Alert over herbal cigarettes

The cigarettes are marketed in some European countries as an aid to stop smoking.

They contain no nicotine or tobacco, but are smoked in the usual way.

However, a team from the University of Vienna has found that the "vegetable-based" cigarettes produce a level of carbon monoxide similar to that produced by tobacco cigarettes.

The researchers, who report their findings in the medical journal The Lancet, investigated vegetable-based cigarettes after initial studies suggested that their combustion might produce toxic substances.

Carbon monoxide

They measured the amount of carbon monoxide breathed out by five student volunteers who smoked two vegetable-based cigarettes.

In two students, the carbon monoxide concentrations after the first vegetable-based cigarette rose from 15 parts per million to 21 parts per million in one, and from 14 parts per million to 26 parts per million in the other.

Smoking the second cigarette led to higher carbon-monoxide concentrations being reached by both students.

Dr Ernest Groman and colleagues conclude that vegetable-based cigarettes are "a potential hazard to health".

They emphasise that current treatment of nicotine dependence should consist of a combination of nicotine substitution and behavioural therapy or psychological procedures without medication.

Carbon monoxide is an odourless, colourless and tasteless gas. In high concentrations - far higher than in cigarettes - it can be deadly.

Symptoms of carbon monoxide poisoning include headache, dizziness, irritability and difficulty breathing.

Nicotine fixation

Dr John Moore-Gillon, chairman of the British Lung Foundation, said people often made the mistake of thinking that nicotine was what made smoking dangerous.

"If you're burning herbal cigarettes all you're doing is substituting the burning leaves of one sort of plant for another.

"A lot of people try herbal cigarettes because they think since they don't contain nicotine they are safer.

"In fact they're giving up the one bit of tobacco that doesn't do you much harm. Nicotine is addictive, but it's the other stuff that gives you lung cancer and emphysema.

"Ordinary cigarettes contain several thousand different compounds, but you still get tar from herbal cigarettes which could do you just as much harm."

Clive Bates, director of Action on Smoking and Health, said using herbal cigarettes was unlikely to be an effective way to give up smoking.

He said: "Using these cigarettes is not going to do you any signficant extra harm compared with continuing to smoke, it is just that I doubt that they would be particularly effective."

Mr Bates said nicotine replacement therapy, such as sprays and patches, was probably the best technique to use.

"These products deliver a small dose of nicotine which can take the edge off the craving smokers get for a cigarette," he said.

"Herbal cigarettes contain all the nasty chemicals in cigarettes, but they do not provide any help in dealing with nicotine addiction."