June 20 -- FRIDAY, June 19 (HealthDay News) -- The smoke from cannabis, the plant from which marijuana is derived, contains compounds that can damage DNA and increase the risk of cancer just like tobacco smoke, says a new study from the United Kingdom.
In laboratory tests, Rajinder Singh from the University of Leicester and colleagues found certain carcinogens in cannabis smoke in amounts 50 percent greater than those found in tobacco smoke. They noted that light cannabis use could possibly prove to be even more damaging because cannabis smokers usually inhale more deeply than cigarette smokers.
"The smoking of three to four cannabis 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 noted in a news release from the university.
The research was based on tests using a new highly sensitive liquid chromatography-tandem mass spectrometry method to analyze the cannabis smoke. It looked specifically at acetaldehyde -- a suspected cancer-causing chemical known to affect human DNA that is found in both kinds of smoke.
"These results provide evidence for the DNA-damaging potential of cannabis smoke, implying that the consumption of cannabis cigarettes may be detrimental to human health with the possibility to initiate cancer development," the researchers concluded in their report, published in the June 15 issue of Chemical Research in Toxicology.
The American Cancer Society has more about marijuana use and cancer.
SOURCE: University of Leicester, news release, June 16, 2009