Cannabis 1988
Old Drug, New Dangers
The Potency Question

Tod H. Mikurya, M.D. [Psychiatrist and Substance Abuse Therapist,
Berkeley, California] & Michael R. Aldrich, PH.D. [Curator, Fitz Hugh
Ludlow Memorial Library, San Francisco, California

Journal of Psychoactive Drugs Vol. 20 (1), Jan. -- Mar. 1988 pp.47-55

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 potent
than the product smoked ten years ago is being used, and the intoxicated
state is more intense and lasts longer." In addition, Cohen (1986)
asserted that "the amount of THC [tetrahydrocannabinol] in confiscated
street samples averaged 4.1 percent THC during 1984. The sinsemilla
varieties were about 7 percent 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."

The average potency of marijuana samples seized by the Drug
Enforcement Administration (DEA) increased from 0.5 percent THC in 1974 to
3.5 percent in 1985-1986, with sinsemilla (seedless marijuana) at 6.5 to 12
percent, announced Dr. Richard Hawks of NIDA later that year (Kerr 1986:
1). "Parents who experimented in their youth are not aware that the
potency is much higher," added Donald M. Delzer, Chairman of the National
Federation of Parents for Drug Free Youth (Kerr 1986: 18).

"Now perceived as a hard drug, marijuana has increased 1,400
percent in potency since 1970," proclaimed the flyer of a national
conference on marijuana (Henry Ohlhoff Outpatient Programs 1986). Drug
abuse treatment professionals soon elaborated on the outcry. Tennant
(1986) asserted that the drug of the 1970's contained one to three percent
THC, while that of the 1980's contained five to 15 percent. Furthermore,
the brain registers the difference exponentially, so the difference between
one percent and 10 percent THC was not nine percent, but more like 900
percent (Garcia 1986: 3). Smith (1987) stated that Cohen "taught us
that marijuana was a lot more dangerous than we originally thought,
particularly with the use of more potent preparations by young people."
Inaba (1987) added that "this new, stronger marijuana has a more
disruptive effect on brain chemistry and body physiology than we had
imagined previously," and mentioned heretofore undescribed side effects
among athletes: "Baseball players who get beaned a lot admit to smoking
marijuana. It impairs their ability to follow the ball."

In a column for drug abuse counselors, Meyers (1987) advised
"supportive therapy" for the effects of the "new" marijuana, which were
described as "depersonalization, disorientation, derealization, changes in
perception, and alterations in body image....acute brain syndromes with
temporary clouding of mental processes....a change of time sense -- where
minutes seem like hours -- slowed thinking, and feared perception of brain
damage." Schick Shadel Health Services drug abuse treatment clinics
(Unsigned 1987) now advertise that "marijuana has increased THC content
from one percent THC in 1975 to six to fourteen percent THC in 1985 due to
hybridization techniques....For those who have become addicted to
marijuana, whether it was years ago, or recently, treatment is necessary --
even more critical today."

Despite the respectability of these authorities, none of these
alarming claims are new, and neither is the potency issue. There are
several claims intertwined: (1) that the marijuana available today is
much stronger than that available previously, particularly since the early
1970's; (2) that the effects of this so-called new marijuana are
different from effects known earlier; and (3) that all previous marijuana
research has been done with weak material and is therefore irrelevant.
Before leaping on lthe bandwagon, one should examine the validity of these
assertions.

HISTORICAL PERSPECTIVE

Extremely potent marijuana has been described for 150 years by
Western scientists and (with the possible exception of the beanball
syndrome) so have the effects of the new marijuana. There has been a
great deal of research on high-potency cannabis in many countries.
In the paper that introduced cannabis to Western medicine,
O'Shaughnessy (1839) discussed the widespread social and medical uses of
ganja (sinsemilla) in India and noted symptoms of "delirium which the
incautious use of the Hemp preparations often occasions, especially among
young men first commencing the practice." Cannabis tinctures soon appeared
in Europe and America (Robertson 1847; Savory 1843) and Fitz Hugh Ludlow
(1857) described florid psychedelic trips after their oral ingestion,
including all the symptoms mentioned by Meyers (1987). The Ohio State
Medical Society (McMeeens 1860) reviewed some 15 years of clinical
experience with the drug and acknowledged the intense but physiologically
benign mental effects caused by high doses or idiosyncratic sensitivity.

