Assessing the Biodegradability of Water‐Soluble Polymers: Scientific and Regulatory Perspectives for Safe and Sustainable by Design Innovation

ABSTRACT

Water‐soluble polymers (WSPs) are widely used in home and personal care products for their functional versatility and performance benefits. However, their environmental fate, particularly biodegradability potential, remains poorly characterised, creating uncertainty under evolving regulatory frameworks such as the EU Chemicals Strategy for Sustainability. Current OECD and ISO biodegradability tests were developed for low molecular weight chemicals and often underestimate the degradability of WSPs due to factors such as high molecular weight, charge density, and limited bioavailability. This review identifies key limitations of existing test methods and proposes a mechanistically informed, tiered testing framework that aligns test selection with degradation pathways and environmental context. The framework integrates polymer‐specific adaptations to OECD/ISO methods, microbial profiling, and advanced analytical tools to improve realism and reproducibility. It also highlights the role of high‐throughput screening for early‐stage prioritisation and the potential of in silico modelling to accelerate biodegradable‐by‐design innovation. By combining empirical, mechanistic, and predictive approaches, the proposed strategy supports proportionate biodegradability potential and persistence assessments, enabling regulatory confidence and innovation aligned with Safe and Sustainable by Design principles. The review concludes with targeted actions for regulators, researchers, and industry to advance polymer‐specific methods, data infrastructure, and predictive capabilities.