Marijuana legalization states have taken no steps to limit the potency of marijuana, which has increased sharply in recent years. A new study suggests this could create public health problems down the road as more users become addicted or otherwise impaired.
The study was conducted in the Netherlands, where marijuana is legally available through “coffee shops.” The researchers examined the level of delta-9-tetrahydrocannabinol (THC), the main intoxicant in marijuana, over a 16-year period. Marijuana potency more than doubled from 8.6 percent in 2000 to 20.3 percent in 2004, which was followed by a surge in the number of people seeking treatment for marijuana-related problems. When potency declined to 15.3 percent THC, marijuana treatment admissions fell thereafter. The researchers estimated that for every 3 percent increase in THC, roughly one more person per 100,000 in the population would seek marijuana use disorder treatment for the first time.
The Dutch findings are relevant to the United States because high THC marijuana products have proliferated in the wake of legalization. The average potency of legal marijuana products sold in the state of Washington, for example, is 20 percent THC, with some products being significantly higher.