Wood (1869) reported the subjective effects of a tincture made
from North American marijuana, experiencing a distortion in time sense,
convulsions and memory loss, but no adverse after effects. He reported
considerable success with it in the treatment of severe neuralgia.
However, 15 years later Wood and Smith (1884) commented on the variable
potency of cannabis and outlined appropriate treatment for overdoses in
medical practice.

Early investigatiors (McMeens 1860; Bell 1857) attributed this
variability to "defective pharmaceutic processes" employed in foreign
countries, and recommended that extracts prepared at home would be
preferable. However, extreme variations in locally manufactured
preparations were soon recognized in the Dispensatory of the United States
(Wood & Bache 1868; 379-382). A practical bioassay technique was
gradually perfected starting from the systematic observations of Hare
(1887), followed by Evans (1894) and Marshall (1898), to compensate for
batch-to-batch potency variations.

Pragmatically, the solution to the overdose/potency problem in both
the United States (Wood & Bache 1868: 382) and England was to titrate
the dose. In London, a patient who signed a letter to the editors of
Lancet, W.W. (1890) reported a typical case: W.W. had inadvertently been
given an overdose of cannabis for treatment of neuralgia by his doctor and
had suffered perceptual distortion, agitation, mood swings, and fear of
death. Sir J. Russell Reynolds, M.D., F.R.S., physician to Queen
Victoria's household, responded with a recommendation based on 30 years of
experience with the drug (Reynolds 1890), stating "that Indian hemp,
when pure and administered carefully, is one of the most valuable medicines
we possess....a minimum dose should be given to begin with, and...the dose
should be very gradually and cautiously increased."

During the nineteenth century, social and scientific research on
marijuana, as well as tinctures, were conducted with much stronger material
than is available on the illicit market today. For example, the Indian
Hemp Drugs Commission of 1893-1894 investigated the social, religious and
medical uses of bhang (marijuana), ganja (sinsemilla) and charas
(hashish). The potencies of varieties from different parts of the
subcontinent were evaluated by government chemists and botanists (Evans
1894; Hooper 1894), using the "acknowledged superiority" of Bengal ganja
as the standard. The Commission found that the moderate use of even highly
potent marijuana caused no significant physical, mental or moral damage
(Kaplan 1969; Mikurya 1968).

In the 1890's, at the peak of medical interest in the drug, British
chemists (Wood, Spivey & Easterfield 1899) isolated an impure active
principle, cannabinol, using a "red oil" distilled from Indian cannabis as
a starting point, which was considered to be the active ingredient until
the 1930's (Work, Bergel & Todd 1939; Cahn 1931). In 1909, Marshall
demonstrated that oxidation during storage was the primary cause of the
drug's variable potency. With this advance the pharmaceutical industry
shifted its attention to the production of standard extracts that could be
used to assay medicinal compounds (Colson 1920). Because it had long been
known that ganja and charas produced the most reliable extracts (Wallich
1883; Robertson 1847), in practical terms this meant the European and
American producers had to learn how to grow ganja.

Sinsemilla cultivation by the Indian technique of culling male
plants from the fields before female plants could set seeds -- the very
process to which recent researchers attribute the potency of the new
marijuana -- was exhaustively described by the British government in India
(Kaplan 1969: 59-84; Prain 1893; Kerr 1877). In an effort to promote
Bengali ganja, the British Raj imposed an export duty on inferior Bombay
ganja at the turn of the century, and pharmacognosists in Europe and the
U.S. began learning sinsemilla cultivation (Mair 1900).
Holmes (1900) discussed the potencies of Calcutta and Bombay ganja
and recommended that the former be used for pharmaceutical preparations,
either by home cultivation of ganja according to the Bengal methods he
outlined (Holmes 1902a) or by extracting it immediately in Bengal and
shipping it in tightly closed containers (Holmes 1902b). Comparing the
potency of cannabis from Uganda,
France and India, Holmes (1905) urged that only Indian sinsemilla
preparations be admitted to the British Pharmacopoeia.

