This is Part 4 of a series of six articles discussing marijuana’s use in medicine and health care. In this part, we discuss marijuana and health risks – even if there is evidence that marijuana had medical benefits, there must be a review of the risks of using it.
Only in junk medicine (see homeopathy or chiropractic, for example) is there a promise of great results with no risks. In real medicine, all benefits are balanced against the real risks of any medication or procedure.
The whole foundation of evidence (or science) based medicine is science – “it is the only set of methods for investigating and understanding the natural world.” Thus, the best factual evidence includes clinical research that describes not only the effectiveness, but also the risks, of a particular medical procedure.
In this article, I’ll look at marijuana and health risks – along with a skeptical analysis of those claims.
Risks of smoking marijuana
Notwithstanding the lack of quality and accurate labeling of current available “medical marijuana,” there are known risks to individuals who smoke marijuana. This is uniformly ignored by everyone, and there are even false claims that somehow smoking cannabis is safer than smoking other plants, like cigarettes. Part of the belief lies in the appeal to nature fallacy, which, in this case, implies that somehow marijuana is purer and healthier. The environmental damage from the poisons used to grow marijuana (which will, in fact, remain on the plant, and make up part of the what is inhaled) are legendary.
One of the reasons tobacco smoking is dangerous is that the epithelial cells in the lung, which make up a huge surface area of cells, are extraordinarily sensitive to environmental damages like air pollution and smoking. Though there is some evidence that marijuana smoking is less carcinogenic than tobacco, and in fact has components that have the opposite effects than tobacco smoke. But that shouldn’t be read that marijuana smoke has no carcinogenic properties, it is just less than cigarettes.
In a recent retrospective epidemiological study, the authors stated, “in conclusion, the results of the present study indicate that long-term cannabis use increases the risk of lung cancer in young adults.”
There is a “belief” that smoking pot is less problematic than smoking other types of plant material, such as tobacco, partially because some people smoke less pot that others who smoke cigarettes. This is a false assertion, because the reason why smoking is so tied to lung cancer is that the epithelial lining of the lung is susceptible to carcinogens; moreover, as the authors state, part of gaining effects of the pot is to inhale deeply and hold the smoke in the lungs for a greater period of time than in cigarettes (and certain cigars), it might actually increase the exposure of lung cells to the smoke and any associated carcinogens.
To be fair, the evidence is conflicting, but even in one large study that shows no conclusive evidence that there is an increased risk of lung cancer in non-cigarette smoking individuals, there appears to be increased risks for some types of cancer amongst marijuana smokers, including prostate cancer.
There’s also some recent evidence, published in a high impact factor journal, Human Reproduction, which found nearly double the risk of poor sperm morphology (with the possible result of infertility) after smoking marijuana (while cigarette smoking, type of underwear, and other myths about male fertility were shown to be irrelevant).
On the other hand, marijuana smoke deposits 4X as much tar in the lungs as do cigarettes. Although this may not be carcinogenic, tar can lead to the same non-cancer long-term damage to the lungs as do tobacco products–emphysema, bronchitis and lung infections.
In other words, if we’re looking at marijuana as a medical product, it’s risks are known and real. All real medications are evaluated on whether they provide a benefit and whether they have a risk. It is simply unscientific to make statements that marijuana treats this or that (even without high quality evidence) while completely ignoring whether it has some safety issues, including minor and major adverse events.
Please help me out by sharing this article. Also, please comment below, whether it's positive or negative. Of course, if you find spelling errors, tell me!
There are two ways you can help support this blog. First, you can use Patreon by clicking on the link below. It allows you to set up a monthly donation, which will go a long way to supporting the Skeptical Raptor
Finally, you can also purchase anything on Amazon, and a small portion of each purchase goes to this website. Just click below, and shop for everything.
Quality of medical marijuana
There is an important issue regarding marijuana–for clinical use, the quality and strength of marijuana must be controlled. When I hear some of the strange comments about Big Pharma and cannabis, what many people fail to note is that Big Pharma invests a huge amount of research into controlling quality and dosage of the various products.
