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(034) Toxicity of diaminonitrotoluene isomers on the earthworm Eisenia andrei following exposure in spiked-forest soil.
Lachance, Bernard*,1, Hawari, Jalal1, Sarrazin, Manon1, Renoux, Agnès1, Ampleman, Guy2, Thiboutot, Sonia2, Sunahara, Geoffrey1, 1 Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, Canada2 Defense Research Establishment - Valcartier, Canadian Ministry of National Defense, Val-Bélair, Quebec, Canada
ABSTRACT- Previous studies have shown that tissue residues of TNT metabolites, 2-ADNT, 4-ADNT, 2,4-DANT and traces of 2,6-DANT are present in earthworms exposed to TNT-spiked soil. These metabolites have been found at TNT contaminated sites but their effects in earthworms have not been well characterized. Our earlier studies have also shown that these metabolites are less toxic for bacteria, algae and cell cultures than TNT. Based on temporal studies, it was suggested that a causal relationship could exist between the appearance of TNT metabolites and the onset of TNT-induced mortality in the earthworm. The objective of the present study was to verify if one of the biotransformation products identified in TNT-exposed E. andrei could be responsible for the observed mortality. This was accomplished by conducting parallel survival experiments with TNT, 2-ADNT, 4-ADNT, 2,4-DANT and 2,6-DANT, and by describing the distribution of TNT and its metabolites in soil and earthworms. It was found that 4-ADNT is as toxic as TNT. LC50 values (mg/kg soil) were 132 ± 22 (n=5), 215 (n=2) and 105 (n=2) for TNT, 2-ADNT and 4-ADNT respectively. Tissue concentrations of these metabolites were inversely correlated with their toxicity. The apparent bioaccumulation factors correlated well with the observed toxicity. Our data suggests that the amounts of 4-ADNT in soils could be used to assess toxicity to soil invertebrates such as earthworms. Also, one cannot presently exclude the participation of 4-ADNT in TNT induced toxicity in the earthworm.
Key words: lethality, biotransformation, bioaccumulation, invertebrates
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