ACUTE TOXICITY, ACCUMULATION AND EXCRETION OF ISOPROTHIOLANE AND ITS DEGRADATION PRODUCTS IN KILLIFISH

Acute toxicity, accumulation and excretion of isoprothiolane and its d egradation products (isoprothiolane sulfoxide, diisopropyl chloromalon ate and diisopropyl dichloromalonate) were studied for killifish (Oryz ias latipes). The 48-h LC(50) was 5.9 mg l(-1) for isoprothiolane, 35 mg l(-1) for isoprothiolane sulfoxide, 4.8 mg l(-1) for diisopropyl ch loromalonate and 7.1 mg l(-1) for diisopropyl dichloromalonate. The to xicities of the isoprothiolane degradation products were nearly equal to or lower than that of isoprothiolane. The bioconcentration factors (BCF) in the whole body of the fish were 45 at low concentration and 4 0 at high concentration for isoprothiolane, 0.2 for isoprothiolane sul foxide, 0.2 for diisopropyl chloromalonate and 0.7 for diisopropyl dic hloromalonate. As reference data, partition coefficients between n-oct anol and water (P-ow) were measured for these compounds. Log P-ow was 3.16 for isoprothiolane, 2.05 for isoprothiolane sulfoxide, 2.45 for d iisopropyl chloromalonate and 3.44 for diisopropyl dichloromalonate. T he excretion rate constants (k) from the whole body of the fish were 0 .32 h(-1) for isoprothiolane and 0.79 h(-1) for diisopropyl dichloroma lonate. The results suggest that the contamination of fish and other a quatic organisms by the isoprothiolane degradation products in the env ironment is low. Copyright (C) 1996 Elsevier Science Ltd.