Marijuana Less Cancerous Than Tobacco

Discussion in 'Marijuana News' started by IndianaToker, Oct 19, 2005.

  1. By Steve Mitchell, Senior Medical Correspondent
    Source: United Press International

    Washington, D.C. -- Marijuana is less carcinogenic than tobacco smoke and may even have some anti-cancer properties, new research suggests. Robert Melamede, chair of biology at the University of Colorado in Boulder, reviewed studies of the illicit drug and published his findings in the Oct. 17 issue of Harm Reduction Journal.

    Melamede's conclusion is certain to factor in the medical-marijuana debate, because the cancer-causing potential of the drug is one of the reasons often cited by those who oppose legalizing it for medicinal uses. He said he was motivated to investigate the issue because the Drug Enforcement Administration has made the argument that marijuana has four times the amount of tar contained in tobacco smoke, so it is potentially carcinogenic.

    "I said, 'Let's see what's true because the government doesn't have a very good record on telling the truth about cannabis,'" Melamede, who classifies himself as a medical-marijuana advocate, told United Press International.

    He said the studies indicated although marijuana smoke does contain carcinogens, it does not appear to induce cancer because of its unique pharmacological properties. Lung cancer, for example, is caused by a combination of carcinogens in conjunction with nicotine found in tobacco smoke.

    "It's the nicotine that's really the cancer-promoting agent," he explained. "That's absent in marijuana smoke so you don't have that enhancing factor."

    Studies to date have not linked marijuana smoking with the lung, colon, rectal and other cancers associated with tobacco smoking, Melamede said. In addition, other studies have indicated compounds found in cannabis might even kill certain cancers, including lung, breast, prostate and skin, as well as leukemia and lymphoma, and a type of brain cancer called glioma.

    "That's not to say smoking marijuana is good," Melamede noted. It is a lung irritant and can cause respiratory problems, such as coughing. Also, it is full of carcinogens, so "even if it's not causing cancer, it's having negative effects," he said.

    One alternative would be to use a vaporizer, rather than smoking, to deliver the marijuana.

    "It should be noted that with the development of vaporizers, that use the respiratory route for the delivery of carcinogen-free cannabis vapors, the carcinogenic potential of smoked cannabis has been largely eliminated," Melamede wrote in the journal.

    At least 10 states, including California and Colorado, have moved in the direction of allowing patients to use marijuana with a doctor's approval. The DEA has attempted to enforce a federal ban on the drug, however, and has arrested patients using it. This policy has discouraged doctors from recommending it for medical use.

    The U.S. Supreme Court ruled last June that the federal prohibition supersedes state laws and the DEA can arrest patients who use the drug.

    Karen Tandy, the DEA's administrator, wrote in an article titled, "Marijuana: The Myths Are Killing Us," which appeared in the March issue of Police Chief magazine, that the drug is hazardous to health and does not help patients.

    "The scientific and medical communities have determined that smoked marijuana is a health danger, not a cure," Tandy wrote in the article, which also appears on the DEA Web site. "There is no medical evidence that smoking marijuana helps patients."

    Tandy did not claim marijuana caused cancer, but she implied it by saying, "marijuana smoke ... contains 50 to 70 percent more carcinogenic hydrocarbons than tobacco smoke and produces high levels of an enzyme that converts certain hydrocarbons into malignant cells."

    She also said marijuana can cause anxiety and depression, particularly in teens. However, a study released last week from Canadian researchers found a synthesized version of a marijuana compound actually promotes development of new brain cells in rats, and this in turn was accompanied by a reduction in anxiety and depression.

    Other risks of marijuana cited by Tandy included impaired cognitive function, such as short-term problems with perception and memory.

    Allen St. Pierre, executive director of the National Organization for the Reform of Marijuana Laws, told UPI that Tandy's assertions "run up against the known science," which indicate the toxicity of the drug is minimal.

    "While not harmless, marijuana comes very close to being benign when compared to other prescription drugs," St. Pierre said.

    He noted that Dr. Tod Mikuriya, a psychiatrist in El Cerrito, Calif., had conducted a study with medical-marijuana patients and did not find evidence they developed cognitive impairments, paranoia, anxiety or other mental problems after they began using the drug.

    "The government has insisted there are no pros and there are only cons of marijuana, but this is totally lacking in science and totally lacking in any realistic credibility," Melamede said.

    He predicted medical marijuana ultimately will be permitted in the United States.

    "It's unavoidable that it will eventually triumph because it works," he said. "The government is lying and it will eventually win out in the end. It's just a matter of how many people have to suffer between now and then."

    Source: United Press International (Wire)
    Author: Steve Mitchell, Senior Medical Correspondent
    Published: October 17, 2005
    Copyright 2005 United Press International
    Website: http://www.upi.com/
    Contact: healthbiz@upi.com
    Link to article: http://www.cannabisnews.com/news/thread21199.shtml
     
  2. By Jennifer Warner, WebMD Medical News
    Source: WebMD

    Washington, D.C. -- Although tobacco smoke and marijuana smoke are chemically very similar, a new report argues that their cancer-causing effects may be very different. Both tobacco and cannabis smoke contain the same cancer-causing compounds (carcinogens). Depending on what part of the plant is smoked, marijuana can contain more of these harmful ingredients.

    But a recent review of studies on the effects of marijuana and tobacco smoke suggests that the cancer-promoting effects of these ingredients is increased by the tobacco in nicotine and reduced by the tetrahydrocannabinol (THC) found in cannabis.

