A New Front in the War Against Pot?

State panel concludes that cannabis causes cancer. But the research is still young, and the industry seems undeterred.

Walk into Coffeeshop Blue Sky in downtown Oakland and breathe in the
intoxicating aroma of the year’s finest herb. Then notice that the
walls are plastered with contradictory information. A government-issued
sign warns that marijuana, when inhaled, has been found by the state of
California to cause cancer. But other signs tout legalization and call
attention to a UCLA study that disputes the state’s findings. A sticker
from Oaksterdam University says further information on the subject is
available. This is what California dispensaries could look like a year
from now.

On June 19, marijuana smoke joined the ranks of 800 other
carcinogens listed under Proposition 65, an initiative passed by
California voters in 1986. Most, if not all, of these cancer-causing
substances are legal. The list includes everything from aspirin to
asbestos, and ranges from harmless chemicals to those that are

Anti-drug advocates are already using the inclusion of marijuana
into California’s roster of carcinogens as a new soundbite for their
opposition. This could be a new front in the war against pot. David
Evans, executive director of the Drug Free Schools Coalition, says the
drug’s designation is long overdue and that marijuana is no longer
benign by any stretch of the imagination. “Based on the studies that
have been conducted, marijuana is at least equal to tobacco and, more
likely, it is worse in terms of the toxic impact it has on the body,”
Evans said. “It combines the worst aspects of tobacco with the worst
aspects of alcohol.”

Such cries of outrage may seem moot considering how thoroughly the
criminal war against medicinal marijuana has been lost in the state of
California. And pro-legalization advocates don’t seem fazed by the
ruling or its potential consequences — which they contend will
not deter marijuana usage. But while Proposition 65 is only applicable
within the state lines of California, Evans and people directly
involved in the ruling believe that this development may provoke
investigations into the association between marijuana and cancer in
other states in which medicinal marijuana is available, such as
Colorado and Vermont.

“Nobody can say California is some right-wing, drug warrior state,”
Evans said. “So if California says it causes cancer, people better pay

However, pot is big business in California and advocates like
Richard Lee, the president of Oaksterdam University, don’t think that
is going to change even after Proposition 65 warning signs are posted
on dispensary walls or in windows. Lee estimates that dispensaries
throughout the state bring in about $1 billion annually in marijuana

Marijuana caught the government’s attention in 2004 when the
California Regulatory Notice Register asked that it and 37 other
substances be tested as possibly cancer-causing. The Office of
Environmental Health Hazard Assessment rounded up a board of seven
science and health experts to review 27 human studies and four animal
studies examining the link between marijuana smoke and lung cancer. Why
31 studies? Because that’s basically all that’s out there at the
moment, said Sam Delson, the agency’s deputy director for external and
legislative affairs.

The board of experts, dubbed the Carcinogen Identification
Committee, reviewed the studies, along with numerous others that tested
for cancers other than lung cancer. After sifting through the available
data, the committee voted five to one in favor of calling marijuana a
carcinogen under Proposition 65. Chairman Dr. Thomas Mack, Dr. Solomon
Hamburg, Dr. Martin L. Hopp, Dr. Joseph Landolph, and Dr. Anna H. Wu
all voted in favor of putting the substance on the list while only Dr.
David A. Eastmond dissented.

But even Eastmond said he doesn’t doubt that cannabis causes cancer.
He simply believed that the studies relied upon were limited in scope,
and that many used outdated techniques or did not live up to the
standards of modern scientific testing. “I certainly believe it is a
carcinogen,” he said. “But there is a lot of circumstantial evidence
that didn’t meet the criteria.” Eastmond was referring to specific
language in Proposition 65 that states a substance must be “clearly
shown through scientifically valid testing according to generally
accepted principles to cause cancer.” To Eastmond and many pot
advocates, a number of the studies relied upon were not up to par.

