Single-use plastics (SUPs) are plastic items intended to be used once and discarded. They do not biodegrade, and as a result they accumulate in the environment, including in urban streams, where they pose threats to biota. Some governments (including around thirty municipalities in southeastern Pennsylvania [PA, USA]) have addressed this issue by banning distribution of common SUPs, but the effectiveness of the bans is still unclear. This study quantifies the abundance of plastics, including SUP pollution, in urban streams with vs. without and before vs. after enactment of municipal-scale SUP bans. Further, this project explores how land use relates to the abundance of anthropogenic litter (AL) in urban streams. The results of this study will inform policy on future bans or other mitigation actions against plastic pollution, especially in southeastern PA.
Between September 2023 and December 2024, we sampled nine stream sites in southeastern PA. Three stream sites and their respective watersheds were within municipalities with a ban in place for at least one year, three had bans take effect during the study period, and three had no ban for the duration of the study. At each site, we collected all AL that could be located and retrieved safely from one stream bed and four riparian plots.
We found 98.4% of plots sampled through May 2024 had at least one piece of AL. By count, most items were made of plastic film. Preliminary results, based on the first 3 months of data, showed no significant difference in the count of plastic items between sites with vs. without bans. Further analyses will compare the count of plastic items before vs. after bans. If municipal-scale SUP bans do not reduce plastic pollution in streams, other solutions may be required.