Abstract
Explosive compounds have been released into the environment during manufacturing, handling, and usage procedures. These compounds have been found to persist in the environment and potentially promote detrimental biological effects. The lack of research on bioaccumulation and bioconcentration and especially dietary transfer on aquatic life has resulted in challenges in assessing ecological risks. The objective of this study was to investigate the potential trophic transfer of the explosive compounds 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) using a realistic freshwater prey/predator model and using dichlorodiphenyltrichloroethane (DDT), a highly bioaccumulative compound, to establish relative dietary uptake potential. The oligochaete worm Lumbriculus variegatus was exposed to 14C-labeled TNT, RDX or DDT for 5 hours in water, frozen in meal-size packages and subsequently fed to individual juvenile fathead minnows (Pimephales promelas). Fish were sampled for body residue determination on days 1, 2, 3, 4, 7, and 14 following an 8-hour gut purging period. Extensive metabolism of the parent compound in worms occurred for TNT but not for RDX and DDT. Fish body residue remained relatively unchanged over time for TNT and RDX, but did not approach steady-state concentration for DDT during the exposure period. The bioaccumulation factor (concentration in fish relative to concentration in worms) was 0.018, 0.010, and 0.422 g/g for TNT, RDX and DDT, respectively, confirming the expected relatively low bioaccumulative potential for TNT and RDX through the dietary route. The experimental design was deemed successful in determining the potential for trophic transfer of organic contaminants via a realistic predator/prey exposure scenario.
Highlights
Explosive compounds were released to the environment during the manufacturing, handling, use, and disposal of munitions at military sites in the United States and throughout the world
This study investigates the potential for dietary uptake of the explosives, TNT and RDX, to the fathead minnow (Pimephales promelas)
Higher relative bioaccumulation of DDT* in L. variegatus was expected based on the major differences in Kow among the compounds used in this study and the positive relationship between log bioconcentration factors (BCFs) and log Kow [30]
Summary
Explosive compounds were released to the environment during the manufacturing, handling, use, and disposal of munitions at military sites in the United States and throughout the world. The result was contamination of ground and superficial waters, and soils and sediments, sometimes at exceedingly high concentrations (e.g., 34 mg/L for TNT in superficial water) [1,2]. Explosives such as 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and their degradation products typically degrade slowly in many environmental matrices, yielding longterm contamination at the military sites where they were released [3]. The nitroaromatic compound TNT was the most abundantly produced explosive in the world and was released to surface and groundwater mainly from runoff and leaching from storage and disposal areas and from receiving lagoons at munitions production and processing plants [1]. RDX has a lower sorption coefficient in topsoil and is more commonly found in groundwater compared to TNT [4]
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More From: International Journal of Environmental Research and Public Health
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