Thimerosal Is Not Mercury. RFK Jr. Still Refuses to Learn Basic Chemistry.
RFK Jr’s Minamata Convention video weaponizes ignorance, ignores basic chemistry, and will cause millions of vaccine-preventable deaths globally.
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This week RFK Jr. released a video addressed to the Minamata Convention on Mercury where he lied about vaccines. Again. And again. The same lies he has been spreading for over twenty years. Twenty years. This man has been lying—and causing preventable deaths—for decades, while making millions and millions of dollars from it.
As someone who has been so painfully aware of how much of a global health threat RFK Jr is, it pains me that so many media outlets, members of the public, and politicians just glossed over his career of lying about life-saving health issues.
Anyway, I digress.
He told the COP6 delegates that now that he has ensured no American have access to vaccines containing thimerosal, he was taking his plan global. This isn’t shaping policy, it’s propagating a deadly lie.
If you recall, he announced a policy earlier this year to ban all thimerosal-containing vaccines here in the US, even though thimerosal is an incredibly safe and effective antimicrobial that prevents contamination in multi-dose vaccines.
He said that “no amount of mercury should ever be injected into a child” and urged the treaty to push for a global ban on thimerosal-containing vaccines.
Thankfully, the Minamata Convention is not staffed with unqualified anti-science profiteers like RFK Jr, but this one statement alone sums up everything wrong with RFK Jr’s war on science.
Samoa was the real-world case study: when RFK Jr’s lies spread faster than the truth, children die. We know the damage this will cause. We’ve seen what happens when RFK Jr’s anti-vaccine lies target people, like in Samoa, where his lies killed more children in a month than thimerosal ever has.
His thimerosal lies will kill children, especially the most vulnerable.
And though scientific experts globally (real ones, not cosplaying grifters like RFK Jr and his ACIP appointees) understand basic chemistry, the difference between thimerosal and mercury, and vaccine safety data, RFK Jr posted this on social media, which means his lies have the potential to influence public opinion and behaviors.
Let’s get into it.
RFK Jr’s central lie: pretending all “mercury” is the same to scare people
For decades RFK Jr has refused to learn basic chemistry. In fact, he hasn’t changed his language even when legitimate experts have, in good faith, tried to educate him.
A note: you will continue to see me say “lies” when referring to his claims: he says falsehoods deliberately, knowing they are false. That is the definition of a lie. I don’t care about media outlets sanitizing him, sane-washing him, trying to talk out of both sides of their mouth. It is long past the time of politeness. He is killing people—and making millions of dollars at the same time.
Like with all chemophobia, his argument relies on people believing that any and all chemical compounds that include an atom or ion of mercury are 1) the same and 2) dangerous in all instances.
This is chemically, biologically, and toxicologically wrong.
Thimerosal isn’t mercury. But to RFK Jr, facts don’t matter.
A decision last month by RFK Jr.’s fake vaccine advisory panel is about to kill children—just not American ones.
He’s financially and ideologically invested in being wrong — he even published a book amplifying these lies (with his anti-science grifting buddy Mark Hyman right there beside him).
But here’s the reality:
Thimerosal is not mercury. It prevents dangerous bacterial and fungal contamination in vaccines.
Thimerosal keeps vaccines safe—it does not make vaccines dangerous.
Thimerosal is a chemical compound with formula C9H9HgNaO2S. The IUPAC name for thimerosal is Ethyl(2-mercaptobenzoato-(2-)-O,S) mercurate(1-) sodium.
That sure doesn’t sound like “mercury” does it?
Thimerosal was developed in the 1920s and is a very effective antimicrobial, meaning it prevents contamination with harmful bacteria and fungi.
Thimerosal is so effective only a miniscule amount is needed. It can inhibit microbial growth at concentrations of 0.001% to 0.01% w/v (weight/volume). In a vaccine vial, this would equate to 50 micrograms (µg) of thimerosal (containing 25 µg mercury ion) per 0.5 mL vaccine dose. This is why it is used to prevent bacterial contamination in multi-dose vaccines.
I’m sure you can see that C9H9HgNaO2S is not the same as mercury. Chemicals are not the sum of their parts. These bonds dramatically change everything about a chemical compound. That’s why table salt, sodium chloride (NaCl), doesn’t explode when you put it in water. Sodium explodes when you put it in water, though!
Claiming thimerosal is mercury is like saying water (formula H2O) is hydrogen gas (H2).
