Generally, in discussions about such ingredients, those who are in some manner opposed to vaccines will say something about "the toxins!" What they actually mean is generally unclear. Just as unclear, at times, is what the supposed toxin is supposed to do; how is it supposed to hurt people? They may not be certain what it does or why it is bad, but they know it is bad and that's that. I thought I might turn my hand, then, toward trying to understand, from a lay perspective, what these ingredients are, how they are used and whether they really are, as claimed, "toxic". Let's start with formaldehyde.
What is Formaldehyde?
|Microscopic molecule or cute Disney robot?|
With the ubiquitous manufacture and use of this chemical, questions about its safety naturally arise. OSHA has rather extensive guidelines on its safe use and health effects. Acute, short-term exposure to large amounts can be fatal. Long-term chronic exposure to inhaled or topical formaldehyde can result in respiratory illnesses, skin irritation and has long been a suspected carcinogen. In 2011, the U.S. government changed its designation from "reasonably likely" to cause cancer in humans, based on cancer studies in animals, to "known carcinogen". However, these health issues are primarily a risk for those who regularly work with large, industrial quantities of the substance; they are exposed to much higher levels than the rest of us.
How Are We Exposed?
I won't go into industrial exposure, as it does not apply to the majority of us, but in addition to off-gassing from products like carpet, upholstery and combustibles, formaldehyde is all around us. The NIH Report on Carcinogens, 12th Edition, profile on formaldehyde states that it is in the "air, soil, food, treated and bottled drinking water, surface water and groundwater". Our primary route of exposure is breathing it, indoors or outdoors. Much of this inhaled formaldehyde comes from car exhaust, tobacco smoke, power plants, forest fires and wood stoves. Outdoors, we are exposed to anywhere from 0 to 100 parts per billion (ppb) every day. Indoors, it can be as much as 500 to 2,000 ppb (temporary housing such as that used after hurricane Katrina measured from 3-590 ppb). To a smaller degree, we ingest it in our food and water (the average American diet contains about 10-20mg of formaldehyde from things like apples, carrots, pears, milk, etc.), as well as some exposure via cosmetics.
What many people may not know is that our own bodies produce and use formaldehyde as a part of our normal metabolism (Final Report on Carcinogens Background Document for Formaldehyde [PDF], 2010). When we are exposed to methanol (e.g., via inhalation or ingestion of foods like citric fruits and juices, vegetables or fermented beverages), our bodies break it down into formaldehyde and other byproducts. Our bodies produce formaldehyde as a result of DNA demethylation (an important process for controlling gene expression, e.g., in developing embryos) and other biological processes. It is such a regular part of human metabolism, that our normal, naturally produced blood concentrations are generally about 2-3μg of formaldehyde per gram of blood (or about 2.12-3.18μg/mL)*. And it is actually a pretty important chemical; our bodies use formaldehyde to form DNA and amino acids (Toxicological Profile for Formaldehyde [PDF], ATSDR, 1999).
Role in Metabolism
Formaldehyde plays an essential role in our metabolism. As part of the metabolic process, formaldehyde, whether from an external source or produced by our bodies, is converted into formate (PDF) by the enzyme formaldehyde dehydrogenase. The resulting formate can then be eliminated in the urine, further broken down into CO2 and exhaled, or used by our cell machinery to synthesize nucleotides and nucleobases, such as purines and thymidine.
Purines include two of the four basic building blocks of DNA: adenine and guanine. When formaldehyde is converted into formate, the body can then use it to synthesize these basic building blocks of life.
Likewise, thymidine, also called deoxythymidine, is integral to life. It is a nucleoside, which is a class of compounds that are components of nucleic acids; in other words, you need thymidine to make the nucleic acid thymine. They also perform a lot of other important functions. Nucleosides mediate hormone signaling and play a role in blood pressure and energy transfer, among other things (Jucker, 1993). Formaldehyde provides your body with the compounds necessary to synthesize thymidine. Just like with purines, if your body stopped using formaldehyde to make these basic compounds, well, all of your worries would disappear, since you'd be dead.
Even before the advent of industrial uses of formaldehyde, humans, as with every other animal on Earth, had been exposed to formaldehyde through the foods they ate, the environments in which they lived and their own metabolic processes. They developed the means to use the chemical for their own cellular function, as well as the ability to get rid of excess amounts that would otherwise be toxic.
How Much Is Too Much?
We know that formaldehyde is actually pretty darn important for life. We also know that too much of it can be a bad thing. But just how much is too much? When do we need to start worrying?
