The Berkeley Science Review: Articles

Green Chemistry
Chemists clean up their act (view PDF)
by Lee Bishop and Mitch Anstey

From 1961 to 1971, over 20 million gallons of the powerful defoliant Agent Orange were sprayed across the jungles of South Vietnam. The herbicidal active ingredients destroyed millions of acres of forests, but perhaps even more tragically, the contamination of Agent Orange with the carcinogen dioxin caused hundreds of thousands of deaths and continues to affect the people of southern Vietnam to this day. Dioxin is now infamous as one of the world's most potent cancer-causing chemicals.

Burning chlorine-containing organic materials produces dioxin, and oftentimes the chlorine is present only as a contaminant and not as the crucial component of the material, making dioxin production difficult to control. Coal fire plants, waste incinerators, and even forest fires are implicated in dioxin production, and until recently, engine exhaust from ships and trains also contributed to the problem. In response, the California Environmental Protection Agency began investigating how chlorinated chemicals could be contaminating these vehicles' fuel. They found that the automotive repair industry was using two chlorine-containing compounds, methylene chloride and tetrachloroethylene, as brake and engine cleaners. These chemicals were then combined with used car oil that was recycled into a cheap source of fuel for dioxin-spewing tankers and trains.

These findings prompted well-intentioned regulations to prohibit the use of those chlorinated chemicals in degreasers in California, and the automotive repair industry adopted a mixture of the chemicals hexane and acetone as a substitute. Tragically, auto mechanics began experiencing numbness of their hands and feet, and some were even rendered wheelchair-bound. It was eventually determined that hexane was being metabolized into a potent neurotoxin in the mechanics' bodies, causing nerve damage. This so-called "regrettable substitution" illustrates the difficulties inherent in designing and regulating chemical tools, weighing their benefits against often unknown environmental and health impacts. It is becoming increasingly apparent that the current chemical production and regulation system is flawed, and the field of green chemistry aims to provide the solution.

The meaning of greening
The term green chemistry was first coined in 1998 by Yale professor Paul Anastas and John Warner of the Warner Babcock Institute in their book "Green Chemistry: Theory and Practice." They defined it as "the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture and application of chemical products." In other words, the green chemistry campaign seeks to reform just about every aspect of chemical production and use. Its principles would be equally embodied by a laboratory chemist who invents a new biodegradable plastic as by a business that discovers how to manufacture that plastic using chemicals that minimize the risk to their workers' health. And it doesn't just apply to people in labcoats: the plastics in water bottles and kids' toys are also potential risks that need to be assessed. The diverse ways that chemicals affect individuals and the environment means the success of the green chemistry movement will require chemists working together with an array of other professionals to ensure that chemicals are created, tested, treated, and disposed of properly.

The green chemistry movement is beginning to take hold at UC Berkeley. An important recent step was a 2008 report commissioned by the California EPA entitled "Green Chemistry: Cornerstone to a Sustainable California," which includes among the authors Drs. Michael Wilson and Megan Schwarzman, research scientists in the UC Berkeley School of Public Health. The wide-ranging report outlines some of the major environmental, health, and economic impacts of California's current approach to regulating chemicals. Over 100 synthetic chemicals and pollutants have been found in umbilical cord blood, breast milk, and adult tissues, and, according to the report, many of these chemicals are "known or probable human carcinogens, reproductive or neurological toxicants, or all three." Thousands of new chemicals are introduced to the marketplace each year and global chemical production is doubling every 25 years. The report highlights the need for comprehensive policy solutions to avoid the potentially disastrous consequences of releasing these chemicals into the environment.

The Carbon Connection
The linkage between two carbon atoms is one of the most common bonds in nature, seen in everything from petroleum to perfume to proteins, and organic chemists often want to create bonds between carbons on different molecules to form a new product.Ê However, forming these bonds in the lab can prove quite difficult.Ê Creating carbon-carbon bonds usually involves preparing two carbon-containing precursors with fairly active chemical elements to aid in the joining of the two carbon atoms.Ê The highly reactive elements used in these "prefunctionalization" steps will not end up in the final product, creating waste, so chemistry professors Robert Bergman and Jonathan Ellman have developed methods that avoid these additional steps and allow bonds to be formed directly between two carbon atoms.Ê The majority of carbon atoms are linked to hydrogen atoms in stable bonds that are very difficult to break (thus, the necessity for prefunctionalization). "Carbon-hydrogen bond activation" is a solution to transform the ubiquitous but difficult to manipulate carbon-hydrogen bond directly into a carbon-carbon bond.Ê These approaches typically involve rare metal catalysts and other extreme conditions to make the reaction occur, but the researchers are able to create new carbon-carbon bonds.