Or that glucose (C6H12O6) is the same as diamonds (a lattice structure of C atoms) because it has carbon in it.
Or that air, a mixture of gases, is nitrogen gas.
If anti-vaccine activists actually applied their own “logic,” they’d be warning people that table salt explodes in water. Funny how chemistry errors only show up when there’s profit involved.
Mercury is a pure chemical element, a metal with formula Hg⁰
Yep, that’s it. A pure metal. Elemental mercury is the silver liquid metal (yes, the only metal that is liquid at room temperature and pressure) that used to fill thermometers.
Mercury poisoning can occur through exposure to mercury metal. Today, this risk is primarily if you inhale mercury gas (liquid mercury that has been vaporized). This potential exposure is mostly a concern for people who work in industries that use mercury metal—for example, mercury is used to catalyze chemical reactions to extract gold from ore.
Elemental mercury poisoning can be quite serious, because metal mercury can accumulate in your body and can cross the blood-brain barrier at high enough exposures. It can lead to neurological damage, kidney damage, and even death.
Elemental mercury? Never used in a vaccine, ever.
Methylmercury CH₃Hg⁺ is a mercury-containing compound with legitimate health concerns
Methylmercury is also not thimerosal. Methylmercury can also cause mercury poisoning. It is an organic mercury compound created by bacteria through methylation of environmental mercury from volcanic eruptions, burning of fossil fuels and coal, and other industrial processes. Methylmercury is found in the environment ubiquitously; almost everyone has a small amount in their bodies.
It can bioaccumulate, crosses the placenta and blood-brain barrier, and in high doses can cause neurological damage.
Methylmercury? Also never used in a vaccine, ever.
For more on mercury chemistry, read the below article:
Ethylmercury (C₂H₅Hg⁺) is an entirely different mercury-containing compound that’s a metabolite of thimerosal
Thimerosal happens to be a salt, which, in chemistry terms, means it is an ionic compound that dissociates in water into its respective positive (cation) and negative (anion) ions.
The positive ion is ethylmercury, with formula C₂H₅Hg⁺. Ethylmercury is not methylmercury. The names might sound a little similar, but the differences are vast.
Ethylmercury is a larger structure, and unlike methylmercury, is rapidly metabolized and eliminated from the body. It does not bioaccumulate. It is not associated with any neurological issues, including autism, seizures, neurodevelopmental delays, cognitive disorders, and more. It is also not linked to other symptoms associated with mercury poisoning that occurs with high exposure to elemental and methylmercury.
Ethylmercury (rather, thimerosal) is associated with making vaccines accessible and safe for billions of people globally.
RFK Jr pretends that thimerosal and its ethylmercury byproduct are identical to methylmercury. This is chemically illiterate and dangerously ignorant, and even though he has been corrected on this for over two decades, he is now trying to make his grift the official position of US health leadership.
The most ridiculous part? RFK Jr is directing his demand for a global thimerosal ban at an organization that couldn’t care less about ethylmercury, underscoring how ignorant he really is.
The Minamata Convention does not care about ethylmercury or thimerosal.
The Minamata Convention was adopted in 2013 to address environmental persistence of mercury. Specifically, this relates to elemental mercury and methylmercury (you know, the one that is constantly forming in the environment and bioaccumulates).
Methylmercury is why the Minamata Convention is so named.
It’s named for the Minamata Bay tragedy and Minamata disease, a condition resulting from severe methylmercury poisoning.
For those not familiar, Minamata disease was a result of widespread methylmercury poisoning through environmental exposure.
Between 1932 and 1968, industrial wastewater containing inorganic mercury (that was used to catalyze chemical reactions) was discharged into Minamata Bay, where microorganisms converted it into methylmercury — the form that bioaccumulates and causes neurological devastation.
This methylmercury accumulated in fish and shellfish in the local waters at much greater levels than what occurs naturally (from those processes noted above).
People and animals who consumed fish and shellfish from these waters experienced severe mercury poisoning. Children born to people who had mercury poisoning had congenital effects including microcephaly, brain damage, and symptoms similar to neurological disorders like cerebral palsy.
Minamata disease was first characterized in 1956 in a 5-year old girl who had difficulty walking, speaking, and presented with seizures. From there, additional cases were quickly identified in a geographic cluster. Unfortunately (and unknown to them at the time), people in these coastal villages had been exposed to high levels of methylmercury for years. In 1959, the cause was identified to be long-term exposure to high levels of methylmercury.
