Plastic pollution in a river. Plastic waste floating along the surface of a river. Single-use plastic objects degrade the environment when not disposed of correctly. Plastics are not biodegradable, but do break down eventually into fragments when exposed to the atmosphere and ultraviolet radiation. These plastic fragments break down further into micro-plastics and nanoparticles. The long-term effects of these plastic particles on the environment is unknown, but they can enter the food chain.