The American College of Physicians (ACP) wrote in its Feb. 15, 2008 position paper "Supporting Research into the Therapeutic Role of Marijuana":

“The chronic effects of smoked marijuana are of much greater concern, as its gas and tar phases contain many of the same compounds as tobacco smoke. Chronic use of smoked marijuana is associated with increased risk of cancer, lung damage, bacterial pneumonia, and poor pregnancy outcomes.”

Feb. 15, 2008