Marijuana Smoke Linked to Cancer

June 23, 2009 -- Smoking pot causes cell damage that could make a person more likely to develop cancer, researchers report.  

Scientists at the University of Leicester have discovered that marijuana (cannabis) smoke alters DNA, the genetic material located in cells of the human body. Some forms of DNA damage can lead to cancer.

Many studies have shown that tobacco smoke damages DNA in a way that boosts risk for lung and other cancers, but until now, it's been unclear whether cannabis smoke could do the same. Of particular concern is a cancer-causing chemical called acetaldehyde, which is found in both tobacco and marijuana smoke. Using new chemistry techniques, study researchers showed that the chemical, when present in marijuana smoke, caused DNA damage in a laboratory setting. 

The discovery suggests that marijuana smoke may be as harmful, or perhaps even more toxic, than tobacco smoke. In fact, study researchers say that smoking three to four marijuana cigarettes a day causes as much airway damage as smoking 20 or more cigarettes a day.

"These results provide evidence for the DNA-damaging potential of cannabis smoke," the researchers write, "implying that the consumption of cannabis cigarettes may be detrimental to human health with the possibility to initiate cancer development."

The findings appear in this month's issue of Chemical Research in Toxicology.