British Research staff report said that they found "convincing evidence" to confirm the smoking of cannabis will affect the person's DNA (DNA), and may lead to cancer.

University of Leicester in Britain on June 16 press release said that the school researchers and colleagues in Sweden launched a joint in this study. They developed a new "high-sensitivity liquid chromatography tandem mass spectrometry", clearly shows that marijuana use on the impact of DNA. They focus on marijuana and tobacco, there are elements of the general toxicity of acetaldehyde have been studied, results show that it can damage DNA and lead to lung cancer and other cancers.

Singh said the researchers, some people often mixed with cannabis in the smoking of cigarettes a day, smoking 3-4 cigarettes that of bronchial damage equivalent to smoking 20 cigarettes or more ordinary .