
1900’s, a researcher named Andrew Wakefield claimed to have found that exposure to
methylmercury, a highly toxic compound to humans and animals, from thimerosal in vaccines
was the underlying cause of autism in children [2]. This sparked debate, which led to the removal
of thimerosal as a preservative in vaccines [2]. Later on, it was found that Wakefield’s findings
and claims were false [2]. From this, it was clear that the terms methylmercury and
ethylmercury were being used interchangeably, when in reality, thimerosal only contains
ethylmercury, which is eliminated from the body much faster than methylmercury and is,
therefore, less likely to be harmful [2]. Further studies also showed that the amount of
thimerosal in vaccines was small enough to not have any major negative effects on children’s
health [2].
Despite the fact that the link between thimerosal and autism has been broken, this preservative
continues to get removed from vaccines as a precautionary action and more parents have
been encouraged to vaccinate their children against the flu virus in order to actually prevent a
disease [3].
[1]Thimerosal https://www.drugbank.ca/drugs/DB11590 (accessed Jan 20, 2018).
[2] Kleinfeld, S. Thimerosal and Childhood Vaccines. http://faculty.virginia.edu/metals/cases/kleinfeld2.html (accessed Jan 20, 2018).
[3] Alternative for Thimerosal as Preservatives for Vaccines. European Medicines Agency http://who.int/immunization/sage/meetings/2012/april/Alternatives_thiomersal_preservatives_vaccines.pdf (accessed Jan 20, 2018).
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