the link in my sig. More are in the "Tobacco vs Cannabis" section.

Cannabis Smoke and Cancer: Assessing the Risk
Cannabis Smoke and Cancer: Assessing the Risk - NORML

Cannabis and tobacco smoke are not equally carcinogenic
Cannabis and tobacco smoke are not equally carcinogenic

Smoking Marijuana Does Not Cause Lung Cancer
US: Web: Study: Smoking Marijuana Does Not Cause Lung Cancer

Enjoy your reading! - Granny:hippy: