WATER-SOLUBLE POLYMERS (POLYVINYL ALCOHOL AND POLYETHYLENE GLYCOL): A NEW THREAT TO THE AQUATIC ENVIRONMENT? EVALUATION OF EMBRYOTOXICOLOGICAL EFFECT ON ZEBRAFISH AND AFRICAN CLAWED FROG.

The impact of emerging contaminants (ECs) on the environment, particularly the aquatic environment, has received increasing attention in recent years. Classified as pseudo-persistent pollutants, these chemicals can affect non-target species at many stages of development. ECs are widely used in the formulation of personal care products (cosmetics, creams, detergents etc.), food packaging and pharmaceuticals, which are constantly released into the aquatic environment, making them a potential threat to the aquatic communities. This group includes two water-soluble polymers, also known as liquid plastics, which have increased their presence, particularly in the formulation of personal care products and pharmaceuticals: polyvinyl alcohol (PVA) and polyethylene glycol (PEG), but despite this proliferation, less is known about their environmental accumulation effects on aquatic species. Using embryotoxicity tests, this study aimed to assess the potential hazards of exposure to PVA and PEG for non-target species, using zebrafish (Danio rerio) and African clawed frog (Xenopus laevis) embryos as models. Fertilised eggs were placed in microwell plates and exposed to the chemicals at different concentrations, for a total of 96 hours. Throughout the experiment, the temperature was maintained at 26 °C for the zebrafish and 23 °C for the frogs, and the water containing the chemicals was changed daily. Embryotoxicity endpoints (mortality, hatching rate, malformations) were observed daily, and heart rate and length were recorded after 48 hours and 96 hours of exposure, respectively. Significant results were obtained for the percentage of mortality for frogs, for the hatching delay for zebrafish, for the occurrence of malformations at almost all concentrations selected for both animals (observation of oedema, body malformations, changes in the pigmentation and spinal and tail deformities) and for the change in the heart rate (decrease or increase in rate) for both zebrafish and African clawed frog. The data and the level of significance obtained during the experiments suggest that PVA and PEG may pose a potential risk to non-target species, but at the same time, further analysis and investigation are needed to understand how these compounds interact with the aquatic environment fully.