Jim Carrey and the long slow death of the antivaccine movement

California governor Jerry Brown recently signed into law a bill that eliminates religious or philosophical exemptions for childhood vaccines. Under the new law, parents may only opt out of vaccinating their child if a doctor signs off on a medical exemption.

The new law was controversial for a while, especially among California’s small but vocal anti-vaccine movement. Prominent vaccine opponent Jim Carrey, for example, made a few headlines with a twitter rant that compared the new law to fascism. (You just couldn’t make this stuff up.)


And apparently a string of tweets in more or less the same vein. “They say mercury in fish is dangerous, but forcing our children to be injected with mercury in thimerosal is no risk. Make sense?” etc. Just to clarify, he added that he is not anti-vaccine but “anti-toxin” apparently..

It’s the same old tired nonsense anti-vaccine groups have been spreading for years. Never mind that none of the vaccines administered to children (with the exception of some flu vaccines) contain thimerosal, and that the dose of thimerosal in a vaccine was tiny to begin with. Never mind that all the plant food you eat contains some aluminum, because aluminum is one of the most common elements in the Earth’s crust, you find it in many soils in the form of aluminosilicate minerals, and various plants take up small amounts, so your diet regularly exposes you to significantly more aluminum than you get from a vaccine. The average human naturally contains somewhere between 30-50 mg of aluminum at any given time, mostly in your bones although blood typically contains 1-3 parts per billion of aluminum — and all of that is again completely normal; it’s a result of dietary exposure. And never mind that a baby’s blood naturally at any given time contains over ten times more formaldehyde than any shot.

I’ve blogged about this before and briefly talked about some of the chemistry; none of that has changed. Jim Carrey’s argument about aluminum and formaldehyde (given that thimerosal isn’t even included in children’s vaccines, it’s kind of irrelevant) is much the same as if I were to argue that coffee is lethal because a tablespoon of caffeine is probably enough to kill you. That part is absolutely true; a high school student tragically died after drinking a beverage he made with caffeine powder last year, for example. But it’s also true that a tablespoon of caffeine is more than you would get from fifty to eighty cups of coffee, depending on what kind of coffee you’re drinking. As always, the questions Carrey should ask are:

1) how long does this chemical stay in the body (how rapidly is it metabolized/excreted),

2) what are the effects of this chemical and what kinds of concentrations are required to cause those effects, and

3) what kind of dose is required to reach a dangerous concentration (given the rate at which the chemical is metabolized/excreted).

Or you could just ask “what is a dangerous dose”? Which is kind of the three questions above just rolled into one. Anyhow.

But let’s leave aside specific ingredients here for a minute and ask what’s the evidence on safety for vaccines as a whole. There have been numerous large studies looking for statistical correlations between vaccines and autism and a variety of other disorders. No evidence of any connection was ever found. This 2009 paper summarizes some of the data available in 2009; there is even more data available now and the conclusion has not changed.

It is possible to have an allergic reaction to a specific component of a vaccine, in the same way that some people are allergic to bee stings or to peanuts. But these kinds of allergic reactions for vaccines are extremely rare and typically start within a few minutes of receiving the vaccine. They exhibit the same kinds of symptoms as an allergic reaction to a bee sting (hives, swelling, shortness of breath, low blood pressure etc.) and pose the same kind of threat. And they can be treated in much the same way as an allergic reaction to a bee sting; in fact, as long as an allergic reaction of this kind is treated ASAP, it’s completely reversible, just like an allergic reaction to (again) a bee sting (did I say that already?) If someone has shown an allergic reaction to a specific vaccine in the past, then obviously they should not receive that same vaccine again in the future; and under CA’s new law they would have a medical exemption. There are also a variety of mild possible side effects like injection site swelling or low fever that are not dangerous or life-threatening.

The best evidence we have suggests that currently available vaccines are very safe. So why have they inspired so much controversy? Why do they keep on inspiring so much controversy? It’s sort of interesting to speculate about this, because this controversy has just kept on going….and going…and going, in spite of abundant evidence that vaccines are not causing any medical problems. (Quite the contrary.)

