1.1: Chemistry in the Age of PFOA (An Introduction)

Connotations of the word “chemical” are less than positive for most people: it conjures images of contaminated oceans, streams, and soils. It ignites fears of cancer and birth defects. Why wouldn’t it? We are bombarded on a daily basis with disturbing news about chemical contamination of groundwater and drinking water, to say nothing of toxins in the food we eat and the air we breathe. And so pervasive have these contaminants become, that everybody on the planet - even those living far from industrialized areas - has been exposed to potentially harmful chemicals. 

Let’s look at one example of a chemical that’s been in the news a lot recently: PFOA. That stands for perfluorooctanoic acid (pronounced PER-floor-oh-OCT-an-OH-ic acid). Sounds horrible, right? But what is it? Well, in its pure form it’s a white powder that would be difficult to distinguish from salt or sugar, at least at first glance. But unlike sugar or salt, its properties make it very useful for a range of industrial applications, such as in the production of water-proof coatings for textiles and in fire-fighting foams among other things. That sounds innocuous enough.  But exposure to PFOA is linked to a number of serious health conditions, including cancer, and the manner in which it has been used in industry has led to its widespread release into the environment. It is resistant to common degradation pathways so, once released, it is remarkably persistent – contaminating drinking water for years after its release to the environment. It has been found in the blood of people all over the world, not just in areas where it is used or manufactured, and was even found in the blood of most polar bears that were specifically tested for it.

Unfortunately, PFOA is not a unique case. There are many other stories one could tell of otherwise useful materials that ended up causing hugely expensive and/or environmentally damaging impacts. Or, more precisely, it is not the chemicals themselves that caused these problems but, rather, the manner in which they were used. Take DDT, for example (Figure 1.1). It’s hard to imagine a chemical with a worse reputation than DDT, a once widely used and very effective pesticide. But is DDT really so bad? On the one hand, yes: the environmental impacts of this pesticide were far-reaching and devastating to wildlife, especially to species such as eagles and hawks. The bald eagle, to name just one, was pushed to the brink of extinction because DDT weakened the eagle’s eggs, making it difficult for this majestic bird to reproduce. On the other hand, no: it is relatively nontoxic to humans and was directly applied to soldiers during World War 2 to kill lice. In fact, in its early days, DDT was seen as a huge advance and the scientist who studied its efficacy as a pesticide, Paul Hermann Müller, won the 1948 Nobel Prize for Medicine and Physiology. It was sprayed with abandon on farms and recreational areas to control insect pests, as well as on streets in cities, suburbs and rural areas for mosquito control (Figure 1-2) with dramatic billowing clouds of the pesticide spewing forth from the back of municipal pick-up trucks (which were irresistible to follow on bicycles, as my friends and I did growing up - good times!).

Figure 1-1 . Detail from an advertisement for Pennsalt DDT products, from Time Magazine, 30 July 1947. Science History Institute. Philadelphia. https://digital.sciencehistory.org/works/1831ck18w.

Figure 1-2. (left) A DDT sprayer applying the insecticide along the streets of San Antonio, Texas in 1946. (Image source: https://unwritten-record.blogs.archives.gov/2014/05/19/this-week-in-universal-news-spraying-ddt-to-prevent-polio-1946/)

The general public became aware of the environmental impacts of the indiscriminate use of pesticides such as DDT when Rachel Carson published her iconic book, Silent Spring (Figure 1-3). It was soon banned from use and, thankfully, many of the impacted wildlife species have recovered. But not without controversy [1]. By at least one estimate, hundreds of thousands of human lives could be saved every year from the effects of malaria by the limited use of DDT in mosquito netting. This compound need not be sprayed from airplanes over vast tracts of land to still be of value. It is possible to use chemicals safely, allowing people to benefit from their properties, without negatively impacting the environment. It is the haphazard way chemicals are used or disposed of that is usually the problem, not necessarily the chemicals themselves.

