DENVER – The easy availability of marijuana in Colorado is raising concerns among police, parents and teachers who worry kids are getting sick from eating pot-infused “edibles.”

Manufacturers are adding marijuana to everything from cookies to chocolate bars, sodas and candies, with strength and serving size varying widely. Colorado on Jan. 1 permitted special stores to sell marijuana to adults but retained a legal ban on possession of pot by minors.

That hasn’t stopped them from getting hold of it: Twelve students were suspended last month after they ate marijuana-infused candies at their suburban Denver middle school. The two students who supplied the candies are being expelled.

“A couple of our teachers noticed some kids who weren’t acting right,” says Steve Saunders, a spokesman for Shaw Heights Middle School in Westminster. “You never know when they’re walking down the hall what they’re eating. It’s a lot harder to tell when they’re eating edibles instead of out smoking a joint in the parking lot.”

Saunders says kids have been bringing pot to school for decades – and getting in trouble for it. What’s changed, he said, is the greater availability.

The Rocky Mountain Poison and Drug Center reports a statistically significant rise in the number of parents calling the poison-control hotline to report their kids had consumed marijuana. While the numbers are small – about 70 cases last year – they have been rising consistently since marijuana became more available in Colorado in about 2009, says poison center director Alvin Bronstein.

Emergency room physician and toxicology expert George “Sam” Wang of Children’s Hospital Colorado says his emergency room is treating one to two kids a month for accidental marijuana ingestion, mostly in the form of edibles such as brownies or candies.

Marijuana was legalized for medical use in Colorado in 2000, but it wasn’t until 2009 that dispensaries started popping up after federal authorities said they wouldn’t raid such establishments licensed by the state.

The Healthy Kids Colorado Survey recently administered by the state found 22 percent of high school students had used marijuana in the past 30 days, compared with 36 percent who had consumed alcohol.

Kids, Wang says, don’t eat pot plants. But they do eat, either unwittingly or on purpose, marijuana-infused foods. Edibles are currently not state-tested for strength. That means the effects can vary widely from product to product. He says parents need to take precautions to keep edibles away from minors.

“It’s a very unique situation,” he says. “There is no other drug that’s built into such an attractive, edible product. You have to treat it like any other medicine.”

Edibles manufacturers say parents must play a role in keeping pot out of the hands of kids – no matter the form.

“There is a level of discretion and education and, frankly, tenacity on the behalf of parents that has to occur,” says Joe Hodas, a spokesman for the Denver-based Dixie Elixirs & Edibles. “If you leave pot lying around, kids are going to find it.”

Wang says Coloradans need to have a conversation about how to keep marijuana away from kids before the problem becomes widespread.

“It’s a trend and a change we need to anticipate and watch going forward, rather than letting it get out of hand,” he says. “We’ve had kids who have been very sick, and we don’t want to wait for a kid to die before we act.”

© 2014 USA TODAY. All rights reserved.