Narrator: This is Science Today. The Environmental Protection Agency is calling for the immediate reduction of MTBE, a gasoline additive used in many states to lower air pollution. The decision was based on a University of California study, which found the carcinogenic chemical was contaminating drinking water. Meanwhile, chemical engineer Mark Deshusses at the University of California, Riverside has been working on ways to biodegrade the MTBE that's still out there.

Deshusses: We use microbes to break down the chemicals and we took some cultures from contaminated sites - some microbial cultures. It does get broken down over time and that's a very interesting finding because it was not known until very recently that MTBE could be degraded.

Narrator: The challenge now is getting MTBE to biodegrade in the field as well as it does in the lab.

Deshusses: It's really important to find a solution because MTBE moves very rapidly in the soil, underground. So when you have a leak, very quickly you will find it in your drinking water.

Narrator: For Science Today, I'm Larissa Branin.