Long-term exposure to tobacco smoke is demonstrably harmful to health. According to the United States Center for Disease Control, tobacco smoking is the leading cause of preventable death in the United States, and chronic exposure to tobacco smoke is linked to increased incidences of cancer as well as vascular disease. Inhaling tobacco smoke is also associated with a variety of adverse pulmonary effects, such as COPD (chronic obstructive pulmonary disease).
Does smoking cannabis pose similar dangers to lung health? According to a number of recent scientific findings, marijuana smoke and tobacco smoke vary considerably in their health effects. So then why are lawmakers in various states, such a Minnesota and New York, imposing new restrictions explicitly prohibiting the inhalation of herbal preparations of cannabis?
Marijuana Smoke vs. Tobacco Smoke
Writing in the Harm Reduction Journal in 2005, noted cannabis researcher Robert Melamede explained that although tobacco smoke and marijuana smoke have some similar chemical properties, the two substances possess different pharmacological activities and are not equally carcinogenic. Specifically, he affirmed that marijuana smoke contains multiple cannabinoids – many of which possess anti-cancer activity – and therefore likely exerts “a protective effect against pro-carcinogens that require activation.” Melamede concluded, “Components of cannabis smoke minimize some carcinogenic pathways whereas tobacco smoke enhances some.”
Marijuana Smoke and Cancer
Consequently, studies have so far failed to identify an association between cannabis smoke exposure and elevated risks of smoking-related cancers, such as cancers of the lung and neck. In fact, the largest case-controlled study ever to investigate the respiratory effects of marijuana smoking reported that cannabis use was not associated with lung-related cancers, even among subjects who reported smoking more than 22,000 joints over their lifetime. Summarizing the study’s findings in The Washington Post, pulmonologist Dr. Donald Tashkin, Professor Emeritus at the David Geffen School of Medicine at UCLA, concluded: “We hypothesized that there would be a positive association between marijuana use and lung cancer, and that the association would be more positive with heavier use. What we found instead was no association at all, and even a suggestion of some protective effect.”
A meta-analysis of additional case-control studies, published in the International Journal of Cancer in 2014, similarly reported, “Results from our pooled analyses provide little evidence for an increased risk of lung cancer among habitual or long-term cannabis smokers,” while a 2009 Brown University study determined that those who had a history of marijuana smoking possessed a significantly decreased risk of head and neck cancers as compared to those subjects who did not.
Marijuana Smoke and Pulmonary Function
According to a 2015 study conducted at Emory University in Atlanta, the inhalation of cannabis smoke, even over extended periods of time, is not associated with detrimental effects on pulmonary function, such as forced expiratory volume (FEV1) and forced vital capacity (FCV). Assessing marijuana smoke exposure and lung health in a large representative sample of U.S. adults, age 18 to 59, they maintained, “The pattern of marijuana’s effects seems to be distinctly different when compared to that of tobacco use.” Subjects had inhaled the equivalent of one marijuana cigarette per day for 20 years, yet did not experience FEV1 decline or deleterious change in spirometric values of small airways disease.
Marijuana Smoke and COPD
While tobacco smoking is recognized as a major risk factor for the development of COPD – a chronic inflammation of the airways that may ultimately result in premature death – marijuana smoke exposure (absent concurrent tobacco smoke exposure) appears to present little COPD risk. In 2013, McGill University professor and physician Mark Ware wrote in the journal Annals of the American Thoracic Society: “Cannabis smoking does not seem to increase risk of chronic obstructive pulmonary disease or airway cancers… Efforts to develop cleaner cannabinoid delivery systems can and should continue, but at least for now, (those) who smoke small amounts of cannabis for medical or recreational purposes can breathe a little bit easier.”
Mitigating Marijuana Smoke Exposure
The use of a water-pipe filtration system primarily cools cannabis smoke, which may reduce throat irritation and cough. However, this technology is not particularly efficient at eliminating the potentially toxic byproducts of combustion or other potential lung irritants.
By contrast, vaporization heats herbal cannabis to a point where cannabinoid vapors form, but below the point of combustion – thereby reducing the intake of combustive smoke or other pollutants, such as carbon monoxide and tar. Observational studies show that vaporization allows consumers to experience the rapid onset of effect while avoiding many of the associated respiratory hazards associated with smoking – such as coughing, wheezing, or chronic bronchitis. Clinical trials also report that vaporization results in the delivery of higher plasma concentrations of THC (and likely other cannabinoids) compared to smoked cannabis. As a result, the authors affiliated with the University of California Center for Medicinal Cannabis Research and elsewhere now acknowledge that vaporizers provide a “safe and effective” way to for consumers to inhale herbal cannabis.
The Bottom Line
Based on this scientific record, it makes little sense for lawmakers to impose legislative bans on herbal cannabis products, such as those that presently exist for patients in Minnesota and New York and which are now being proposed in several other states (e.g., Georgia and Pennsylvania). Oral cannabis preparations, such as capsules and edibles, possess delayed onset compared to inhaled herbal cannabis, making these options less suitable for patients desiring rapid symptomatic relief. Further, oral administration of cannabis-infused products is associated with significantly greater bioavailability than is inhalation – resulting in more pronounced variation in drug effect from dose to dose (even in cases where the dose is standardized). These restrictions unnecessarily limit patients’ choices and deny them the ability to obtain rapid relief from whole-plant cannabis in a manner that has long proven to be relatively safe and effective.
