Narrator: This is Science Today. About 5 to 10 percent of breast cancers in U.S. women have a primary, genetic link. And researcher Megan Schwarzman of the University of California, Berkeley, says even that figure is a guess estimate.
Schwarzman: Because in fact we don't know what causes most breast cancer, but there certainly is a large, untapped pool of breast cancers that we don't know what caused and there is reason to believe that there are environmental triggers for a lot of that.
Narrator: Schwarzman is part of the California Breast Cancer Research Project, which is funded by the University of California. Schwarzman and her team are looking into what chemicals in the environment are linked to breast cancer.
Schwarzman: One of the directions that this research has sparked interest in is from the federal initiatives that are working on how chemicals are tested — developing new methods, developing higher throughput methods to test many more chemicals and so we are working with them to make sure that breast cancer relevant end points are included in those tests.
Narrator: For Science Today, I'm Larissa Branin.