Rating is available when the video has been rented.
This feature is not available right now. Please try again later.
Published on Jan 9, 2012
http://www.ucsf.edu/news/2012/01/1128... UCSF's Dr. Mark J. Pletcher talks about the finding in his study that suggests low to moderate use of marijuana is less harmful to users' lungs than exposure to tobacco, even though the two substances contain many of the same components.