Plastic from urban runoff is the largest source of marine debris worldwide. The United Nations Environment Program estimated in 2006 that every square mile of ocean hosts 46,000 pieces of floating plastic.
Polystyrene foam presents unique management issues because of its lightweight nature, floatability, and likelihood to be blown from disposal sites even when disposed of properly. The lightweight and buoyant polystyrene travels easily through gutters and storm drains, eventually reaching the ocean.
Pollution of waterways and waterfront negatively affects tourism and quality of life. When polystyrene travels down waterways and storm drains into the ocean, it breaks down into smaller, non- biodegradable pieces that are ingested by marine life and other wildlife thus harming or killing them. In one Californian study, at least 162 marine species including most seabirds were reported to have eaten plastics and other marine litter.
As a result of the impacts on marine pollution and adverse effect to marine wildlife, several coastal cities across the United States, have banned the use of polystyrene foam food packaging altogether.