Casual treatment of correspondence rules is not the only
indication self-serving comparisons. The well-publicized accusation
that marijuana has increased in potency over the last twenty
years is classic. The primary reason marijuana prevention
campaigns were successful with High School students in the
1980's was the declaration that marijuana was 10 times more
potent than it was in the 1970's, and consequently more dangerous.
There are two problems here. For one thing, marijuana
is a non-toxic substance; overdoses produce sleep, not death,
because of a lack of cannabinoid receptors in the medullary
region of the brain that controls breathing and heart rate.
(27) Marijuana users reduce consumption to compensate for
increased potency. According to Lloyd Johnston of the University
of Michigan Monitoring the Future Project:
"Those who are [using marijuana] seem to be using less
frequently and to be taking smaller amounts (and doses of
the active ingredient) per occasion."(28)
By analogy, beer and whisky are both alcohol, and any danger
is a function of the relative quantity consumed.
The other problem is that the finding itself is false.
Tod Mikuriya and Michael Aldrich were among the first
to document the fallacies of the allegation that increased
marijuana potency rendered marijuana a dangerous drug regardless
of past research. (29)
"The story of the new allegedly stronger and more dangerous
marijuana was rebirthed in January 1986 by the late Sidney
Cohen, M.D., Professor of Psychiatry at UCLA. ". . .material
ten or more times more potent than the product smoked ten
years ago is being used, and the intoxicated state is more
intense and lasts longer." In addition, Cohen asserted that
"the amount of THC in confiscated samples averaged 4.1 percent
THC during 1984. The sinsemilla [seedless] varieties were
about 7% with some samples reaching 14 percent . . . all marijuana
research to date has been done on 1 or 2 percent THC material
and we may be underestimating present day smoking practices."(30)
After a careful consideration of historical records,
reports of recent potency estimates, and the practice of marijuana
smokers to self-adjust their dose, the authors reached the
"While it may be true that sinsemilla is more widely
available than 10 or 15 years ago, its potency has not changed
significantly from the 2.4 to 9.5 percent THC materials available
in 1873-1974, or the five to 14 percent sinsemilla of 1975.
The range of potencies available then (marijuana at 0.1% to
7.8% THC, averaging 2.0% to 5.0% THC by 19750 was approximately
the same as reported now. With such a range, the evidence
simply cannot support the argument by Cohen that marijuana
is "ten or more times more potent than the product smoked
ten years ago." And to say that marijuana potency has increased
1,400 percent since any date in history is patent nonsense."
"It is not legitimate to imply that average low potencies
represent the full range of potencies available in reality.
Neither is it valid to cite the low end of the range then
as a baseline to compare the high end of the range now. The
claimed baseline for THC content in the early 1970's would
appear to be too low, probably because confiscated stored
police samples were utilized; and this low baseline makes
the claimed difference in potency appear to be greater than
it has been in reality."(31) (emphasis in original)
An examination of the government's actual potency data
(rather than what they have reported in press releases) was
conducted by Dr. John Morgan of the City University of New
York Medical School, and indicated that the finding was based
on a comparison of the highest THC percentage in the 1980's
with the lowest percentage of the 1970's. Also, the data from
the 1970's was derived from a sample of decaying, imported
Mexican marijuana composed of leaf and flower; it was compared
to recently harvested, domestically grown marijuana flowers.
Finally, marijuana of similar potency to 1980's standards
was available during the 1970's. (32)
Morgan's debunking of marijuana potency findings relies
on data presented by the NIDA potency project at the University
of Mississippi. This data shows that the arithmetic average
potency of domestic cannabis tested by the project has ranged
from 1.5% to 4.75% THC. (33) In 1973 Gabriel Nahas reports
that the THC content of drug-type cannabis ranges from 3.4
to 4.8%. (34) In 1975, before the emergence of high quality
domestic marijuana cultivation in the U.S., John Langer of
the DEA reports that:
"Marihuana produced in the United States is considered
inferior because of the low concentration of psychoactive
ingredients, which varies between 0.2 and 2.0 percent. Marihuana
of Mexican origin is known to be slightly stronger. The variety
known as Jamaican ganja, which consists primarily of the flowers
and breacts, has a THC content of 4 to 8 percent."(35)
These citations from Nahas and the DEA independently
demonstrate that a broad range of marijuana potencies was
available in the 1970's, and provide additional evidence that
assertions otherwise are without factual or scientific foundation.
It is important to understand the fallacy of the increased
potency argument for several reasons.
1) It is just wrong. It is factually incorrect.
2) It is ironic that advocates of marijuana prohibition
claim prior research is inadequate to explain the effects
of this new, high potent marijuana when as explained in section
3, most of the contemporaneous research was later criticized
for using extremely unrealistic potencies.
3) It is convenient. The hypothesis that marijuana is
now much more potent than in the past provides convincing
support for the assertion that any use of the drug is drug
abuse. Rhetoric about marijuana potency substitutes for scientific
findings in efforts to legitimize existing policy.
4) Most importantly, the scientific research reported
in section 3 renders the potency question irrelevant to an
assessment of the acute and chronic effects of marijuana use.
Remember, in the mid 1980's when this hypothesis gained popularity,
the dominant research paradigm was (incorrectly) based on
cell membrane perturbation. Certainly, if marijuana produced
dangerous effects by toxic seepage into cell membranes, than
increases in potency represent increases in danger. Certainly
if marijuana produced tolerance by desensitizing brain cells,
a result of this toxic seepage, then increases in potency
would increase the danger of adverse effects. However marijuana
produces its results by way of a neural receptor system, not
membrane perturbation, and the brain can tolerate extremely
high potent doses of cannabinoids. Tolerance to marijuana
develops through receptor down-regulation; the body's response
to high potency marijuana is seek a manageable equilibrium
through receptor down-regulation. The potency hypothesis may
have had some relevance in the 1980's, regardless of its foundation.
However in the 1990's, the potency hypothesis has neither
foundation nor relevance.