Thimerosal carries no health risks and is almost never used anyway. So why are anti-vaxxers obsessed with it?
Publisher’s note: this story does not reflect the more recent developments of the advisory committee on immunization practices, which has Now recommended against the use of flu vaccines containing Thimérosal. Experts, including a single member of the committee, questioned the decision given the lack of risk posed by the curator.
A committee of experts who advise the centers for disease control and prevention on vaccines is a meeting for the first time since the health secretary Robert F. Kennedy Jr. suddenly replaced the 17 members of the Committee With eight hand picked on June 11, 2025.
The Committee called on the advisory committee for vaccination practices, generally discusses and votes on recommendations for specific vaccines. For this meeting, taking place from June 25 to 26, 2025, vaccines for COVID-19, human papillomavirus, flu and other infectious diseases were on the calendar. According to An updated programHowever, the Committee is now also planned to hear a presentation on a chemical called Thimeralal and vote on proposed recommendations concerning its use in antigrippal vaccines.
Public health experts have raised concerns Regarding the presentation, noting that anti-vaccine defenders continue to promote confusion concerning the so-called Thimérosal health risks despite in-depth research demonstrating its safety.
I am a Pharmacist and expert in medication information With 35 years of experience by critically assess the safety and effectiveness of drugs in clinical trials. No evidence supports the idea that Thimérosal, used as a preservative in vaccines, is dangerous or has health risks.
What is Thimérosal?
The Thimérosal, also known as Thiomersal, is a curator who has been used in certain drug products since the 1930s Because it prevents contamination by killing microbes and preventing their growth.
In the human body, thimérosal is metabolized or modified into ethylmercure, an organic derivative of mercury. Infants studies have shown that ethylmercur Quickly eliminated blood.
Ethylmercury is sometimes confused with methylmercury. Methylmercury is known to be toxic and is associated with Many negative effects on brain development even with low exposure. Environmental researchers have identified the neurotoxic effects of mercury in children in the 1970s, resulting from Fish exposure to fish. In the 1990s, the Environmental Protection Agency and the Food and Drug Administration established limits for Maximum exposure recommended to methylmercurEspecially for children, pregnant women and women of childbearing age.
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Why is Thimérosal controversial?
The fears concerning the safety of the Thimérosal in vaccines propagate for two reasons.
First, in 1998, a report now discredited was published in a great medical journal entitled The Lancet. In this document, a British doctor named Andrew Wakefield described eight children who have developed autism After receiving the Ror vaccine, which protects against measles, mumps and rubella. However, patients were not compared to a control group which was vaccinated, so it was impossible to draw conclusions on the effects of the vaccine. In addition, the data report was later found falsified. And the ROR vaccine that children received in this report have never contained Thimérosal.
Secondly, the federal directives on exposure limits for the toxic methylmercury substance were almost at the same time as the publication of the Wakefield study. During this period, autism became more widely recognized as a development condition and its Diagnostic rates increased. The people who believed that the results of Wakefield confused methylmercury and ethylmercure and Promoted the unfounded idea that ethylmercure in Thimérosal vaccines led to the increase in autism rates.
The Wakefield study was retracted in 2010And Wakefield was found guilty Ethics protocols of dishonesty and fluffy UK General Medical Council, as well as stripped of its medical license. Subsequent studies have not shown a relationship between the ROR vaccine and autism, but despite the lack of evidence, the idea was interested and proved to be difficult to dislodge.
Have scientists tested if the Thimérosal is sure?
No impartial research to date has identified the toxicity caused by ethylmercure in vaccines or a link between substance and autism or other development concerns – and not for lack of appearance.
A 1999 review Led by Food and Drug Administration In response to federal directives on the limitation of exposure to mercury No evidence of thimerosal damage As a vaccination preservative other than rare allergic reactions. Despite this, as a precaution in response to concerns about Mercury Exposure in infants, the American Academy of Pediatrics and the US Public Health Service published a joint declaration in 1999 Recommend the abolition of the Thimerosal of Vaccines.
At that time, only one infant vaccine was only available in a version that contained the thimérosal as an ingredient. It was a vaccine called DTP, for diphtheria, tetanus and darling. Other infantile vaccines were only available in formulations without Thimérosal or could be obtained in versions that did not contain it.
In 2001, American manufacturers had withdrawn the Thimérosal from almost all vaccines – and All vaccines in the infant vaccination calendar.
In 2004, the American Institute of Medicine Immunization security review committee examined more than 200 scientific studies and concluded that there is no causal relationship between vaccines and autism containing Thimérosal. Well -conducted additional studies examined independently by the CDC And by the FDA did not find a link between vaccines containing thimerosal and autism or neuropsychological delays.
How is Thimérosal used today?
In the United States, most vaccines are now available in single-dose bottles or syringes. Thimérosal is only found in multidose bottles that are used to provide vaccines for large -scale immunization efforts – especially in a Small number of antigrippal vaccines. It is not added to modern childhood vaccines, and people who obtain a flu vaccine can avoid it by requiring a vaccine provided in a single dose bottle or syringe.
Thimérosal is always used in vaccines in certain other countries to ensure the continuous availability of the necessary vaccines. THE The World Health Organization continues to assert That there is no evidence of toxicity in infants, children or adults exposed to vaccines containing Thimérosal.
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