You often hear people, particularly anti-legalization advocates, say that marijuana is stronger today than it was in the past. But is there any science backing that up? Well, yes and no.
Business Insider recently published a story about the increased potency of marijuana, which said that marijuana is stronger but there is a catch. A professor fro the University of Colorado noted that in dispensaries today, you can purchase cannabis that is 25 percent THC, the compound that causes the "high" when using the drug. In the past, he says, marijuana was usually "two to five percent" THC, which would make today's marijuana at least five times more powerful than in the past.
Another recent study showed that from 1995 to now, the THC content in marijuana has tripled. They used data from cannabis seized by the DEA. In 1995, the average THC content in seized marijuana was 4 percent, but in 2014 that number rose to 12 percent. They also found that CBD, one of the compound's in cannabis with therapeutic qualities, dropped.
But there are some issues with these studies. A 2012 review of various potency studies found that the researchers didn't adequately describe how they stored the marijuana and what condition it was in, meaning they might've had samples that degraded over time, making it seem like cannabis from the past was less potent than it actually was.
And a 2014 study found that even though marijuana potency is increasing, people are also changing their consumption habits to make up for it. They determined that people inhale less marijuana smoke when they know it's a more powerful strain.
So yes, marijuana has probably gotten stronger over the past few decades. But people are also getting smarter about how they use it.
(h/t Business Insider)