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(040) Distribution and target tissues of TNT in fathead minnow.
Yoo, Leslie*,1, Houston, Jerre2, Gibson, Alfreda2, Faulkner, Alison2, Steevens, Jeffery2, 1 Analytical Services, Inc., Vicksburg, MS, USA2 U.S. Army Engineer Research and Development Center, Vicksburg, MS, USA
ABSTRACT- Few studies have determined the bioaccumulation potential of explosive compounds in freshwater fish. In the present study, fathead minnow larvae (Pimephales promelas) age 10 days were exposed to a range of 2,4,6-trinitrotoluene (TNT) (0-6 mg/L) for 96 hours. Significant decreases in survival occurred at 3.92 mg/L TNT. Significant toxicity was observed at tissue concentrations greater than 6 mg/kg and less than 9 mg/kg TNT. To study the bioaccumulation of TNT in fathead minnow, adults (age 10 weeks) were exposed to 0.23 mg/L 14C-TNT for 96 hours. Rapid bioaccumulation of TNT occurred without reaching steady state. Greater levels of the parent compound (TNT) were detected after 6 hours of exposure in comparison to 4-amino-2,6-dinitrotoluene (4ADNT) and 2,4-diamino-6-nitrotoluene (2ADNT). In contrast, 4ADNT was present at higher concentrations in tissue and less TNT at 96 hours, suggesting the induction of metabolic activity. In support of this observation, the proportion of solvent extractable TNT decreased during the 96-hour exposure suggesting TNT metabolism increased. To determine the target organ for TNT in fish, fathead minnow adults were exposed to a sublethal concentration of 14C-TNT (0.10 mg/L). TNT primarily bioaccumulated in the internal organs of the fish followed by the gill tissue in comparison to brain, muscle, and remainder tissue groups. Lower levels of TNT were detected in all tissue groups after the 144-hour collection, further supporting the induction of TNT metabolism in fathead minnow. Autoradiography will be used to identify the specific sites of TNT accumulation and activity within individual tissue groups of freshwater fish. The current study demonstrates muscle tissue accumulated lower levels of TNT (3 mg/L) in comparison to the other tissue groups, suggesting decreased human exposure when consuming freshwater fish exposed to sublethal levels of TNT.
Key words: tnt, bioaccumulation, fathead minnow, target tissues
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