Getting high may not be as harmless as some
smokers think it is. Doctors in Scotland warned on Tuesday that smoking a joint
or two a day of marijuana for many years could cause serious lung disease.
"It might be that the psychoactive part of cannabis is harmless but the
actual process of smoking, whatever you are smoking, can do your lungs harm,"
said Dr. Martin Johnson, of Glasgow Royal Infirmary.
He and his colleagues treated four men with a type of emphysema, a lung
disease normally caused by heavy smoking that makes breathing difficult. They
could find no genetic susceptibility or explanation for the illness, apart from
the fact that all of the men were reasonably heavy cannabis smokers.
A 27-year-old man smoked several pipes of pot a day for several years. Two
men in their 40s smoked two or three joints a day and another man in his 30s had
smoked two joints a week for about 20 years. All the men also smoked cigarettes
or cigars, but not in sufficient quantities to normally cause emphysema.
The men studied had large areas in their lungs in which tissue was
destroyed, although in a different pattern than usually seen in cigarette
smokers with emphysema.
"When you smoke tobacco cigarettes they normally have a filter and that
protects you to a certain extent. But when people smoke marijuana they tend to
roll their own or smoke a pipe so they are not protected from some of the
noxious substances," Johnson explained in a telephone interview.
The dynamics of smoking marijuana are also different. People tend to take
much bigger breaths when smoking a joint and hold them for much longer.
"It could be that these two elements together might explain this
association," Johnson said.
He added that the study, reported in the March issue of the journal Thorax,
could not conclusively determine that marijuana smoking was the cause of the
type of emphysema seen in the men.
But he added that sufficient quantities of marijuana could be just as
harmful as smoking tobacco and might lead to the same types of disease.
"Studies that have tried to compare amounts of marijuana and amounts of
tobacco seem to come to the conclusion that about three to four joints a day is
about as harmful to your lungs as smoking a pack of cigarettes a day," he said.
"What I would like to see is a properly designed study to see if the
association is a true one," Johnson added.
