Cannabis smokers beware: puff for puff, smoke from the plant contains significantly more chemicals and carcinogens than that from tobacco.
Cannabis smoke is well known to be more harmful to the lungs than tobacco, because smokers inhale cannabis one-third more deeply and hold it in their lungs for up to four times as long as cigarette smokers do. Yet while we have a list of more than 4000 chemicals and toxins present in tobacco smoke from dozens of studies, there is no comparable list for cannabis.
So David Moir of 午夜福利1000集合 Canada and his colleagues set out to make a direct comparison, using machines that 鈥渟moke鈥� the cigarettes and then collect and analyse the smoke. They found that directly inhaled cannabis smoke contained 20 times as much ammonia and five times as much hydrogen cyanide as tobacco smoke. Nitrogen oxides, known to affect the circulatory and immune systems, were five times as concentrated in cannabis smoke (Chemical Research in Toxicology, ).
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鈥淒irectly inhaled cannabis smoke contained 20 times as much ammonia and five times as much hydrogen cyanide as tobacco鈥�
The machine also measured the concentration of these chemicals in 鈥渟idestream smoke鈥� 鈥� which would account for 85 per cent of the smoke you would be exposed to if you were sitting next to a smoker. Amounts are different because directly inhaled smoke has been produced at a higher temperature as air is drawn through the ember during inhalation. In each case, sidestream smoke contained higher concentrations of almost every chemical measured, although levels of polycyclic aromatic hydrocarbons 鈥� which affect reproduction and can cause tumours in animals 鈥� were higher in directly inhaled tobacco smoke.
鈥淭his study highlights that cannabis contains similar carcinogens to tobacco, in particular volatile organic compounds,鈥� says British Lung Foundation spokesman Stephen Spiro. 鈥淭hat these exist in similar or even greater proportions to tobacco smoke is a great worry.鈥�
Drugs and Alcohol 鈥� Learn more in our comprehensive special report.
