To be or not to be plastics? Protein modulation and biochemical effects in zebrafish embryos exposed to three water-soluble polymers

Water-soluble polymers (WSPs) are a particular category of polymers that, due to their capability to be soluble in water, come out of the classic definition of plastic and therefore also from its regulation and control, representing a possible new environmental problem considering the number of consumer products in which they are contained. For this reason, the aim of this study was to evaluate the possible adverse effects of three of the most used WSPs (polyacrylic acid - PAA, polyethylene glycol - PEG, polyvinylpyrrolidone - PVP), administered at relevant environmental concentrations (0.001, 0.5 and 1 mg/L) to Danio rerio (zebrafish) embryos up to 120 h post fertilization. To assess the WSP toxicity at the molecular, cellular and organism level we used an integrated ecotoxicological approach of both biomarkers and high-throughput technology based on gel-free proteomics. The main results showed how all the three WSPs up-regulated many proteins (up to 74 in specimens exposed to 1 mg/L PVP) with a wide range of molecular functions and involved in numerous cellular pathways of exposed specimens. On the other hand, the measurement of biomarkers showed how PAA and PVP were able to activate the antioxidant machinery following an over-production of reactive oxygen species, while PEG produced no significant changes in the biomarkers measured. Based on the obtained results, the use and application of WSPs should be revised and regulated.