THE TOXICITY OF THE MUTAGEN MX AND ITS ANALOG, MUCOCHLORIC ACID, TO RAINBOW-TROUT HEPATOCYTES AND GILL EPITHELIAL-CELLS AND TO DAPHNIA-MAGNA

The cytotoxicity of the, in Salmonella, potent mutagenic compound, chl oro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and its structura l analogue 3,4-dichloro-5-hydroxy-2[5H]-furanone (mucochloric acid, MC A), was studied in freshly isolated rainbow trout hepatocytes and gill epithelial cells by determining Rb-86-leakage and decrease in fluores cence intensity in calcein AM-loaded cells. The acute toxicity of the compounds to Daphnia magna was studied by determining the concentratio n causing immobilization of the organism, MX proved to be more toxic t han MCA both in the cellular assays and in the acute toxicity test wit h D. magna. MX was more toxic to hepatocytes than to gill epithelial c ells. The uptake of [C-14]MX was also much more efficient in hepatocyt es than in gill epithelial cells, The uptake of [C-14]MX in hepatocyte s was not inhibited by taurocholic acid in excess, indicating that MX is not taken up by the carrier complex responsible for the uptake of t aurocholate in the hepatocytes. Both the acute toxicity to D. magna an d cytotoxicity of MX and MCA was rather low (EC(50) values > 0.1 mM) a nd we conclude that it is very unlikely,that MX and MCA at concentrati ons occurring in recipients receiving chlorination effluents from pulp mills or chlorinated domestic sewage, as regards their acute toxicity , implies a risk for aquatic animals.