MARIJUANA'S HEALTH RISKS OUTWEIGH ANY BENEFITS, EXPERTS SAY

Small Margin Between Good, Bad Effects

As a teenager, Dom Cramer's anti-drug attitudes would have made any parent
proud. He bought into the "Just Say No" government campaigns and the
warnings from the police who visited his high school that marijuana was a
surefire gateway to more hardcore drugs.

Today, Cramer owns the Toronto Hemp Company, a Yonge Street store that
sells everything from hemp soaps and lip balms to rolling machines and
"defunk smell remover spray." Cramer, now 30, began smoking pot in
university, after he stopped believing "all the lies I was taught in high
school." He smokes marijuana frequently, although says he can go for weeks
or months without it.

Cramer calls cannabis the ideal "social lubricant -- something to do
instead of drinking alcohol, something to share with people and bond
people." The drug also "helps take your mind off things, it helps you relax."

Even experts believe cannabis can have positive health and physiological
effects, and groups such as Canadians for Safe Access argue that the health
repercussions of recreational marijuana use would never come close to
matching the harm done by cigarettes or alcohol.

The debate over the health impact of marijuana took on renewed significance
when the Liberal government introduced Bill C-10 in the House of Commons
last month.

The bill would decriminalize the possession of small amounts of marijuana.
Possession of up to 15 grams of pot and up to three marijuana plants would
be punishable under the new law by fines of between $100 and $500.

According to the 2002 special Senate committee report on illegal drug use,
close to 30 per cent of the Canadian population aged 12 to 64 has used
cannabis at least once.

About two million Canadians aged 18 and older have used cannabis sometime
during the past 12 months, 600,000 have used the drug in the past 30 days,
and approximately 10,000 use it daily. (The committee sharply criticized
health officials for failing to monitor pot use, saying knowledge of
patterns of cannabis use in Canada "verges on the abysmal." They relied on
epidemiological data from two surveys, in 1989 and 1994, to estimate
marijuana use.)

Canada has one of the highest rates of cannabis use among youths, the
committee estimated. About one million teens aged 12 to 17 used pot at some
time in the previous year.

But experts say that many recreational users don't smoke enough marijuana
to produce the high concentrations that are needed to do serious harm.

"It's like cigarettes," says Dr. Thomas Klein, professor of medical
microbiology and immunology at the University of South Florida.

"I think most rational people would say, 'Well, you smoke a cigarette from
time to time, or a cigar from time to time, it's not going to hurt you. But
if you smoke three packs a day it is.' It's the same situation with marijuana."

Still, like most drugs, there's a relatively narrow margin of safety
between the effects you want, and the ones you don't.

"Let's begin with the beneficial effects, because there's much less to say
about that, " says Harold Kalant, professor emeritus in the University of
Toronto's department of pharmacology.

Marijuana induces relaxation "and a sense of easier communication with
other people," Kalant says. After the initial acute phase, people feel
drowsy "and it may help some people get to sleep." Doctors commonly
prescribed marijuana as a sedative in the 19th century.

As well, THC or tetrahydrocannabinol, the active ingredient in pot, has
been shown to blunt nausea and vomiting caused by cancer treatments and
anti-HIV drug cocktails. THC can also lower the pressure within the
eyeball, making it a potential treatment of glaucoma.

Researchers at the McGill Pain Centre in Montreal are testing the effects
of different strains of smoked cannabis on neuropathic pain -- the
electric, burning, stabbing pain caused by severed or damaged nerves.
Anecdotal reports suggest it may also help ease muscle spasms in diseases
such as multiple sclerosis.

At high enough concentrations, THC works like an anti-inflammatory.
Scientists are investigating whether the drug may help with autoimmune
disorders such as rheumatoid arthritis, where the immune system attacks the
body's own tissues. A synthetic form of marijuana also has been shown to
reduce agitation in Alzheimer's patients.

That's the good news. Here's the bad.

THC, the main ingredient in marijuana, is extremely fat soluble, which
means it can easily seep through the fatty part of the lining of the cells
in our body. Once inhaled, pot is absorbed through the lungs, where it's
diffused into the blood via tiny capillaries, then immediately ferried to
the brain and the rest of the body.

Researchers have found THC "receptors" -- the communication link between
the outside of the cell and the machinery within -- in the brain, stomach,
pancreas, spleen, lymph nodes and disease-fighting white blood cells in
bone marrow.

When THC binds to cells, it changes their function. In some cases, that can
be good. In the spleen, for example, THC is believed to help suppress
inflammation.

But there is an increased risk of cancers among children born to women who
smoked marijuana during their pregnancy, and THC may further impair a
person's immune defences in those who are already immune suppressed,
including persons living with HIV or AIDS.

Marijuana also has been found to be a potent trigger for heart attacks.

THC causes blood vessels to relax, which in turn can lower blood pressure,
decreasing blood flow to the heart and causing the heart rate to go up by
about 10 to 20 beats per minute. It's not enough to cause trouble for most
people, but could harm those who already suffer from restricted blood flow
to the heart.

Other studies have found regular pot use can lead to male infertility by
causing sperm to swim abnormally fast; that it may fuel the growth of
cancerous tumors; and that it may be linked to an increased risk of depression.

Then there are the neurotoxic effects of heavy use -- defined as more than
five joints a week -- on learning, memory, intelligence and other brain
functions.

Researchers at Carleton University in Ottawa once tracked 70 people and
compared their IQ scores at two stages: when they were aged nine to 12,
before they started using marijuana, and again at ages 17 to 20. They found
the IQ scores of heavy users dropped by about four points on average.

However, the effects on the brain of long-term, recreational use (fewer
than five joints a week) appear to be minimal. The Carleton intelligence
study, in fact, found IQ scores increased in light users by a mean score of
nearly six points.

Despite his concerns, Kalant supports Ottawa's move to convert possession
of small amounts of marijuana to a civil violation, saying there's no
convincing evidence that decriminalization will lead to a significant
increase in use.