The Pharmaceutical Journal
Vol 269 No 7224 p704
16 November 2002

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British Lung Foundation (www.lunguk.org)

Cannabis as hazardous as tobacco, says British Lung Foundation report

Smoking three to four cannabis cigarettes a day is associated with the same degree of damage to bronchial mucosa as 20 or more tobacco cigarettes, a report from the British Lung Foundation (BLF) has concluded.

The report, which is a review of 90 studies on cannabis smoking and respiratory health, also states that tar from cannabis cigarettes contains 50 per cent more carcinogens than tobacco, and that there is a clear, increased negative health impact on people who smoke cannabis compared with non-smokers. Cannabis smokers suffer more chronic coughs, wheezing, acute bronchitis episodes and sputum production, it says.

In addition, the BLF says that cannabis is smoked in a way that leads to a greater respiratory burden of carbon monoxide and smoke particulates, such as tar, compared with tobacco smoking. The harmful effects of tobacco and cannabis are additive when the two are smoked together.

The report also points out that today's cannabis is more potent than that smoked in the 1960s, when the average "joint" only contained about 10mg tetrahydrocannabinol (THC). Today, it contains about 150mg. Therefore, longitudinal studies carried out in the 1960s and 1970s might not be indicative of the effects of cannabis cigarettes smoked today. And although research has shown that THC in cannabis can act as a short-term bronchodilator, the report concludes that the noxious gases, chronic airway irritation and malignancy associated with long-term cannabis smoking are likely to negate any benefits.

BLF chairman Dr Mark Britton believes the report's findings will come as a surprise to many, "especially those who choose to smoke cannabis rather than tobacco in the belief it is safer for them." He added: "Our report is not about the moral rights and wrongs of cannabis, but simply making sure everyone is clear about the respiratory health risks involved."

The charity has called on the Government to mount a public education campaign highlighting the health risks associated with cannabis smoking, including the increased risk of pulmonary infection and respiratory cancers. It also says that more research is needed to investigate the potential link between cannabis and chronic obstructive pulmonary disease.

The BLF report, entitled "A smoking gun?" was published this week and can be viewed on the internet (www.lunguk.org).