TOXICOKINETICS OF FLUORANTHENE TO THE AMPHIPOD, LEPTOCHEIRUS-PLUMULOSUS, IN WATER-ONLY AND SEDIMENT EXPOSURES

The ability of the equilibrium partitioning (EqP) and critical body re sidue (CBR) approaches to predict the toxicity of the polycyclic aroma tic hydrocarbon, fluoranthene, to a standard sediment toxicity test or ganism, the amphipod Leptocheirus plumulosus was examined in a series of water-only and sediment exposures. Concentrations of fluoranthene i n water that resulted in 50% mortality (10-d LC50) were 39.2 (35.1-43. 8, 95% C.I.) and 39.2 (34.1-45.1, 95% C.I.) mu g/liter in replicate te sts. CBR or tissue concentrations that produced 50% mortality after re plicate 8-d water-only exposures (LDS50) were 0.694 (0.596-0.876, 95% C.I.) and 2.44 (1.83-3.68, 95% C.I.) mmol total fluoranthene-equivalen ts/kg wet wt tissue, values somewhat lower than the range of CBR estab lished for nonpolar narcotics in other organisms (2-8 mmol/kg). No sig nificant mortality of L. plumulosus was observed over 26-d sediment to xicity tests, even though estimated interstitial water concentrations (up to 212 mu g/liter) exceeded the average water-only LC50 (39.2 mu g /liter) by more than a factor of five, suggesting that the EqP approac h over-estimated toxicity to this species. Average tissue concentratio ns attained in sediment tests (0.30 mmol/kg) were substantially lower than the CBR for nonpolar narcotics in other organisms, and in the wat er-only tests. Thus, lack of mortality in sediment exposures agrees wi th CBR predictions. The CBR approach appears to be a useful complement to the EqP approach for predicting the toxicity of sediment-associate d contaminants. (C) 1998 Elsevier Science Ltd. All rights reserved.