TOBACCO, POT USERS AT HIGHER DISEASE RISK

Chances Of Serious Lung Disease About Three Times More Likely Than In
Non-Smokers, Study Says

People who habitually smoke both tobacco and marijuana are about
three times more likely than non-smokers to develop serious lung disease.

That affects a lot of people because nearly 20 per cent of
Vancouverites over the age of 40 do or have done just that, according
to a new study by a team from St. Paul's Hospital.

People who smoked only cigarettes were 2.7 times more likely than
non-smokers to have chronic obstructive lung disease. Those who smoke
or smoked both cigarettes and marijuana were 2.9 times more likely to
have the disease.

The study, published today in the Canadian Medical Association
Journal, included nearly 900 Vancouver residents recruited into the
study by random telephone dialing.

It showed that 14 per cent of participants now smoke only pot and 14
per cent smoke tobacco. Only 38 of the 856 participants now smoke
both marijuana and tobacco. But 160 participants (18 per cent) were
either current or previous users of both.

Consistent with previous population surveys showing B.C. has the
highest marijuana use in the country, 45.5 per cent of participants
in the current study said they had used marijuana in the past.

The study was designed to estimate the prevalence of chronic
obstructive lung disease (COPD) among adults over the age of 40 in
the general population and the associations with smoking.

Researchers from iCapture Centre for Cardiovascular and Pulmonary
Research, a department at St. Paul's, had expected 15 per cent would
have lung disease, but the study found it was 19.3 per cent.

About half of the people with clinical signs of lung disease had not
yet been diagnosed with it -- they found out when they did lung
function tests for the purposes of the study.

Lead author and respirologist Dr. Wan C. Tan said those study
participants were given the results of their tests so they could
share them with their family doctors, get referred for specialist
care or, ideally, "take smoking cessation more seriously."

COPD -- which includes chronic emphysema or chronic bronchitis -- is
often indicated by a continuing cough with phlegm and wheezing or
shortness of breath. Tan said COPD is a progressive disease and is
the fourth leading killer in North America, behind cancer, heart
disease and stroke.

In the study, researchers found that participants with COPD had a
greater likelihood of other illnesses like asthma, heart disease and
high blood pressure. They were more likely to have a history of
hospital admission for respiratory problems.

Marijuana smoking alone did not appear to cause COPD.

Although marijuana-only users had a 1.6 times greater risk of COPD
than non-smokers, Tan said researchers are not convinced of the
statistical power of that odds ratio because there were too few study
participants who used marijuana alone in the COPD group.

Experts have found one marijuana joint is equal to the effects (on
lungs) of 2.5 to five cigarettes. But while there is well-established
evidence of lung damage from cigarettes, research has shown
conflicting results on marijuana use.

The current study does not appear to provide clear answers, except
for users of either tobacco alone or users of both marijuana and tobacco.

Since the study will now be repeated in other Canadian cities, the
larger data set should reveal a more convincing picture of
marijuana's role in the development of lung disease, Tan said.

"Innately, it seems logical that marijuana would be a risk factor for
COPD. The noxious fumes are identical except for the THC in marijuana
and the nicotine in tobacco," said Tan, adding there is a synergistic
effect between marijuana and tobacco smoking. Marijuana may sensitize
the lungs and exacerbate the effects of tobacco on the airways.

Study authors said the findings should have implications for public
policy and additional research. "Anti-smoking campaigns should
include a reduction in marijuana use among their goals, aiming
especially at those who regularly use both marijuana and tobacco,"
states the paper's conclusion.

The local research was funded through a $200,000 grant from
pharmaceutical companies AstraZeneca, Boehringer-Ingelheim,
GlaxoSmithKline and Pfizer Canada. Tan said the companies provided an
unrestricted grant and had no role in the study design, data
collection, analysis, interpretation or writing.