Chemistry Goes Green

Thinking about the implications before we formulate new materials can prevent a plethora of human and environmental ills

In the decades since the publication of Rachel Carson’s environmental classic Silent Spring, since the incidents of pollution that caused the Cuyahoga River to catch fire in 1969 and contaminated residents of Love Canal in the 1970s, our knowledge of how synthetic chemicals—chemicals that are made in laboratories but not found in nature—make their way into the environment and how they interact with living cells has grown remarkably.

We now know that many such chemicals enter the environment, not only from smokestacks, drainpipes, leaky storage tanks and waste sites, but also as they migrate from furniture, textiles, building materials, electronics, toys, personal care products, packaging and many more manufactured goods we encounter every day. As a result, many of these chemicals are present in indoor air and dust. Many are traveling the global environment with air and ocean currents. Many are in the food web and in our bodies.

At the same time our understanding of the sources of chemical exposure has been expanding, so has our knowledge of how chemicals behave biologically. Since well before the publication of Silent Spring, scientists have been aware of the potential adverse environmental and health effects of industrial chemicals. Attention to these impacts typically focused on acute and immediate effects resulting from high levels of exposure. But we now know that many widely used synthetic chemicals can interact with living cells at very low levels of exposure in ways that produce profound effects on development, metabolism, neurological function, reproduction and other vital body systems, sometimes affecting more than one generation. Almost every week, new scientific studies are published documenting adverse health effects of synthetic chemicals such as bisphenol A, brominated flame retardants, phthalates, persistent pollutants or endocrine disruptors—chemicals most of us encounter daily.

The discovery that our lives are filled with so many potential sources of exposure to chemicals with so many subtle but significant impacts has prompted the need for a pollution prevention strategy that goes well beyond putting filters and scrubbers on chimneys or treating wastewater. It has catalyzed the creation of a new approach to designing molecules that aims to prevent problems from occurring in the first place: green chemistry.

Radical Departure

The most fundamental principle of green chemistry is that the best way to prevent harmful chemical pollution is to design materials that are inherently environmentally benign and safe for human health. Green chemistry works toward this goal by using resources efficiently, eliminating use of inherently toxic ingredients and chemical combinations, eliminating waste and hazardous by-products, and minimizing use of energy throughout a product’s entire life cycle.

While this seems like common sense, it represents a radical departure from the status quo.

Asking synthetic chemists—scientists in the business of creating new molecules—to think about a molecule’s biological and ecological behavior and its environmental footprint adds an entirely new dimension to their work. Historically, such considerations have been absent from synthetic chemistry. Chemists are not required to have any formal training in toxicology or other environmental health science that would enable them to understand ecological impacts at the molecular level. John Warner, president and chief technology officer at the Warner Babcock Institute for Green Chemistry, has said of his early career as a commercial chemist, “I have synthesized over 2,500 compounds but have never been taught what makes a chemical toxic.”

Warner and Paul Anastas, assistant administrator for the U.S. Environmental Protection Agency’s Office of Research and Development, are widely regarded as the founders of green chemistry. In their book, Green Chemistry Theory and Practice, Anastas and Warner outlined 12 principles of green chemistry, guidelines for working chemists to consider as they set out to design new compounds to minimize—and ideally eliminate—the risk of creating molecules that will threaten the health of humans or the environment.

But Warner points out these principles are just the start. “We have to realize [that bringing green chemistry into practice] is an endless process,” he says.

Understanding what makes a chemical product safe is the challenge of green chemistry, Lynn Goldman, dean of George Washington University School of Public Health and Health Services, told attendees at the American Chemistry Society’s 15th Annual Green Chemistry & Engineering Conference in Washington, D.C., in June.

Knowledge of how chemicals behave has grown well beyond that on which our current system of regulating chemicals was based, Goldman explained. To understand what makes a molecule safe or toxic, we now have to take into account endocrine active compounds, how environmental exposure to chemicals can alter how genes behave, and the many ways in which chemicals can interact with the various dynamic parts of living cells. To put this knowledge into practice, Goldman said, will require “new collaborations between clinicians, chemists, engineers and biologists.”

Firmly Established

Since it was introduced almost 20 years ago, green chemistry has become firmly established as an approach to designing new chemical products and manufacturing processes in ways that make them less hazardous to human health and the environment.

EPA started a green chemistry program in the 1990s that supports research aimed at developing and promoting pollution prevention through the design and synthesis of nontoxic, resource efficient materials. For the past 16 years the agency has awarded Presidential Green Chemistry Challenge Awards to honor “outstanding examples of green chemistry.” These have included new ways to synthesize ibuprofen, bio-based plastics, nontoxic adhesives, water-based high-performance paint and non-toxic chemical cleaning agents that can neutralize persistent toxics.

EPA’s Design for the Environment Program is using green chemistry to support work to develop nontoxic commercial cleaning products, to assess alternatives to hazardous flame retardants and to find safe replacements for products based on bisphenol A. Green chemistry is also part of numerous individual state policies aimed at preventing exposure to hazardous chemicals, among them efforts in California, Maine, Massachusetts, Michigan and Washington. In Europe, chemicals management policies—among them the European Union directive known as REACH (Registration, Evaluation, Authorization and Restriction of Chemical Substances)—are providing incentives for green chemistry innovation, and green chemistry education is being incorporated into university-level curricula in China and India.

What’s the Problem?

What’s the problem? Plain and simple, it’s putting atoms together in ways nature has not—and so doesn’t know how to handle. Over the decades, scientists have formulated entirely new compounds to make our clothes whiter, our skin softer, our plastics more pliable, our pans less sticky, our carpets less vulnerable to stains and more, without considering the full range of how these novel molecules will behave in nature—or in us.

Now we’re discovering that the consequences can stray far beyond what we ever imagined. When let loose in the environment, many of these molecules can become serious health hazards, knocking biological systems off balance in ways that cause cancer, reproductive disorders, developmental disabilities and other problems.

Video: Adding Value through Green Chemistry

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Green chemistry founding father John Warner spoke at an IonE-co-hosted forum in Minneapolis earlier year. Check out Warner's talk to learn, among other things, the importance of learning what molecules want, how chemistry education has to change, and why Minnesota is superbly positioned to take a lead in this emerging and important field.

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