Effects of polyoxyethylene (20) sorbitan monooleate on the acute toxicity of linear alkylbenzenesulfonate (C12LAS) to fish

Effects of polyoxyethylene (20) sorbitan monooleate (SMOE20) on the acute toxicity of linear alkylbenzenesulfonate (C12LAS) to fish were investigated in red killifish (Orizias latipes) and carp (Cyprinus carpio). By adding polyoxyethylene sorbitan ester to C12LAS solution, the acute toxicity of C12LAS decreased. As a decreasing toxic effect of these nonionic surfactants, the depression of gill damage was histopathologically observed. No significant hematological and blood biochemical differences were observed between two test using a single C12LAS solution and a mixed solution of C 12 LAS SMOE 20 . The addition of SMOE20 to C12LAS decreased the incorporation of C12LAS into blood and each organ except and spleen gall bladder as well as the adsorption of C12LAS to the gill. The farther inward the phenyl position in the alkyl side chain, the lower the adsorption of C12LAS to gill. Since the acute toxicity of LAS phenyl isomers to fish was known to decrease according to the order adsorption, these results suggest that the decreasing toxic effect of SMOE20 on the acute toxicity of C12LAS is due to depression of more toxic C12LAS adsorption on the gill.