Likewise, Whineray (1909) and Hooper (1908) described ganja
cultivation and manufacture, pointing out that cannabis grown in North
America by the Indian methods could be as fully potent as Indian hemp. The
National Standard Dispensatory of 1909, which included medicines from the
pharmacopoeias of the U.S., Britain and Germany, gave the details of
sinsemilla cultivation and featured a drawing of a perfect Calcutta ganja
flower top (see Figure 1) as an example to be emulated by Western
cultivatgors (Hare, Caspari & Rusby 1909: 374).

In the U.S., Hamilton and his colleagues (Hamilton 1918; Hamilton
1915; Hamilton, Lescohier & Perkins 1913; Houghton & Hamilton 1908)
demonstrated that if care was exercised in cultivating and processing the
plant for extraction, American-grown ganja and its extracts were as
reliable as those from India and would not deteriorate significantly if
stored properly. Information on cultivation of extremely potent seedless
marijuana was thus widely disseminated to Western pharmaceutical producers
during the first two decades of the twentieth century.

The U.S. government ignored these sinsemilla cultivation techniques
at the first federal marijuana farm established in 1904 on the Potomac
Flats (where the Pentagon now sits) in Washington, D.C. (Silver 1979:
262-263), and as a result the 10-foot marijuana plants grown there and
elsewhere in America proved to be much less potent than good samples of
Indian hemp (Eckler & Miller 1912). However, private pharmaceutical firms
were more successful. The Eli Lilly and Parke-Davis companies ran a
cooperative venture at Parkedale (Parke-Davis's farm near Rochester,
Michigan) from 1913 until 1938 to develop cannabis extracts for medical
use, at first from Cannabis indica, but later standardized on a highly
potent strain they developed that they called Cannabis Americana (Wheeler
1968). Pharmaceutical companies were marketing cannabis extracts that were
uniformly effective at 10 mg dose levels (Parke-Davis & Company 1930:
82) 11 years before its official removal from medicinal availability.

In 1941, cannabis was removed from the United States Pharmacopoeia
(USP) at the behest of the Federal Bureau of Narcotics, which suddenly
claimed that marijuana had no medical uses (Mikurya 1973: xx). Yet even
the removal of cannabis from the USP did not end scientific and social
research on highly potent forms of cannabis, ranging from the red-dirt
marijuana of the Midwest to the red oil of the laboratories. Adams, Pease
and Clark (1940) described improved procedures for preparing purified red
oil from Minnesota wild hemp, and comparison of the potencies of Minnesota
marijuana and red oil was of significant interest to Loewe, pharmacological
director of the LaGuardia Committee (Mayor's Committee on Marihuana 1944:
186ff). Red oil concentrates were used along with marijuana in the
LaGuardia Committee's experiments on prisoners, under Loewe's personal
direction (Mayor's Committee on Marihuana 1944: 32); for a subjective
account see Mezzrow and Wolfe (1946: 317ff). In the 1940's, Adams and
Loewe in the U.S. and Todd in England isolated other cannabinoids,
including THC, which Adams (1940) postulated as the active principle.

Such isolates were the mainstay of marijuana research during the
1940's and 1950's. A potent marijuana oil created as a truth drug for
interrogation purposes by the Office of Strategic Services during World War
II (Lee & Shlain 1985: 3-5) was the forerunner of later clandestine
experiments conducted by the CIA and the Department of Defense at the
Edgewood Arsenal in Maryland from the 1950's to the 1970's (Mikurya 1973:
xxii). Experiments with the designer drug synhexyl, a potent analog of
delta-3-THC, were conducted from the 1940's (Adams et al. 1941) until the
mid-1970's (Lemberger 1976; Pars & Razdan 1976), but were abandoned
before its potential was fully explored.

