*The following is excerpted from an online article from New York Daily News.
Today's marijuana is three times more potent than it was in the 1980s, experts say.
A new study carried out by Andy LaFrate, president of Charas Scientific, a research lab in Colorado, tested the potency in more than 600 marijuana samples from (legal Colorado) recreational pot merchants and concluded that it's more potent than illegal pot from past decades.
"We've seen a big increase in marijuana potency compared to where it was 20 or 30 years ago," LaFrate said in a video released by the American Chemical Society. "I would say the average potency of marijuana has probably increased by a factor of at least three."
LaFrate said that the tetrahydrocannabinol or THC levels — the psychoactive chemical that makes people high — 30 years ago were all under 10%, but now test samples mark THC levels anywhere between 20% and 30%.
"As far as potency goes, it's been surprising how strong a lot of the marijuana is," LaFrate said. "We've seen potency values close to 30% THC, which is huge."
The potency level reported by LaFrate is a "huge" difference from what was reported by the National Institute on Drug Abuse in 2012. The institute reported that marijuana confiscated by police agencies nationwide had an average THC concentration of 15%.
The reason why THC levels have increased over the years is because pot producers have been cross-breeding strains due to users demanding stronger drugs.
Cross-breeding has led to the small amounts or absence of cannabidiol or CBD, which is a compound in pot believed to have multiple medicinal uses. LaFrate reported that cross-breeding has also led to the increase of contaminants like bacteria, fungi and butane found in marijuana.
"It's pretty startling just how dirty a lot of this stuff is," LaFrate said. "It's a natural product. There's going to be microbial growth on it no matter what you do. So the questions become: What's a safe threshold? And which contaminants do we need to be concerned about?"
Source: New York Daily News