Don’t expect those Styrofoam coffee cups littering the street and filling the state landfill to disappear anytime soon.

Dunkin’ Donuts, the state’s largest chain of coffee shops, isn’t quite ready to give up its signature polystyrene coffee containers for the sake of the environment. But the 24-hour breakfast and caffeinated beverage giant says it is trying to be somewhat green.

“Finding an alternative to the Styrofoam cup is our number one sustainability priority,” wrote Christine Riley, Dunkin’s director of corporate social responsibility, in a letter to a Senate commission studying waste and packaging.

Styrofoam cups are inexpensive and ideal for keeping coffee warm and hands from burning. But they are terrible for the environment. They don’t biodegrade. Styrene, the principal ingredient in Styrofoam, is also a toxin and suspected carcinogen.

Nevertheless, Dunkin’ Donuts with 142 locations in Rhode Island, says it is doing a few things to cut waste. An “internal cup team” at its Canton, Mass., headquarters is testing every cup on the market to find one that is affordable, recyclable in curbside collection and better for the environment than Styrofoam. “A cup that meets the aforementioned criteria does not exist right now, not even paper,” Riley wrote.

She also informed the Senate commission that an outside design firm has been hired to explore designing a a more environmentally friendly cup. A new cup design has cut 4.6 million pounds of Styrofoam and plastic from the waste stream annually, and a “cross-functional recycling team” will begin trials of in-store recycling at some locations this year. Franchise owners have the option of instituting a hot and cold reusable mug program.

The world’s largest coffee chain, Starbucks, with 10 stores in Rhode Island, moved beyond Styrofoam cups years ago. But the global chain struggles to get customers to remember to bring a reusable mug — this type of behavior doesn’t help. The goal of 25 percent of drinks served in reusable mugs by 2015 has been trimmed to 5 percent. Starbucks hopes to boost its chances of 5 percent success by recently announcing plans to roll out a $1 reusable mug. The chain offers a 10-cent discount for reusable mug use.

Starbucks has a few other sustainable practices related to recycling and sourcing. But like all the other majors brands its paper cups aren’t recyclable, biodegradable or compostable. It’s plastic cups are recyclable, but as any customer can tell you, it’s not convenient or promoted by the store.

Other area coffee shops also are making attempts to cut waste. Honey Dew Donuts, based in nearby Plainville, Mass., is a devoted Styrofoam cup user. The chain plans to test paper cups at a few stores in Massachusetts this year. The store is swapping wax-coated bags for 100 percent recyclable paper bags.

“Trying to make everybody happy can be tough. We recognize it’s an eco-friendly choice and that’s why we are working that way,” said Kara Bowen, community manager for Honey Dew Donuts.