Part of it is that we humans are so good at spotting patterns and correlations we find them even where they don’t actually exist; where they’re just a narrative our minds have imposed onto real events. As Paul Offit pointed out, roughly 50,000 British children received the MMR vaccine every year in the late 90s; usually they were between ages 1 and 2, an age at which autism is often diagnosed. Given the number of children immunized and the number of children diagnosed with autism each year, statistically the odds are that in any given year 25 children will be diagnosed with autism shortly after they are vaccinated simply through sheer chance. Even though there is no link, the parents will assume there is a link because the one happened shortly before the other. It’s a little like if you got a call on your cell from an area code you didn’t recognize, say 303, and got in a car wreck three minutes later. Even the most level-headed of us might wonder for a moment whether there was some connection, even though there is obviously no connection between the call and the crash. But the human brain always tries to find connections, and when one event precedes another we tend to wonder if they might be linked (even if they aren’t).

Bear in mind this pattern-recognizing ability is actually one of our great strengths; in fact, our ability to recognize and remember patterns is arguably one of the traits that makes us good at science (at figuring out the natural world). XKCD cartoonist Randall Munroe once pointed out, for example, that if I show you a picture of an adult angrily talking to a kid with a lasso while a cat investigates a broken lamp in the background, your brain will immediately guess what happened. While a supercomputer that can do calculations many times faster than you would have no way to figure out what happened in that picture, at least not as quickly as you could. Which suggests that humans tend to be good at one kind of thinking, while computers tend to be good at another, and that this may remain true even once current limitations in software are surpassed. (I like to speculate that if self-aware computers are developed and go to war with us a la Terminator, the very different ways in which humans and computers think would make such a war more asymmetrical than any other in our history. Each side would have certain advantages because the ways in which human brains and computers function are so different. But I’ll stop there, because I’m speculating wildly…and getting way off topic.) We’re so good at recognizing patterns we can find faces in clouds and shapes in static. And that’s where we have to be careful. We are almost too good at spotting possible correlations. As I like to point out:

Do you really think organic food is actually the cause of autism? This sounds silly, but keep in mind that some anti-vaccine folks have made exactly the same argument vis-a-vis the MMR vaccine and autism.

Another part of it of course is that once you start a controversy it’s very difficult to end it. There are always a handful of conspiracy theorists and other tinfoil-hat types out there who will keep pretty much any controversy going for years or even decades after it should have ended. Even leaving the wingnuts aside, however, I think controversies of this kind tend to take on a life of their own because it’s much easier to scare people than to reassure them. And that’s where I fault the people who originally started this controversy; British doctor Andrew Wakefield and the journalists who briefly made him a household name.

Also I think many people don’t realize how dangerous some of these vaccine-preventable diseases truly were. Take pertussis. About half of all babies who get whooping cough will end up in the hospital. Of those who are hospitalized, one in four will get pneumonia; two-thirds will have slowed or stopped breathing, and 1.6% or 1-2 in a hundred will die. And all this is with appropriate medical treatment. (You can imagine what it was like before modern medical care.)

Or take diphtheria. According to the CDC, the fatality rate for diphtheria is 5-10%, and in kids under five it’s more like 20%. (Back before modern medical care it was 50%). That means even with appropriate medical treatment as many as 1 in 5 small children infected with diphtheria will possibly die.

And OK, sure, rubella is significantly more mild; the fatality rate for this disease is low. Only problem is, ~90% of pregnant women who get rubella will pass it to their fetus, which can cause either birth defects or miscarriage. That’s kind of a problem. Before the vaccine, an estimated 4 out of every 1000 babies was affected with birth defects or problems caused by a rubella infection.

So what I’m trying to say is…this is not your common cold. These are nasty diseases. These are not diseases you want spreading around.

And perhaps it would be good for the anti-vaccine folks out there (the ones still fighting anyway) to take a moment and think about that. We’ve managed to largely eliminate diseases like diphtheria and pertussis, and we’re saving millions of lives. If we can completely eliminate some of these diseases around the world as we did with smallpox, we can eventually stop vaccinating for them altogether, the same way we did with smallpox. (It will take some international cooperation to make that happen, but if we can work together to make it happen it would be awesome.)

And to Jim Carrey and those of like mind. If you are still worried about the safety of vaccines, please, read up on it (and I don’t mean trawling Google for random crank websites — you’re in real trouble if you believe everything you read on the Internet). Try that 2009 paper I linked to for example; or try this list of studies on vaccine safety. Please read up on this before you keep making the same tired nonsense arguments about it. Because this is getting kind of old already.

