REPLY TO 'MARIJUANA, THE DECEPTIVE DRUG'

Biernson's Review Of The Evidence On Marijuana'S Effects Is Highly Skewed

We requested Prof. Jeffrey A. Miron to reply to the article which appeared
in our last issue about the dangers of marijuana. Prof. Miron is the
founder of the Bastiat Institute, a libertarian think tank in Wellesley and
a professor at Boston University. Needless to say, the author of the
original article, George Biernson and others, are anxious to reply to Prof.
Miron in our next issue. We hope this exchange will allow you to sharpen
your views on the subject. - Massachusetts News

February 1--In Marijuana, the Deceptive Drug, which appeared one month ago
in this newspaper, George Biernson argues that marijuana is a dangerous
drug, more dangerous than heroin, cocaine, alcohol or tobacco. Biernson
claims, in particular, that regular marijuana use substantially damages the
brain, the immune system, the reproductive system, and the lungs. He also
suggests that regular marijuana smoking causes sedation and confusion,
implying these effects can persist for more than a month after the use of
marijuana. Biernson also asserts that marijuana is a "gateway drug'' –
meaning its use encourages a progression toward other drugs like cocaine or
heroin – and he implies that marijuana use causes crime.

Biernson's conclusions are based on his reading of the scientific
literature that examines the medical and other effects of marijuana. This
literature is vast, and it contains at least one or two studies that appear
to support almost any view. Yet all scientific studies are not created
equal. Some employ careful controls, use appropriate statistical
techniques, and are easily replicated by independent researchers. Many
other studies are poorly controlled, employ problematic statistical
methods, or fail to be replicated by subsequent research. An objective
assessment of the evidence, therefore, must consider all the evidence, and
it must attempt to place greater weight on well-designed, carefully
interpreted, and easily replicated studies than on those that do not
satisfy these standards.

Highly Skewed

My contention is that Biernson's review of the evidence on marijuana's
effects is highly skewed. The pages of this newspaper are not an
appropriate forum in which to debate the merits of the individual studies
cited by Biernson in the longer work on which he based his article, nor is
it possible to present here the vast array of research findings that
reaches substantially different conclusions from those suggested by
Biernson. What I attempt, instead, is to show the reader that alternative
reviews of the evidence have reached strikingly different conclusions than
Biernson's. Moreover, even without recourse to the scientific literature,
thoughtful consideration of Biernson's assertions should leave the reader
skeptical regarding the more extreme claims made in his article.

A first alternative assessment of the evidence is provided in Goodman &
Gilman's The Pharmacological Basis of Therapeutics, Ninth Edition (1996),
which is the standard reference work on basic pharmacology. The editors of
this text are an associate vice-chancellor of the Vanderbilt University
School of Medicine, a chairman of the Department of Pharmacology at the
Vanderbilt School of Medicine, a chairman of the Department of Pharmacology
at the University of Pennsylvania School of Medicine, a director of the
cancer center at the University of Nebraska Medical Center, and a chairman
of the Department of Pharmacology at the University of Texas Southwestern
Medical Center. The authors of the various chapters in the volume include
professors at most of the elite universities and medical centers in the
United States, including Harvard, Stanford, Duke, Virginia, Michigan, and
Pennsylvania, amongst others; the author of the section on marijuana is
Chief of Psychiatry, Veterans Administration Medical Center, and Professor
and Vice-Chairman of Psychiatry, at the University of Pennsylvania School
of Medicine.

The portion of this text that discusses marijuana says that "there is no
evidence that marijuana use damages brain cells or produces any permanent
functional changes.'' Regarding the claims that marijuana smoking makes
users confused or sedated, it states that "there are no data that
demonstrate a causal relationship between marijuana smoking and these
behavioral characteristics.'' The text also notes that relatively few
patients ever seek treatment for marijuana addiction.

