Rental car workers at Denver International Airport say that people who are looking to avoid illegally bringing marijuana into the airport just leave it in the car or offer it to the rental agencies, according to one Avis Rent A Car airport agent.

"We see quite a few cases," said an 18-year Avis employee in Denver, who declined to give her name, to ABC News. "We basically don't touch it. Usually, the manager will take it and flush it down the toilet.

"We are a drug-free environment. We don't take it or give it back; we just flush it," added the employee.

Recreational marijuana use by adults over the age of 21 has been legal in Colorado since late 2012.

Possession of up to 1 ounce is legal, bit it is illegal to take any amount across state lines.

Occasionally customers offer their leftovers to rental agents.

"I have had customers come up to the counter and give it to us, asking 'Do you want it?'" said the Avis rental agent, according to ABC News.

She immediately declines and offers to help the customer get rid of it.

Denver International's formal policy is that "marijuana is not allowed on airport property," said spokesman Heath Montgomery, according to ABC News.

At least 16 cases this years have occurred where individuals have tried getting marijuana through security to take it with them.

Montgomery cites this as "infinitesimally small" when compared to the 25 million people to date who have made it through.

No one has been cited yet, usually police just have them "throw it in the trash," according to Montgomory.

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