A lot of studies have shown marijuana is not good for you. It can fry the brain and contribute to psychosis. The latest one finds "convincing evidence" that marijuana smoke damages the genetic material DNA in ways that could increase the risk of cancer.
Toxic substances in tobacco smoke can damage DNA and increase the risk of lung and other cancers. However, there has been uncertainty over whether marijuana smoke has the same effect.
Scientists are especially concerned about the toxicity of acetaldehyde, present in both tobacco and marijuana. However, it has been difficult to measure DNA damage from acetaldehyde with conventional tests.
Using a highly sensitive new method called modified mass spectrometry, Rajinder Singh at the University of Leicester and colleagues found the data they sought, they report in the June 15 issue of Chemical Research in Toxicology, a journal of the American Chemical Society.
"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 researchers write. "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."
Earlier this year, a separate study found evidence that adolescents and young adults who smoked a lot of marijuana are more likely than non-users to have disrupted brain development. Research in 2007 found pot smokers have on average a 41 percent increased risk of developing psychotic disorders later in life.
The study was funded by the European Union Network of Excellence, the Medical Research Council and other groups.
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