Not Harmful

A different assessment of the evidence on marijuana comes from Lester
Grinspoon and James B. Bakalar, associate professor of psychiatry and
lecturer in law, respectively, in the Department of Psychiatry at Harvard
Medical School. In their 1997 book, Marihuana, The Forbidden Medicine, they
write that "after carefully monitoring the literature for more than two
decades, we have concluded that the only well-confirmed deleterious
physical effect of marihuana is harm to the pulmonary system.'' As they
note, moreover, even this effect can be minimized by the use of high
potency marijuana (which means relatively little marijuana need be smoked)
or by means of filtering devices, as occurs with cigarettes. In the
introduction, Grinspoon notes that when he began studying marijuana,
several decades ago, he was convinced it was a harmful drug, and he aimed
to document those dangers scientifically. Yet upon reviewing the evidence
he concluded that marijuana was "considerably less harmful than tobacco and
alcohol.''

New Evidence

The most recent comprehensive review of the evidence is provided in the
1997 book Marijuana Myths, Marijuana Facts, by Lynn Zimmer and John P.
Morgan. Zimmer is an associate professor of sociology at Queens College of
the City University of New York, and Morgan is a professor of pharmacology
at the City University of New York and an adjunct professor of pharmacology
at the Mount Sinai School of Medicine. They review most if not all of the
marijuana studies cited by Biernson; but they also consider hundreds of
other studies, many of which explicitly reply to those Biernson relies on.

According to Zimmer and Morgan, some of the studies cited by Biernson have
been flatly contradicted by subsequent work; in other cases these studies
suffer from poor research designs, small samples, or inapplicability to
humans. And more generally, they are but a small portion of the available
evidence, most of which reaches substantially different conclusions. With
respect to every claim made by Biernson – regarding health, addiction,
gateway effects, psychological damage, criminogenic effects, and the like –
as well as with respect to numerous other issues, Zimmer and Morgan
conclude that marijuana's negative effects have been drastically
exaggerated, and that in most cases there is little evidence of any harm
even from regular marijuana use. They note that their evaluation is simply
the most recent in a long line conducted in the United States and
elsewhere, including the Indian Hemp Drugs Commission (1894), the Panama
Canal Zone Report (1925), the LaGuardia Commission Report (1944), the
British Wooten Report (1969), the Canadian LeDain Commission Report (1970),
the National Commission on Marihuana and Drug Abuse (1972), the Dutch Baan
Commission (1972), the Commission of the Australian Government (1977), the
National Academy of Sciences Report (1982), and the Report by the Dutch
Government (1995). All these reviews of the evidence find that marijuana's
harms have been highly exaggerated and conclude that moderate, responsible
use poses little demonstrable risk.

Beyond the fact that numerous, reputable experts have drawn radically
different conclusions than Biernson from reviews of the evidence on
marijuana, a further fact to consider is the large amount of marijuana
consumption that occurs in the United States every year. According to
government surveys, approximately 72 million Americans have used marijuana
in their lifetime, and more than 18 million have used it recently. These
numbers plausibly understate the true number of persons with marijuana
experience, since many persons are plausibly reluctant to admit illegal
behavior to government surveys. If Biernson's claims about addiction or
gateway effects are even partially accurate, we ought to observe a large
fraction of those who try marijuana becoming regular users, and a
substantial fraction of these users progressing to cocaine or heroin use.
Similarly, if Biernson's's claims about marijuana's health, or
psychological, or criminogenic effects are accurate, we ought to observe
inordinate numbers of teenagers exhibiting a motivational syndrome and
committing large numbers of crimes, as well as legions of patients
presenting with marijuana-induced ailments. Yet none of these implications
has any basis in fact. Most of those who try marijuana, or who use it
occasionally, stop using it of their own volition, without serious
difficulty. Only a small fraction of those who use marijuana ever try
cocaine or heroin, let alone become regular consumers of these drugs. And
any "epidemic'' of marijuana-induced ailments is simply nonexistent.

Not Harmless

None of this evidence, it must be emphasized, shows that marijuana is
harmless; indeed, several of the scientific reviews cited above note
explicitly the possibility that marijuana smoking causes lung damage, and
they note the possibility (as yet not convincingly documented) that
marijuana use during pregnancy has adverse effects on the fetus. These
scientific reviews also note that marijuana use can impair the ability to
drive a car or perform other complex tasks (although several studies find a
larger negative effect of alcohol on driving ability and other activities).
Thus, these reviews are not necessarily endorsements of marijuana or
suggestions that it can be consumed without risk by all persons under any
circumstances. But these reviews paint a far different picture than the one
suggested by Biernson. Moreover, they are written by authors with
credentials at least the equal of those cited by Biernson, and they are
based on far more extensive and recent reviews of the evidence.

