Avaliação da toxicidade do solvente eutético profundo à base de ácido cítrico e cloreto de colina em Lithobates catesbeianus e Eisenia fetida

Abstract

Deep eutectic solvents (DES) have emerged as promising alternatives to conventional organic solvents and are frequently classified as green solvents due to their presumed low toxicity and high biodegradability. However, recent studies show that their toxicity can vary substantially depending on composition, molar ratio, and concentration, reinforcing the need for broader ecotoxicological assessments across different organisms and trophic levels. This study evaluated the toxicity of a 1:1 DES composed of citric acid (CA) and choline chloride (CHCL), as well as its isolated components, using the micronucleus test in Lithobates catesbeianus tadpoles and an avoidance test with Eisenia fetida earthworms. Tadpoles were chronically exposed for 14 days to five concentration levels, followed by analysis of micronuclei and nuclear abnormalities in peripheral blood. The earthworm avoidance test was conducted for 48 hours. Citric acid was identified as the primary driver of acute toxicity, causing complete mortality at higher concentrations, whereas choline chloride induced only sublethal nuclear alterations. The CA:CHCl mixture exhibited enhanced toxicity, evidencing synergistic interactions that resulted in significantly elevated micronucleus frequencies even at the lowest concentrations tested. In earthworms, significant avoidance behavior occurred only at the highest DES concentration (10,000 mg·L⁻¹), indicating impairment of soil habitat function. Overall, the combined results from aquatic and terrestrial bioindicators demonstrate that the evaluated DES poses ecological risks, causing cellular-level genotoxicity in amphibians and behavioral alterations in annelids. These findings indicate that citric-acid-based eutectic solvents may affect both aquatic and terrestrial ecosystems even at low concentrations, underscoring the need for thorough toxicological evaluation before environmental application and caution in categorizing these solvents as inherently green.