Oxidative stress and genotoxic effects in earthworms induced by five imidazolium bromide ionic liquids with different alkyl chains

In this study, the acute and subchronic toxicity of 1-alkyl-3-methyl imidazole bromide ionic liquids (ILs) [Cnmim]Br (n = 2, 4, 6, 10, 12) was evaluated utilizing earthworms (Eisenia fetida) as a basis for their impact on terrestrial ecosystems. The filter paper tests and artificial soil tests were conducted as acute toxicity tests to investigate the LC50 of ILs, while in subchronic toxicity tests, earthworms were exposed to ILs in artificial soil (5, 10, 20 and 40 mg kg−1) for 28 d. Reactive oxygen species (ROS), antioxidant enzymes, detoxifying enzymes and oxidative damage were measured to determine subchronic effects of ILs on E. fetida. The results showed that when the earthworms were exposed to these five ILs in acute toxicity experiments, [C2mim]Br had the lowest toxicity, as the alkyl length increased, the toxicity increased up to [C10mim]Br: a “cut-off effect” (decreased toxicity) was observed at [C12mim]Br. The results highlight the varying toxicity of ILs with different alkyl chains to E. fetida and provide valuable data for detailing the impact of ILs on ecological receptors.