White House drug czar John Walters said high-potency marijuana coming from Canada is causing an increase in marijuana-related emergency-room cases in the U.S., “Canada is exporting to us the crack of marijuana and it is a dangerous problem,” Walters said. “We need to have political leadership in Canada that recognizes the problem. Addiction is going to spread in Canada dramatically. It has in many places.”

Walters blamed Canada’s more relaxed attitude towards marijuana and an increase in hydroponically-grown marijuana, which is grown in nutrient-rich solutions rather than soil, for the growing number of ER cases. Walters said such marijuana contains 20 to 30 percent of psychoactive Delta-9-Tetrahydrocannabinol (THC), compared with 1 percent THC of marijuana from the 1960s and 1970s.

“It is extremely dangerous. It is one of the reasons why we believe we have seen a doubling of emergency-room cases involving marijuana in the last several years from 60,000 to 120,000,” Walters said.

Despite U.S. criticism, Canadian Prime Minister Paul Martin said he plans to proceed with his strategy to decriminalize possession of small amounts of marijuana.