Calif. regulators warn of pot's cancer capability

Jul 04, 2009 By MARCUS WOHLSEN , Associated Press Writer

(AP) -- It might take Californians a puff or two to get their heads around an apparent contradiction recently enshrined in state law. The same marijuana smoke that doctors can recommend to ease cancer patients' suffering must soon come with a warning saying it causes the disease.

State environmental regulators last month voted to place marijuana smoke on its list of hundreds of substances known to cause . The decision could lead to warning signs in medical marijuana dispensaries and labels on packaged pot within a year.

A voter-approved measure made medical marijuana legal in California in 1996. Key backers included patients with serious illnesses such as cancer and AIDS who said pot helped them manage pain and nausea.

Medical marijuana advocates sought to downplay the significance of the state's decision, arguing researchers have long known that the smoke contains cancer-causing compounds.

"This does not mean in any way that those that appear in smoked marijuana, smoked cannabis, have any kind of causal relationship to cancer," said Kris Hermes, spokesman for Americans for Safe Access, a pro-medical marijuana group.

Regulators disagree. Scientists with the state's Office of Environmental Health Hazard Assessment reviewed 27 studies of the links between marijuana and cancer in humans. Though not all the studies showed a link, regulators found that "marijuana smoke was clearly shown, through scientifically valid testing according to generally accepted principles, to cause cancer," according to an agency statement.

Dr. Thomas Mack, a University of Southern California epidemiologist and chairman of the committee, said the decision to list marijuana smoke as a cancer-causing substance should not surprise anyone.

"If you take a piece of vegetable material, a leaf, and burn it, you're going to get the type of compounds that cause cancer," Mack said.

Marijuana smoke and tobacco smoke share 33 of the same cancer-causing compounds, according to agency scientists.

Even so, the existing evidence is merely "suggestive" of a link between marijuana and cancer in humans, Mack said. Only in tests that subjected animals to ultrahigh doses of marijuana was the connection between the drug and cancer totally clear, he said.

To counter the conclusion that smoking marijuana carries major health risks, advocates were quick to jump on the flaws in studies reviewed by the committee.

For instance, regulators reviewed three studies that found connections between marijuana and lung cancer. Of those, two were conducted in North Africa, where smokers regularly mix marijuana with tobacco, a problem the committee acknowledged.

The committee also considered a large 2006 study that found not only did marijuana smokers show no higher risk for cancer than nonsmokers but possibly even less.

"If they want to classify marijuana smoke as carcinogenic, then that is true. It contains carcinogens," said Donald Tashkin, a longtime University of California, Los Angeles marijuana researcher who led the study. "That doesn't mean it causes cancer."

One possible explanation is that marijuana contains chemicals that have an anti-cancer effect that cancels out the carcinogens, though that has not been proven, Tashkin said.

Marijuana supporters have hailed Tashkin's findings as evidence that pot can actually protect against cancer. He said he doesn't know whether marijuana has that power or not. But Tashkin himself believes the carcinogens present in pot mean it will never be approved by federal regulators as medicine.

The decision to list marijuana smoke as a cancer-causing agent falls under California's Proposition 65, a voter-approved measure that instructs regulators to identify substances that can cause cancer, birth defects or other reproductive harm. The law also requires warnings on products and in buildings where chemicals on the list are present in potentially unsafe levels.

Since the law was passed in 1986, the list has grown to nearly 800 substances, including such common products as aspirin, gasoline and acrylamide, a naturally occurring chemical in potato chips and french fries. Critics contend the list has grown so long that the warnings have little impact on consumers.

Dr. Frank Lucido of Berkeley has recommended pot to his patients since medical marijuana became legal in the state 13 years ago. He has become so convinced of the drug's potential that he now serves as vice president of the recently formed American Academy of Cannabinoid Medicine, a group of physicians who study and set standards for medical marijuana use.

Lucido said he will not stop recommending pot. But he might suggest patients take the drug in other forms, such as marijuana-infused foods or vaporizers, which pass hot air through to create a smokeless way to inhale the drug.

"Obviously, it's never good to breathe smoke if you can avoid it," Lucido said.

©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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User comments : 3

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tamago
5 / 5 (2) Jul 04, 2009
Too bad there's not a way to safely consume marijuana, say with some sort of vaporizer device. Oh wait, there is? Oh, well then too bad legalizing it would seriously undermine the disastrously profitable War on Drugs.
Crucialitis
5 / 5 (1) Jul 05, 2009
Bake brownies.. problem solved. Non-issue.
Who is still supporting this criminalization crap? As if hippies are going to overrun.. well, anything other than a fridge or a festival.
What a stupid world we inhabit.
Mandan
not rated yet Jul 05, 2009
Radiation (both therapy and scanning technology) and chemo don't cause cancer?

All smoke is probably carcinogenic to one degree or another. But nicotine is the real culprit in tobacco-- not just the smoke. Chewers don't smoke it, but get oral/digestive tract cancers at a high rate. Thus, people who think they've done themselves some good by getting their nicotine fix from gum or whatever have probably not.

And, as the first two posters point out, cannabis can be safely eaten or vaporized, while clearly orally ingesting or even vaporizing nicotine does not lessen its carcinogenic qualities completely if at all.

Cannabis-- and probably other drugs as well-- should be immediately legalized, regulated, and taxed. This country could use the money-- not just the billions in revenue, but the billions which would be saved by only having to keep real criminals in prison, freeing up courts and police to pursue only real criminals, and keeping people who are not criminals out in the economy working and spending money, instead of spending the equivalent of a public college education on them every year to keep them behind bars for consuming a safe, relaxing, enjoyable, and very ancient, widespread form of recreational intoxicant-- which if it harms anyone, only harms themselves. Alcohol harms people. Tobacco harms people. Religion harms people. They are all legal. Let's be consistent for once.

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