Jailynn received her B.S. from the University of Oregon in biology and physiology. She currently studies protein biochemistry.
As millennials, we are becoming increasingly conscious about what goes into our bodies. Many of us favor food grown organically, if not home-grown. We advocate for the strict labeling of foods. We (rightfully) want to know what foreign compounds are added to consumer goods. We are in the midst of an era that questions everything, especially in the context of our own well-being. But what about questioning tried-and-true healthcare practices? To what extent are our reservations with the experts? And when do we trust the very infrastructure that has all but eliminated plagues that ravaged generations for millennia?
This article will highlight one of the chemicals found in vaccines (and other consumables) that has been on the receiving end of much scrutiny lately: formaldehyde. What is it? Why is it in vaccines? Is there actually reason for concern?
Here are the basics: formaldehyde is the name of a chemical compound (CH2O). You may recognize H2O as water but formaldehyde is much more than just a C plus an H2O. Here is the structure for any chemists out there (left).
It's simple and elegant if you ask me. Formaldehyde also goes by the name “methanal,” which I’m not sure is any less toxic-sounding. Formaldehyde got a bad wrap early on probably because of its pungent aroma and the fact that it is used in the embalming process (preserving bodies after a person has passed). The most common use of formaldehyde to date is actually its use in resins.
In researching this compound I was shocked at just how ubiquitous formaldehyde is to our surroundings. It’s everywhere: wood, paint, varnishes, and carpeting. I say that not to scare you but to emphasize that it’s more abundant than most people know. The average level of formaldehyde exposure by indoor air is estimated to be 0.5-2.0 milligrams daily. Keep this number in mind as we move forward.
Formaldehyde is not just a product of our homes; it is also a constituent of the upper atmosphere, produced during the combustion of methane. It is also a product within our own bodies when we synthesize amino acids. Amino acids are one of the most bio-relevant molecules; they are the building blocks of proteins, which we need to stay alive. There’s nothing different about the formaldehyde made in a factory and that produced by your body. It’s the same chemical structure. Your body recognizes formaldehyde and knows exactly what to do with it!
The average level of formaldehyde in the blood of an adult is about 2.5 micrograms per milliliter. An adult has a blood volume of 5 liters. That means, at any given moment, you have approximately 12.5 grams of formaldehyde circulating throughout your body. A similar calculation for an infant’s blood volume reveals 1.1 milligrams of circulating formaldehyde, still far greater than the largest amount found in any vaccine: the maximum exposure to formaldehyde in any vaccine is 0.1 milligrams. To be clear, one milligram is one one-thousandth of a gram. One gram is one one-thousandth of a kilogram.
So we know formaldehyde is fine. But why is it present in DTap (against diphtheria, tetanus, and whooping cough), polio, and other vaccines at all? Formaldehyde is found in trace amounts of some vaccines because it is a byproduct of the manufacturing process. It is used to deactivate bacterial products (such as toxins) which might otherwise make us sick. For example, tetanus is caused by a bacterial toxin wreaking havoc on the nervous system. The vaccine works by incorporating an inactive form of the toxin that the body can recognize to elicit a proper immune response. This inactive toxin does not cause disease, but it resembles the disease-causing toxin just enough to tell your body to arm itself against it. Formaldehyde’s job is to make sure the toxin is in fact inactive; otherwise, an injection of the active toxin would lead to actual tetanus disease.
If you have ever Googled “formaldehyde” you have likely seen reports that formaldehyde is a “known carcinogen to humans” according to the National Toxicology Program (NIEHS). Those words have caused quite the stir on the public health forum, and are echoed on many anti-vaccine websites. However, a headline rarely ever tells the full story. Delving into the toxicology report gives the following excerpt:
“Causality is indicated by consistent findings of increased risks of nasopharyngeal cancer, sinonasal cancer, and lymphohematopoietic cancer, specifically myeloid leukemia among individuals with higher measures of exposure to formaldehyde (exposure level or duration), which cannot be explained by chance, bias, or confounding.”
To translate, the “formaldehyde causes cancer” conclusion is based off of individuals who were exposed to abnormally high levels of formaldehyde for long periods of time. The people who fell victim to these cancers were typically occupationally exposed, such as embalmers and industrial workers. The amount of formaldehyde these patients were exposed to was much higher than the level found in any vaccine, which is barely a fraction of the natural amount in our blood. The precise dose of formaldehyde needed to cause cancer remains unknown, but suffice to say it is not on the level of ten milligrams, let alone 0.1 milligrams.
We witness campaigns every day that aim to avoid exposure to anything that has been linked to cancer in humans. Alcohol consumption and processed meats (e.g. bacon) have been linked to cancer. Physical inactivity, some infections, and pollution are all closely linked to carcinogenesis. Some risk factors are avoidable, some are not. Unfortunately, carcinogens are everywhere. Consider skin cancer: just because high exposure of the sun’s UV rays is known to cause cancer doesn’t mean that 1) it will happen to you, or 2) you should never ever go out into the sun. And that brings me to my final point: as with anything in life, too much of anything is never a good thing. In diet, exposure, and questioning the experts, moderation is key.
Francesca Tomasi received her B.A. from the University of Chicago in 2015 and currently does microbiology research.
