Marijuana potency increased last year to the highest level in more than 30 years, posing greater health risks to people who may view the drug as harmless, says a White House report quoted by the Associated Press. An analysis from the University of Mississippi’s Potency Monitoring Project tracked the average amount of THC, the psychoactive ingredient in marijuana, in samples seized by law enforcement agencies from 1975 through 2007. The average amount of THC reached 9.6 percent in 2007, compared with 8.75 percent the previous year.
The 9.6 percent level represents more than a doubling of marijuana potency since 1983, when it averaged just under 4 percent. The White House attributed the increases in marijuana potency to sophisticated growing techniques. “The increases in marijuana potency are of concern since they increase the likelihood of acute toxicity, including mental impairment,” said Dr. Nora Volkow, director of the National Institute on Drug Abuse, which funded the University of Mississippi study.