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

Abstract

Cationic polymers are considered by the scientific and regulatory communities as a group of greater interest amongst the polymers in commerce. As a category, relatively little hazard information is available in the public literature. Very few examples exist of published, high-quality polymer characterization and quantification of exposure. In the present study we describe a series of fish embryo toxicity (FET) and fish gill cytotoxicity assays used to establish a baseline understanding of several representative polyquaternium categories (PQ-6, PQ-10, PQ-16) in animal alternative models, accompanied by highquality analytical characterization. Materials were chosen to encompass a range of molecular weights and charge densities to determine the influence of test material characteristics on toxicity. Both chorionated and dechorionated FET assays were generally similar to published acute fish toxicity data. Toxicity was correlated with cationic polymer charge density, and not with molecular weight, and was a combination of physical effects and likely toxicity at the site of action. Toxicity could be ameliorated by humic acid in a dose-dependent manner. Fish gill cytotoxicity results were orders of magnitude less sensitive than FET test responses.

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

“…Furthermore, other characteristics such as surface charge, especially cationicity, may result in marked toxicity, even for polymers with very high MW n . 21…”

“…Furthermore, other characteristics such as surface charge, especially cationicity, may result in marked toxicity, even for polymers with very high MW n . 21 While PLC identication is a pragmatic approach to dealing with diverse sets of polymers, it has to be noted that many of the PLC criteria have been debated, and that some thresholds rely on seemingly arbitrary values rather than being backed by rigorous testing and scientic assessment. 22 For some criteria, the cut-off values in some jurisdictions were based on internal documents, reviews or registration data, which were provided to the OECD Expert Group in the early 1990s for discussion; 18,19 however, most of these documents are not publicly accessible.…”

Water-Soluble Synthetic Polymers: Their Environmental Emission Relevant Usage, Transport and Transformation, Persistence, and Toxicity

“…The potential physical harms caused by cationic polymers were observed in all the tested trophic levels, including algal clumping, adhesion effects on Daphnia, and blocking oxygen exchange on gills. , An acute toxicity study was conducted on rainbow trout using a cationic flocculant with the ingredients of poly­(dimethyldiallylammonium chloride). By the end of the 48-h exposure period, rainbow trout showed an LC 50 response of approximately 0.3 mg/L and a reduction in conventional metabolic oxygen consumption of >50%–60% .…”

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

“…Intrinsic viscosity has been hypothesized to correlate with aquatic toxicity (Costa et al, 2008); however, no strong relationship was observed with cationic polyacrylamides (Pereira et al, 2018). Relating cationic polymer rheological and/or physicochemical properties to environmental hazard remains an active area of research (Rawlings et al, 2022;Simones et al, 2022).…”

“…Animal alternative assays have been developed to address the ethical concerns associated with testing on vertebrate organisms; however, special considerations should be made when using these tests to determine polymer toxicity. Bioavailability considerations may be especially important (Rawlings et al, 2022). In the Fish Embryo Toxicity test (OECD TG 236), newly fertilized zebrafish embryos are exposed to test chemicals for 96 h. This encompasses periods of embryonic development and hatch out of the protective chorion but ends before the eleutheroembryo is capable of feeding independently.…”