    Previous studies have shown that THC can inhibit carcinogens in mice, and the report suggests it may have the same protective effect against the carcinogens found in smoke in humans. But researchers warn that even if THC lessens the effects of these cancer-causing ingredients, cannabis smoke remains carcinogenic.

    The Role of THC

    In the article, published in Harm Reduction Journal, researcher Robert Melamede, PhD, of the University of Colorado at Colorado Springs, argues that tobacco smoke and marijuana smoke are not equally cancer-causing.

    Research shows that nicotine and THC act on related pathways in the body, but they bind to different receptors to activate these pathways. For example, Melamede says the cells of the lungs are lined with nicotine receptors but do not appear to contain receptors for THC.

    He says that may explain why marijuana use has not been linked to lung cancer as cigarette smoking has.

    However, Melamede says the effects of cannabis and cannabis-like compounds are complex and sometimes contradictory. The long-term effects of marijuana on an aging population of users are not known; the effects may become similar to what we see with tobacco.

    Also, marijuana is frequently used in combination with tobacco and the two drugs may interact in yet unknown ways.

    SOURCES: Melamede, R. Harm Reduction Journal, Sept. 22, 2005; vol 2. News release, BioMed Central.

    Note: Researchers Say THC May Curb Cancer-Causing Effects of Marijuana Smoke.

    Reviewed By Louise Chang, MD

    Source: WebMD (US)
    Author: Jennifer Warner, WebMD Medical News
    Published: Monday, October 17, 2005
    Copyright: 2005 WebMD Inc.
    Contact: news@webmd.net
    Website: http://www.webmd.com/
    Link to article: http://www.cannabisnews.com/news/thread21200.shtml
     
  3. By Andre Picard, Public Health Reporter
    Source: Globe and Mail

    Canada -- Marijuana smokers are less likely to contract cancer than cigarette smokers, new research suggests. While cannabis and tobacco smoke are chemically similar, the key difference is that cigarettes contain nicotine, which appears to bolster the cancer-causing properties of tobacco, while cannabis contains tetrahydrocannabinol (THC, the active ingredient in pot), which may actually reduce the carcinogenic properties of some chemicals.

    "Current knowledge does not suggest that cannabis smoke will have a carcinogenic potential comparable to that resulting from exposure to tobacco smoke," said Robert Melamede, chairman of the department of biology at the University of Colorado at Colorado Springs.

    The new study, published in today's edition of the medical journal Harm Reduction, is a review and analysis of research that has already been published.

    The research has important political implications in the ongoing debate about medical marijuana.

    One of the principal reasons public-health officials and medical experts oppose the use of marijuana as a prescription drug is the belief that the risks outweigh the benefits, and the fear that endorsing medical marijuana undermines anti-smoking campaigns.

    Marijuana contains about four times the level of tar found in cigarettes, and is believed to place smokers at risk of lung cancer and other cancers related to smoking.

    But Dr. Melamede said there is no solid evidence that cannabis smoking increases the risk of lung cancer or other cancers related to tobacco smoking such as breast, colon and rectal cancer.

    He said there is evidence from studies done on laboratory rats that the THC in cannabis smoke "exerts a protective effect" against potential carcinogens and evidence that nicotine found in cigarettes activates the growth of tumours.

    "While both tobacco and cannabis smoke have similar properties chemically, their pharmacological activities differ greatly," Dr. Melamede said.

    But Roberta Ferrence, director of the Ontario Tobacco Research Unit and professor of public health at the University of Toronto, expressed grave doubts about the research, likening it to splitting hairs.

    "It may be that cannabis is slightly less carcinogenic but tobacco smoke is extremely carcinogenic so that doesn't tell us very much," she said.

    Dr. Ferrence said that most carcinogens are a byproduct of combustion, so "anything you burn and inhale is going to be carcinogenic -- including tobacco and cannabis. There is no way, based on this research, that you can say that smoking cannabis is safe."

    She also noted that many people who smoke marijuana mix it with tobacco, and that makes the chemical distinctions moot. "From a public-health perspective, smoking is smoking," Dr. Ferrence said.

    Tobacco smoke contains more than 4,000 chemical compounds, dozens of which are known carcinogens.

    An estimated 5.1 million Canadians, or 20 per cent of the population 15 and older, report smoking cigarettes regularly, according to the Tobacco Use Monitoring Survey. More men (22 per cent) smoke than women (17 per cent).

    By contrast, an estimated three million people, or 12.2 per cent of those 15 or older, reported that they smoked marijuana at least once in the past year, according to Statistics Canada.

    Nearly half (47 per cent) of those who had used cannabis in the previous year smoked less than once a month, 10 per cent reported weekly use, and another 10 per cent said they smoked pot daily.

    Canada has had a medicinal marijuana program since 2001. Since then, Health Canada has issued about 750 licences for people to smoke marijuana for the treatment of chronic pain and other ailments.

    Note: Nicotine in cigarettes appears to boost carcinogenic properties, researchers find.

    Complete Title: Pot Less of a Cancer Risk Than Tobacco, Study Suggests

    Source: Globe and Mail (Canada)
    Author: Andre Picard, Public Health Reporter
    Published: Tuesday, October 18, 2005 Page A23
    Copyright: 2005 The Globe and Mail Company
    Contact: letters@globeandmail.ca
    Website: http://www.globeandmail.com/
    Link to article: http://www.cannabisnews.com/news/thread21201.shtml
     

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