One reason for the different assessments of the evidence, especially the
evidence of sociological or criminogenic effects of marijuana, is the
difficulty in distinguishing cause from effect. The set of persons that
chooses to use drugs is not likely to be a random sample of the population,
and this has key implications for interpreting correlations between
marijuana use and other kinds of behavior. Thus, a finding that marijuana
users are unmotivated or underachieving, or prone to psychological
difficulties, or the like, does not demonstrate that marijuana causes these
phenomena. Any evidence of such a correlation might instead suggest that
the decision to use marijuana results from emotional difficulties or more
serious psychological problems, including ones that have yet to manifest
openly. Similarly, the fact that a substantial fraction of those arrested
have consumed marijuana does not demonstrate a causal effect of marijuana
use on criminality, any more than the fact that most arrested persons wear
blue jeans shows denim causes criminality. Instead, the correlation between
marijuana use and criminal behavior plausibly reflects the fact that
certain types of people are both prone to consume marijuana and to commit
crime, without any causal relation.

Biernson's Response?

A possible response that Biernson might make to these arguments, even if he
were to accept this milder assessment of marijuana's effects, is that
marijuana is still dangerous because it leads to consumption of other
dangerous substances, such as cocaine or marijuana (the so-called
"gateway,'' or "stepping-stone'' effect). One important response to this
argument is the fact that, although by no means without risks, cocaine and
opiate consumption are also far less dangerous than commonly portrayed, and
can themselves be consumed without substantial harm even over long periods.
Many of the hazards associated with cocaine and opiate consumption result
from their prohibition, which encourages users to accept uncertain quality,
pay higher prices, purchase drugs from potentially violent criminals, and
employ risky administration techniques that can transmit HIV or other
infectious diseases.

But whether or not one accepts this point, the claim of a gateway effect
for marijuana is problematic and unsubstantiated. It is true that most
users of cocaine and opiates consumed marijuana before consuming these
other drugs, just as they consumed alcohol in most cases before consuming
marijuana. But these same persons also consumed french fries before they
consumed alcohol, and milk before they consumed french fries; the temporal
sequencing of different kinds of consumption does not mean that one causes
the other. The vast majority of those who use marijuana do not go on to
other drugs, so any gateway effect is small at best. Moreover, exaggerating
marijuana's health effects might encourage a gateway effect. When teenagers
are told that marijuana is dangerous, but inevitably find out this claim is
misleading, they conclude (correctly) that adults are lying about
marijuana. This can only encourage them to think the claims about cocaine
or heroin are manufactured as well (which they are to a substantial
degree), and thus make them more likely to experiment further.

A balanced review of the evidence, therefore, suggests a far more nuanced
picture of marijuana than suggested by Biernson. To repeat, this does not
mean marijuana is risk free; but no substance is safe for all persons, or
under all circumstances, or in arbitrarily high doses. Common over the
counter medications, such as aspirin, cause hundreds of deaths per year;
common foods, such as peanuts, or medications such as penicillin, readily
kill persons who are allergic. And the treatments for many diseases, such
as chemotherapy for cancer, can easily cause death in doses only modestly
above the clinically recommended amounts. Tobacco, alcohol and saturated
fats all cause disease or death under some circumstances, as do
automobiles, swimming pools, and children's toys.

The relevant question for consumers of any commodity, therefore, is whether
the benefits outweigh the potential harms. Biernson's characterization of
marijuana's effects is meant to suggest that the harms from marijuana are
so great that no person who understood these harms would ever voluntarily
consume marijuana. That characterization is not consistent with an
objective assessment of the evidence.

References

1. Grinspoon, Lester and James B. Bakalar (1997), Marihuana, The Forbidden
Medicine, New Haven: Yale University Press.

2. Hardman, Joel G., Lee E. Limbird, Perry B. Molinoff, Raymond W. Ruddon,
and Alfred Goodman Gilman, eds. (1996), Goodman & Gilman's The
Pharmacological Basis of Therapeutics, Ninth Edition, New York: McGraw-Hill.

3. Lynn and John P. Morgan (1997), Marijuana Myths, Marijuana Facts, New
York: The Lindesmith Center.