CancerMarijuana (Cannabinoids)

Cannabis alters DNA and might increase cancer risk

These are the results of a laboratory study by researchers at the University of Leicester, in the UK.

Admittedly, this is not the typical study covered on this site. However, it’s unlikely to be confirmed under controlled conditions in humans. So, let’s give it ago.

First, the details.

  • Acetaldehyde is a ubiquitous compound that is toxic to genes and is classified as a possible carcinogen to humans.
  • The researchers developed a liquid chromatography tandem mass spectrometry system that measured the results of that toxic reaction — N2-ethyl-dG adducts.
  • Calf thymus DNA was treated with acetaldehyde or the smoke generated from 1, 5, and 10 cannabis cigarettes

And, the results.

  • Higher doses of cannabis resulted in higher levels of the toxic reaction between the cannabis and the calf thymus DNA.

The bottom line?
This study focused on the toxicity of acetaldehyde, which is present in both tobacco and cannabis.

“There have been many studies on the toxicity of tobacco smoke,” say the authors. “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% more carcinogenic polycyclic aromatic hydrocarbons including naphthalene, benzanthracene, and benzopyrene, than tobacco smoke.”

“It is well known that toxic substances in tobacco smoke can damage DNA and increase the risk of lung and other cancers. Scientists were unsure though whether cannabis smoke would have the same effect. Our research has focused on the toxicity of acetaldehyde, which is present in both tobacco and cannabis.”

6/18/09 20:06 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.