Environmental hazard of cationic polymers relevant in personal and consumer care products: A critical review.

Historically, polymers have been excluded from registration and evaluation under the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) program, the European chemical management program. Recently, interest has increased to include polymers. A tiered registration system has been envisioned and would begin with classes of polymers of greater interest based on certain properties. Cationic polymers are one such class. There is a pressing need to understand the quality and limitations of historical cationic polymer studies and to identify key sources of uncertainty in environmental hazard assessments so we can move toward scientifically robust analyses. To that end, we performed a critical review of the existing cationic polymer environmental effects literature to evaluate polymer characterization and test methodologies to understand how these parameters may affect test interpretation. The relationship between physicochemical parameters, acute and chronic toxicity, and relative trophic level sensitivity were explored. To advance our understanding of the environmental hazard and subsequent risk characterization of cationic polymers, there is a clear need for a consistent testing approach as many polymers are characterized as difficult-to-test substances. Experimental parameters such as dissolved organic carbon and solution renewal approaches can alter cationic polymer bioavailability and toxicity. It is recommended that OECD TG 23 "Aqueous-Phase Aquatic Toxicity Testing of Difficult Test Substances" testing considerations be applied when conducting environmental toxicity assays with cationic polymers. Integr Environ Assess Manag 2023;19:312-325. © 2021 SETAC.