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 deadly.

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 attention."

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 sales.

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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