Printed Rethink Foam. Show customers that you're taking their needs and the environment seriously. EPS (Expandable polystyrene) cup is specially treated to biodegrade. Cups biodegrade 92% over 4 years and lids biodegrade 86.8% over 7.9 years. Tested under conditions that simulate both wetter and biologically active landfills using the ASTM D5511 test. Wetter or biologically active landfills may not exist in your area. The stated rate and extent of degradation do not mean that the product will continue to decompose.