Embryonic and developmental toxicity of the ionic liquid 1-methyl-3-octylimidazolium bromide on goldfish

The embryonic developmental toxicity of the ionic liquid (IL) 1-methyl-3-octylimidazolium bromide ([C(8)mim]Br) on the goldfish Carassius auratus was evaluated in this study. First, the 72 h 50% lethal concentrations (72 h-LC(50)) for [C(8)mim]Br in goldfish embryos at the stages of cleavage, early gastrula, closure of blastopore, and heart beating were determined by preliminary acute toxicity tests. After that, fish embryos in different developmental stages (cleavage, early gastrula, closure of blastopore, and heart beating) were exposed to 10.4, 20.8, 41.6, and 104 mg/L of [C(8)mim]Br until their hatching stage. The results of the acute toxicity tests showed that 72 h-LC(50) values at the early cleavage, early gastrula, closure of blastopore, and heart beating stages of development were 208.96, 187.1, 245.03, and 298.33 mg/L, respectively. In the subchronic tests, [C(8)mim]Br exposure prolonged the duration of embryo dechorionation and decreased the hatching rates of the treated embryos compared to control embryos. In addition, [C(8)mim]Br treatment also caused remarkable increases of embryonic malformation and mortality ratio in most treatment groups. Finally, we also found that the embryonic and developmental toxicity of [C(8)mim]Br on fish embryos was dose-response and developmental stage-specific. These results indicate that [C(8)mim]Br has toxic effects on the early embryonic development of goldfish, and the risk to aquatic ecosystem by ILs leaking into the water body must be evaluated in the future.