A recent study examined the quality of marijuana available for sale in three major US cities. They looked at the drug (that’s what it is) in three forms: baked, beverages and candy. Here’s what they found:
- Edible cannabis products failed to meet basic label accuracy standards for pharmaceuticals. If a real pharmaceutical company provide products with labelling this bad, the FDA would probably have every executive arrested.
- “Greater than 50% of products evaluated had significantly less cannabinoid content than labeled, with some products containing negligible amounts of THC.” If a real neurologist were to prescribe cannabis to treat symptoms from multiple sclerosis, the problem is that the physician has no idea if the patient can get a real dose. This point, this single point, is why medical claims about marijuana are so dangerous. This is why marijuana for medical uses should be strongly regulated. And that’s why Big Pharma will, some day, be the source of such products.
- “Such products may not produce the desired medical benefit.”
- “Other products contained significantly more THC than labeled, placing patients at risk of experiencing adverse effects.” Again, it’s not just that some product is worthless, some may have so much THC that it could be dangerous.
The researchers supported my own view of the medical marijuana business, that is,:
[infobox icon=”quote-left”]Because medical cannabis is recommended for specific health conditions, regulation and quality assurance are needed.[/infobox]
If I were a medical researcher (oh wait….), and if marijuana had a real value medically (say it did cure breast cancer), smoking it would be the worst possible way to deliver the drug to the body. As I mentioned in the second part of this series, a real medical researcher would isolate the compound in marijuana that actually killed breast cancer cells, figure out a way to carry that molecule to the target site at the appropriate dose, and avoid harming the lungs. That’s how a real medical product is designed and tested.
See the next article in this series, Part 5. Marijuana and pregnancy – assessing the science.
Editor’s note: This article is a substantial update of an article that was originally published in April 2014. It has been completely revised and updated to include more comprehensive information, to improve readability and to add current research. I’ve also sub-divided into six separate articles to improve readability, and to allow a reader to choose the marijuana and medicine article that is of highest interest.
Another editor’s note: I have a policy of open commenting and dissent to my articles. I only delete spam, racism, and just random nonsense. Please comment here if you wish, because I know everyone has an opinion on marijuana. But ad hominem hatred, strawman arguments and other logical fallacies will be mocked–bring high quality, peer-reviewed evidence. I might even rewrite or add another section if it’s high quality and peer-reviewed.
- Aldington S, Harwood M, Cox B, Weatherall M, Beckert L, Hansell A, Pritchard A, Robinson G, Beasley R; Cannabis and Respiratory Disease Research Group. Cannabis use and risk of lung cancer: a case-control study. Eur Respir J. 2008 Feb;31(2):280-6. doi: 10.1183/09031936.00065707. PubMed PMID: 18238947; PubMed Central PMCID: PMC2516340.
- Aviello G, Romano B, Borrelli F, Capasso R, Gallo L, Piscitelli F, Di Marzo V, Izzo AA. Chemopreventive effect of the non-psychotropic phytocannabinoid cannabidiol on experimental colon cancer. J Mol Med (Berl). 2012 Aug;90(8):925-34. doi: 10.1007/s00109-011-0856-x. Epub 2012 Jan 10. PubMed PMID: 22231745.
- Caffarel MM, Andradas C, Pérez-Gómez E, Guzmán M, Sánchez C. Cannabinoids: a new hope for breast cancer therapy? Cancer Treat Rev. 2012 Nov;38(7):911-8. doi: 10.1016/j.ctrv.2012.06.005. Epub 2012 Jul 7. Review. PubMed PMID: 22776349.
- Gloss D, Vickrey B. Cannabinoids for epilepsy. Cochrane Database Syst Rev. 2014 Mar 5;3:CD009270. doi: 10.1002/14651858.CD009270.pub3. PubMed PMID: 24595491.
- Guzmán M, Duarte MJ, Blázquez C, Ravina J, Rosa MC, Galve-Roperh I, Sánchez C, Velasco G, González-Feria L. A pilot clinical study of Delta9-tetrahydrocannabinol in patients with recurrent glioblastoma multiforme. Br J Cancer. 2006 Jul 17;95(2):197-203. Epub 2006 Jun 27. PubMed PMID: 16804518; PubMed Central PMCID: PMC2360617.
