Drug makers: reuse solvents, reduce emissions.

Raymond, MJ, CS Slater and MJ Savelski.  2010.  LCA approach to the analysis of solvent waste issues in the pharmaceutical industry. Green Chemistry 12:1826-1834.

Synopsis by Evan Beach, Jan 04, 2011

It might seem like a common-sense approach for pharmaceutical makers to re-use solvents instead of incinerating them, but many companies don’t. A new study suggests they should.

Researchers for the first time have quantified the benefits of reusing the solvents. They find that recycling produces fewer emissions and uses less energy than making those chemicals from scratch. These results show the most important way that manufacturers can reduce waste – particularly carbon dioxide emissions.

However, the benefits were seen only when the entire life cycle of the solvent was evaluated. If the solvent is only considered within the boundaries of the pharmaceutical factory, the total emissions are underestimated. The study clearly shows the importance of considering the entire life cycle of solvent production, use and disposal.

By far, solvents are the biggest contributors to pharmaceutical-related emissions, the authors report in the December issue of Green Chemistry. Their research shows that the amount of energy needed to produce fresh solvent and burn waste is much higher than the energy needed to run reduction and recycling programs.

Solvents far outweigh other chemicals in pharmaceutical manufacturing; pound for pound they account for more than 80 percent of the materials used in the average process. They serve a useful role, helping to bring reactants closer together and washing away impurities between steps.

But, this comes at a price: solvents also account for more than 80 percent of the nearly 200 million pounds of waste emitted by the industry. Beyond the factory gates, there are also hidden costs in terms of carbon dioxide emissions. Carbon dioxide is produced from the fuel used to heat chemical reactions and transport products between plants. Considering the entire life cycle of a solvent, as much as 98 percent of the environmental emissions can be due to carbon dioxide.

The scientists considered three case studies: one was an oncology drug being developed by Bristol-Myers Squibb, the second was Pfizer’s Celebrex product, and the last was a manufacturing intermediate used by Novartis to produce a hypertension drug. In each case, the researchers tallied up all the energy and materials used as well as all of the environmental emissions. Their analysis included manufacturing of solvents that occurred outside the pharmaceutical factory itself. They compared scenarios with or without the use of solvent reduction and recycling techniques.

In every case, cutting back on fresh solvent or burning less solvent waste reduced emissions by more than 90 percent. It was also seen that some solvents have a much greater impact than others. For example, one of the most widely used solvents is tetrahydrofuran, which causes 10 times as much water use in the manufacturing plant and accounts for more energy use – cradle-to-grave – than any other solvent tested.

This research shows there are definite environmental benefits to solvent reduction and recycling and provides examples of how this can be put into practice.