Unless you've been living in a ditch, you know there is one drug that will quickly be removed the "Drug War". According to a recent Gallup poll, the percentage of Americans who are in favor of legalization of marijuana has risen to the highest levels since the polling began. Marijuana will be fully legalized at some point close and will hit the pinnacle when the UN Drug Conventions are altered to adjust for the past moral reasoning behind drug use and law accounts for scientific health-based research.
One of the most common health issues exclaimed by many anti-marijuana proponents and propaganda is that marijuana smoke has four times the amount of tar as tobacco smoke. This one statement is just enough for most common Americans for some time to remain constant on their stand on keeping it illegal and choosing to keep tobacco as the smoked plant of choice. Yet this fact is not nearly as simple as many Americans presume.
According to a US Department of Health and Human Services drug survey marijuana is the second most smoked substance after tobacco in the US. A 2010 National Survey on Drug Use and Health reported 17.4 million past-month users with a 2011 report stating 41.9% of Americans using marijuana at least once in their lifetime. This was actually the first time I really saw that number and had to do a double-take; it is amazing how high that percentage is yet it is still illegal. It might be interesting to see what the percentage of people who try tobacco smoking is?
The US government in our life time has done an amazing job of harm-prevention programs with tobacco smoking. You would be hard to find someone in today's society who doesn't know how harmful cigarettes are to the body. Due to these efforts, the number of smokers in America has rapidly decreased. All for good measure, as according to the CDC more than 440,000 US deaths are pointed towards cigarette smoking every year. 2.5 million Americans died in 2011. A little math will show that tobacco smoking accounts for 17% of American morality. Tobacco use is the leading preventable cause of death in the United States. We already have a huge issue on our hands with that epidemic, the country can't afford another. It took decades for research to catch up to the truth behind tobacco smoke and it is obviously a smart move on a health stand point to be weary of calling cannabis begin with the past as it is.
It is easy to associate smoking tobacco with smoking cannabis, because well they're both combustion thus they both emit similar chemicals. Yet in extensive scientific literature there are no recorded deaths blamed on marijuana. How can we compare the two substances when one is seen as a society-killing menace and the other as a begin substance?
In my epidemiological review of research which studied marijuana use and cancer risk, I came to one conclusion that all of the studies also concluded to, there just isn't enough research on marijuana available yet. One would assume that the most widely-used illegal drug in the world would have some solid research behind it, yet sadly it is mostly a gray area of semi-conclusive results. The only way, the only way for science to fully grasp its hands around the practically unknown plant is for legalization. There are two reasons for this; 1. The only way for research to be done on marijuana in the US is through a difficult application process, security measures and the product can only come from the University of Alabama. 2. Surveys and data polled from the population will always be considerably skewed due to the criminal nature behind marijuana. We know so much about alcohol harm and tobacco harm which allows us to actually do something about them. I am here to tell you that there is no good piece of evidence dismissing or proving the cancerous effects of marijuana.
It is true, "one of the most potent carcinogens in tobacco smoke, benzo(α)pyrene, is present in even greater amounts in marijuana smoke". Also if you have experience around pot smokers, frequently we inhale……………hold the the smoke………….. then exhale (and sometimes cough…) According to (Tashkin, 2005) this increases the "amount of tar deposited in the respiratory system by a factor of four". The same study does admit that higher THC content, water pipes, filters, vaporizers, and edibles reduces or eliminates all risk of the carcinogenic tar. Yet why people can continue this "tar" debate is that smoked marijuana is by far the most used way of ingesting the THC.
Pulmonary Function
Before diving into the whole cancer risk idea, I want to bring up an interesting finding from (Pletcher, 2012). Low use marijuana smokers actually scored higher FEV1 and FVC scores (amount of air passing in/out of body) when compared to non-smokers. This is explained later in this article that the method marijuana is typically smoked actually stretches the lungs, which as assumed, forms a nonlinear relationship with high levels of long term smoking.
Previous Studies
Previous studies on cancer risk with smoked cannabis are numerous, but mostly all lack valid data to make a scientific conclusion. "Limitations of previous studies include possible confounding due to cigarette smoking and other risk factors, error in measuring marijuana use and potential confounders, and the small number of cancer cases with a history of long-term or heavy use of marijuana" (Tashkin, 2006).
"Several lines of evidence support the suggestion that marijuana smoking may be a risk factor for aerodigestive tract cancers:
1. Marijuana smoke contains several of the same carcinogens and co-carcinogens as those in tobacco smoke, including vinyl chlorides, phenols, nitrosamines, reactive oxygen species, and various poly- cyclic aromatic hydrocarbons (PAHs) (Hoffmann et al., 1975).
2. Benzo[a]pyrene, a procarcinogenic PAH, is present in marijuana tar at a higher concentration than in tobacco tar (Hoffmann et al., 1975).
3. Relative to tobacco smoking, marijuana smoking may involve inhalation of approximately three times the amount of tar and the retention of one third more of the inhaled tar in the respiratory tract (Wu et al.,1988).
