IS POT FAR MORE POTENT THAN IN THE PAST?

With the Resurgence of the Marijuana Debate, Supporters of the Status Quo
Have Made Several, Related Claims: Marijuana Is Far More Potent Today; More
Potent Marijuana Is More Dangerous; and Recent Research Conclusively Proves
That Marijuana Can Damage Intelligence and Cause Mental Illness. In This
First of Two Parts, Citizen Senior Writer Daniel Gardner Tackles the Questions.

Pot today is "as much as seven times stronger than the 'grass' available
four years ago," warned an article in Newsweek. That was in 1980. It was
already a well-worn theme.

And it continues to be a media standard, appearing several times in this
newspaper over just the last two weeks. Marijuana strength has "skyrocketed
from the giddy low potency highs experienced by happy sixties hippies,"
Margret Kopala wrote, a claim that has been repeated so often by so many
sources that journalists and politicians take it as an accepted fact,
something "everybody knows."

But this claim, although widely accepted, is substantially inaccurate.

In 2004, the European Monitoring Centre for Drugs and Drug Addiction
(EMCDDA), a European Union agency, conducted a comprehensive review of
available evidence in Europe, the United States, Australia and New Zealand.
"Statements in the popular media that the potency of cannabis has increased
by 10 times or more in recent decades are not supported by the limited data
that are available from either the USA or Europe," the report concluded. In
New Zealand, the report added, researchers found no increase in potency
between 1976 and 1996. In Australia, there was only a "modest" rise.

The EMCDDA report also cautioned that increases in potency should be kept
in context. "The natural variation in the THC content between and within
samples of herbal cannabis or cannabis resin at one any one time or place
far exceeds any long-term changes that may have occurred either in Europe
or the USA. This natural variation is even greater when material from
different geographic locations is examined."

One reason why the myth of exploding pot potency started is that
measurement of potency prior to the 1980s is very poor. There was no
established protocol and improperly stored marijuana -- such as bags of
weed sitting in police evidence rooms for weeks -- rapidly loses THC
content. As a result, samples tested during the era of lava lamps and bell
bottoms were commonly found to have THC content of less than one per cent
- -- a patently absurd result because marijuana with less than one per cent
is incapable of producing any psychoactive effect. Claims today by U.S.
drug czar John Walters and others that pot potency has exploded to such an
extent that marijuana is no longer the drug baby boomers remember are
partly the result of using these faulty baselines in potency calculations.

To untangle the reality, Mitch Earleywine, a professor of psychology at the
University of Southern California, carefully assessed the credible evidence
on potency in his book Understanding Marijuana (Oxford University Press
2002). He concluded average pot in the early 1970s was likely 1.5 per cent
THC. By the late 1990s, that had risen to 4.5 per cent. According to the
U.S. government's Marijuana Potency Monitoring Project, the average potency
in 2001 was 5.2 per cent.

According to an RCMP report, seized samples of Canadian pot in the late
1990s had an average THC content of 5.5 to six per cent -- marginally above
the U.S. average. Almost one-third of the pot tested at the time was below
three per cent THC.

In 2003, the average potency of the seized samples tested by Health Canada
was 9.7 per cent. However, that average is misleading because it is skewed
high by a small number of high-potency samples. Slightly more than
one-quarter of the 2003 samples had a THC content between zero and five per
cent. One-third came in between six and 10 per cent, while another
one-third were in the range of 11 to 15 per cent. Just seven per cent of
marijuana tested had a potency 15 per cent or greater.

Clearly, growers have successfully used traditional selective breeding
principles and intensive cultivation to produce strains of marijuana that
are far more potent than average pot 30 years ago. But these strains are
still relatively rare. Most marijuana today is only modestly more potent
than that remembered wistfully by baby boomers, and there are no grounds
for claiming, as many politicians and police officers have, that marijuana
today is so much stronger as to be a wholly different drug.

The evidence also shows there is no major difference in potency between
Canadian and U.S. marijuana. Some strains of Canadian marijuana are very
potent but, as a report of the National Drug Intelligence Center of the
U.S. Department of Justice noted, "growers in both Canada and the United
States have access to the same strains of cannabis seeds and the same
cultivation techniques." There is simply no solid evidence to show that
Canadian marijuana is uniquely potent. It is an urban legend repeated by
politicians, police officers, journalists, gullible customers and dealers
happy to pocket a premium for a "unique" product.

(Ms. Kopala's claim that "90 per cent" of Canadian-grown marijuana is
smuggled into the United States is dubious. Numbers such as these are
simply guesses made by police officers who have no evidence to support
them. RCMP reports frankly admit they don't know how much pot is being
smuggled. And a report from the National Drug Intelligence Center of the
U.S. Department of Justice noted that although "a number of international
publications have reported that approximately 50 to 60 per cent of the
marijuana produced in Canada is smuggled into the United States annually
.. in-depth analysis and consultations between officials of both countries
have concluded these estimates cannot be substantiated through current
reporting.")

Is More Potent Pot More Dangerous?

This is the tacit assumption behind fears of rising marijuana potency, but
few commentators have attempted to provide any evidence to support it. One
who recently did was the U.S. drug czar.

"The number of Americans admitted to hospital emergency wards because of
marijuana use has doubled to 120,000 annually in the past five years," said
a recent news story in this newspaper, paraphrasing Mr. Walters at a
Washington news conference. Mr. Walters also noted the number of U.S. teens
seeking treatment for marijuana dependency has increased so greatly that it
now exceeds the treatment demand for all other drugs combined. The "big new
factor" accounting for this alarming shift, Mr. Walters said, is "the
enormous growth of very-high-potency marijuana coming from Canada."

