U.S. marijuana grows stronger than before: report

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - The marijuana being sold across the United States is stronger than ever, which could explain a growing number of medical emergencies that involve the drug, government drug experts on Wednesday.

Analysis of seized samples of marijuana and hashish showed that more of the cannabis on the market is of the strongest grade, the White House and National Institute for Drug Abuse said.

They cited data from the University of Mississippi's Marijuana Potency Project showing the average levels of THC, the active ingredient in marijuana, in the products rose from 7 percent in 2003 to 8.5 percent in 2006.

The level had risen steadily from 3.5 percent in 1988.

National Institute on Drug Abuse Director Dr. Nora Volkow fears the problem is not being taken seriously because many adults remember the marijuana of their youth as harmless.

"It's really not the same type of marijuana," Volkow said in a telephone interview.

"This could explain why there has been an increase in the number of medical emergencies involving marijuana."

According to the Substance Abuse and Mental Health Adminstration, marijuana was involved in 242,200 visits to hospital emergency rooms in 2005. This means that the patient mentioned using marijuana and does not mean the drug directly caused the accident or condition being treated, SAMHSA says.