Marijuana consumers do not typically use cannabis and alcohol in combination with one another, regardless of whether they are consuming cannabis for medicinal or social purposes, according to data published online ahead of print in the journal Addiction.
Investigators with the RAND Drug Policy Research Center and the University of California, Irvine surveyed marijuana use patterns among participants between the ages of 18 and 91 in four states: Colorado, New Mexico, Oregon, and Washington. (The use of marijuana for medicinal purposes is legal in New Mexico, while laws in Colorado, Oregon, and Washington permit adults to possess and purchase cannabis for both medicinal and/or recreational purposes.)
Authors reported, ”Individuals who use cannabis do not commonly use it with alcohol, irrespective of whether they are consuming cannabis recreationally or medically.” They concluded, “Fewer than one in five recreational users report simultaneous use of alcohol and cannabis most or all of the time and less than three percent of medicinal users report frequent simultaneous use of alcohol and cannabis.”
An abstract of the study, “A baseline view of cannabis use among legalizing states and their neighbors,” appears online here.
The enactment of statewide laws permitting the use of cannabis for therapeutic purposes is associated with an annual reduction in obesity-related medical costs, according to data published online ahead of print in the journal Health Economics.
Investigators at Cornell University in New York and San Diego State University in California reviewed twelve years of data from the CDC’s Behavioral Risk Factor Surveillance System to examine the effects of medical marijuana laws on body weight, physical wellness, and exercise.
Researchers reported, “[T]he enforcement of MMLs (medical marijuana laws) is associated with a 2% to 6% decline in the probability of obesity. … Our estimates suggest that MMLs induce a $58 to $115 per-person annual reduction in obesity-related medical costs.”
For those age 35 or older, authors determined that the passage of medical cannabis laws is “associated with an increase in physical wellness and frequent exercise consistent with the hypothesis of some medicinal use of marijuana.” For younger adults, researchers theorized that obesity declines were the result of less alcohol use.
They concluded, “These findings are consistent with the hypothesis that MMLs may be more likely to induce marijuana use for health-related reasons among older individuals, and cause substitution toward lower-calorie recreational ‘highs’ among younger individuals.”
The abstract of the study, “The Effect of Medical Marijuana Laws on Body Weight,” appears online here.
Cannabis use is associated with improved outcomes in opioid-dependent subjects undergoing outpatient treatment, according to data published online ahead of print in the journal Drug and Alcohol Dependence.
Researchers at Columbia University assessed the use of cannabinoids versus placebo in opioid-dependent subjects undergoing in-patient detoxification and outpatient treatment with naltrexone, an opiate receptor antagonist. Investigators reported that the administration of oral THC (dronabinol) during the detoxification process lowered the severity of subjects’ withdrawal symptoms compared to placebo, but that these effects did not persist over the entire course of treatment. By contrast, patients who consumed herbal cannabis during the outpatient treatment phase were more readily able to sleep, were less anxious, and were more likely to complete their treatment as compared to those subjects who did not.
“One of the interesting study findings was the observed beneficial effect of marijuana smoking on treatment retention,” authors concluded. “Participants who smoked marijuana had less difficulty with sleep and anxiety and were more likely to remain in treatment as compared to those who were not using marijuana, regardless of whether they were taking dronabinol or placebo.”
The findings replicate those of two prior studies, one from 2001 and another from 2009, reporting greater treatment adherence among subjects who consumed cannabis intermittently during outpatient therapy.
Population data from states where medicinal cannabis is permitted report lower rates of opioid-abuse and mortality as compared to those states where the plant is prohibited. Clinical data and case reports also indicate that the adjunctive use of cannabis may wean patients from opiates while successfully managing their pain. Survey data of state qualified medical cannabis patients demonstrates that subjects with access to the plant often substitute it for opioids because they perceive it to possess fewer adverse side effects.
Overdose deaths involving opioids have increased dramatically in recent years. While fewer than 4,100 opiate-induced fatalities were reported for the year 1999, by 2010 this figure rose to over 16,600 according to an analysis by the US Centers for Disease Control.
An abstract of the study, “The effects of dronabinol during detoxification and the initiation of treatment with extended release naltrexone,” appears online here.
Cannabinoids are safe and effective for the treatment of chronic pain, according to the results of a systematic review of randomized controlled trials published in the Journal of Neuroimmune Pharmacology.
Investigators from Dalhousie University in Halifax, Nova Scotia and McGill University in Montreal evaluated the results of 11 placebo-controlled trials conducted between the years 2010 and 2014. Trials assessed the use of various types of cannabinoid preparations, including herbal cannabis, liquid and oral cannabis extracts, and nabilone (a synthetic analog of THC), in pain treatment.
Cannabinoids possessed “significant analgesic effects” and were “well tolerated” in the majority of studies reviewed.
Authors concluded, “The current systematic review provides further support that cannabinoids are safe, demonstrate a modest analgesic effect and provide a reasonable treatment option for treatment chronic non-cancer pain.”
A 2011 review of 18 separate randomized trials evaluating the safety and efficacy of cannabinoids for pain management similarly reported, “[C]annabinoids are a modestly effective and safe treatment option for chronic non-cancer (predominantly neuropathic) pain.”
In September, Canadian researchers reported that pain patients who consumed herbal cannabis daily for one-year experienced decreased analgesia and no increase in serious adverse side effects compared to matched controls.
An abstract of the study, “Cannabinoids for the treatment of chronic non-cancer pain: An updated systematic review of randomized controlled trials,” appears online here.