Figure 1-3. (right) Rachel Carson’s Silent Spring (1962) led to a public outcry over indiscriminate use of pesticides, resulting in the banning of DDT in 1972 in the US. (Image source: https://en.wikipedia.org/wiki/File:SilentSpring.jpg)

Another example of chemicals run amok: chlorofluorocarbons (CFCs). These were used on a massive scale all over the world for a wide-range of applications because they have all the desirable qualities one would hope for in a chemical: they are non-toxic, they are not flammable, they are safe to transport, they are very stable (and so can’t explode unexpectedly), they are easily manufactured, and relatively inexpensive. They had it all. But no one thought to check how these remarkable compounds would interact in the upper atmosphere when exposed to ultraviolet radiation from the Sun. Ozone depletion was the result, a global environmental crisis that is still being felt, decades after most CFC’s have been banned.  CFC’s would pose no hazard whatsoever if they could be used without letting them escape into the atmosphere. To be sure, that would be a challenging hurdle for practical reasons, but the point is that the chemicals themselves are not necessarily the problem, but how they are used.

One last example: plastics. As a replacement for glass and paper, plastic is seemingly ideal. It is safe to use, lightweight (and therefore saves energy when transporting goods packed in it), provides for an airtight barrier to keep food from spoiling, etc. In fact, when the 1963 Nobel Prize in Chemistry was presented, the following passage was included in the award ceremony:

Our epoch has witnessed the gradual replacement of traditional materials by synthetic ones. We have all seen that plastics can often substitute glass, porcelain, wood, metals, bones, and horn, the substitutes being frequently lighter, less fragile, and easier to shape and work. It has in fact been said that we live in the Age of Plastics.

Such optimism for the possibilities of these materials! Have they lived up to expectations? Yes and no. One could say that they are a victim of their own success. Plastic pollution is one of the more pressing environmental crises of our time because plastics have become so useful and so inexpensive that we are producing and then disposing of them at such a torrid pace that the planet can’t keep up. “Islands” of floating plastic debris, larger than the state of Texas, have formed in the world’s oceans (Figure 1.4). The impact on wildlife is as heartbreaking as it is perilous.

Figure 1-4.  An example of the all-to-common injuries to wildlife by plastics in the ocean: an olive ridley sea turtle entangled in a ghost net in the Maldives (Image source: https://commons.wikimedia.org/wiki/F...cea_Landaa.JPG)

What lessons can we learn from the stories of PFOA, DDT, CFC’s, and plastics?  However well-intended, chemicals have been manufactured, used and released on sometimes massive scales without sufficient information about their long-effects on the environment or with proper concern for their safe disposal. These stories all have a similar theme: materials created to serve useful purposes ended up causing serious problems because certain aspects of their widespread application were either unknown or not considered. 

This is a book about chemistry - the branch of science that investigates the nature of matter and its transformations. While many of the conveniences and necessities of modern society are made possible by applications of chemistry, injudicious use of chemical technology has, unfortunately, made the problems described above possible too. One might reasonably ask, “So, why study chemistry? If it causes so many serious problems, shouldn't we learn from previous mistakes and avoid it?”

Good questions. Like so many other fields, the knowledge that comes from a study of chemistry can be used for a myriad of purposes, most of which are well-intended and very beneficial. Most chemists pursue their craft with an aim to make people’s lives better and to learn about the way Nature works to, for example, more effectively preserve the environment. The benefits of chemistry are so numerous that we all take them for granted. Clothing, phones, medical equipment, antibiotics and other medications, computers, automobiles, and building materials all require modern chemistry in their production. For a world of eight billion people, an understanding of chemistry will be critical to solve the ever-growing problem of climate change and will make possible improved health and living conditions for many people. Mistakes of the past need to inform and guide future action, but shouldn’t deter us from tackling serious problems out of fear that doing so will cause problems even more serious than they solve. Being a Luddite might be tempting on an individual level, but it’s not a serious option for modern society. 

Take the issue of climate change. It is caused by the widespread burning of fossil fuels, which releases carbon dioxide into the atmosphere. Why use fossil fuels? Because they are a relatively abundant source of energy. Without plentiful energy, the standard of living throughout the world would be far lower and, in all likelihood, there would be even greater, and certainly more immediate, environmental pressures as forests would be cut down to harvest wood (another source of energy). Most so-called sustainable energy sources are not nearly as benign as you might think and inflict their own environmental damage, e.g., wind power can kill wildlife, and hydroelectric power can flood habitats. This is not to say, however, that we need to burn fossil fuels. Everyday, a nearly inexhaustible energy supply rains down on us from the Sun. If we can develop technology that can convert sunlight into a form that can power vehicles and generate electricity, the need to burn fossil fuels is largely eliminated and the local environmental damage of sustainable energy generation can be avoided, all while allowing people to lead safer, more productive lives. 