Indeed, many of the studies relied upon by the panel are riddled
with mixed and/or unsatisfactory results. For example, perhaps the most
heavily weighted study was a 2008 study from New Zealand. It is
considered by experts to be the most comprehensive study to date
because it was conducted in a place where pot is rarely mixed and
smoked with tobacco — a problem with many of the other studies,
which were conducted in places such as Morocco and Tunis. Participants
were asked if they had ever smoked marijuana. The study concluded that
people who said yes were at a 20 percent higher risk for contracting
lung cancer than those who had never smoked. The study says it adjusted
for people who also smoked cigarettes.

Another study examined closely because of its geographical
significance was conducted here in the Bay Area by Kaiser Permanente.
It cataloged the responses of almost 65,000 Kaiser health plan members
who said they had smoked more than seven joints in their lifetime. Its
conclusion found no greater incidence of cancer among either men or
women. But the Carcinogen Identification Committee concluded that
because carcinogens can take more than twenty years to manifest
themselves, the fourteen-year-long study may therefore have been
analyzed too early in this process.

Despite the mixed evidence, the Office of Environmental Health
Hazard Assessment was satisfied with the committee’s ruling.
“Individual studies were not a slam dunk but the combined bulk of
evidence supported this decision,” Delson said.

The direct consequences of pot making the cancer list are that, in
twelve months, health department-issued warning signs stating that
cannabis is considered cancer-causing by the state of California must
be posted on dispensary walls or directly on marijuana packaging. The
warnings will only apply to businesses with at least ten employees at
which customers are “knowingly and intentionally” exposed to smoke.
Office of Environmental Health Hazard Assessment spokesman Chris Bowman
says a similar requirement has led businesses in other industries to
withdraw or reformulate their products or simply add the label to
product packaging.

Lee predicts that most dispensaries, including his own, will simply
opt to increase the flow of information available to the public. “It’s
just an opportunity for us to get our own literature out there,” he
said. He expects that many dispensaries will point to a study conducted
by Dr. Donald Tashkin of UCLA, which is considered by some pot
supporters to be the “Gold Standard” of marijuana studies to date.
Tashkin, a former opponent of legalization, studied ten marijuana
smokers who had smoked three to four joints daily for an average of
fifteen years. Tashkin waited years to turn up some sort of link but
found none. He now speaks openly about the positive effects of the
substance. “If they put those [warning] stickers up, you know every
dispensary will put up something right next to it about Tashkin’s
study,” said Lee.

Indeed, while marijuana opponents such as Evans jumped on the
committee’s conclusions, pot advocates seem unfazed and relatively
calm. They see the evidence as methodologically flawed and inconclusive
overall. “The reality is if there was a very good population base that
showed marijuana caused cancer we would all know about it,” said Paul
Armentano, deputy director of NORML and co-author of the new book
Marijuana Is Safer, So Why Are We Driving People to Drink? “That
study just doesn’t exist.”

And while Evans points to the New Zealand study, Armentano notes
that it equates one joint with five cigarettes, which he believes is
completely bogus. “You can put any number you want in the blank,” he
said. “I don’t even know what that statement means because the number
is always changing.”

The committee conceded that heavy marijuana users usually smoke at
most a couple joints a day, while heavy cigarette smokers can smoke as
much or more than a pack a day. Some studies infer that marijuana could
be considered more dangerous than cigarettes because marijuana smoke is
inhaled more deeply than cigarette smoke, and held for a longer period.
But in its final presentation, the committee concluded, “Other than
cannabinoid- and nicotine-derived compounds, comparisons of the
individual chemical constituents of marijuana smoke and those in
tobacco smoke indicate that the two smokes are quantitatively very
similar, although quantitative differences in the levels of individual
chemical constituents are apparent.”

It cannot be contested that anything inhaled into the lungs is not
good for the respiratory system. But Lee notes that inhalation is
becoming a thing of the past with the increasing popularity of edible
and vaporized marijuana, which eliminates dangerous chemicals such as
carbon monoxide.

The medical marijuana industry is not likely to appeal the judgment,
mainly because it doesn’t need to. Traffic is predicted to remain
fruitful and the label means nothing considering the laundry list of
other substances on the list. “Now we’re right there with candy bars
and everything else,” Lee said. “The only way for cannabis to kill a
lab rat is by dropping 20 pounds on it from 25 feet.”


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