In the late 20th and early 21st century, there has been a global movement towards the phase-out of polystyrene foam as a single use plastic (SUP). Early bans of polystyrene foam intended to eliminate ozone-depleting chlorofluorocarbons (CFCs), formerly a major component. 
Expanded polystyrene, often termed Styrofoam, is a contributor of microplastics from both land and maritime activities. Polystyrene is not biodegradeable but is susceptible to photo-oxidation, and degrades slowly in the ocean as microplastic marine debris. Animals do not recognize polystyrene foam as an artificial material, may mistake it for food, and show toxic effects after substantial exposure. 
Full or partial bans of expanded and polystyrene foam commonly target disposable food packaging. Such bans have been enacted through national legislation globally, and also at sub-national or local levels in many countries.