4. Smoking a few marijuana cigarettes a day has been reported to have similar effects, as observed on histopathologic evaluation of the tracheobronchial epithelium, as those observed with daily smoking of more than 20 tobacco cigarettes (Fligiel et al., 1997; Gong et al., 1987).
5. Evaluation of bronchial mucosal biopsy specimens obtained from marijuana smokers without any clinically apparent disease showed more abnormalities than were observed for non–marijuana smokers in molecular markers of dysregulated growth, such as Ki-67 (a proliferation marker), epidermal growth factor receptor, and DNA ploidy (marker of genetic instability) (Barsky et al., 1998)" (Hashibe, 2005).
Carcinogenic?
Many of these studies are measuring a quantifiable value of tar released in the smoke of cannabis but the difficult factor in all this research is the human interaction. "Smoke from tobacco and cannabis contains many of the same carcinogens and tumor promoters. However, cannabis and tobacco have additional pharmacological activities, both receptor-dependent and independent, that result in different biological endpoints… Despite potentially higher levels of polycyclic aromatic hydrocarbons found in cannabis smoke compared to tobacco smoke (dependent on what part of the plant is smoked), the THC present in cannabis smoke should exert a protective effect against pro-carcinogens that require activation. In contrast, nicotine activates some CYP1A1 activities, thus potentially increasing the carcinogenic effects of tobacco smoke" (Melamede, 2005). Even though the same chemicals are in the two different smoked substances, the way the body is affected by the chemicals is different. This alone already disproves the propaganda line about tar risks in cannabis. Many marijuana activists will point you in the "magic plant" direction at this point!
A bit more in depth with this:
"The differential expression of receptors may account for the apparent difference in carcinogenic activity that results from smoking tobacco compared to cannabis. Both types of smoke contain a complex mixture of compounds, some of which are carcinogenic. They both contain hot gasses and irritating particulate matter (tars). However, the anti-apoptotic response that results from the stimulation of the nicotine receptors, under mutagenic conditions, creates a worst-case scenario" (Melamede, 2005).
"The carcinogenic potential of smoke is increased by tobacco, whereas it is uniquely reduced by the specific immune regulatory activity of cannabinoids in cannabis smoke" (Melamede, 2005).
"While both tobacco and cannabis smoke have similar properties chemically, their pharmacological activities differ greatly. Components of cannabis smoke minimize some carcinogenic pathways whereas tobacco smoke enhances some. Both types of smoke contain carcinogens and particulate matter that promotes inflammatory immune responses that may enhance the carcinogenic effects of the smoke. However, cannabis typically down-regulates immunologically-generated free radical production by promoting a Th2 immune cytokine profile. Furthermore, THC inhibits the enzyme necessary to activate some of the carcinogens found in smoke. In contrast, tobacco smoke increases the likelihood of carcinogenesis by overcoming normal cellular checkpoint protective mechanisms through the activity of respiratory epithelial cell nicotine receptors" (Melamede, 2005).
In fact there could be some good from this plant… "There is recent evidence from cell culture systems and animal models that 9-tetrahydrocannabinol, the principal psychoactive ingredient in marijuana, and other cannabinoids may inhibit the growth of some tumors by modulating key signaling pathways leading to growth arrest and cell death, as well as by inhibiting tumor angiogenesis... Such inhibitory effects in some preclinical models do not necessarily imply that exposure to marijuana smoke can prevent cancer occurrence in humans" but it "...has been shown to augment lung cancer growth in an immunocompetent mouse model due to its potent effect on immunosuppression" (Tashkin, 2006).
Negative Studies
One of the most recent predominate studies "proving" lung cancer risk in marijuana smoking is (Callaghan, 2012). Obviously due to my point of view I walked into the research with caution and I was not disappointed as the entire tone of the research paper was mostly just trying to get it highly publicized and used with current movement of marijuana legalization. They found that " ‘‘heavy’’ cannabis smoking was significantly associated with more than a twofold risk (hazard ratio 2.12, 95 % CI 1.08–4.14) of developing lung cancer over [a] 40-year follow-up period" (Callaghan, 2012). The study only referenced heavy cannabis use while also mentioning that a majority of those heavy users were typically heavy tobacco users. Overall their cohort study did much stirring, suggested that cannabis might elevate the risk of lung cancer but never actually offering scientific proof taking into account the complex issue that I presented earlier.
Heavy Use
According to the above research, "heavy cannabis use, defined as self-report of smoking marijuana more than 50 times in lifetime, was significantly associated with more than a twofold risk of lung cancer" (Callaghan, 2012). This fact is skewed in that 91% of heavy cannabis users also smoked tobacco in their lifetime. Besides this study, others did not have conclusive results due to low level of heavy use participants.
Conclusion
Overall one statement should be made about this analysis; that more research must be done to have valid, factual health-based information for users of what will soon become a legal drug. It is easy for opponents of legalization, as well as the general health field to compare the health hazards of tobacco smoke with cannabis smoke but the complexities of the plant must be explored before we can place such a stigma against it.