DEBATE RAGES OVER HEALTH EFFECTS OF MARIJUANA

California Voters Will Decide Nov. 2 Whether to Legalize Recreational
Use of Drug

The marijuana cigarette, with its pungent smell, became a symbol of
the 1960s.

Bill Clinton tried it, but didn't inhale. Comedians joked about
burned-out dopers with brains altered by a variety of drugs, including
pot.

College students and young professionals passed around joints at
parties and wondered: Why all the fuss?

Now, four decades later, Californians will decide Nov. 2 whether to
legalize recreational use of the drug. Proposition 19 would allow
people 21 or older to possess up to an ounce of marijuana and to grow
it in spaces of 25 square feet or less.

Although marijuana has been in use for years, voters will head to the
polls with only a hazy understanding of its health effects.

Research has been difficult because the drug is illegal, and the
limited studies that have been done often paint conflicting pictures.
Among the murky areas:

# Marijuana smoke is laced with carcinogens and can lead to
respiratory problems, but no link has been established with lung
cancer. Some studies suggest the drug's active ingredient may even
have anti-cancerous properties.

# It can be addictive -- one federal survey found that 4.3 million
people had a problem with marijuana abuse or dependence in 2009 -- but
research indicates it may not be as addictive as other drugs or alcohol.

# While people are under its influence, marijuana can impair memory
and hinder the brain's cognitive abilities. But whether such effects
are long-lasting is not clear.

# In rare instances, it can lead to psychotic episodes, but whether it
can be linked to mental illness in vulnerable people remains an open
question.

One of the biggest unknowns is marijuana's effect on a developing
brain. Many experts consider this question particularly important
because brains mature until people are in their 20s.

Also open to debate is whether legalizing marijuana would lead to more
fatal traffic accidents, especially if people combine drinking with
the drug.

All of these uncertainties provide plenty of fodder for those on both
sides of the Prop. 19 debate.

Some medical professionals view marijuana as clearly less harmful than
alcohol.

"It seems to be a rather safe substance with very low potential for
addiction and withdrawal," said Dr. Donald Abrams, a professor of
medicine at UC San Francisco and chief of hematology and oncology at
San Francisco General Hospital. Abrams recommends marijuana for many
of his cancer patients.

"There are 8 million people in the United States that are relatively
chronic marijuana users," he said, "and many of them are highly
functioning people that hold full-time jobs and are creative members
of society."

But others see reason for caution.

Alan Budney, a professor of psychiatry and behavioral sciences at the
University of Arkansas for Medical Sciences, studies marijuana
dependence and withdrawal.

"If you start using it way too much, it starts affecting your life
just like alcohol or any other drug does," he said. "Your
relationships suffer. Financially, you suffer. Employment and
school-wise, you suffer. All the things that go along with dependence
on any drug, I see that as the most chronic problem with marijuana.
People abuse it."

So how addictive is it?

One well-known study found that one out of every 10 or 11 people who
use marijuana will develop an abuse or dependence problem.

That compares to one out of three people who use tobacco, one out of
six who drink alcohol, one out of six who use cocaine, and one out of
five who use heroin.

This suggests that marijuana is not as addictive as other drugs and
alcohol. But Budney cautions that if it is legalized and becomes
cheaper and easier to get, its dependence numbers may rise.

Marijuana comes from the dried, shredded leaves, stems, seeds and
flowers of the hemp plant. It is the most commonly used illegal drug
in the United States. A 2008 federal survey found that 15.2 million
people had used it within the past month.

Most people inhale it in hand-rolled cigarettes, but it also can be
mixed into foods such as brownies or used to brew tea.

When smoked, the active ingredient in pot, delta-9-tetrahydrocannabinol
or THC, has an almost immediate effect. It passes from the lungs to
the bloodstream and travels to organs throughout the body.

In the brain, THC attaches to sites called cannabinoid receptors on
nerve cells, changing the way those cells work. These receptors are
abundant in parts of the brain that regulate memory, thinking,
concentration, movement, coordination, time perception, and pleasure.

Within a few minutes, the heart rate may speed up and even double in
some cases. This could pose problems for those with heart conditions,
but Budney and others said it usually is a mild reaction that does not
lead to serious heart troubles.

One of the biggest concerns is the potential effect on the lungs,
particularly since marijuana smoke contains 50 to 70 percent more
carcinogenic hydrocarbons than tobacco smoke.

