Data on the effects of MP from biodegradable polymers on biota are currently not available. Since those MP consist of many different polymers, ESR1 will focus on the polymer type and shape which is closely connected to environmental degradation. ESR1 will expose freshwater key species to MP from relevant biodegradable polymers on the market to determine their toxicity. The diverse toxicological endpoints investigated in vivo comprise life cycle parameters, metabolism, and stress.