U.S. government reports have repeatedly confirmed that Canadian marijuana
- -- high-potency or not -- only accounts for a tiny fraction of the total
marijuana available in the U.S., so it's difficult to accept Mr. Walters'
claim that Canadian pot is responsible for such dramatic trends. It's also
telling that Canadian hospitals and treatment programs are not being
overwhelmed by desperate Canadian pot smokers.

However, in other statements, Mr. Walters made the same claims while
leaving Canada out of the equation. The surge in emergency-room visits and
treatment admissions is proof of the damage done by high-potency marijuana,
he argued.

Is it? As it turns out, Mr. Walters was playing fast and loose with the
statistics.

The emergency-room data Mr. Walters' cites are not a tally of people whose
marijuana use caused them to rush to hospital. Rather, the data come from a
system that records emergency-room "mentions." To be counted, a person
checking into emergency merely has to mention marijuana, in any context. A
w oman who says she was smoking a joint when she tripped over a footstool
and sprained her ankle would be added to the tally. So would someone who
tells a doctor he was quietly smoking marijuana in his living room when he
was hit by a stray bullet from a gunfight outside.

Obviously, emergency "mentions" will be heavily influenced by patients'
beliefs about acceptable conduct. If they believe they will be looked down
on, or suffer legal consequences, for mentioning marijuana use, they will
be reluctant to do so. If they think it's no big deal, they will be more
likely to mention it. As these beliefs rise and fall, so will the data.
Similarly, the beliefs of doctors and nurses will influence their decision
to record a marijuana mention.

Mr. Walters' use of treatment data is even more misleading. It is true that
there has been a surge in the numbers of U.S. teens entering marijuana
treatment. But Mr. Walters neglected to mention that almost 60 per cent of
those admissions were ordered by judges. Nor did he mention that the
proportion of people entering treatment as a result of a court order has
risen substantially.

This reflects a sea-change in U.S. criminal justice. Since 1990, there has
been an explosion in the number of U.S. "drug courts" which allow
individuals charged with some drug offences to avoid jail if they follow a
carefully supervised treatment program.

At the same time, the idea of "therapeutic justice," as it is sometimes
called, has been widely adopted by regular U.S. courts. As a result,
Americans charged with pot offences today are routinely given a choice
between punishment or treatment. Not surprisingly, most choose treatment.

Mr. Walters' dubious statistics aside, is there any evidence that more
potent marijuana is more dangerous?

Experience with hashish suggests not. Hashish is a typically very potent
derivative product of marijuana that is typically between 15 and 20 per
cent THC but can be as potent as 50 per cent THC. Consumption of hashish
varies greatly from place to place but the EMCDDA report notes that hashish
is more common than herbal marijuana in several European countries. If
higher potency meant greater danger, the damage should be obvious in
countries where hashish predominates. But that's not the case. In fact,
there doesn't seem to be any evidence that hash consumers suffer worse
harms than marijuana smokers.

Another substance that casts doubt on the idea that greater potency means
greater risk is Marinol, a pill developed with the strong backing of the
U.S. government and officially approved for the control of nausea in cancer
patients and appetite stimulation in AIDS patients. Marinol is synthetic
THC. Its potency is 100 per cent.

The 2004 EMCDDA report found there is "an absence of direct evidence of any
clear additional health risk" posed by more-potent marijuana, but the
report also added that despite all the talk about higher potency there
hasn't been a great deal of systematic research on the subject. The report
cited a recent Dutch government study that concluded "higher-potency
cannabis products did not pose any additional risk than those for present
cannabis products as a whole, either to the individual, to society, to
public order or criminality." The medical marijuana provided to Dutch
patients, the report added, is a highly potent 18 per cent THC.

It may seem counter-intuitive that more potent pot may not be more
dangerous, but the explanation is actually straightforward.

First, the assumption that higher potency is more dangerous rests on
another assumption: that THC is the source of whatever harms marijuana can
cause. But THC is only one of hundreds of components of marijuana smoke.
Unless THC is shown to be the specific cause of a specific harm, higher THC
content is irrelevant.

But there's an even more basic explanation: Most cannabis users, like most
ordinary users of alcohol and other drugs, are not seeking to become as
inebriated as possible for as long as possible. "Most people on a six-point
scale say they want to get to a three or a four and they don't want to
spend more than about three or four hours high," says Mitch Earleywine,
citing surveys he and another researcher have conducted among pot smokers.

Users of a drug -- any drug -- regulate their intake according to potency
and desired effect. A person sipping vodka with a potency of 40 per cent
alcohol will consume a much smaller volume of liquid than he would if he
were drinking wine with a potency of 16 per cent alcohol or beer at five
per cent. Similarly, someone smoking pot with 15 per cent potency will
inhale far less smoke than he would if he were smoking pot with two per
cent potency. (The parallel with alcohol breaks down in one respect,
however: Someone who drinks an entire bottle of vodka can overdose and die
whereas it is physically impossible for a person to consume enough
marijuana to cause a fatal overdose.)

Although this simple equation is rarely mentioned in debates about
marijuana, it is common sense among pot smokers. And it has been borne out
by research, including a University of Michigan study of teen pot smokers
which concluded that rising THC levels caused users to inhale "less
marijuana as measured by volume."

Mr. Earleywine notes that surveys asking users how high they get show no
change since the 1970s, despite the increase in marijuana potency. "It's
just that they're smoking less of it, rather than getting higher."

Oddly enough, this suggests that rising marijuana potency may produce a
modest health benefit. "When smoking stronger pot, you smoke less and you
have less exposure to tars and respiratory irritants," Mr. Earleywine says,
adding with a laugh, "so in some ways it's worth smoking the best pot you
can afford."