Biodegradation of Pharmaceutical Surfactants: Polysorbates, Poloxamers, and Their Derivatives in OECD 301 Screening Tests−Insights into “Benign-by-Design”

Non-ionic surfactants, such as polysorbates (PS) and poloxamers, are widely used in the pharmaceutical industry. However, data on their biodegradability in the environment remains limited. In line with the “Safe and Sustainable by Design” (SSbD) framework, this study presents a harmonized dataset based on OECD 301 screening tests to evaluate ready biodegradation behavior. Using lag phase duration as an indicator of microbial adaptation, we identified structure-specific degradation patterns. For poloxamers, the ratio of polyethylene glycol (PEG) to polypropylene glycol (PPG) blocks appears to be a key factor influencing biodegradability. Notably, high-molecular-weight poloxamers with larger PEG blocks showed no biodegradation. For the first time, we have elucidated the biodegradation pathway of PS and identified ethoxylated sorbitan residues as potential dead-end transformation products that may persist in the environment. These findings highlight the significance of polymer structures and transformation products in determining environmental fate. This approach combines standardized testing, a systematic analysis of molecular features, and indicators of microbial adaptation to provide insights that may eventually contribute to the design of more environmentally friendly surfactants (“Benign-by-Design”, BbD).