Biodegradable plastics, how can we verify the claims?

On any given day around the planet we produce and dispose of countless tons of plastic or Styrofoam containers and products that are environmentally destructive and non-biodegradable, meaning that they will not readily break down in nature even over long time scales. Relatively little of this waste is recycled and is also known to contain carcinogens such as styrene in addition to being derived from petroleum, a nonrenewable resource. Adding to the problem, extremely powerful greenhouse gases known as HFCs (hydrofluorocarbons) are released during the production of Styrofoam. While Styrofoam and traditional plastic can be convenient for food and other products we consume on a daily basis, it is critical that we pursue alternatives that are safer for our health, environment and climate. Do some of these alternatives already exist?