How will we harness solar energy? While the specific technology needs to be developed, the basic idea is well understood. Green plants have been doing it for millions of years: absorbing energy from the Sun and using it to synthesize a fuel (Figure 1-5). In the case of plants, the fuel they synthesize is glucose, a type of sugar, but other types of fuels can conceivably be made by artificial processes.  The molecular structures involved in photosynthesis are devilishly clever (evolution is an amazing problem-solver!) - constructed with exquisite precision, they capture sunlight and use its energy to literally take molecules of water and carbon dioxide apart and then recombine them into sugars. Unfortunately, our ability to mimic those structures is sorely wanting, but an understanding of the underlying logic of the transformation can inspire chemists to develop simpler, more robust versions of them to achieve the same ends. Given the dire predictions of the consequences of climate changes, and the increasing pace at which it appears to be unfolding, this is a problem that must be solved. And chemistry will be at the heart of the solution.

Figure 1-5. Green plants use energy from the sun to convert carbon dioxide and water into high-energy "fuels". The way they do so is inspiring chemists to develop similar energy conversion schemes to end our dependence on fossil fuels and, in so doing, slowing down and reversing climate change.(Image source: https://www.pexels.com/photo/nature-...rees-fog-4827/  Used under under the Creative Commons Attribution-Share Alike 4.0 International license.)

Chemistry will also be at the heart of developments in medicine (you can’t possibly understand biology without a solid grounding in chemical principles), computer technology (microprocessors are not made out of ones and zeros, but silicon and other elements), and virtually all material aspects of the modern world. There’s a reason chemistry is sometimes called “The Central Science”. 

Yet, despite its far-reaching utility and benefits, chemistry, as a discipline, is in sore need of a public relations overhaul. It lacks the panache of physics, which searches for the Theory of Everything and pushes the boundaries of our understanding on scales as vast as the universe and as small as theoretical structures billions of times smaller than the atom. It lacks the timeliness and relevance of biology, which is enjoying a decades-long explosion of new discoveries, from the completion of the human genome, CRISPR gene editing technology and, more recently, the amazingly fast development and deployment of, not one but several, vaccines against Covid-19. Chemistry, on the other hand, is the cause of pollution, birth defects, and floating islands of debris. The chemical industry makes things like paint, plastics, and pesticides, not life-saving vaccines or instruments to probe the edges of the universe. From most people’s perspectives it’s hardly romantic and downright diabolical in some cases. Is that a fair depiction of chemistry as a field of study? Not at all, but perceptions are important, and chemistry has an image problem.

Unpopular opinion: Chemistry is a beautiful science. There is a logic to it that empowers those who understand it to do amazing things. It is the aim of this book to not only convey the basics of the discipline, but to instill a sense of wonder about the world. A knowledge of chemistry makes the miracle of life understandable (in some ways), and inspires wonder at everyday phenomena that are all too easy to pass by unnoticed. Add to that the many practical benefits it continues to produce, and the promise of solutions to our most pressing problems, and the rationale to study and enjoy chemistry are clear. 

Hence this book. It is our intention to provide you, Dear Reader, with the tools you will need to be a successful professional in a scientific field. You will need to understand chemistry and chemical principles. And the best way to achieve that end is via an approach that emphasizes the underlying logic of the discipline. We will not ask you to memorize vast amounts of information, but we will ask that you develop a deep understanding of what matter is and how it behaves on a molecular level. Whether your goal is to be a biologist, physician, policy-maker, or chemist, we believe that a deep understanding of key ideas is essential. We will also be eschewing traditional presentation and organization of introductory texts in favor of a unified approach. Concepts from general, organic, analytical and inorganic chemistry are presented throughout the text because practicing scientists must draw on all of these fields in any meaningful work. The rationale is simple: to apply and practice chemistry, you need not be exposed to an encyclopedic range of detail. Rather, if you can develop a deep understanding of a rather limited number of concepts, you will be in an excellent position to teach yourself the details of whatever specific field you find yourself in down the road. 

As the pages above attest, it is not our intent to present chemistry as any sort of magic bullet for the world’s problems. Life is complicated and the world is too. We can’t abandon technology in a romantic urge to return to simpler times, but we must learn from past mistakes. Our goal is to empower you to make wise decisions while also making headway on some of the most serious problems our world has ever confronted.   

Footnotes and References.

[1]  see letter in Nature: Trewavas, T. Carson no 'beacon of reason' on DDT. Nature 486, 473 (2012). https://doi.org/10.1038/486473a