Pubdate: Thu, 31 Jul 2014
Source: New York Times (NY)
Copyright: 2014 The New York Times Company
Contact: http://www.nytimes.com/ref/membercenter/help/lettertoeditor.html
Website: http://www.nytimes.com/
Details: http://www.mapinc.org/media/298
Author: Philip M. Boffey
Note: Editorial Series
http://www.nytimes.com/interactive/2014/07/27/opinion/sunday/high-time-marijuana-legalization.html 

WHAT SCIENCE SAYS ABOUT MARIJUANA

For Michele Leonhart, the administrator of the Drug Enforcement
Administration, there is no difference between the health effects of
marijuana and those of any other illegal drug. "All illegal drugs are
bad for people," she told Congress in 2012, refusing to say whether
crack, methamphetamines or prescription painkillers are more addictive
or physically harmful than marijuana.

Her testimony neatly illustrates the vast gap between antiquated
federal law enforcement policies and the clear consensus of science
that marijuana is far less harmful to human health than most other
banned drugs and is less dangerous than the highly addictive but
perfectly legal substances known as alcohol and tobacco. Marijuana
cannot lead to a fatal overdose. There is little evidence that it
causes cancer. Its addictive properties, while present, are low, and
the myth that it leads users to more powerful drugs has long since
been disproved.

That doesn't mean marijuana is harmless; in fact, the potency of
current strains may shock those who haven't tried it for decades,
particularly when ingested as food. It can produce a serious
dependency, and constant use would interfere with job and school
performance. It needs to be kept out of the hands of minors. But, on
balance, its downsides are not reasons to impose criminal penalties on
its possession, particularly not in a society that permits nicotine
use and celebrates drinking.

Marijuana's negative health effects are arguments for the same strong
regulation that has been effective in curbing abuse of legal
substances. Science and government have learned a great deal, for
example, about how to keep alcohol out of the hands of minors.
Mandatory underage drinking laws and effective marketing campaigns
have reduced underage alcohol use to 24.8 percent in 2011, compared
with 33.4 percent in 1991. Cigarette use among high school students is
at its lowest point ever, largely thanks to tobacco taxes and growing
municipal smoking limits. There is already some early evidence that
regulation would also help combat teen marijuana use, which fell after
Colorado began broadly regulating medical marijuana in 2010.

Comparing the Dangers

As with other recreational substances, marijuana's health effects
depend on the frequency of use, the potency and amount of marijuana
consumed, and the age of the consumer. Casual use by adults poses
little or no risk for healthy people. Its effects are mostly euphoric
and mild, whereas alcohol turns some drinkers into barroom brawlers,
domestic abusers or maniacs behind the wheel.

An independent scientific committee in Britain compared 20 drugs in
2010 for the harms they caused to individual users and to society as a
whole through crime, family breakdown, absenteeism, and other social
ills. Adding up all the damage, the panel estimated that alcohol was
the most harmful drug, followed by heroin and crack cocaine. Marijuana
ranked eighth, having slightly more than one-fourth the harm of alcohol.

Federal scientists say that the damage caused by alcohol and tobacco
is higher because they are legally available; if marijuana were
legally and easily obtainable, they say, the number of people
suffering harm would rise. However, a 1995 study for the World Health
Organization concluded that even if usage of marijuana increased to
the levels of alcohol and tobacco, it would be unlikely to produce
public health effects approaching those of alcohol and tobacco in
Western societies.

Most of the risks of marijuana use are "small to moderate in size,"
the study said. "In aggregate, they are unlikely to produce public
health problems comparable in scale to those currently produced by
alcohol and tobacco."

While tobacco causes cancer, and alcohol abuse can lead to cirrhosis,
no clear causal connection between marijuana and a deadly disease has
been made. Experts at the National Institute on Drug Abuse, the
scientific arm of the federal anti-drug campaign, published a review
of the adverse health effects of marijuana in June that pointed to a
few disease risks but was remarkably frank in acknowledging widespread
uncertainties. Though the authors believed that legalization would
expose more people to health hazards, they said the link to lung
cancer is "unclear," and that it is lower than the risk of smoking
tobacco.