The efforts of the Minamata Convention are aimed at phasing out use of elemental mercury in batteries, lamps, and as a chemical catalyst.
It has zero to do with a thiosalicylate salt that is a safe and effective vaccine preservative, critically important for multi-dose vaccines where contamination is a risk. If you ban thimerosal, you don’t eliminate mercury, you eliminate vaccines.
The bigger issue?
RFK Jr’s lies about thimerosal, now directed at the Minamata Convention, undermine global vaccine efforts.
In fact, the Minamata Convention explicitly exempts thimerosal-containing vaccines from their scope, because real experts understand vaccines are life-saving. There is no health concerns related to thimerosal-containing vaccines.
This will cost children their lives, even if countries ignore RFK Jr. because his lies are out there and we live in a world where fear matters more than facts.
Countless countries globally use multi-dose vaccines that contain thimerosal. Why? Because multi-dose vaccines offer substantial benefits, particularly among underserved and low income countries.
Multi-dose vaccines are more cost-effective to manufacture, about 2.5 times less costly per dose than single-dose vaccines.
Multi-dose vaccines require less cold storage volume per dose (about 50% less) which is significant in regions with inconsistent access to refrigeration.
Multi-dose vaccines reduce the cost of transport per vaccine dose—so in developing nations with infrastructure limitations, this also reduces barrier to access vaccines.
UNICEF can procure inactivated polio vaccine at $1.25 per dose for multi-dose vaccine compared to $2.80 per dose for single-dose vaccines. When you are talking about low income countries, that 124% difference in cost per dose is substantial.
I know MAHA and RFK Jr. don’t care about these people, but you should.
You should also care about what happens when infectious diseases aren’t controlled by vaccines in one country—because contrary to discourse on social media, pathogens don’t adhere to country borders. Disease anywhere becomes risk everywhere. That’s how outbreaks go global. It’s exactly why we are losing our measles-free status here in the US, only twenty-five years after we eliminated it through vaccination efforts.
Many vaccines contain thimerosal, especially formulations used in low- and middle-income countries.
These include:
Inactivated influenza vaccines
DTP (diphtheria, tetanus, pertussis) vaccines, used in many Gavi-supported countries as it is much lower cost than the DTaP vaccine
Tetanus toxoid (TT), DT, and Td vaccines
Multi-dose hepatitis B vaccines
Meningococcal vaccines, especially those used in Africa’s meningitis belt
Vaccination saves between 3-5 million lives every year. RFK Jr is deliberately undermining this.
RFK Jr is trying to accelerate fear of vaccines. What do you think will happen? You already know, because it happened here in the 1990s. People will be afraid of vaccines that contain this safe and effective preservative.
If they are afraid of those vaccines, they will refuse to receive them for themselves and their children. If vaccine rates decline, that means more preventable illness and death. It also means increased spread of those preventable infectious illnesses that are transmitted person-to-person. Increased spread means more outbreaks, harder to control infections, increased demand on healthcare infrastructure, which will strain healthcare systems so badly that people with unrelated medical needs suffer too.
It also means increased chance of microbial mutation and evolution, potentially opening the door to new strains of pathogens.
Thimerosal has been studied extensively. It is not linked to any neurological issues.
If you live in a country that offers thimerosal-containing vaccines, do not be concerned: your vaccines are safe and effective. The benefits of vaccination far outweigh even a hypothetical risk of miniscule exposure to thimerosal.
If RFK Jr gets his way and countries move to “ban” thimerosal-containing vaccines, nearly 150 million children every year will lose access to life-saving medicines.
For decades, RFK Jr. and his MAHA allies have worked to unravel that progress. His latest move will accelerate the damage. We cannot allow blatant falsehoods to shape science, medicine, and public policy.
RFK Jr. is a threat to global health.
His personal crusade, now cemented in federal policy and amplified as the “official voice of US health agencies”, is reckless, self-serving, and deadly. Science is not the threat. His ignorance is.
We all must join in the fight for science.
Thank you for supporting evidence-based science communication. With outbreaks of preventable diseases, refusal of evidence-based medical interventions, propagation of pseudoscience by prominent public “personalities”, it’s needed now more than ever.
Stay skeptical,
Andrea
ImmunoLogic is written by Dr. Andrea Love, PhD - immunologist and microbiologist. She works full-time in life sciences biotech and has a lifelong passion for closing the science literacy gap and combating pseudoscience and health misinformation. Follow on Instagram, Threads, Twitter, and Facebook, or support the newsletter by subscribing: