Toxic Effects of an Anionic Detergent on the Gills of Trout

Abstract

The literature on the toxicity of synthetic detergents to fish and aquatic invertebrates is reviewed. The pathological effects of an anionic detergent, sodium lauryl sulphate, on the gills of rainbow trout have been studied by light and electron microscopy. At lethal concentrations up to about 120 mg/1, epithelial cell death is associated with lysosome formation. Acute inflammation of the gill tissue, extensive detachment of the epithelium and collapse of the pillar cell system occur. At concentrations above about 120 mg/1, very rapid lysis of cells results in the complete disruption of cellular and tissue structure. Changes in the gross structure of the gills are explainable in terms of the rate and nature of toxic action at the cellular level. Review of the biomedical literature suggests that the observed effects of SLS on gill cells correspond to the two mechanisms by which detergents cause death in isolated cells. These are autolysis, i.e. lysis by the action of the cells' own enzymes, induced by an initial lesion in the cell membrane whose precise nature is not known; and rapid lysis by the direct action of the detergent on the cell constituents. The occurrence of these two modes of lethal toxic action is also indicated by probit analysis of toxicity data. At sub-lethal concentrations of SLS, below about 30 mg/1 depending on the species and/or age of the fish, the epithelium of the secondary lamellae becomes swollen and abnormally detached, its total thickness increasing to about three times its normal value. There is a redistribution of chloride cells and sub-acute inflammation of the gill tissue occurs. These anatomical changes probably impair respiratory exchange to a significant extent. The findings are discussed in relation to areas of general interest in fish toxicology