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

Abstract

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.

Understanding Ecotoxicological Responses of Fish Embryos and Gill Cells to Cationic Polymers

“…Publicly available literature for polymers used in toxicity testing often lack detailed identification and characterization information (Connors et al, 2022). This type of information is important to allow comparison to historic data and to aid in understanding toxicity drivers.…”

“…Very few examples exist of published, high-quality polymer characterization and quantification of exposure in ecotoxicity studies. There is also a distinct lack of acute and chronic fish toxicity data on polymers (Connors et al, 2022;Duis et al, 2021;ECETOC, 2019ECETOC, , 2020. Most investigations of the aquatic toxicity of these materials have focused on invertebrates (Environment and Climate Change Canada and Health Canada, 2020;Salinas et al, 2020).…”

Assessing and managing environmental hazards of polymers: historical development, science advances and policy options

“…Surface interactions produced by cationic (positively charged) polymers have received the most attention so far as being the most obvious. 66 However, also uncharged polymers seem to be capable of producing biologically relevant responses based solely on surface (extracellular) interactions without intracellular uptake. These may occur, e.g., through interactions with outward-facing cellular receptors or impacts on the extracellular matrix structures.…”

Glutathione-triggered biodegradable poly(disulfide)s: ring-opening copolymerization and potent antibacterial activity

“…Therefore, the biocompatibility of these cationic poly(disulfide)s is highly improved by its fast degradation triggered by GSH, which eliminates the potential risks of longterm toxicity and environmental hazards that generally arise among cationic polymers. 67,68…”