rinitrotoluene fathead minnow toxicity bioaccumulation

摘要

Few studies have determined the toxicity and bioaccumulation potential of explosive compounds in freshwater fish. In the present study, fathead minnow (Pimephales promelas) were exposed to a range of 2,4,6-trinitrotoluene (TNT) concentrations (0.44-44 μmol/L [0.1-10 mg/L] and 4.4-22.0 μmol/L [1.0-5.0 mg/L] in 4- and 10-d experiments, respectively). Median lethal concentrations of 11.93 μmol/L (2.7 mg/L; 95% confidence limit [CL], 10.29-13.83 μmol/L) and 9.68 μmol/L (2.20 mg/L; 95% CL, 9.17-10.22 μmol/L) were calculated in the 4- and 10-d experiments, respectively, and median lethal body residue of 101.0 μmol/kg (95% CL, 86.0-118.7 μmol/kg) was calculated in 4-d experiments. To study bioaccumulation, fish were exposed to 4.4 μmol/L (1 mg/L) of TNT for 12 h. Rapid bioaccumulation of TNT occurred within the first 10 min of exposure (k_u = 30.4 L/kg/ h). Elimination of ΣTNT (molar sum of TNT and degradation products 2- and 4-aminodinitrotoluenes) was fast, with an elimination rate (k_e) of 2.24/h and a short half-life (0.31 h). The bioconcentration factors determined using 6-h mean tissue and water concentrations of ΣTNT were 8.40 and 4.68 L/kg for the uptake experiment and the uptake portion of the elimination experiments, respectively. To determine the target organ for TNT in fish, juvenile fathead minnow were exposed to 2.2 μmol/L (0.5 mg/L) of [~(14)C]TNT for 10 d. Radiolabeled compounds primarily bioaccumulated in the visceral tissues and spleen in comparison to gill, brain, muscle, and remainder tissue groups. The present study demonstrates the low bioaccumulation potential and rapid uptake of TNT in the fathead minnow.