Biodegradable plastics (BDPs) are a growing market and are discussed as options to mitigate environmental plastic pollution. In some cases, BDPs are applied as substitute materials and are exempt from regulations. One of the most prominent examples is the current discussion concerning the restrictions on intentionally added microplastics from ECHA. In addition, BDPs are also perceived as a more sustainable alternative for applications in the natural environment (e.g. agriculture, fisheries) and where loss is intrinsic to the use (abrasion, wear & tear). However, biodegradability, as an inherent material property, also brings along (new) risks for the environment such as carbon enrichment, release of greenhouse gasses, and for society such as dis-/misinformation, greenwashing and the possibility of favoring littering. Additionally, the work on methods to characterize the biodegradation of these materials and their degradation products in different compartments are sometimes questioned and are still objects of research. For this session we invite contributions on the performance of BDPs in the natural environment, their environmental effects both on ecosystem and organism levels and the methods related to the above-mentioned aspects. Societal effects, life-cycle assessment and substitution potential might also be addressed. Dr. Miriam Weber HYDRA Marine Sciences, Germany Dr. Katharina Schlegel/Dr. Glauco Battagliarin, BASF SE, Germany