Green Chemistry

Green Chemistry

Relying extensively on nonrenewable petroleum feedstocks, conventional industrial chemistry disseminates a cocktail of synthetic chemicals throughout the global environment, presenting substantial risks to humans and other organisms. In contrast, the emerging field of green chemistry develops chemicals to be benign by design. Rather than presuming to keep human and ecological exposures to chemicals within levels of toxicity deemed “acceptable,” practitioners of green or sustainable chemistry aim to make chemicals that are inherently safe.

Principles of green chemistry include:

• Design chemical products that have little or no toxicity and that break down to innocuous substances after use so that they do not accumulate in the environment.
• Use renewable feedstocks, such as corn and soybeans.
• Design syntheses so that the final product contains the maximum proportion of the starting materials, with few atoms wasted.
• Minimize use of solvents, separation agents, or other auxiliary chemicals; when these chemicals are necessary, use innocuous chemicals such as water.
• Increase energy efficiency by manufacturing at ambient temperature and pressure.

Examples of green chemistry now in commerce include substitution of supercritical carbon dioxide for perchloroethylene (perc) as a solvent in professional dry cleaning. Water has replaced petroleum distillates in paint. And manufacture of ibuprofen no longer creates cyanide and formaldehyde as hazardous wastes.

No one knows exactly how far chemists and chemical engineers can go in learning to do their work with far less environmental harm. However, historians and sociologists studying technology find that technical systems usually are far more malleable than would first appear; and many green chemists suggest that the main barriers to chemical greening are economic and political rather than scientific.

Some of these barriers are within chemistry itself. “Use the word ‘green’ in a grant application and you might as well stamp it: ‘DO NOT FUND,’” says one green chemist who did not get tenure. The American Chemical Society now houses the Green Chemistry Institute, but premier chemistry conferences still devote little attention to environmental sustainability. The American Institute of Chemical Engineers code requires members to “serve their communities … and alert authorities to business practices that endanger health and environment”—yet environmental sustainability plays little role in the organization’s activities. Most university chemistry and chemical engineering departments do not offer a single course on green chemical design/production or even require students to study toxicology.

Pfizer now has a vice president for green chemistry, DuPont is making more than 10 percent of its products from corn and other renewable feedstocks, and the carpet industry is learning how to make its products biodegradable. Nevertheless, the inertia of “brown” chemistry is evident across industry—for example, in aggressively expanded production of vinyl siding, doors, and windows despite significant toxic releases over the material’s lifecycle (e.g., in fires).

Governments also are moving slowly. The Toxic Substances Control Act has failed to keep dangerous new chemicals off the market since enactment in 1976. The U.S. government has refused to sign the Stockholm Convention on Persistent Organic Pollutants and has assisted chemical industry efforts to undermine the European Union’s new unified regulatory system for chemicals. Meanwhile, only 7 percent of U.S. federal spending on chemical research and development is devoted to green chemicals, and with the partial exception of Greenpeace, environmental groups have been slow to take up the cause.

Altogether, green chemistry has great potential and dovetails with other environmental thinking, including cradle-to-cradle design, the Natural Step, clean production, and life-cycle assessment. Activating that potential would require some combination of pressure from environmentalists, improved coverage in the media, taxes on toxic chemicals, subsidies for green chemical research and development, and changes in university curricula. In the meantime, “brown” chemistry continues to prevail.

See Also: Green Production and Industry; Greenpeace; Life-Cycle Analysis; Maize; Petroleum; Soybeans; Sustainability.

Bibliography

Matlack, Albert. Introduction to Green Chemistry. Washington, D.C.: CRC Press, 2001)

Thornton, Joe. Pandora’s Poison: Chlorine, Health, and a New Environmental Strategy.

Cambridge, MA: MIT Press, 2001

U.S. Environmental Protection Agency, “Green Chemistry,” Available online at:

www.epa.gov/opptintr/ greenchemistry/ (cited March 2006)

Woodhouse, Edward J. and Steve Breyman, “Green Chemistry as Social Movement?” Science,

 Technology and Human Values (v.30/Spring, 2005).

Edward Woodhouse

Rensselaer Polytechnic Institute

Jeff Howard

University of Texas at Arlington