ATLANTA, Georgia (CNN) -- The prescription drugs allegedly found in Al Gore III's possession this week are favorites among young people, according to drug abuse experts, who say prescription drugs may soon overtake street drugs in popularity.

Some young people perceive that prescription drugs are safer than street drugs, experts say.

"I wouldn't be surprised if right now at this point in time, there are more kids abusing prescription drugs than abusing marijuana," said Joseph A. Califano Jr., chairman and president of CASA, the National Center on Alcohol and Substance Abuse at Columbia University.

Gore was arrested on charges of possessing -- in addition to marijuana -- Vicodin, Xanax, Valium and Adderall.

According to a CASA report, between 1993 and 2005 the proportion of college students abusing Vicodin and other opiods went up 343 percent, about 240,000 individuals. The numbers increased 450 percent, or by 170,000 students, for tranquilizers such as Xanax and Valium, and 93 percent, or 225,000 students, for stimulants, including Adderall.

Prescription drug abuse is particularly common among upper middle class students, according to Lisa Jack, a clinical psychologist at Augsburg College in Minneapolis, Minnesota.

"It just goes to show that where you're from doesn't matter," Jack said.

And young people don't have to go far to get these drugs. "Prescription drugs are very easy for kids to get," Califano said. "They can get them from the Internet. They can get them from their parents' medicine cabinets. They can get them from their friends."

He said often students get them from friends who were prescribed these drugs legitimately.

"Kids sell them to each other," Jack said. "Drug trading happens all the time."

Experts say it's particularly a problem with Adderall, a drug prescribed legitimately to millions of young people with attention-deficit hyperactivity disorder.

According to CASA, more than a third of children ages 11-18 in Wisconsin and Minnesota who'd been prescribed Adderall and other ADHD medications reported being approached to sell or trade their drugs.

And often they say yes, according to one Canadian study that found one out of four teens who'd been legitimately prescribed Ritalin gave or sold some of their drugs.

Another appeal to prescription drugs, besides the easy access, is that young people often perceive them as safer.

"They don't have to go to the streets and deal with some guy they don't know and get marijuana where they don't know what's in it," Califano said. "Also, they see their parents using these drugs, so they seem safe."

Jack said prescription drugs can be more challenging to treat than addiction to street drugs. "In traditional drug abuse, addicts can say, 'I've been using meth or coke or pot,' and an addiction specialist knows what to do," she said. But with prescription drugs, "sometimes the kids don't even know what they've been taking. They just pass the pills around."

Part of the solution would be for drug makers to formulate their products so they're harder to abuse, said Califano, adding that anti-drug campaigns also should focus more on prescription drug abuse.

Parents need to do their part as well, he said. "When I was a kid in Brooklyn, when parents had liquor, they locked up the liquor cabinet," he said. "Maybe parents need to lock up the medicine cabinet." E-mail to a friend

Elizabeth Cohen is a correspondent with CNN Medical News. Senior producer Jennifer Pifer, producer Amy Burkholder and intern Rachel Zelkowitz contributed to this report.

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