Marijuana smoke may cause cancer: Study

Study author Rajinder Singh said previous studies have revealed a connection between toxic substances in tobacco smoke and DNA damage, which is further associated with an increased risk of developing lung cancer or other cancers.

But this connection was never before substantiated with regard to marijuana smoke.

Toxic chemical acetaldehyde focus of the study
The focus of the research was the toxicity of the chemical acetaldehyde, present in both tobacco and marijuana. The experts used a high-sensitivity process of modified mass spectrometry in order to determine exactly how acetaldehyde affected DNA under laboratory conditions.

The scientists declared: "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."

Damaging potential of marijuana smoke
The researchers added that because marijuana smokers inhale more deeply than cigarette smokers, it may give the toxic substance more time to damage DNA.

"The smoking of 3-4 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 scientists said.

“These results provide evidence for the DNA damaging potential of cannabis [marijuana] smoke, implying that the consumption of cannabis cigarettes may be detrimental to human health with the possibility to initiate cancer development.

“The data obtained from this study suggesting the DNA damaging potential of cannabis smoke highlight the need for stringent regulation of the consumption of cannabis cigarettes, thus limiting the development of adverse health effects such as cancer,” they further said.

The study was funded by the European Union Network of Excellence ECNIS, the Medical Research Council and Cancer Research UK.

The findings were 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.