FW: What Science Says About Marijuana

The New York Times
July 30, 2014

What Science Says About Marijuana
http://www.nytimes.com/2014/07/31/opinion/what-science-says-about-marijuana.
html

By PHILIP M. BOFFEY

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.

Who Got Hooked

An Institute of Medicine study found dependency rates for marijuana were far
lower than those for other substances.

PERCENT

OF GENERAL

POPULATION

WHO HAD

EVER USED:

OF THOSE USERS, PERCENT WHO EVER

BECAME DEPENDENT ON THE DRUG:

Tobacco

Heroin

Cocaine

Alcohol

Anti-anxiety drugs

Marijuana

76

2

16

92

13

46

%

32%

23

17

15

9

9
Source: Institute of Medicine, 1999

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.

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. Marijuana was
found -- alone or in combination with other drugs -- in more than
455,000 patients visiting emergency rooms in 2011. 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.


--
Transnational Institute (TNI)
Drugs & Democracy Programme
De Wittenstraat 25
1052 AK Amsterdam
The Netherlands
Tel: + 31 20 662 66 08
Fax: + 31 20 675 71 76
Email: drugs@tni.org
http://www.druglawreform.info/en/home
http://www.tni.org/work-area/drugs-and-democracy

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