MARIJUANA SMOKE OBSTRUCTS AIR FLOW

Damaging Effect Equals Inhaling Up To Five Tobacco Cigarettes, But
Long-Term Use Doesn't Increase Emphysema Risk, Study Says

WELLINGTON, New Zealand (AP)-- A single joint of marijuana obstructs
the flow of air as much as smoking up to five tobacco cigarettes, but
long-term marijuana use does not increase the risk of developing
emphysema, new research suggests.

The study by New Zealand's Medical Research Institute found that
longtime marijuana smokers can develop symptoms of asthma and
bronchitis, along with obstruction of the large airways and excessive
lung inflation. The paper was released Tuesday ahead of its
publication in the journal Thorax.

"The study shows that one cannabis joint causes a similar degree of
lung damage as between 2.5 and five tobacco cigarettes," lead author
Sarah Aldington said.

However, the researchers found that the progressive chronic lung
disease emphysema, often associated with cigarette smoking, was
uncommon among marijuana smokers. Only 1.3 percent of the long-term
marijuana smokers were found to have signs of the disease compared
with 16.3 percent of those who combined marijuana and tobacco, and
18.9 percent of those who smoked only tobacco.

Marijuana smokers had symptoms that included wheezing, coughing,
chest tightness and phlegm -- all of which were associated with
tobacco smokers, except chest tightness.

The study, which used lung function tests, high-resolution X-rays and
questionnaires, also revealed that among marijuana smokers damage
occurred to the small, fine airways that are important for taking in
oxygen and removing waste gases. The extent Advertisement of damage
rose in proportion to the number of joints smoked.

Last week, another study published in the Lancet medical journal
suggested that using marijuana may increase the likelihood of
becoming psychotic, with even infrequent use potentially raising the
overall small risk by as much as 40 percent.

The three-year Thorax study involved 339 people in New Zealand, where
marijuana smoking is fairly common. An estimated 160 million people
use marijuana worldwide.

Participants were recruited into four groups based on smoking habits
-- nonsmokers, tobacco-only smokers, tobacco and marijuana smokers,
and marijuana-only smokers.

To qualify as a long-term marijuana user, participants had to have
smoked a minimum of one joint a day for five years, said institute
director Richard Beasley, who also participated in the study. Tobacco
users had to have smoked a pack a day for one year.

Earlier studies have shown that smoking one joint results in three to
five times more carbon monoxide and tar inhaled than smoking a
cigarette of the same size. The New Zealand research also showed that
the "products of combustion" in marijuana are very similar to
tobacco, Beasley said.

Part of the reason for this is the way joints are smoked, with users
often inhaling and holding the smoke in longer for a better hit.
Marijuana joints typically do not have filters and they have shorter
butts than cigarettes with a higher smoke temperature. Marijuana also
is commonly smoked through pipes.

Jeff Garrett, president of the Australia-New Zealand Thoracic
Society, who was not involved in the study, said that although
researchers found emphysema among marijuana smokers relatively rare,
he emphasized that it does occur.

Hospital specialists also are seeing an increasing number of people
with emphysema specifically related to marijuana smoking, he said.

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EFFECTS OF SMOKING

One marijuana joint obstructs air flow as much as up to five
cigarettes, a recent study shows.

THE FINDING: A single joint of marijuana obstructs the flow of air
as much as smoking up to five tobacco cigarettes, but long-term
marijuana use does not increase the risk of developing emphysema, a
study by New Zealand's Medical Research Institute suggests.

THE SYMPTOMS: Marijuana smokers suffered wheezing, coughing, chest
tightness and phlegm -- all of which were associated with tobacco
smokers, except chest tightness.

A WARNING: Damage also occurred to the small airways key to taking
in oxygen and removing waste gases, and rose in proportion to the
number of joints smoked.