Plastic bags take 20 years to biodegrade, plastic foam cups 50 years, straws 200 years, bottles 450 years and soda sixpacks 450 years.
A plastic alternative that degrades in 33 days was invented by a teen from Australia.She investigated materials that are similar to plastic. One is shrimp shells. She ground them to a powder to remove minerals and added fobroin, a silkworm cocoon protein. The result is plastic that is 90% stronger than grocery bags.