Concerns for the environment have led chemists to develop plastics that are degradable  All degradable plastics, which are potentially useful packaging materials, need just the right conditions to break down  Some need exposure to sunlight, some need to be buried in soil and some need to be submerged in water
It should be cautioned that some degradable plastics leave residues of unknown toxicity
Some degradable plastics need both sunlight and submersion in order to break down.