- Hill KP. Medical Marijuana for Treatment of Chronic Pain and Other Medical and Psychiatric Problems: A Clinical Review. JAMA. 2015 Jun 23;313(24):2474-2483. doi: 10.1001/jama.2015.6199. PubMed PMID: 26103031.
- Koppel BS, Brust JCM, Fife T, Bronstein J, Youssof S, Gronseth G, Gloss D. Systematic review: Efficacy and safety of medical marijuana in selected neurologic disorders: Report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology 2014;82:1556–1563.
- Krishnan S, Cairns R, Howard R. Cannabinoids for the treatment of dementia. Cochrane Database Syst Rev. 2009 Apr 15;(2):CD007204. doi: 10.1002/14651858.CD007204.pub2. Review. PubMed PMID: 19370677.
- Lutge EE, Gray A, Siegfried N. The medical use of cannabis for reducing morbidity and mortality in patients with HIV/AIDS. Cochrane Database Syst Rev. 2013 Apr 30;4:CD005175. doi: 10.1002/14651858.CD005175.pub3. PubMed PMID: 23633327.
- Melamede R. Cannabis and tobacco smoke are not equally carcinogenic.Harm Reduct J. 2005 Oct 18;2:21. PubMed PMID: 16232311; PubMed Central PMCID: PMC1277837.
- Moyer MW. Nutrition: vitamins on trial. Nature. 2014 Jun 26;510(7506):462-4. doi: 10.1038/510462a. PubMed PMID: 24965635.
- Pacey AA, Povey AC, Clyma JA, McNamee R, Moore HD, Baillie H, Cherry NM; Participating Centres of Chaps-UK. Modifiable and non-modifiable risk factors for poor sperm morphology.Hum Reprod. 2014 Aug;29(8):1629-36. doi: 10.1093/humrep/deu116. Epub 2014 Jun 4. PubMed PMID: 24899128.
- Parsa CF, Hoyt CS, Lesser RL, Weinstein JM, Strother CM, Muci-Mendoza R, Ramella M, Manor RS, Fletcher WA, Repka MX, Garrity JA, Ebner RN, Monteiro ML, McFadzean RM, Rubtsova IV, Hoyt WF. Spontaneous regression of optic gliomas: thirteen cases documented by serial neuroimaging. Arch Ophthalmol. 2001 Apr;119(4):516-29. PubMed PMID: 11296017.
- Shrivastava A, Kuzontkoski PM, Groopman JE, Prasad A. Cannabidiol induces programmed cell death in breast cancer cells by coordinating the cross-talk between apoptosis and autophagy. Mol Cancer Ther. 2011 Jul;10(7):1161-72. doi: 10.1158/1535-7163.MCT-10-1100. Epub 2011 May 12. PubMed PMID: 21566064.
- Sidney S, Quesenberry CP Jr, Friedman GD, Tekawa IS. Marijuana use and cancer incidence (California, United States). Cancer Causes Control. 1997 Sep;8(5):722-8. PubMed PMID: 9328194.
- Skopp G, Richter B, Pötsch L. [Serum cannabinoid levels 24 to 48 hours after cannabis smoking]. Arch Kriminol. 2003 Sep-Oct;212(3-4):83-95. German. PubMed PMID: 14639811.
- Thompson AE. Medical Marijuana. JAMA. 2015 Jun 23;313(24):2508. doi: 10.1001/jama.2015.6676. PubMed PMID: 26103044.
- Tramèr MR, Carroll D, Campbell FA, Reynolds DJ, Moore RA, McQuay HJ. Cannabinoids for control of chemotherapy induced nausea and vomiting: quantitative systematic review. BMJ. 2001 Jul 7;323(7303):16-21. Review. PubMed PMID: 11440936; PubMed Central PMCID: PMC34325.
- Vandrey R, Raber JC, Raber ME, Douglass B, Miller C, Bonn-Miller MO. Cannabinoid Dose and Label Accuracy in Edible Medical Cannabis Products. JAMA. 2015 Jun 23;313(24):2491-2493. doi: 10.1001/jama.2015.6613. PubMed PMID: 26103034.