Dynamic flows and stocks of plastics in the United States and pathways towards zero plastic pollution by 2050

Abstract

The United States (U.S.) is the second-largest national consumer of plastics in the world, which directly leads to a large amount of plastic waste. Due to low recycling and incineration rates in the U.S., 53% of plastic waste was discarded (landfilled or mismanaged) in 2018. Scientific studies have proved that pollution from discarded plastics has a significant negative impact on the environment. This study aims to explore feasible pathways for the U.S. to achieve zero plastic pollution by 2050. This study first developed a dynamic material flow analysis (MFA) model to assess flows and stocks of nine commonly used plastic polymers in seven commodity sectors with five end-of-life pathways in the U.S. for almost seven decades (1950 – 2018). The results show that national plastic pollution increased from 176 thousand metric tons in 1950 to 34,393 thousand metric tons in 2018. Plastic packaging contributed the most to plastic pollution because it has a shorter lifespan and a higher discard rate compared with plastics in other sectors. This study also developed six scenarios to explore pathways of plastic pollution reduction from 2019 to 2050 through seven strategies including 1) adapting a national plastic grocery bag ban, 2) reducing plastic consumption, 3) improving the lifespan of plastic products, 4) increasing waste recycling rate, 5) abandoning waste export, 6) avoiding mismanaged waste leakage, and 7) increasing waste incineration rate to utilize waste resources. Even though each strategy can reduce plastic pollution to different extents, the U.S. cannot achieve the zero plastic pollution target by 2050 through implementing one strategy solely. Thus, a combined scenario that implementing multiple strategies would help the U.S. to achieve zero plastic pollution.