Marijuana is being smoked regularly by more Lake County high school students than tobacco, according to a new in-depth study of five local school districts.

And among the districts surveyed, East Chicago students reported by far the highest rates of alcohol and marijuana usage, the study from the Lake County Drug Free Alliance found.

But the study's analysis of arrest records found that Merrillville and Crown Point arrested people under age 25 for DUI and public intoxication at about twice the rate that East Chicago, Gary and Hammond did.

The study was presented as an inaugural epidemiological profile of Lake County for the Drug Free Alliance. The alliance intends to use the study to help convince local organizations to focus their drug-prevention efforts in areas that need the most attention.

The organization also is hoping to use the study to diversify its funding sources, because right now its only source is the federal government, Executive Director John Key said.

"Before you attack an issue, you've got to study it and understand the issue," Key said. "A lot of the information came from youth, anonymous of course, through surveys."

A draft of the 100-page study was released to local media Thursday. The analysis focuses on arrest information in Crown Point, East Chicago, Gary, Hammond and Merrillville. Also, 1,500 surveys were distributed to teens in the school districts of East Chicago, Gary Hammond, and Lake Ridge. Crown Point did not take part in the student surveys.

The study found several encouraging signs. In all the districts but East Chicago, the students reported drinking less than state and national averages, and the communities as a whole had fewer DUI and public intoxication arrests than average.

But in Crown Point, 45 percent of all of DUI arrests in 2006 and 2007 were for drivers ages 18 to 25.

East Chicago teens reported drinking more alcohol than anyone else in the study. A "staggering" 88 percent of high school students reported having at least one drink in their lifetimes, compared to rates between 60 and 72 percent for the other districts.

Twenty eight percent of East Chicago middle school students also reported smoking marijuana at least once in their lives, compared to rates between 6 and 13 percent in the other districts.

Overall, ninth grade was by far the most common time when teens reported first exposure to marijuana.

But after years of aggressive anti-tobacco advertising, only one district -- Merrillville -- had fewer high school students reporting less regular use of marijuana than tobacco.