Since it's invention by Dow Chemical in 1941, extruded polystyene, better known by the brand name Styrofoam, has been a menace to soil and water around the world.
Although its mass is 98% air, the beads which contain the air are not biodegradable or recyclable and have been designated by the EPA as a possible carcinogen.
Because it is extremely lightweight, foam is easily blown by wind and washed by rain. Styrofoam plates, cups and boxes brake up into tiny pieces as they age, fouling soil and the water and poisoning animals that ingest them. Their glossy white color stands out against earth tones.
As of January 1, 2016, it in unlawful for restaurants, carry outs, food trucks and cafeterias in the District of Columbia to use foam containers.