In the 1960's, the identification of pure delta-9-THC as the active
principle in cannabis (Gaoni & Mechoulam 1964) made it possible to assay
the relative potencies of cannabinoids directly in human subjects (Isbell
et al. 1967). Although Weil, Zinberg and Nelsen (1968) demonstrated the
safety of human marijuana research, much of the U.S. research of the 1970's
was conducted with low-potency marijuana because the government would not
approve human research with high-potency strains. Indeed, in one early
study (Jones & Stone 1970), a THC concentrate was removed from Mexican
marijuana and then redistributed back into the bulk marijuana to return its
potency to 0.9 percent THC. Outside the U.S., these strictures did not
apply: The fact that cannabidiol interferes with the effects of
delta-9-THC was discovered in Brazil, using both purified cannabinoids on
humans (Karniol et al. 1974).

The 1960's and 1970's saw a worldwide flowering of cannabis
research, including its social, psychological, chemical, botanical and
legal aspects as well as covering an enormous range of potencies and
dosages. Major botanical work involved potency questions: observing
phenotypes at the University of Mississippi (Fetterman et al. 1971) and
in Canada (Small 1979); establishing a lectotype for Cannabis sativa L.
(Stear 1974); distinguishing C. sativa from C. indica and C. ruderalis
(Schultes et al. 1974); and cultivation techniques for increased THC
production (Clarke 1981; Frank & Rosenthal 1978).

Thus the claim by Cohen (1986) that "all marijuana research to
date has been done on 1 or 2 percent THC material" is not accurate for the
1970's or for any other decade going back to 1839. It ignores much of the
laboratory research in the U.S. that was summarized by Cohen himself
(Cohen & Stillman 1976), Hollister (1986) and the National Academy of
Sciences (1982), and all of the social research on high-potency marijuana
in Jamaica (Rubin & Comitas 1975; Bowman & Pihl 1973), Costa Rica
(Carter & Doughty 1976), Greece (Fink et al. 1976) and Africa (DuToit
1980). It is difficult to think of any country in which the claim is true.


RECENT ESTIMATES OF POTENCY

Since the advent of quantitave analysis technology, there has been
sporadic reportage of the percentage of delta-9-THC and other cannabinoids
in natural and semisynthetic cannabis products. Notwithstanding the
psychophysical effects of other cannabinoids, the amount of THC present in
a marijuana sample is believed to determine the drug's potency (National
Commission on Marihuana and Drug Abuse 1972: 50), and potency is usually
expressed in percent THC by weight. The results of quantitative analyses
performed on street samples of marijuana have been published since the late
1960's. These results are generally higher than the alleged 0.5 percent
THC content of marijuana cited for the early 1970's.

Lerner and Zeffert (1968) described the development of
quantitative analysis for the determination of THC content, and noted much
variation among samples of marijuana, hashish, and red oil (still being
used experimentally in the 1960's). The THC content of confiscated Mexican
marijuana was 0.8 to 1.4 percent, hashish averaged eight percent and red
oil 31 percent in 1968.
Quantitative analyses of street samples of marijuana and hashish
conducted by Canadian laboratories in 1971 for the Commission of Inquiry
into the Non-Medical Use of Drugs (1972: 28-29) showed a range of 0.02
to 3.46 percent THC (median=0.93%) for marijuana, with hashish ranging
from 1.0 to 14.3 percent THC (median=4.82%). Samples seized in police
raids were less potent: marijuana was 0.05 to 1.65 percent THC
(median=1.3%). The reported difference between confiscated police seizures
and street samples submitted to laboratories for analysis may be due to the
voluntary samples being submitted precisely because of their extraordinary
potency, or that storage conditions in police evidence lockers are hardly
optimal for potency stability.

This has a bearing on the potency question because the low potency
cited by both Cohen (1986) and Hawks (see Kerr 1986) referred to
samples confiscated by the DEA. It has been known since the early days of
its isolation (Wollner et al. 1942) that THC oxidizes to cannabinol
rapidly in samples stored at room temperature (24 degrees C). Lerner
(1963) reported that the concentration of THC in marijuana decreased at a
rate of three to five percent under normal room conditions, and Razdan
(1970) reported a rate of 10 percent per month. The influence of
temperature, light and age on potency was addressed by Starks (1977):
13-15). The low-baseline percentage of THC reported for the early 1970's
may be due to this deterioration in confiscated, stored samples. In any
case, the low baseline makes the difference in the THC content of
later-reported samples appear much greater than it may have been in
actuality, assuming that the marijuana smoked by consumers was fresher than
stored police seizures.