Marijuana joints have no filter and are more loosely packed than a
tobacco cigarette. People tend to hold marijuana smoke in their lungs
for about 16 seconds, much longer than the three or four seconds for
cigarette smokers, notes Donald Tashkin, a professor of medicine at
UCLA and one of the world's leading researchers on marijuana and the
lungs.

"You smoke marijuana differently from tobacco, so more of the
particles have time to deposit," he said.

Marijuana smokers are at increased risk of developing such respiratory
problems as coughing, phlegm and bronchitis, studies have shown.

Tashkin and his colleagues have found evidence of swelling,
inflammation and microscopic injury in the lining of the major airways
of marijuana smokers. So they speculated that this could lead to lung
cancer and chronic obstructive pulmonary disease, or COPD.

But to their surprise, when they conducted a large study in the Los
Angeles area, they found no increased risk for these conditions among
marijuana users, no matter how heavily they smoked. Other researchers
have replicated their findings.

"So the bottom line is that it doesn't appear marijuana increases the
risk for causing COPD or lung cancer," Tashkin said. "We also failed
to find any risk for head and neck cancer."

No one knows why marijuana has not been linked to lung cancer, but
Tashkin has a theory. He notes that at least 12 studies have shown
that THC has properties that may inhibit the development of tumors by
limiting cell division and promoting the death of unhealthful cells.

"It's presumably on the basis of these properties that THC inhibits
the production of cancer," he said. But more research is needed.

Another unclear area involves marijuana's effect on cognitive
abilities. One study found that long-term, heavy pot users one week
after they quit using were still impaired in their ability to recall
words from a list, but returned to normal by four weeks. Another study
found the effect on the brain can build up and deteriorate life skills
over time.

When performing a memory task, marijuana smokers "activate either
different parts of the brain or more parts of the brain than somebody
who is not a marijuana smoker," said Susan Weiss, chief of the science
policy branch at the National Institute on Drug Abuse.

"So what does that mean?" she added. "You could interpret it to mean
that the marijuana smokers' brains are less efficient than somebody
who is not a marijuana smoker. Or that there's some other way that the
brain has compensated for being exposed to marijuana. It's very hard
to know how to interpret that."

Although studies have shown an association between marijuana and
schizophrenia, "at this time, it is not clear whether marijuana use
causes mental problems, exacerbates them, or is used in an attempt to
self-medicate symptoms already in existence," notes the National
Institute on Drug Abuse.

Among the Prop. 19 supporters is Dr. Larry Bedard, an emergency
physician who practiced 21 years at Marin General Hospital before
retiring. Throughout his career, he said, he saw fewer than 10
patients whose chief complaint related to marijuana. That was
minuscule compared to the number of people he saw with alcohol-related
problems.

"Marijuana is safer, with the least health consequences," he
said.

In 2008, California hospitals had 181 admissions in which marijuana
abuse or dependence was listed as the primary cause, according to a
recent RAND Corp. report. In an additional 25,000 hospital admissions,
marijuana was listed as a secondary, third or fourth diagnosis.

State officials said they could not readily produce comparable numbers
for alcohol-related hospitalizations, but many experts said, like
Bedard, that it would be many times more than the marijuana-related
cases. However, Rosalie Pacula, co-director of RAND's Drug Policy
Research Center, cautioned that the marijuana numbers may be
artificially low because some doctors have been hesitant to code for
pot because that can make it tougher to get reimbursement from
insurance companies.

Pacula wrote a paper in July concluding that the health care costs
associated with an increase in marijuana use, if it is legalized, are
likely to be small compared to the expected revenue and criminal
justice savings. But she also noted that as research proceeds, if
marijuana is found to be a cause of more significant health problems
including schizophrenia and driving under the influence, that
conclusion could change.

Studies have shown a much higher percentage of traffic accidents
linked to alcohol than to marijuana. After using marijuana, "most
people drive slower, so there's less risk of a fatality," Pacula said.
But she added that studies have also shown that combining marijuana
use and drinking impedes people's ability to drive more than does
alcohol alone.

"So the question that we really don't have a definitive answer about
is whether alcohol and marijuana are going to get used together, or if
they're going to be used as substitutes," Pacula said. "People have
lots of opinions about that. There's research that shows both. So that
is a big, big question."