¿Que es el timerosal? ¿Es peligroso?

What Is Thimerosal and Why Is It In My Kid’s Vaccines?

By Dr. Byron WhyteApril 14, 2016 2 Comments

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“I don’t wanna put mercury in my baby, Doc; it’s poison.”

After Robert DeNiro’s anti-vaccination massive misstep Tuesday, I’m yet again, dreading hearing these words.

This is where, as a pediatrician, I grit my teeth (sorry, dentists). I know, at this point, that science has lost another battle with fear in the race to inform families first. Since the race has been lost, I know I’m going to have to work from behind to get this child protected from deadly diseases.

There will likely be questions for me.

Questions based on faulty premises.

I will try to counter with evidence-based information.

I will bring up the fact that Andy Wakefield, controversial spokesman for the anti-vaxx movement has had his medical license revoked. I will remind them that they don’t know many people that sleep in iron lungs because of Salk’s polio vaccine. Reluctantly, I may even have to go into my personal life and divulge that my entire household (my wife, two girls and I) is fully vaccinated. These things may or may not sway the family. The conversation may end in an awkward stalemate. There could be a conversion that occurs over months.

I hope not, though, “because deadly diseases ain’t waitin’ on you to decide.” I get colloquial once we’re all good friends.

Sometimes people change their hearts and minds right away when I reassure them; those conversations are more fun, but I am usually wary of the spurious information that is just outside the hospital doors, lurking to seduce patients again.

Robert De Niro Appeared on NBC’s Today Show on Tuesday

Like Tuesday, during The Interview Heard Around the Internet, when one of the greatest (the greatest?) screen actors of all time went full anti-science on the Today Show. Robert DeNiro, in explaining why he regrets the pulling of the movie “Vaxxed: from cover-up to catastrophe” from his Tribeca Film Festival, made some dangerously inaccurate statements about vaccines and autism.

In case you missed the discussions from a few weeks ago, here’s the skinny: Big-time festival announces the screening of a pro-disease (or, anti-vaccination) motion picture, the scientific community loses our collective mind and lets them know it’s a dangerous choice, Big-time festival pulls the movie, anti-vaxxers go up in arms. The science community was FINE with this result (you know, the support of actual scientific fact), even tentatively giddy.

Bobby D pulled no punches in his NBC interview, citing most of the tried-and-true tropes of the antivax movement: he stated that vaccine science is not “settled,” claimed “overnight” changes in children after immunizations, and even gave the ol’ “I’m not anti-vaccine” speech, which is pretty much only said by people that are. I’d love to make a reference to the classic “Just when I thought I was out, they pull me back in”… but that was Pacino’s line.

The reality is that vaccine programs have been heralded as the greatest medical innovation of the last hundred years. We have drastically decreased death from pneumonia, epiglottitis and measles. Even cervical cancer is getting its butt kicked.

Yet we still have neighbors, family members, and very high-profile celebrities who are against or that “question” the safety of vaccinations. You know the ones: they show up on your Facebook timeline once a week with a story about “the medical industrial complex” or tell you that Big Pharma is out to make money by “making our kids zombies.” These folk often have a dubious story to share about a medical catastrophe or grand claims about medical marijuana along the lines of “it also raised my cousin Scott from the dead.”

They seem to be proliferating: an intentionally unvaccinated child recently died of diptheria in Spain, the first case seen there since the 1980s. Then there was the measles outbreak that began in Disneyland last year, largely fueled by families that had refused to vaccinate their children.

How did we get to this point? Why are parents distrusting of the scientists and physicians they chose, and continue to choose to help their own children when they’re ill?

I believe that two, concurrent events happened almost twenty years ago that set this phenomenon in motion:

1) The FDA Modernization Act of 1997 required vaccine manufacturers to give detailed information to the government about all mercury-containing products. At the time, jabs for Hepatitis B, DTaP (diphtheria, tetanus and pertussis) and inactivated Polio had trace to small amounts of thimerosal (a mercury-based preservative) in their ingredients.

2) In 1998, Andrew Wakefield, a UK gastroenterologist published his infamous study in the Lancet that claimed a link between the MMR vaccine and autism (that’s since been retracted – more on that in a moment).

While unrelated scientifically (MMR vaccines have never had mercury as an ingredient), these two events became the bedrock of the modern anti-vaccination movement. The headlines falsely claiming that vaccines cause autism spread quickly throughout the Western world, and vaccine rates plummeted.

As a parent, this stuff sounds terrifying to us. Who would want to cause harm to their own child? Fortunately, we can easily rest our minds against these claims. Let’s start with the thimerosal.

Thimerosal is a mercury-based substance used in multi-dose vials of vaccines as preservative. It kills bacteria and prevents the growth of fungus in the vial, to help keep it sterile and safe for injection. It’s also a substance found in tattoo ink in concentrations thousands of times higher than what is found in vaccines. The compound breaks down into ethylmercury, half of which is broken down and rendered “ineffective” by the body in about a week. Then, we poop it out!

In term of quantities, the amount of mercury given in a yearly flu vaccine is 25 micrograms (mu). The amount needed to kill 50% of living organisms (LD50) is 98 milligrams (mg) per kilogram (kg) of body weight. Remember, 1 milligram is equivalent to 1,000 micograms – so this means that, for a 10 kilogram (about 22 pound) child to have life-threatening effects, the child would need to have 980,000 micrograms of mercury. At one time.

Contrast this with methylmercury, which is found in tuna and old-school thermometers. You may have even played with spheres of it as a kid (if you’re an old fogey, like me). This is the type of mercury about which we worry. Methylmercury is the one that makes us warn pregnant women about salmon intake, and the same one that gave hat-makers neurological damage centuries ago, i.e. The Mad Hatter. It takes about six weeks for the body to break this substance down to its ineffective state. In the meantime, the compound binds strongly to fat and neurological tissue; it finds its way to the brain, where it causes intellectual deficits.

After the FDA Modernization Act, and widespread fears about autism following the paper published by Wakefield, there was quite a bit of public outcry for changes to be made in vaccines. In spite of good scientific evidence that there was no link between thimerosal and autism, government agencies and vaccine manufacturers decided to make all childhood vaccines thimerosal free. This decision placated some, but many pediatricians feel that it served as a capitulation to non-science. Thimerosal, at this point, only exists for children in certain flu vaccines. There is no thimerosal in the dose for children from 0 to 3 years-old.

In terms of Wakefield’s claim, his paper stating that a combined MMR vaccine was linked to autism was retracted in 2010 and his license to practice medicine was stripped in the same year. In the eyes of many health professionals, however, the damage had already been done. Vaccine rates dropped in several Western nations in the early 2000s, leading to multiple outbreaks of diseases that had been on a steady decline or even eradicated from some countries.

In spite of the overwhelming, worldwide, scientific evidence that vaccinations are safe and effective, claims of “toxins” and “poisonings” continue on the internet and at family gatherings. I won’t link to them here, but trust me. My job, as I see it, is to continue to fight the good fight against vaccine misinformation. The more people understand what we are giving their children, the more vaccine uptake and suffering prevented.