A good place to start is to figure out what is the NOAEL, or No Observable Adverse Effect Level. That is the largest dose at which there are no significant adverse effects among those exposed to the substance in question. Thankfully, the EPA has looked at that and extrapolated from animal experiments what a safe level of formaldehyde exposure should be. According to their calculations, a human could consume 0.2 mg/kg of formaldehyde every day, in addition to what their own body produces, without showing any adverse effects, such as weight loss, and that is factoring in a lot of safety buffers; the real safe exposure level is likely around 10-100 times higher than that. But, this is the EPA; they like to play it safe. Similarly, Health Canada lists a NOAEL for indoor air concentrations of formaldehyde of 615 μg/m3, though for avoiding observable respiratory effects in children, they set the safe level for 8-hour indoor exposure at about 50 μg/m3. Again, these levels include pretty big safety buffers, with the level at which adverse effects first become apparent being much, much higher. Serious effects, like death, don't occur until even higher levels.
It has also been observed (PDF) that low-level chronic irritation and damage is reversible, that damage tends to be localized to the specific point of exposure and that it does not produce any negative effects on reproductive health or in fetuses. Carcinogenic effects appear to be only related to inhalation, affecting tissues along the respiratory pathways. But even then, there is little data in the literature showing a consistent causal relationship. Any cancerous effects, then, appear to be primarily at rather high levels of exposure.
In the end, small exposures (but still higher than average daily exposure) probably will not do you much harm beyond some irritation or minor tissue damage; it's the bigger amounts you really need to worry about.
What About Vaccines?
That brings us to vaccines. Just how much formaldehyde are we talking about? Why is it even used?
The first thing to make clear is that not every vaccine contains formaldehyde. In vaccine production, it is used to kill or inactivate the antigens being used. Because of its anti-microbial properties, it cannot be used in any of the "live" vaccines (e.g., MMR, rotavirus, varicella, and some flu vaccines), or else they would be rendered useless. Only inactivated vaccines use formaldehyde during the production process. Once the bacteria or viruses are inactivated, the formaldehyde is diluted out, leaving only minute amounts.
So how much are we talking? Not too long ago, I provided a table of all approved vaccines and their thimerosal content. I got the numbers from the package inserts, where available. It seemed to work well, so I've done the same thing for formaldehyde. Here are the formaldehyde contents of the approved vaccines (I'm only showing those that are on the recommended vaccination list):
|Click to enlarge|
Looking at the recommended schedule of vaccines from the CDC, let's pick the vaccines from that list that a child might receive in their first 6 years of life (picking the highest amounts, just for illustration). Note, not all of these are actually required for school entry and lower formaldehyde content vaccines are available for most of these:
- HepB - Recombivax - 3 doses (birth, 1-2 mos. and 6-18 mos.) - 7.5μg/dose
- DTaP - Infanrix - 5 doses (2 mos., 4 mos., 6 mos., 15-18 mos. and 4-6 yrs.) - 100μg/dose
- Hib - ActHIB - 3 doses (2 mos., 4 mos. and 12-15 mos.) - 0.5μg/dose
- IPV - IPOL - 4 doses (2 mos., 4 mos., 6-18 mos. and 4-6 yrs.) - 100μg/dose
- Influenza - Fluzone - 7 doses (6 mos., 12 mos. and yearly 2-6 yrs.) - 100μg/dose
- HepA - Havrix - 2 doses (12 mos. and 6-18 mos. after first dose) - 100μg/dose
So what's the most a child might get in a single office visit? That would probably be at their 6 month visit (when they are, on average, 16.5lbs or 7.5kg) with HepB, DTaP, IPV and flu, for a total of 307.5μg. That is about 160 times less than the total amount their body naturally produces every single day*. Compare that to the 428.4-1,516.4μg of formaldehyde in a single apple.
Now, some might try to claim that the formaldehyde in vaccines is different from the formaldehyde in your body, but they are wrong. Formaldehyde, whether it is in a vaccine or your body, consists of two hydrogen atoms and an oxygen atom bound to a carbon atom. The chemical structure is the same.
Formaldehyde has a lot of scary connotations and images associated with it. It's very easy to let that fear lead us astray and blow things out of proportion. But when you step back and look at things, you realize that, where formaldehyde and vaccines are concerned, there really is nothing to be afraid of. The amount that is present is so small as to be only a negligible exposure, one that the body very quickly handles by either using it for normal cell functions or getting rid of it completely. The beginnings of adverse effects aren't even seen until exposed to many times the residual amounts present in vaccines. While reductions in the amount of environmental exposure are a good thing, the tiny amounts in vaccines are not a health concern.
The bottom line is, put things in perspective and you'll find that what sounds scary really isn't.
[Edited to add, per Ren's request: 1kg = 1,000g = 1,000,000mg = 1,000,000,000μg
Here are some real-world examples of those weights (technically masses):
1kg = a 1L bottle of soda
1g = a paper clip
1mg = a very, very small snowflake
1μg = take your paper clip, cut it into a million pieces and take one of those]
*With a blood half-life of about 1.5 minutes, this means that the human body produces about 50,000μg of formaldehyde every day.
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