According to a new study by Dr. Zuo-feng Zhang of the Johnson cancer center at the university of California Los Angles, smoking marijuana can cause cancer.“many people may think marijuana is harmless, but it is not”, Zhang said in a statement. “The carcinogens in marijuana are much stronger than those in tobacco. the big message here is the marijuana, like tobacco, can cause cancer.”Zhang studied 173 patients diagnosed with head and neck cancer, and compared them to 176 cancer free control patients. Those who said they habitually smoked marijuana were more likely to be in the group with head and neck cancers. And the more they smoked , the bigger the risk.
Source: Dr Zhag , Jonsson cancer center University of California,Reported in
journal of cancer Epidemiology Biomarker and prevention Dec 1999.