Since most organic chemicals already have an abundance of carbon-hydrogen bonds, Bergman and Ellman are now attempting to target one carbon-hydrogen bond in the presence of all the others. Most organic molecules, and specifically pharmaceuticals, contain elements such as nitrogen and oxygen, and the current strategy to selectively "activate" carbon-hydrogen bonds exploits these common atoms as "directing groups" to guide their catalysts to the desired location on the molecule. Little to no modification of the molecules is necessary, but the list of useful molecules is limited to those that have the correct "directing groups" already built in. Nevertheless, the method has proven successful in the synthesis of incarvillateine, a molecule with potent analgesic properties, as well as possible anti-inflammatory, anti-malarial, anti-tumor, and anti-HIV drugs. As this technology matures, its application in the large-scale synthesis of pharmaceuticals and other molecules of interest could dramatically decrease the amount of waste generated by the chemical industry.

Most consumer product manufacturers are not required to assess the safety of chemicals in their products, so this vast responsibility is left to government agencies. With the current costs of a full toxicological screen approaching five million dollars, the government does not have the resources to screen each new chemical as it comes to market. This means there just isn't enough information about the potential health or environmental hazards of chemicals currently in production, and this lack of data is the first of three main challenges cited as an obstacle to a comprehensive policy solution. The second is that most companies are not required to assume full responsibility for the health and environmental impacts of their products. This means that producers have little impetus to design safer chemicals or processes, and government agencies must wait until harmful effects are observed to take action instead of instituting preventative measures. The final obstacle is a lack of public and private investment in green chemistry research and education. Without investment in the chemicals and processes of the future, the field of green chemistry will be relegated to banning old harmful chemicals instead of creating new benign ones.

Green making green
Early on, chemical companies were thinking creatively about waste disposal for financial reasons—why throw something away when it can be made into something you can sell? In the 1930s, the chemical company I. G. Farben began converting styrene, a byproduct of the oil and gas industry, into polystyrene, one of today's most widely used types of plastic. Polystyrene may not be a sustainable material by today's standards, but producing a valuable product from a chemical that would otherwise have to be disposed of is certainly a step in the "green" direction.

Despite this example, industry and the environment have had a historically rocky relationship. In the past, manufacturing plants were strategically placed along bodies of water so that they could be used as dumping grounds for unwanted waste. "One could say that was economically advantageous at the time because it was cheap," says chemistry professor Robert Bergman. "But if those costs to the environment had been assigned to the company, instead of having to be picked up by society, then a much different economic situation would have occurred. The whole problem with how our economy operates is not that some things are cheap and some things are costly, especially in the chemical arena. The problem is the costs are not assigned in the right place."

As waste disposal prices and regulations have grown, this "cost assignment" has begun to shift, and corporations are becoming keenly aware that green chemistry can be a huge benefit for the bottom line. "Companies don't want to create waste and don't want to create emissions," says Tony Kingsbury of the Haas School of Business. "You can't, literally, from a dollars and cents standpoint, afford to send it to a landfill, hazardous waste site, or dump it in the ground." For modern companies, it's a combination of economic and social advantages. "Dow is very interested in green chemistry for economic reasons, but I think also for societal reasons as well," explains Professor John Arnold of the College of Chemistry. "They do want to be stewards of the environment, and it makes sense economically for them to do that."

Interdisciplinary troubles and triumphs
While businesses may be making strides in the right direction, they can't do it alone. According to Schwarzman, tackling the obstacles to green chemistry will take "a blend of many different fields working together." To this end, staff and faculty from across campus have begun roundtable discussions under the auspices of the Berkeley Institute of the Environment towards the creation of a center for green chemistry at UC Berkeley—one that brings chemists, toxicologists, health scientists, public policy experts, and business experts to the same table. "The basic purpose of the center is to bring all these disciplines to bear on these problems," Schwarzman says.

In assembling a faculty panel, the center is already confronting scientists' hesitance to become involved in matters of policy. Of speaking to the press, Bergman says, "Have you ever talked to a reporter and then read what they wrote about what you said? It's a scary experience." Misrepresentation of scientific results or opinions can compromise a researcher's integrity and lead to confusion about what the scientific facts really are. Professor Dale Johnson in the School of Nutritional Science and Toxicology explains another cause of apprehension. "As a scientist, when you know that policy decisions will be riding on your research, you run the risk of introducing bias. And this bias can potentially cause you to skew your results and scientific conclusions." Schwarzman outlines a third cause, saying, "Scientists shy away very quickly from something that's being dealt with in the public arena because then it feels like they have to take sides or be an advocate just because there are advocates in the process."

In some cases, chemists shy away from the concept of green chemistry because they don't understand what it means. "I think from a lot of academic chemists' perspectives, the situation is a little confused by what people mean by green chemistry," says Arnold. Chemists often view green chemistry negatively, seeing it as a list of "bad chemicals," the avoidance of which merely narrows the field of scientific possibilities. While policymakers may be primarily interested in removing toxic chemicals from the environment, chemists are more excited about green chemistry as an opportunity to make new, environmentally friendly discoveries. Importantly, these two goals are not mutually exclusive. Schwarzman strikes a conciliatory note, explaining that green chemistry is "science in the service of precaution," and should not be misinterpreted as "precaution versus science." "Any sort of initiative that's going to get chemists behind it has to be framed in the positive," says chemistry graduate student Marty Mulvihill. You can't talk about bad chemicals and sick babies, you have to talk about saving the earth and doing fundamentally new and interesting chemistry."
The good news is that voices remain optimistic about the future of this field. "It's rare in my experience that talking about things and getting information is bad. I nearly always see good come out of that," says Arnold. Creating the center for green chemistry represents a crucial step towards solving the communication difficulties between its constituent disciplines.

