Lotufo Guilherme R, Farrar J Daniel
US Army Engineer Research and Development Center, 3909 Halls Ferry Road, EP-R, Vicksburg, Mississippi 39180, USA.
Arch Environ Contam Toxicol. 2005 Oct;49(3):333-42. doi: 10.1007/s00244-004-0213-y. Epub 2005 Sep 15.
The explosive trinitrotoluene (TNT) is a prevalent contaminant in many military installations worldwide. Limited knowledge of the comparative toxicity of sediment-associated TNT and related compounds contributes to uncertainty when assessing ecological risks in contaminated sites. Trinitrotoluene undergoes transformation when associated with soils and sediments and typically occurs as a mixture dominated by its reduction products. The objective of this study was to comparatively evaluate the single-compound toxicity of TNT and its major transformation products to the freshwater midge Chironomus tentans in 10-day exposures to sediment spiked with TNT, 2-aminodinitrotoluene (2-ADNT), 2,4-diaminonitrotoluene (2,4-DANT), or trinitrobenzene (TNB). In addition, the nature of the toxicological interactions of the latter compounds in a mixture was evaluated. Upon spiking to sediment, TNT and TNB rapidly degraded to reduced products, and disappearance of extractable compounds suggested irreversible binding to sediment particles. The high degree of transformation and reactivity occurring during 10 days at spiking concentrations as high as 4000 micromol/kg dry weight suggests that TNT and related compounds are unlikely to be encountered in fine-grained sediments at contaminated sites. Similar to previous investigations, the high reactivity of the spiked compound hampered determination of accurate toxic concentrations of TNT and related compounds, and of the nature of toxicological interaction of compounds in a mixture in this study. Sediment concentrations associated with decreased survival were similar for all four compounds, with the 10-d median lethal concentrations (LC50s) determined using initial concentrations ranging from 175 (2-ADNT) to 605 (2,4-DANT) micromol/kg dry weight. Sublethal decrease in growth was not observed for any compound. Results from the mixture experiment suggest additive interaction among TNT and related compounds in sediment exposures.
爆炸性化合物三硝基甲苯（TNT）是全球许多军事设施中普遍存在的污染物。由于对沉积物中TNT及相关化合物的相对毒性了解有限，在评估受污染场地的生态风险时存在不确定性。三硝基甲苯与土壤和沉积物结合时会发生转化，通常以其还原产物为主的混合物形式存在。本研究的目的是比较评估TNT及其主要转化产物对淡水摇蚊（Chironomus tentans）的单一化合物毒性，将其暴露于添加了TNT、2-氨基二硝基甲苯（2-ADNT）、2,4-二氨基硝基甲苯（2,4-DANT）或三硝基苯（TNB）的沉积物中10天。此外，还评估了后几种化合物在混合物中的毒理学相互作用性质。添加到沉积物中后，TNT和TNB迅速降解为还原产物，可提取化合物的消失表明其与沉积物颗粒发生了不可逆结合。在高达4000微摩尔/千克干重的添加浓度下，10天内发生的高度转化和反应表明，在受污染场地的细粒沉积物中不太可能遇到TNT及相关化合物。与之前的研究类似，添加化合物的高反应性妨碍了本研究中准确测定TNT及相关化合物的毒性浓度以及混合物中化合物的毒理学相互作用性质。所有四种化合物导致存活率降低的沉积物浓度相似，使用初始浓度范围为175（2-ADNT）至605（2,4-DANT）微摩尔/千克干重测定的10天半数致死浓度（LC50）。未观察到任何化合物对生长有亚致死性降低作用。混合物实验结果表明，在沉积物暴露中，TNT及相关化合物之间存在加和相互作用。