The very heaviest users can experience symptoms of bronchitis, such as
wheezing and coughing, but moderate smoking poses little risk. A 2012
study found that smoking a joint a day for seven years was not
associated with adverse effects on pulmonary function. Experts say
that marijuana increases the heart rate and the volume of blood pumped
by the heart, but that poses a risk mostly to older users who already
have cardiac or other health problems.

How Addictive Is Marijuana?

Marijuana isn't addictive in the same sense as heroin, from which
withdrawal is an agonizing, physical ordeal. But it can interact with
pleasure centers in the brain and can create a strong sense of
psychological dependence that addiction experts say can be very
difficult to break. Heavy users may find they need to take larger and
larger doses to get the effects they want. When they try to stop, some
get withdrawal symptoms such as irritability, sleeping difficulties
and anxiety that are usually described as relatively mild.

The American Society of Addiction Medicine, the largest association of
physicians specializing in addiction, issued a white paper in 2012
opposing legalization because "marijuana is not a safe and harmless
substance" and marijuana addiction "is a significant health problem."

Nonetheless, that health problem is far less significant than for
other substances, legal and illegal. The Institute of Medicine, the
health arm of the National Academy of Sciences, said in a 1999 study
that 32 percent of tobacco users become dependent, as do 23 percent of
heroin users, 17 percent of cocaine users, and 15 percent of alcohol
drinkers. But only 9 percent of marijuana users develop a dependence.

"Although few marijuana users develop dependence, some do," according
to the study. "But they appear to be less likely to do so than users
of other drugs (including alcohol and nicotine), and marijuana
dependence appears to be less severe than dependence on other drugs."

There's no need to ban a substance that has less than a third of the
addictive potential of cigarettes, but state governments can
discourage heavy use through taxes and education campaigns and help
provide treatment for those who wish to quit. Continue reading the
main story

Impact on Young People

One of the favorite arguments of legalization opponents is that
marijuana is the pathway to more dangerous drugs. But a wide variety
of researchers have found no causal factor pushing users up the ladder
of harm. While 111 million Americans have tried marijuana, only a
third of that number have tried cocaine, and only 4 percent heroin.
People who try marijuana are more likely than the general population
to try other drugs, but that doesn't mean marijuana prompted them to
do so.

Marijuana "does not appear to be a gateway drug to the extent that it
is the cause or even that it is the most significant predictor of
serious drug abuse," the Institute of Medicine study said. The real
gateway drugs are tobacco and alcohol, which young people turn to
first before trying marijuana.

It's clear, though, that marijuana is now far too easy for minors to
obtain, which remains a significant problem. The brain undergoes
active development until about age 21, and there is evidence that
young people are more vulnerable to the adverse effects of marijuana.

A long-term study based in New Zealand, published in 2012, found that
people who began smoking heavily in their teens and continued into
adulthood lost an average of eight I.Q. points by age 38 that could
not be fully restored. A Canadian study published in 2002 also found
an I.Q. loss among heavy school-age users who smoked at least five
joints a week.

The case is not completely settled. The New Zealand study was
challenged by a Norwegian researcher who said socio-economic factors
may have played a role in the I.Q. loss. But the recent review by
experts at the National Institute on Drug Abuse concluded that adults
who smoked heavily in adolescence had impaired neural connections that
interfered with the functioning of their brains. Early and frequent
marijuana use has also been associated with poor grades, apathy and
dropping out of school, but it is unclear whether consumption
triggered the poor grades.

Restricting marijuana to adults is more important now that Colorado
merchants are selling THC, the drug's active ingredient, in candy
bars, cookies and other edible forms likely to appeal to minors.
Experience in Colorado has shown that people can quickly ingest large
amounts of THC that way, which can produce frightening
hallucinations.

Although marijuana use had been declining among high school students
for more than a decade, in recent years it has started to climb, in
contrast to continuing declines in cigarette smoking and alcohol use.
Emergency room visits listing marijuana as the principal cause of
admission soared above 455,000 in 2011, up 52 percent from 2004.
Nearly 70 percent of the teenagers in residential substance-abuse
programs run by Phoenix House, which operates drug and alcohol
treatment centers in 10 states, listed marijuana as their primary problem.

Those are challenges for regulators in any state that chooses to
legalize marijuana. But they are familiar challenges, and they will
become easier for governments to deal with once more of them bring
legal marijuana under tight regulation.  
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