For a short while in the early 1970's, PharmChem Laboratories in
Palo Alto, California, tested and reported the percent of the THC content
in anonymously submitted marijuana samples. For 1973, PharmChem reported
an average THC content of 1.62 percent in marijuana, compared with hashish
at 4.6 percent ahd hash oil (a refined extract of hashish) at 13.5
percent (Ratcliffe 1974).
In 1974, the DEA published guidelines that no longer allowed
laboratories to provide quantitative results directly to the sample donors.
This, in effect, restricted public access to analysis information to
whatever government officials wished to reveal. However, nonspecific
summaries of THC percentage ranges were allowed to be published (Unsigned
1974).

The results of an independent examination of gas-liquid
chromatographs of street samples of marijuana from California that were
submitted to PharmChem during 1973 and 1974 are shown in Table I. Seeded
varieties ranged in THC from an average of 2.2 percent (Mexican) to 4.9
percent (Panama Red), while sinsemilla averaged 2.8 percent for Big Sur
"Holy Weed" to above six percent for Thai Sticks and Hawaiian "Maui
Wowie." This would appear to be a much more representative sample of the
types of marijuana available in California in 1973-1974 than the
half-percent grade cited by Cohen (1986) and Hawks (see Kerr 1986), or
the one to three percent grade cited by Tennant (1986).

A retrospective summary of street-drug analysis trends from 1969
through 1975 published by PharmChem (Perry 1977) confirms the fact that
quite potent forms of cannabis were available on the illicit U.S. market by
1975: "Early quantitative work showed a range of 1.0-2.5 percent THC for
average marijuana. In 1975, the range was 1.0-2.5 percent ; samples in
the range of 5.0-10.0 percent were not uncomon, and some contained as much
as 14.0 percent THC....Hash oil (concentrated from hash, usually amber or
red in color) and grass oil (from marijuana, dark green or black in
color)....vary greatly in potency, some samples [containing] up to 40
percent THC." Abundant information on the comparative potencies of
cannabis grown in the U.S. and other countries in the mid-1970's was
summarized by Starks (1977: 41-87).

In lthe spring of another election year, 1980, Cohen and DuPont
launched a similar campaign, stating that confiscated marijuana in 1975
contained only 0.4 percent THC, while in 1979 the average was four percent,
a tenfold increase (Brody 1980: C1). This data conflicts directly with
that published by PharmChem for 1975 street samples (Perry 1977) and that
shown in Table I. Perhaps one should be thankful that, according to these
estimates, marijuana potency dropped from four percent THC in 1979 to 3.5 %
percent THC in 1986 (Kerr 1986).
The most recent comparison of cannabis potencies was compiled from
published sources from 1972 through 1981 by the National Academy of
Sciences (1982: 16), and is summarized in Table II. It again
demonstrates the great range of products available legally (i.e., NIDA
samples) and illegally during that decade, and may in fact underestimate
some potencies. For example, the 2.8 percent THC content cited for
Jamaican ganja (Marshman, Popham & Yawney 1976) is slightly lower than
the mean 2.96 percent THC material studied by Rubin and Comitas in 1970
through 1972 (Unsigned 1973), and significantly lower than the four to
eight percent THC Jamaican ganja cited by the National Commission on
Marihuana and Drug Abuse (1972: 50).

The government "research harvests" in Table II (Rosenkrantz
1981) are considerably less potent than the sinsemilla samples that
averaged three to 11 percent THC (Turner 1981, 1980). Perhaps this is
because cultivators at the government marijuana farm at the University of
Mississippi, like their predecessors in 1904, never learned proper
sinsemilla cultivation (Turner et al. 1979), while illicit cultivators in
California and Hawaii were making it standard for the industry (Frank &
Rosenthal 1978: 258-259). If so, this alone could explain the wide
discrepancies between the potency of marijuana reported by government
sources and that actually being grown in the U.S. during the 1970's and
1980's.

[continued]

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