Marijuana has the health risks of tobacco say researchers

By SCOTT MacLEOD

Smoking cannabis five times a week does as much lung damage as 20 cigarettes a day, causing disease, phlegm and coughing fits.

That is the verdict of Otago researchers who studied the lungs of 943 people aged 21 and whose findings will be published next month in the international journal Addiction.

The Otago University respiratory research group looked at symptoms such as wheezing, shortness of breath, early morning coughing and sputum production.

It found that 36 per cent of cannabis-dependent smokers had those symptoms, followed by smokers of 21-plus cigarettes a day (29 per cent), 10-20 cigarettes a day (24 per cent), and up to 10 cigarettes a day (17 per cent).

Twenty per cent of non-smokers had the symptoms, some of them from asthma.

The head of the study, Associate Professor Robin Taylor, said the results showed cannabis had a similar effect on the lungs to tobacco and was therefore just as likely to cause chronic bronchitis, emphysema and lung cancer.

Asked to interpret the figures, he said smoking cannabis five times a week would have similar effects to a daily pack of cigarettes. The cannabis smokers were not asked how much they smoked during each session.

The research team reported being struck by the fact that the effects of smoking were noticeable at such a young age, 21, and that two-thirds of the cannabis-dependent subjects had used the drug for less than three years.

It said the report was "ground-breaking" because of the great number of people studied.

But the National Organisation for the Reform of Marijuana Laws said the cannabis users were obviously heavy smokers, and studies overseas had found fewer health problems with the drug.

National coordinator Chris Fowlie said that taking any smoke - not just marijuana - into the lungs was bad. He urged cannabis users to smoke through a good-quality water pipe or vaporiser, or eat their weed.

"Eating it will give more of a body-stone," he said, "otherwise you should only smoke the highest-quality gear rather than a sackload of cabbage."

The Asthma and Respiratory Foundation issued a cannabis "fact sheet" warning that the drug was dangerous.

Its medical director, Associate Professor Ian Town, said the research scotched claims that cannabis was less harmful than tobacco. Even though cannabis users tended to smoke smaller amounts than cigarette users, they also took deeper breaths and held the smoke in their lungs longer.

"Marijuana smoke - like tobacco smoke - can trigger asthma symptoms in some people when inhaled either directly or in the form of secondhand smoke."