Study: Marijuana may alter human DNA

LEICESTER , England, June 18 (UPI) -- Researchers in Britain say marijuana damages DNA in ways that could potentially increase the risk of cancer development in humans.

University of Leicester researchers used a newly developed, highly sensitive, liquid chromatography-tandem mass spectrometry method and found clear indication that cannabis smoke damages DNA, under laboratory conditions.

Researchers Rajinder Singh, Jatinderpal Sandhu, Balvinder Kaur, Tina Juren, William P. Steward, Dan Segerback and Peter B. Farmer say there have been many studies on the toxicity of tobacco smoke.

It is known that tobacco smoke contains 4,000 chemicals, of which 60 are classed as carcinogens. In contrast, marijuana 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 percent more carcinogenic polycyclic aromatic hydrocarbons -- including naphthalene, benzanthracene and benzopyrene -- than tobacco smoke, Singh says.

"It is well known that toxic substances in tobacco smoke can damage DNA and increase the risk of lung and other cancers," Singh said in a statement.

"Scientists were unsure though whether cannabis (marijuana) smoke would have the same effect. Our research has focused on the toxicity of acetaldehyde, which is present in both tobacco and cannabis."

The smoking of three to four marijuana cigarettes a day is associated with the same degree of damage to bronchial mucus membranes as 20 or more tobacco cigarettes a day, the researchers say.

The findings are published in the journal Chemical Research in Toxicology.