Narrator: This is Science Today. While it's now a well-known fact, the link between tobacco smoke and lung cancer didn't start to emerge in this country until the late Fifties and early-Sixties. Dr. Sanford Barsky, a professor of pathology at UCLA, explains why.
Barsky: We didn't recognize that tobacco was dangerous for at least fifty years of this century because of the long latency that's required for full lung cancer development.
Narrator: For years, tobacco was the only smoked substance linked to lung cancer, but now Barsky's lab has found a similar cancer link between heavy marijuana and crack cocaine use.
Barsky: Habitual smoking of marijuana and crack cocaine, as far as the respiratory tract goes, is not beneficial. We think of these drugs in terms of an organ - mainly the brain. They're targeting that sight but we have to remember that the route of administration is through the bronchial tract and through the lungs and therefore, obviously, those are potential sites of action. We've demonstrated in this study that these smoked substances do cause damage to these sites.
Narrator: For Science Today, I'm Larissa Branin.