Toxicity of trinitrotoluene to sheepshead minnows in water exposures.

Lethal effects of trinitrotoluene (TNT) to juvenile sheepshead minnows (JSHM) (Cyprinodon variegatus) were assessed in ten-day water exposures. Ten-day median lethal concentrations (LC50s) were 2.3 and 2.5 mg L(-1), the 10-d median lethal residue value (LR50) was 26.1 micromol kg(-1) wet weight (ww), and bioconcentration factors (BCFs) ranged from 0.7 to 2.4 L kg(-1). The lethal effects of TNT and its transformation products 2-aminodinitrotoluene (2-ADNT), 2,4-diaminonitrotoluene (2,4-DANT) and trinitrobenzene (TNB) to JSHM were compared in 5-d static-renewal exposures. Nitroreduction decreased the toxicity of TNT to SHM, as the 5-d LC50 for 2-ADNT was 8.6 mg L(-1) and the lowest lethal concentration of 2,4-DANT was 50.3 mg L(-1). TNB (5-d LC50=1.2 mg L(-1)) was more toxic than TNT to SHM. The 5-d LR50s were 4.3 mg kg(-1)ww (20.4 micromol kg(-1)) for SumTNT (TNT exposure) and 54.2 mg kg(-1)ww (275.3 micromol kg(-1)) for 2-ADNT and significant mortality occurred at 47.4 mg kg(-1)ww (283.6 micromol kg(-1)). The range of BCF values was from 1.8 to 2.4, 5.6 to 8.0, and 0.6 to 0.9Lkg(-1) for TNT, 2-ADNT, and 2,4-DANT, respectively.

Toxicity and bioconcentration evaluation of RDX and HMX using sheepshead minnows in water exposures.

Lethal effects of the explosives RDX and HMX were assessed using ten-day water exposures to juvenile sheepshead minnows (Cyprinodon variegatus). For RDX, maximum mortality occurred during the first two days of exposure with a 10-d median lethal concentration (LC50) of 9.9 mg L(-1). The RDX 10-d median lethal residue (LR50) was 9.6 mg kg(-1) (34.9 µmol kg(-1)) wet weight (ww), the first RDX critical body residue reported for fish. Previous investigations reported that RDX body residues in marine amphipods up to 96 µmol kg(-1) ww and in marine mussels up to 86 µmol kg(-1) ww failed to result in significant mortality. The highest HMX concentration tested, corresponding to its apparent solubility limit in seawater (2.0 mg L(-1)), and the associated mean body residue (3 mg kg(-1) or 14 µmol kg(-1) ww) resulted in no significant mortality for exposed minnows. The mean 10-d bioconcentration factors for RDX (0.6-0.9 L kg(-1)) and HMX (0.3-1.6 L kg(-1)) were typically lower than 1, reflecting the low bioaccumulative potential for these compounds.

Toxicity and bioaccumulation of 2,4,6-trinitrotoluene in fathead minnow (Pimephales promelas).

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 micromol/L [0.1-10 mg/L] and 4.4-22.0 micromol/L [1.0-5.0 mg/L] in 4- and 10-d experiments, respectively). Median lethal concentrations of 11.93 micromol/L (2.7 mg/L; 95% confidence limit [CL], 10.29-13.83 micromol/L) and 9.68 micromol/L (2.20 mg/L; 95% CL, 9.17-10.22 micromol/L) were calculated in the 4- and 10-d experiments, respectively, and median lethal body residue of 101.0 micromol/kg (95% CL, 86.0-118.7 micromol/kg) was calculated in 4-d experiments. To study bioaccumulation, fish were exposed to 4.4 micromol/L (1 mg/L) of TNT for 12 h. Rapid bioaccumulation of TNT occurred within the first 10 min of exposure (ku = 30.4 L/kg/ h). Elimination of sigmaTNT (molar sum of TNT and degradation products 2- and 4-aminodinitrotoluenes) was fast, with an elimination rate (ke) 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 sigmaTNT 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 micromol/L (0.5 mg/L) of [14C]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.