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PH05 Fate and Effects of Energetic Compounds
(PH023) Toxicokinetics and toxicity of explosive compounds in fish.
Lotufo, G1, Lydy, M2, Wild, W3, 1 U.S. Engineer Research and Development Center, Vicksburg, MS, USA2 Southern Illinois University, Carbondale, Il, USA3 Space and Naval Warfare Systems Center, Marine Environmental Quality Branch, San Diego, CA, USA
ABSTRACT- In an effort to better understand the potential environmental risks associated with explosive compounds in aquatic systems, we evaluated the bioaccumulation and toxicity of the explosives TNT, RDX and HMX, and the TNT aminated breakdown products 2ADNT and 2,4DANT to sheepshead minnows, Cyprinodon variegatus. Toxicokinetics parameters were derived by exposing juvenile fish to sublethal concentrations those compounds from 5 min to 6 h and analyzing whole body concentrations. Exposed fish were transferred to clean water from 5 min to 18 h for depuration and analyzed for tissue concentration. TNT was rapidly biotransformed, therefore body residues were expressed as the sum molar concentration of TNT, ADNTs and DANTs (SumTNT). The uptake rates were substantially higher for TNT (7.3 ml/mg/h), 2ADNT (12.6 ml/mg/h) and 2,4DANT (1.3 ml/mg/h) than for RDX (0.15 ml/mg/h) and HMX (0.06 ml/mg/h). Similarly, elimination rates were extremely high for TNT (0.77/h), 2ADNT (0.80/h) and 2,4DANT (2.7/h), resulting in steady-state within few hours, but much lower for RDX (0.09/h) and HMX (0.12/h). Bioconcentration factors (ml/g) were <1 for 2,4DANT and HMX, 9.6 for TNT, 13.1 for ADNT and 1.7 for RDX, confirming their low bioaccumulation potential, expected due to their low hydrophobicity. Exposure to radiolabeled TNT and RDX indicated that explosives accumulate at much higher concentration in the liver and gill tissues compared to skin and muscles, therefore posing lesser exposure to potential human receptors that consume only filets. Moreover, a substantial portion of the radioactivity resisted solvent extraction and was likely covalently bound to peptides. Lethal concentrations and lethal body burdens (LBB) were assessed in 10 day exposures. TNT (LC50 = 2.3 mg/L, LBB = 19 nmol/g) was more toxic than 2ADNT (LC50 = 8.6 mg/L, LLB = 268 nmol/g) or RDX (LC50 = 9.9 mg/L, LBB = 41 nmol/g). Exposure to a saturated solution of HMX or high concentration of 2,4DANT (51 mg/L) did not result in decreased fish survival. Our toxicological evaluation indicates that adverse effects of explosives to fish are expected only at constant exposure to concentrations that may not be observed even at highly contaminated sites. Therefore exposure conditions associated with the presence of unexploded ordnance in aquatic systems are unlikely to pose unacceptable risks to fish.
Key words: Explosives, Toxicokinetics, Fish, CBR
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