What is thimerosal?
Thimerosal is a preservative that contains mercury that was used regularly in the United States, until 1999 when the American Academy of Pediatrics and Public Health Service Agencies called for a reduction or elimination of the vaccine in order to take precautions. The type of mercury found in thimerosal is ethlymercury which is cleared at faster rates than other types of mercury exposure and less likely to cause harm. When thimersoal enters the body, it is eliminated fairly quickly which makes it a low risk for accumulating harmful levels in the body.
Although it has been showed to be very safe and effective, the most common side effect are minor reactions such as swelling or redness at the site of injection. Thimerosal is implemented into vaccine in order to prevent the growth and reproduction of bacteria and fungi. This is done because vaccines can contain more than one does and there is potential of the syringe needle that enters a vial being contaminated by germs which can cause illness.
In the late 1990s, single dose preservative free vaccines were spread widely across high-income countries because of the concerns that the mercury contained in thimerosal may build up and cause toxicity. Although, this fear is false it has had great impact on low and middle income countries where vaccine preventable diseases thrive, because multidose vials of vaccine containing the preservative are critical in immunization programs abroad. The switch to single dose vials increases the cost of shipping, cold-chain storage, manufacturing, administration, and waste handling.
In 2013, multidose vaccines containing the ingredient thimerosal were used in almost 120 countries and saved the lives of 1.4 million people annually so a potential ban would prove catastrophic. This method of vaccine is responsible for the manufacturing of tetanus toxoid, diphtehria- tetanus-whole cell pertussis, and the Hep B vaccine. Utlimately a ban would be an injustice to many. Complying with a ban of the ingredient would require the countries involved to use only single dose vaccines which would put a strain on the public health infrastructure of many countries and they also may face interruptions in the supply of vaccines.
After rigorous review, thimerosal was approved for multidose vials of vaccine in accordance with the World Health Organization (WHO) standards. Although it is possible to replace this ingredient with other preservatives on the market, none compare to the viability of thimersosal. Replacing thimerosal could also cause instability in vaccine safety and efficacy and would require progressive and detailed testing which may prove very time-consuming.
In conclusion, thimerosal has not revealed any evidence that it causes harm, except for acute local hypersensitivity reactions to those who may be allergic. Although, thimerosal has been proven safe some infants exposed to cumulative levels of mercury found within the preservative that exceed EPA recommendation for those under 6 months of age. However, other products are available and formulated without thimerosal that can eliminate the risk for those under 6 months.
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