From Roman candles to Catherine wheels: the chemistry of fireworks

Nearly everyone likes fireworks, with the exception of cats. (Cats hate them with a fiery passion like the cuddly little haters they are.) Something about the bright colors against a black sky appeals to our imagination. For me as a chemistry-type person, I love fireworks shows for an additional reason — because fireworks are a beautiful display of some simple yet violent chemistry in action.

As a general rule, selfish people don’t get along well with other selfish people, and the same is true of elements. As you go towards the upper right-hand corner of the periodic table, elements get more selfish about how they share electrons, as you can see in the chart below. The higher the number, the more selfish the element. Fluorine is the undisputed king. This is by no means the only trend that determines how elements behave; other things like size and available orbitals are very important. But it’s a good general rule that if you see oxygens, chlorines and/or fluorines bonded to each other, the resulting molecule is probably not very happy. It may blow up at room temperature or it may need you to give it a push in the form of heat and a spark, but make no mistake, it wants to react with a molecule made mostly of less selfish elements (aka a fuel).

So chlorine trifluoride, for example:

ClF3 is a hideously unhappy molecule, and you don’t need to make it to know that. It’s dying to react with somebody, anybody, really. From what I’ve heard (most chemists have never worked with this stuff) chlorine trifluoride reacts explosively and violently with water, brick, concrete, asbestos, wood, sand and safety gloves. Basically anything and everything, in other words. Some Nazi scientists made some of this because they were looking for new ways to blow things up and even they decided it was too nasty to play with.

OK, so that’s kind of an extreme example. How about this one? Oxygen gas.


We don’t think of this as very dangerous, because it’s in the air we breathe, but watch what it does when you give it a spark and some fuel. Those two oxygen atoms aren’t very happy about being stuck together, and they’d really like to react with some carbon-containing compound to make water and carbon dioxide, both of which are much more stable. The two oxygens are joined by a double bond, however, and breaking that double bond takes a reasonable amount of energy, which is why these reactions are very slow at room temperature. Increasing temperature speeds up most reactions exponentially; this one is no exception.

What if you have two oxygen atoms joined by a single bond, aka a peroxide? Now you’re talking about something a little more dangerous. The two oxygens are unhappy they’re stuck to each other and now they’re only joined by a single bond, which is easier to break. H2O2 is the simplest of the peroxides:


You probably have it in your medicine cabinet, and you probably think of it as pretty harmless. And it is — because the stuff you have in your medicine cabinet is about 3% hydrogen peroxide, 97% water, with some stabilizer to keep the hydrogen peroxide from breaking down too quickly by itself. 10% hydrogen peroxide, by contrast, is corrosive to your skin. 30% hydrogen peroxide has to be handled very carefully, and 70% hydrogen peroxide is extremely dangerous. Another reason why hydrogen peroxide seems so innocuous is because your cells contain an enzyme called catalase that breaks it down very quickly, releasing water and oxygen gas (bubbles!)

You also know peroxides from the hair salon, where chemicals that contain a peroxide group react with the molecules that give your hair its color and thereby bleach it, although they probably damage your hair a little and make it more brittle in the process (more split ends). Or my favorite peroxide: benzoyl peroxide! At high concentration it’s an explosive; at the low concentration in your spot cream, by contrast, you’re reasonably ok (although it will bleach your pillowcase pretty effectively).

benzoyl peroxide

Or how about this?

sodium hypochlorite

This is sodium hypochlorite, better known as bleach. This molecule is obviously far more stable than say chlorine trifluoride, but it’s still not a very happy partnership; the chlorine would really rather be a chloride ion with a negative charge on it, and the oxygen would rather go find some hydrogen or carbon to hook up with. So it reacts with a wide variety of carbon-based stuff, which is part of the reason why it’s such a brutally effective bacteria-killer, and also part of the reason why it’s good at removing stains from tile and color from your clothes. Most swimming pools are basically very dilute solutions of calcium hypochlorite that has been pH-adjusted down to pH 7.4 or so with some acid. The result is that your pool now contains a mixture of hypochlorite salt and hypochlorous acid:

hypochlorous acid

The hypochlorous acid is an even more brutally effective bacteria-killer than the hypochlorite ion.

