Narrator: This is Science Today. Kent Pinkerton, a researcher at the University of California, Davis, spends his time blowing cigarette smoke at rats. The reason:

Pinkerton: We're interested in understanding how exposure to environmental tobacco smoke may affect the development of children.

Narrator: But since he can't use children in his experiments, Pinkerton uses rats, exposing the animals to second hand smoke for four to six hours a day. He found that exposure to second hand smoke made a significant change in the growth and development of the young rats' lungs, particularly in the cells that form the lining of the airways inside the lung. He also found that those cells don't divide and reproduce as well as they should.

Pinkerton: So we see a significant reduction in their ability to divide during their first two weeks of life, which is the most critical time for lung growth and development in the animals.

Narrator: Doctors have observed damaging effects in children, but Pinkerton is looking for hard data to back up those observations. For Science Today, I'm Steve Tokar.