Cannabis More Dangerous Than Tobacco
Two new studies suggest that heavy use of cannabis could be a greater risk factor for chronic lung disease, including cancer, than tobacco.
One study found a higher risk of lung cancer for those who smoked one joint a day compared with those who smoked 20 cigarettes a day over the same period. Another found a form of emphysema called bullous occurs 20 years earlier in cannabis smokers.
Researchers at the Medical Research Institute of New Zealand conducted a lung cancer study using 79 patients, and found the risk of the disease rose 8% for each year of smoking one joint a day, and 7% for each year of smoking a packet of cigarettes a day.
The research team admitted it was a small study, but said nonetheless "it shows clearly that long-term cannabis smoking increases lung cancer risk.” They speculated the increased risk could be connected to the fact that the cannabis smokers inhale deeper and for a longer time, increasing the amount of carbon monoxide in the lungs.
This was also thought to be the case in a second, smaller study of 10 patients who were treated for chronic respiratory problems at the Alfred Hospital in Melbourne. All admitted intense cannabis use for at least a year, and had developed bullous lung disease, a condition where air becomes trapped in the lungs, at an average age of 41. However, the average age in tobacco smoking patients is 65.
Steve Rolles of the Transform Drug Policy Foundation told BBC it was very difficult to separate cannabis from tobacco use as the two were so often smoked together.
"Variations on the ‘cannabis is more dangerous than tobacco’ have been emerging sporadically for several decades. Different research using different methodologies has suggested very different conclusions, making such comparisons problematic," he said.
He added that inhaling smoke from any burning object was intrinsically harmful, and that policy should focus more on educating people about the risks of taking a drug in this way.
"Many people don’t know that smoking a joint is more harmful to the lungs than smoking a cigarette, as marijuana is often inhaled more deeply and held for longer," Dr Noemi Eiser, honorary medical director of the British Lung Foundation, told BBC News.
She added that the debate about cannabis’s effect on the lungs had tended to be overlooked, with more emphasis on cannabis’ mental effects.
"The New Zealand study highlights the carcinogenic properties of cannabis smoke and it is a great worry that these exist in similar or even greater proportions to tobacco smoke," Dr. Eiser added.
The studies appear in Respirology and the European Respiratory Journal. The full European Respiratory Journal report can be viewed here.
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