Or how about this critter, the nitrate ion?

Nitrate is actually way less reactive than any of these other critters we’ve met so far; nitrogen is a much smaller atom than chlorine, and the bonds that connect it to the oxygen atoms are short and reasonably strong. At room temperature, it doesn’t do much of anything. Many organisms can use it as a source of nitrogen for making amino acids, which is why you find nitrate salts in many of the plants and vegetables you eat. But if you take a concentrated nitrate salt, give it some fuel to react with and a nice push in the form of a spark, it too will blow up. Part of the incentive here is that this reaction will form nitrogen gas, which is extremely stable, and water and carbon dioxide, which are very stable as well. (Nature always wants to go from less stable to more stable in chemical reactions.) Hence gunpowder. Gunpowder is a mixture of potassium nitrate (what used to be called potash), sulfur and charcoal.

What if — instead of nitrogen in the center of that molecule — you had a chlorine atom? Now you’re talking hideously unstable and violently explosive — and that brings us back to fireworks.


On the left is the chlorate ion; on the right is perchlorate. At first glance perchlorate looks like it should be the more violent of the two, but in fact chlorate is much more dangerous because it takes a lot less effort to get chlorate to lose its cool, and in fact some chlorate-fuel mixtures have been known to detonate rather unpredictably — not a quality you want in a firework (or anything else for that matter). So perchlorate salts are more common in fireworks, although nitrates are used too. The firework is a mixture of the oxidizer (perchlorate, nitrate etc.) with a fuel, a carbon-based compound or less-selfish element that the oxygen from the oxidizing agent can partner with; say aluminum or a magnesium-aluminum alloy for example. The reaction between fuel and oxidizer gives you heat, gas and explosion. A binder like dextrin (starch) holds the fuel and oxidizer together in chunks called stars that scatter from the firework shell casing as it bursts. And the binder also serves as additional fuel.

But what about the colors? That’s the cool part. The colors come from metals, mostly metals in the first two columns of the periodic table like sodium or strontium or barium. All of these metals have either 1 (in the first column) or 2 (in the second column) electrons in their outermost shell, and they badly want to give those outer electrons away; so they’re never found in Nature as the pure metal. Instead they’re found as salts, compounds where the metal has a +1 charge (1st column) or +2 charge (second column) and is paired up with negatively charged ions like chloride to balance the charge out. Most of these salts are considerably more stable and nonreactive; the folks who wanted to give electrons away gave them away, the folks who wanted the electrons got them; everybody’s happy. That’s why the color doesn’t come from a chemical reaction, because the metal ion doesn’t do any reacting; it comes from radiation emitted by the metal ion itself.

As the star explodes it releases a ton of energy as heat. Colliding molecules heat up the metal salt, causing electrons in the metal ions to jump to higher energy levels. The metal ion is now in an “excited state”; it wants to get back to the stable state it was in before. So the electron bounces back down to the lower energy level, releasing that excess energy in the form of radiation. The difference in energy between the higher energy level the electron was at and the energy level it went back to determines the wavelength of the light that’s emitted, and that’s why each element has its own characteristic “emission spectra”, wavelengths of light it emits when heated. Here are sodium, hydrogen and neon gas, for example: Each metal has its own emission spectra, so each metal salt gives a firework a distinctive color; like this: The colors you see in the firework are a lovely illustration of quantum chemistry in action.

Much as we all love fireworks, I have to admit they may not be completely innocuous. For example, there have been some reports that fireworks displays deposit a little leftover perchlorate in the water beneath them, which is interesting because perchlorate is a dangerous carcinogen. Whether this is worthy of concern I don’t know. The paper I cited, for example, looked at perchlorate concentrations in a lake after fireworks displays and found that although concentrations jumped right after the display, they dwindled quickly after that as microorganisms converted the perchlorate to harmless chloride ions and oxygen. (Bacteria that break down perchlorate? Yep, believe it or not. I swear…sometimes it seems like there are bacteria that can break down pretty much anything.) So it’s possible that whether or not this is a problem depends partly on the nature of the local microbial ecosystem, IDK.

Either way…the fireworks this year are gonna be awesome. Get out there and let’s go enjoy watching some noisy, brightly-colored chemistry.