Three key observations resulted from this analysis. First, the MI for environmental lifetime indicated that CDA foam was optimal (215 times better than PS foam), followed by paper (146 times better than PS foam) and PET (14 times better than PS foam). Second, the MI for embodied water usage spanned a wide range of values, reflecting the major differences in the water requirements used by the feedstock and in processing the materials. PP, CDA foam, and PET were 2, 4, and 6 times less optimal than PS foam, respectively. PLA and paper were even poorer choices compared to PS foam by 11 and 57 times, respectively. Third, for all other MIs, PS foam was the optimal material. However, the ranges in values for these MIs were far less than for environmental persistence and water usage. By and large, and in agreement with previous LCAs, the MIs indicated that PS foam could be the best choice of material when persistence is not a factor. However, when persistence is considered, CDA foam can be the best choice. As noted, the current standing of each material was based on what we know now (Supplementary Table ) and is subject to change with new and improved data. One way for biodegradable bioplastic foams to be more competitive with PS foams across all these metrics is to attain greater material efficiency by moving to lower relative densities (<0.10).