Acute Toxicity of 2,4,6-Trinitrotoluene in Earthworm (Eisenia andrei)

Abstract

2,4,6-Trinitrotoluene (TNT) is an worldwide recalcitrant environmental contaminant and is toxic to a number of organisms including humans. This study examines the acute effects (lethal and biomass changes) of TNT on the oligochaetes species Eisenia andrei, using the 3-day filter paper, and the 7- and 14-day direct contact spiked soil (OECD artificial and forest soil) toxicity tests. Studies using the filter paper test indicated that the lethality of TNT could be detected in the range 1.5 to 14.2 μg/cm2, with significant biomass (body weight) changes occurring at the lowest concentration. Acute effects (lethality) could not be measured when earthworms were placed on filter paper containing a saturated aqueous solution of TNT. This may indicate that with these exposure conditions, TNT may have been adsorbed to the filter paper, and that this matrix should be saturated with TNT before becoming available to the earthworms. Spiked soil toxicity tests indicated that the E. andrei lethality by TNT was >1.5 times higher when earthworms were exposed to TNT-spiked forest soil (LOEC:260 mg/kg; LC50 14 days 222.4 mg/kg) than to spiked OECD artificial soil (LOEC:420 mg/kg; LC50 14 days: 364.9 mg/kg). The sublethal effect on biomass change at the selected TNT concentrations in soil was not significant compared to controls. Results indicate that the bioanalytical methods described in this article could be used as TNT toxicity assessment tools. This soil quality test method gives valuable information for the screening of soil toxicity.