Fact Check: "Thimerosal has been proven safe in vaccines for over 20 years."
What We Know
Thimerosal is a mercury-based preservative that has been used in vaccines, particularly in multi-dose vials, to prevent bacterial and fungal contamination. According to the CDC, there is no evidence of harm caused by the low doses of thimerosal in vaccines, with the most common side effects being minor reactions like redness and swelling at the injection site. In 1999, a precautionary measure led to the agreement to reduce or eliminate thimerosal in vaccines, although it was never found to be harmful in the doses used.
Research has consistently shown no link between thimerosal and autism or neuropsychological delays. For instance, a 2010 study by the CDC concluded that prenatal and infant exposure to thimerosal-containing vaccines does not increase the risk of autism spectrum disorder (ASD) (CDC, 2010). Furthermore, the Institute of Medicine reviewed over 200 studies and found no association between thimerosal-containing vaccines and autism.
Despite its safety profile, thimerosal has been removed from most childhood vaccines in the U.S. since 2001, although some flu vaccines still contain it in multi-dose vials. The World Health Organization has stated that thimerosal does not need to be removed from vaccines for safety reasons, while the European Medicines Agency recommended favoring mercury-free alternatives for children.
Analysis
The claim that thimerosal has been proven safe in vaccines for over 20 years is partially true. While extensive research supports the safety of thimerosal in the doses used in vaccines, the context of its removal from most childhood vaccines and the ongoing debate about its use in some flu vaccines complicates the assertion.
The CDC and other reputable sources have consistently affirmed the safety of thimerosal, stating that there is no evidence linking it to autism or any significant health risks. However, the precautionary measures taken to eliminate thimerosal from most childhood vaccines reflect a response to public concern rather than a definitive finding of harm. This indicates that while thimerosal is considered safe based on scientific evidence, the decision to remove it was influenced by social factors and public perception.
The reliability of sources such as the CDC and the Institute of Medicine is high, as they are backed by extensive research and expert consensus. However, the ongoing discussions around thimerosal, particularly in the context of vaccine safety debates, can lead to misunderstandings about its safety profile.
Conclusion
The claim that "thimerosal has been proven safe in vaccines for over 20 years" is partially true. While scientific evidence supports the safety of thimerosal in vaccines, the removal of thimerosal from most childhood vaccines and the ongoing debates surrounding its use indicate that the issue is more nuanced than the claim suggests. The safety of thimerosal is well-documented, but the precautionary measures taken reflect a broader context of public health policy and perception.
Sources
- Thimerosal and Vaccines | Vaccine Safety | CDC
- Tiomersaali – Wikipedia
- Thiomersal - Wikipedia
- What to Know About the Vaccine Preservative Thimerosal
- Thiomersal - World Health Organization (WHO)
- What Is Thimerosal? Why Most Vaccines Don’t Contain Mercury Anymore
- What to know about thimerosal, a target of RFK Jr.’s new CDC
- Is There Thimerosal in Vaccines, And Is It Safe? Here's What The Science Says
