Cannabis smoke ‘less likely’ to cause cancer than cigarettes
The study appears to contradict the official line from the State, which maintains cannabis contains more cancer-causing chemicals than tobacco and doubles the risk of certain types of cancer. The country’s top drug advisor, Dr Des Corrigan, said some research linked cannabis with cancer of the lip, tongue and tonsil and that much of its damage was caused by the fact that it usually smoked with tobacco.
Research published in the Harm Reduction Journal claims that while cannabis smoke and tobacco smoke are very similar chemically, their effects are very different, and that cannabis smoke was less carcinogenic, or cancer-causing.
“Current knowledge does not suggest that cannabis smoke will have a carcinogenic potential comparable to that resulting from exposure to tobacco smoke,” said author Dr Robert Melamede. Dr Melamede, a researcher in the University of Colorado in the US, said that while cannabis has been linked to causing respiratory problems it had not been directly linked with tobacco-related cancers, such as lung, colon or rectal cancers.
“Furthermore, compounds found in cannabis have been shown to kill numerous cancer types: lung cancer, breast and prostrate, leukaemia and lymphoma.
“While both tobacco and cannabis smoke have similar properties chemically, their pharmacological activities differ greatly.
“Components of cannabis smoke minimise some carcinogenic pathways whereas tobacco smoke enhances some,” he said.
Dr Corrigan, chairman of the National Advisory Committee on Drugs (NACD) and expert on cannabis, said there was some evidence that pure THC did have a beneficial impact on tumours at cell level.
“But there’s also some evidence in the literature that smoking cannabis plant material can activate certain pathways in the body that convert inactive compounds into active compounds.”
He said the main link between cannabis and cancer, was not lung cancer, but cancer of the lip, tongue and tonsil.
Dr Corrigan said the crucial factor was the combination of cannabis and tobacco in joints resulting in “the worst of both worlds”.
A detailed overview of scientific research on cannabis published by the NACD last year identified a number of links between cannabis and cancer.
“It is estimated that up to four times the amount of tar can be deposited on the lungs by smoking a cannabis joint compared to a standard tobacco cigarette,” said Dr Corrigan.
