More than 60 percent of people booked into the Hennepin County jail during a four-month period last year tested positive for drug use, according to a study released Monday.
The federal study tested inmates within 48 hours of their arrest at 10 sites nationwide from July through October 2009.
In Hennepin County, marijuana was the most common drug detected. About 46 percent of adult male inmates tested positive for marijuana, but among arrestees ages 18-21, nearly 80 percent tested positive for marijuana.
According to the study, 17 percent of Hennepin County inmates tested positive for cocaine, 6.9 percent for opiates such as heroin, 2.2 percent for oxycodone and 2 percent for methamphetamine. About 14 percent tested positive for more than one drug.
Among people arrested for violent crime, 56 percent tested positive for drug use.
Hennepin County Sheriff Rich Stanek said the study shows an increase over the past few years in the percentage of inmates testing positive for drug use. This is the first year the study has been released, he said.
"I'm concerned about the trends I'm seeing, particularly in the area of illegal drugs," he said. "We want people to know there is an association between crime and illegal drug use and these numbers bear that out."
Stanek said it does not appear that drug use leads to criminal activity. Instead, people involved in the illegal drug trade tend to be involved with other criminal activity. And those involved in the drug trade are often drug users, Stanek said.
"It's the activities surrounding the buying and selling of the drugs that leads to the shootings, the robberies, the murders, the assaults," Stanek said.
The federal study shows Hennepin County was toward the low end of the range in percentages of inmates testing positive for drug use.
Mecklenburg County, N.C., which includes the city of Charlotte, had 56 percent of its inmates test positive. Cook County, Ill., including Chicago, had 82 percent.
(MPR reporter Tim Nelson contributed to this report.)