Indian-origin researchers at the University of Leicester have found "convincing evidence" that cannabis smoke damages DNA in ways that could potentially increase the risk of cancer development in humans.

Using a newly developed highly sensitive liquid chromatography-tandem mass spectrometry method, the scientists found clear indication that cannabis smoke damages DNA, under laboratory conditions.

Findings of the study have been published in the journal Chemical Research in Toxicology.

The research was carried out by Rajinder Singh, Jatinderpal Sandhu, Balvinder Kaur, Tina Juren, William P Steward, Dan Segerback and Peter B Farmer from the Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine and Karolinska Institute, Sweden.

Raj Singh said: "Parts of the plant Cannabis sativa, also known as 'marijuana', 'ganja', and various street names, are commonly smoked as a recreational drug, although its use for such purposes is illegal in many countries.

"There have been many studies on the toxicity of tobacco smoke. It is known that tobacco smoke contains 4000 chemicals of which 60 are classed as carcinogens. Cannabis in contrast has not been so well studied. It is less combustible than tobacco and is often mixed with tobacco in use. Cannabis smoke contains 400 compounds including 60 cannabinoids. However, because of its lower combustibility it contains 50 per cent more carcinogenic polycyclic aromatic hydrocarbons including naphthalene, benzanthracene and benzopyrene than tobacco smoke."

Scientists wrote in the journal describing the development of a mass spectrometry method that gives a clear indication that cannabis smoke damages DNA, under laboratory conditions.

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