T8 AM Ecological Fate and Effects of Explosives and Related Compounds
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 337-338

(LOT-1117-839335) Toxicokinetics, biotransformation, dietary uptake and critical body residues of explosives in aquatic animals.

Lotufo, G¹, Lydy, M², ¹ U.S. Army Engineer Research and Development Center, Vicksburg, MS, USA² Department of Zoology, Southern Illinois University, Carbondale, IL, USA

ABSTRACT- The biological effects of explosives and related compounds in aqueous exposures have been extensively investigated. However, despite the high environmental relevance of those compounds, reports on their bioaccumulation potential in relevant aquatic animals are scarce. Explosive compounds are weakly hydrophobic and therefore their predicted bioaccumulative potential is very low, as confirmed empirically. The bioconcentration factors (BCFs) for TNT and aminodinitrotoluenes ranged from 0.8 to 14.8 ml/mg for a variety of invertebrates and fish species. Similar BCFs (2.1-13.1 ml/mg) were derived for aminodinitrotoluenes, dinitrotoluenes and dinitrobenzenes but lower BCFs (0.5 to 2.1 ml/mg) were determined for RDX, HMX and 2,4-diaminonitrotoluene. The elimination rate constants determined for TNT, aminodinitrotoluenes, diaminonitrotoluenes, RDX and HMX in aquatic invertebrates and fish were high (), and led to steady-state bioaccumulation within hours. The dietary uptake of the explosives TNT and RDX has been examined using two species of fish and different routes of contaminant delivery. Steady-state bioaccumulation factors (concentration in fish relative to concentration in the diet) and all its breakdown products, determined using radioactivity, were low for TNT (up to 0.02 g/g) and RDX (up to 0.01 g/g). Nitroaromatic explosives and related compounds undergo fast transformation in soils and sediments. Efficient biotransformation of TNT has been reported for a variety of aquatic invertebrates and fish. Exposure to TNT resulted in the formation of aminodinitrotoluenes as well as non-identified solvent-extractable and non-extractable transformation products in invertebrate and fish species. The ability of aquatic animals to biotransformation other explosives and related compounds is currently unknown. Lethal body residues in fish and aquatic invertebrates were 4 to 20 nmol/g for TNT (sum concentration of TNT), 268 for 2-aminodinitrotoluene, and 41 nmol/g for RDX exposures. Because of the fast elimination rate and exceedingly low bioaccumulative potential, exposure to explosives at contaminated sites are unlikely to pose unacceptable risks to aquatic animals.

Key words: Explosives, Bioaccumulation, Toxicokinetics, Critical body residue