Fate of radioactivity in Atlantic Salmon (Salmo salar) following intragastric administration of (methyl-14C)-trichlorfon

Abstract

The antiparasitic drug Neguvon (Bayer), with the active component trichlorfon (O,O-dimethyl-(1-hydroxy-2,2,2-trichloroethyl)-phosphonate), is extensively used in fish farms in Norway. The fate of (methyl-12C)-trichlorfon was tested in Atlantic salmon (Salmo salar) by liquid scintillation counting at day 1, 4, 7, 14, and 30 post administration, and by autoradioraphy on selected organs 24 h after administration. The remaining radioactivity was found to be high compared to earlier measurements of the trichlorfon content made by gas chromatography (Brandal 1977). The grains in autoradiographic preparations of muscle were unevenly distributed both in the muscle as a whole and within muscle fibers. In liver the grains were evenly distributed, but were absent from fat vacuoles. The study indicate that the radioactive residues in salmon muscle do not represent trichlorfon or its derivative dichlorvos (O,O-dimethyl-O-(2,2-dichlorovinyl)-phosphate), but rather hydrophilic metabolites of these compounds.