I took a History in Philosophy and Science course in college that examined the birth and evolution of medicine. Just as most history classes go, our professor started us off with ancient texts and we worked our way through the centuries into modern literature. We raised eyebrows at the claims that pestilence was a form of divine intervention and that the plague discriminately infected only those who sinned. We chuckled sagaciously at Aristotle and Hippocrates, who proposed that illness had only to do with a discordance between the four humours in our bodies (blood, phlegm, black bile, and yellow bile). Our professor told us we were wrong to laugh, though; as naïve as ancient thinkers were to the intricacies of the human body, they actually had an impressive grasp on the big picture. Hippocrates in fact predicted that public health was contingent on environmental factors around 400 BCE. 2000 years later, an Italian physician named Giovanni Maria Lancisi propagated the idea that humans, animals, and the environment are inextricably linked (amongst other major medical contributions, he proposed the use of mosquito nets as malaria prevention). During the French Revolution about a century later, public hygiene became practice and health less of an exception and more of a rule in communities. By the turn of the 20th century, the term “zoonosis” was coined by the Germans: diseases could (and often did) arise from animals infecting humans.
One hundred years later in 2003, the Washington Post published an article titled Africa’s Apes Are Imperiled, Researchers Warn. The third paragraph gives the overt cause: “With hunters venturing ever deeper into the forest along newly cut logging roads, and the Ebola virus poised to sweep into parks…disaster is close at hand.” Ebola was a dangerous hemorrhagic fever to apes well before it spilled into humans. A decade before the Ebola epidemic in West Africa, scientists were scrambling to slow the virus’s spread, “in large part because they don’t know whether it is passed only from ape to ape or via other animals,” according to the Washington Post. The link between man and ape then became increasingly immutable as demand for food, land, and work went up. Today we know at least part of the answer to a question posed in 2003. Yes, Ebola is spread from and amongst various mammals: non-human primates, bats, and humans. In this case, as is the case with many other diseases, the health of one species is no longer independent of the health of another. The Washington Post article ended with an augury whose words bear this very implication. William Karesh, head of the field veterinary program of the Wildlife Conservation Society, was quoted: “Human or livestock or wildlife can’t be discussed in isolation anymore. There is just one health. And the solutions require everyone working together on all the different levels.”
Modern health issues have been linked time and again to the increasing contact (and intensification thereof) between humans and animals. Changes in land use (such as the deforestation described in the Washington Post article), large-scale emissions, and massive food production units are all significant environmental changes with substantial health impacts. The twentieth century saw an alarming surge in emerging infections that were rapidly attributed to zoonoses. International travel and globalization as a whole only made it easier for an emerging infection that 100 years ago would have been confined to a single region to infiltrate any pocket of the globe. According to a literature review published in 2001, there are at least 1,415 species of infectious agents known to be pathogenic to humans (this number is likely higher now). Of these, 868 are transmitted between animals and humans: about 61 percent of known human infectious diseases have been linked to animals. The authors of this study also examined 175 emerging infections at the time and found that 132 (75%) of them were zoonotic. The conclusion? “Overall, zoonotic pathogens are twice as likely to be associated with emerging diseases than non-zoonotic pathogens.” What would the conclusions of a similar analysis have been a century earlier? Five centuries? A thousand years ago? Scientists would not have been aware of the vast majority of these pathogens, by virtue of the fact that they would still have been confined deep in the throes of Mother Nature’s most species-rich and isolated rainforests. But today, we know that rodents brought about the bouts of Plague that inundated the Middle Ages. We know that measles, mumps, and pertussis arose from the domestication of livestock. We know that HIV came from chimpanzees. A 1999 outbreak of West Nile virus in New York City killed off wild crows about a month before people started getting ill, yet it was the same exact infectious agent that ultimately sickened both species. We know the flu is a disease of birds, pigs, and people, and that the interactions between these three species are what bring about novel flu strains every year – some more dangerous than others.
None of this would be known today if it weren’t for the marriage of multiple fields: human medicine, veterinary medicine, ecology, and environmental studies. Partnerships between doctors, veterinarians, ecologists, and epidemiologists are exactly what brought about the commissioning of the One Health initiative in 2007. One Health seems a campaign inevitable in the 21st century, but it’s really a concept that has been millennia in the making, starting with the Greeks observing a relationship between people’s environment and their well-being. One Health is “a worldwide strategy for expanding interdisciplinary collaborations and communications in all aspects of health care for humans, animals, and the environment.” It goes without saying that such a synergism will “accelerate biomedical research discoveries, [enhance] public health efficacy…and [improve] medical education and clinical care.” There are now over 1000 scientists, physicians, and veterinarians around the world who have endorsed One Health. In addition, countless organizations – from the CDC to the National Oceanic and Atmospheric Administration to the European Union – support it. The World Bank in 2012 published a cost-effectiveness study of a One Health approach to global health, concluding that the “early control of zoonotic disease is both cost-effective and prevents human disease.”
I am writing this article with my beautiful cat Charlotte purring contentedly by my side, blissfully unaware of the fact that her health and mine are in fact inextricably connected. Her ancestors and mine didn’t share a roof; ancient humans would be hard-pressed to kiss a feline’s head, let alone share their pillow with a cat. Yet here we are today, two species sharing a couch, propagating each other’s mental and physical health. One Health. It bears a vague resemblance to the ancient Greek idea that illness comes from disharmony between four distinct humours within our bodies. But instead of phlegm, bile, and blood, the humours are animals, humans, and the environment. The body is Earth. In college, we found humor in the humours. The fact of the matter, however, is that the Greeks get the final laugh.
Anshu Sinha is a third-year undergraduate at the Pennsylvania State University studying environmental systems engineering. She is interested in pursuing a career in sustainable design and consulting.