Cannabis joints damage lungs more than tobacco - study

[Al-khiyal]

July 31, 2007 -- A single cannabis joint may cause as much damage to the lungs as five chain-smoked cigarettes, research has found. Medical examinations of cannabis and cigarette smokers found the drug increased specific lung problems, including obstructed airways and hyperinflation, a condition where too much air remains in the lungs when a person exhales.

Smoking one cannabis joint caused damage equivalent to smoking 2.5 to five cigarettes in rapid succession, researchers at the Medical Research Institute of New Zealand found. Doctors who carried out the study believe the damage is linked to the difference in the way cannabis is usually smoked, with users inhaling hard, holding their breath for longer and failing to use filters.

The report follows a flurry of confessions from ministers who admitted having used the illegal drug and comes days after a review of cannabis research, published in the Lancet medical journal, revealed that cannabis use may be to blame for 800 cases of serious psychosis in Britain.

The scientists set out to investigate whether smoking cannabis put users at greater risk of developing emphysema, a progressive and potentially fatal lung disease.

A group of 339 volunteers aged 18 to 70 were divided into four groups according to whether they smoked only cannabis, only tobacco, both, or were non-smokers. Each volunteer was then subjected to lung function tests and x-ray scans of their chests to assess the level of damage to their lungs and airways.

In the study, published in the journal Thorax, all smokers complained of coughs and wheezing, while only tobacco smokers showed signs of emphysema. Coughing was reduced among people who smoked cannabis and tobacco, possibly because these people smoked pure cannabis joints and so less tobacco leaf.

The extent of lung damage was directly related to the number of joints smoked. "The most important finding was that one joint of cannabis was similar to 2.5 to five tobacco cigarettes in terms of causing airflow obstruction," the authors write. "This pattern is likely to relate to the different characteristics of the cannabis joint and the way in which it is smoked. Cannabis is usually smoked without a filter and to a shorter butt length, and the smoke is a higher temperature," they add.

Cannabis joints damage lungs more than tobacco - study

[Al-khiyal]

December 19, 2007 -- Cannabis smokers are exposed to more toxic chemicals in each puff than those who smoke only tobacco, scientists have found. Earlier research shows cannabis smokers are more prone to lung damage than cigarette smokers.

In tests, directly inhaled cannabis smoke contained 20 times more ammonia than cigarette smoke, five times more hydrogen cyanide and five times the concentration of nitrogen oxides, which affect circulation and the immune system.

Researchers led by David Moir at Health Canada investigated after noting there are 4,000 chemicals and toxins listed for tobacco smoke but no such list for cannabis.

They set up machines that "smoke" the plants and collect the fumes.

The scientists first analysed smoke that would be inhaled directly, but later examined "sidestream smoke", which accounts for 85% of the fumes you inhale if you sit next to a smoker. This smoke contained higher levels of almost every toxin measured, except for compounds known as polycyclic aromatic hydrocarbons, which were more concentrated in directly inhaled cigarette smoke.

The chemicals combine to cause harmful health effects. Polycyclic aromatic hydrocarbons have been linked to reproductive disorders and cancer, while, at high levels, ammonia can cause asthma.

"Cannabis contains similar carcinogens to tobacco, in particular volatile organic compounds," Stephen Spiro of the British Lung Foundation told New Scientist magazine.

"That these exist in similar or even higher proportions to tobacco smoke is a great worry."

In July scientists in New Zealand reported that smoking a single cannabis joint could cause as much lung damage as five chain-smoked cigarettes. Much of the damage is believed to be caused by smokers inhaling cannabis more deeply than tobacco and holding it in up to four times as long.

Cannabis smoke more toxic than puffing tobacco