Narrator: This is Science Today. Two years ago, the FDA banned the importation of herbal products containing aristolochic acid or aristolochia. Lois Swirsky Gold, director of the Carcinogenic Potency Project at the University of California, Berkeley says aristolochic acid is a toxin known to cause kidney failure and cancer in humans

Gold: Aristolochia is an ingredient in many herbal products that are used for arthritic-type symptoms, premenstrual symptoms, stomach ailments, colds and so on.

Narrator: Even with the FDA ban, Gold says these products can be easily purchased through the Internet.

Gold: And so what we've identified is the need to have a policy that when we know something is a hazard, how are we going to deal with it? We've made it clear to the government that this product that they don't intend to be available is very available and they better do something else to make it unavailable to people.

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