The Doctors Next Door

What are Health Hazards of Smoking Marijuana

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There's a lot of excitement around the nation about medical marijuana. In one of my prior posts I talked about it's health benefits.Illinois has even proposed such a pilot program. So how are those that seek medical marijuana consuming the stuff?  Well, most are going the traditional route of smoking it a la Cheech and Chong. Now, last I checked my lungs were generally opposed to the whole concept of smoking. So what are the specific health hazards of consuming marijuana in this fashion?

Here are some honest and for true medical facts.

  • Like tobacco, the smoke of marijuana, contains a toxic mixture of gases and particles that are well known to be harmful to the lung.
  • The lung effects of marijuana smoking may be magnified compared to those of tobacco by greater deposits of harmful particles due to the manner in which marijuana is smoked. About 4 times the tar from marijuana  smoke than that from tobacco gets deposited in the respiratory tract.
  • People that smoke marijuana on a regular basis often complain of chronic cough and phlegm  production.
  • A view under the microscope of lung and airway tissue isn't pretty--there's widespread inflammation and injury. The cells look
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    like they want to grow big and mean, like they're aspiring to become cancer cells. 
Infection fighting cells in the lung are also impacted, so the likelihood of infection may be increased. This means that habitual marijuana smokers may be at greater than normal risk for development of pneumonia. This is especially problematic for folks that can legitimately benefit from medical marijuana--I'm talking those with cancer or HIV.  Now there's a conundrum.

One U.S. study found that a history of daily or near-daily marijuana smoking was associated with a 2.6-fold greater risk of head and neck cancers. These are nasty, disfiguring kinds of cancers.

Marijuana has also been shown to be contaminated with gram-negative bacteria that can also cause pneumonia, especially if your immune system is impaired.

What don't we know about the effects of marijuana smoking on your health?  Well we don't know for sure if it can cause chronic obstructive lung disease (COPD) , emphysema being one example. And while those cells I described above look like they mean business, they may be all talk and no action--we're not really sure if they have the right stuff to become a real cancer.

Marijuana smoke has many of the same harmful ingredients that are present
in tobacco smoke (e.g., carbon monoxide, cyanide, vinyl chlorides, to name a few).  The major exception of course is the unique presence of tetrahydrocannabinol (THC) and a bunch of other cannabinoids that are not found in tobacco smoke.  Of course tobacco's shining feature comparatively is that famously addictive substance, nicotine.

So how do the health effects of smoking compare between the tobacco and marijuana?  Well, strangely, marijuana causes the airways to open up briefly.  Since it's opposite, airway constriction,
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is a source of big problems for people with asthma. But DON'T start thinking of using it for that purpose.  Some of the long-term effects of marijuana smoking make this a very bad idea.  Case in point, I once talked to a guy who told me he'd gone off all his asthma medicines and had turned to smoking weed to treat his condition. Needless to say he was feeling pretty good about the results.  Interestingly, he turned up dead about a week after sharing this little health tidbit with me. While that's no randomized controlled trial, is it a coincidence? I think not.  

A study done in (no surprise) Los Angeles, compared three groups of people: regular marijuana only smokers, regular tobacco only smokers and those who regularly indulged in both. The results told us:
on the other hand...

  • the additive effects of marijuana and tobacco on chronic and acute respiratory symptoms were not apparent.
Similar findings have been reported by other researchers in studies based in Tucson, Arizona and New Zealand with the only difference being that an additive harmful effect of marijuana and tobacco was found in the Arizona study.

Does marijuana smoking cause respiratory cancer?

There some reasons to suspect that it probably does.

First, marijuana smoke contains several of the same cancer-causing ingredients as tobacco smoke, including vinyl chorides, phenols, nitrosamines, reactive oxygen species and various polycyclic aromatic hydrocarbons (PAHs) ... try to say those words three times fast after your third toke...One of the worst of them, benzopyrene, is present in marijuana tar at a higher concentration than in tobacco tar.

Additionally, as I already pointed out,  the difference in the manner in which marijuana and tobacco are smoked (don't pretend you don't know what I'm talking about here), magnifies the level of exposure to carcinogens from each marijuana cigarette.

In our consideration of the benefits of medical marijuana use, we need to balance the harms with the true benefits, of which there are some. You can read about some of those benefits in one of my prior posts.

I'd like to thank Dr. Donald Tashkin, Professor of Medicine; Division of Pulmonary & Critical Care Medicine at UCLA.  I found his illuminating article on this topic to be a great resource in the writing of this post.



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