One argument I often hear from the “legalize marijuana” camp is that it is actually safer to consume than alcohol. Conor Gaffey of Newsweek reports that new research indicates marijuana is 114 times safer than alcohol. Boy do I love bold statements like that! Let’s look into this claim.

We’ll begin by looking at the paper that Conor sources. The publication he refers to is really a methods paper, describing a new way to look at how dangerous a drug is. The number they come up with to describe relative risk is called the “Margin of Exposure” or MOE. Basically it’s the ratio between the dosage at which adverse effects occur and the dosage at which most people use the drug. In other words, it describes how close the typically used dose of a drug comes to being dangerous. So the higher the MOE, the better.

However, the problem with this study (which the authors admit to) is that for a lot of the drugs they looked at, there is no data on what dose is needed to kill people (scientists call this the LD50, or dose at which 50% of patients die). Instead, they have to estimate this number using data collected from animals. On top of that, their method doesn’t take into account addiction or drug-drug interactions, which adds another whole layer of risk to the issue.

So at the end of the day, the authors aren’t really trying to say marijuana is 100 times safer than alcohol (or 114 times more, a number I can’t seem to find anywhere in the paper). They’re simply trying to prove that past methods of calculating the relative risk of different drugs may have understated the risks of some drugs, while also overstating the risk of others. Nonetheless the authors do say they support a “legalized regulatory approach over a “prohibitionist”.

Most importantly though, Conor missed the most crucial statement of the paper:

Aside from the limitations in data, our results should be treated carefully particularly in regard to dissemination to lay people. For example, tabloids have reported that “alcohol is worse than hard drugs” following the publication of previous drug rankings. Such statements taken out of context may be misinterpreted, especially considering the differences of risks between individual and the whole population.”