One benefit of scientists interacting across fields is that it helps them gain a new perspective on their research. "I think that it is important for scientists to be aware of the broader implications of what they do," says Professor Richard Mathies, dean of the College of Chemistry. "There's no reason why a chemist shouldn't think about what's going to happen to his or her product after it gets made," Bergman agrees.

The general sentiment in the department is that chemists and chemical engineers can provide the ultimate solutions to problems caused by toxic chemicals in the environment because they understand how these molecules are designed and produced in the first place and therefore are the most capable of improving them. Not only will this work help the environment, but it will also provide chemists with fresh challenges to tackle in their research. "Chemistry will play a very important role in the overall concept of sustainable development," Arnold says. "It will require new chemistry, which is why I'm interested in it. We will have to do things in new ways, so there will be new processes, new reactions that need developing, and that's what I like."

Education for a green generation
Though the green chemistry movement at UC Berkeley is still in its early stages and its adherents varied in their approaches, everyone seems to agree that education is a central component of addressing the sustainability problem. Within the Department of Chemistry, Mulvihill has been on the forefront of the current educational effort. "Throughout graduate school I've been trying to organize graduate students to realize that the work we do here does have a broader social impact," Mulvihill says. Most chemists are not offered any formal training in toxicology, so even if they are interested in decreasing the toxicity of the chemicals they work with, they generally do not possess the requisite knowledge. To address these issues, Mulvihill and some graduate student colleagues started the Green Chemistry and Sustainable Design seminar series, offered for the first time this past fall. The series covers toxicology, as well as green chemistry in academia, industry, and public policy. Experts in these fields were invited from within the university and across the country, and in demonstration of support for the seminar, many speakers even offered to pay for their own travel expenses. Mulvihill was pleased by the response to the seminar series; according to surveys, student interest in green chemistry and sustainability dramatically increased after participating. "Students are more and more interested in pursuing research that relates to issues of importance in our society," Mulvihill says.

This seminar series was the first significant effort to introduce elements of green chemistry into the chemistry department's curriculum. Tony Kingsbury, executive-in-residence of the Sustainable Products and Solutions Program, a collaboration between the Dow Chemical Company Foundation, the Haas School of Business, and the College of Chemistry that provides the primary funding for the green chemistry seminar series, remarks that he is seeing increased interest in sustainable chemistry all the way up to Dean Mathies. "What this college should be doing," says Mathies, "is providing the knowledge and information and education necessary to put people out there who can work for chemical companies, who can work for the government, who can work with advocacy groups and so on, such that they all have an understanding of chemistry, chemical principles, sustainability, and toxicology." He feels that students educated in this way "can improve the processes in chemical companies, improve the way chemicals are handled, and improve the legislation that is put forward."

Toward this end, as part of the college's effort to revamp the undergraduate laboratory courses, Mathies plans to make sustainability an integral part of the undergraduate chemical education. He feels that broad promotion of sustainability concepts has been hampered by the lack of a common language and understanding to allow communication between groups with diverse interests. Citing the fact that 54% of the students that pass through this university will take at least one course in chemistry, Mathies feels that the college can provide that "common language and common understanding that allows people to communicate better and achieve solutions." Furthermore, laboratory spaces are being renovated to operate in a more environmentally friendly fashion and experiments are being updated to use greener chemicals. Mathies hopes to incorporate the 12 principles of green chemistry, as outlined by Anastas and Warner, into the laboratory curriculum in an effort to illustrate to the students the kind of careful, integrated thinking involved in evaluating the sustainability of a chemical or a reaction.

Where do we go from here?
The challenges posed by the principles of green chemistry cannot be addressed through legislation, business practices, or research alone. Our society and economy depend on chemicals that often pose hazards to ourselves and our environment. "Our world is becoming a chemical world, and it affects not only the environment but every person and natural resource we have," says Johnson. If no green alternative to a given hazardous chemical or process exists, then one has to be created, which requires focused research with sustainability as an explicit goal. Creating a society that fosters that kind of research and its translation into economically viable products will require a population that is educated in the principles of green chemistry and other aspects of sustainability. Appreciation of this is beginning to take hold at UC Berkeley, leading to dramatic changes in the way students are educated and research is carried out. On the potential impact of these changes, Mathies says, "If we train the students properly, then they will go out into the world and we will see a transformation."

Lee Bishop and Mitch Anstey are graduate students in chemistry.

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