New bans on polystyrene foam food containers took effect in the District of Columbia, Montgomery County, Maryland and even the South American nation Guyana on the first of January. Plastic foam cups and clamshells have been falling further out of favor since the city of Berkeley, California, outlawed them in the late 1980s. Last year the New York Supreme Court overturned New York City’s ban, but restaurants in Seattle, San Francisco and Miami Beach are among those free of the containers.

The original Styrofoam was patented by Dow Chemical in 1944, and by the 1950s was widely used to insulate buildings, float life rafts and even make Christmas ornaments. But what we think of as Styrofoam cups and takeout containers are actually made from a similar material called expanded polystyrene.

“We’ve just sort of latched onto the name Styrofoam and applied it to cups and plates and cafeteria lunchboxes and whatever else, but they’re not technically Styrofoam,” said Douglas McCauley, a marine scientist at the University of California, Santa Barbara.

That container we use for a few minutes and discard, he said, sits in landfills for hundreds of years, or ends up in rivers and oceans, where it acts as a sponge for toxic chemicals and is often mistaken for food by fish and sea turtles. Recycling it is too expensive, he said.

“It’s technically feasible, but it is not economically rational to do that,” McCauley said.

Juan Amaya was working the counter at Don Juan Restaurant in Washington, D.C., on the day the ban took effect. He says the Central American restaurant switched to brown biodegradable containers for its takeout pupusas and fried plantains.

“We actually started doing a smooth transition before the effect came in, so everybody could get used to it,” he said.

The American Chemistry Council, which represents plastics manufacturers, has said those alternatives can be two to five times pricier, but some companies have found it more expensive not to switch. After pressure from customers, big chains like McDonald’s and Jamba Juice recently ditched polystyrene cups in favor of paper.