Chlorine, for example, can be extremely hazardous. Not only is it deadly if inhaled, but various formulations have harmed the ozone layer, triggered multibillion-dollar excavations of rivers and nearly wiped out some birds of prey.
It also is perhaps the most essential chemical in use today.
"I'm hard-pressed to find another chemical with the breadth of use," said Rob Simon, managing director of the American Chemistry Council's chlorine division.
Though there are alternatives for some uses of chlorine, there are few viable substitutes for others, such as water disinfection. About 93% of drugs are manufactured with it.
The pharmaceutical industry lags behind many industries in finding greener technologies.
For every kilogram of a drug they make, pharmaceutical companies use more than 100 kilograms of chlorinated compounds and other solvents that are thrown away. In comparison, the oil industry wastes a much smaller amount of solvents: 0.1 kilogram for every kilogram of product.
"Higher-tech products often are much more wasteful, and the pharmaceutical industry is an example," said Tracy Williamson, chief of the EPA's industrial chemistry branch.
Kim Albizati, former executive director of chemical research at Pfizer, said a more efficient technique -- using catalysts made of enzymes, cloned from natural organisms -- can replace solvents. Pfizer, he said, saved $1 billion over the lifetime of a drug after his team invented a way to transform enzymes into catalysts.
"If you practice green chemistry, you are going to bring down the costs. No question about it," said Albizati, who co-founded BioVerdant, a chemical research firm in San Diego that specializes in environmentally friendly solutions for pharmaceutical companies.
Many pharmaceutical manufacturers still see green chemistry as slowing down their research. Being first with a drug is more important to most companies than being green or cutting costs.
Neil Hawkins, vice president of sustainability at Dow, which manufactures chlorine and about 20,000 compounds, said his company "is looking at all times for alternatives to every product."
"Compared to a decade ago, it is much easier to commercialize some of these [green] products," Hawkins said. "I see real movement in all the major chemical companies."
For consumer products, green chemicals often cost more initially than petrochemicals because extracting raw materials from plants is a more complicated process and manufacturing occurs on a smaller scale, said Josef Koester of Cognis, a specialty chemical company that created coconut-and-corn detergents for household cleaners.
"Starting green chemistry is a niche application, so that means it's exotic and it's expensive," Koester said. However, as the scale enlarges, it becomes more competitive, he said.
Nilesh Shah, Rohm and Haas' research director for performance materials, said many nontoxic products are doomed to fail because of cost.
"Any of the ones that cost more and are green for the sake of being green are unsustainable," Shah said. But "if they are green and more expensive and they bring some other attribute, then there's hope."
Ease, not cost
Regulation continues to be the most powerful force driving the market.
Rohm and Haas in the 1980s developed a biodegradable compound that prevented algae from growing on ship hulls. But the shipping industry didn't have much interest in green antifoulants until a few years ago, when the EPA banned the old tin-based compound, which built up in waterways and killed aquatic life.
"There's a big barrier to change. I demonstrate to so many companies that their costs would be much lower and they still don't convert, and they won't until there's a regulation forcing them to," said Katy Wolf, a former Rand Corp. scientist who directs the Institute for Research and Technical Assistance in Glendale.
"People think American industry looks at the bottom line," she said. "But they don't. They look at what's easiest."
For now, petrochemicals remain the foundation of the modern industrial revolution. Many conventional chemicals are made of petroleum.
Yet a new economic force -- the high cost of oil -- may finally lead reluctant companies to take a closer look at green chemicals.
"The notion that petrochemicals are cheap or inexpensive, that's a transient notion," said Dow's Hawkins. "All you have to do is look at oil at more than $100 per barrel."