Toxicity Of Trinitrotoluene Research Articles

Analysis of the biodegradation and phytotoxicity mechanism of TNT, RDX, HMX in alfalfa (Medicago sativa)

The aim of this study was to reveal the mechanism underlying the toxicity of TNT (trinitrotoluene), RDX (cyclotrimethylene trinitroamine), and HMX (cyclotetramethylene tetranitramine) explosives pollution in plants. Here, the effects of exposure to these three explosives were examined on chlorophyll fluorescence, antioxidant enzyme activity, and the metabolite spectrum in alfalfa (Medicago sativa) plants. The degradation rates for TNT, RDX, and HMX by alfalfa were 26.8%, 20.4%, and 18.4%, respectively, under hydroponic conditions. TNT caused damage to the microstructure of the plant roots and inhibited photosynthesis, whereas RDX and HMX induced only minor changes. Exposure to any of the three explosives caused disturbances in the oxidase system. Non-targeted metabolomics identified a total of 6185 metabolites. TNT exposure induced the appearance of 609 differentially expressed metabolites (189 upregulated, 420 downregulated), RDX exposure induced 197 differentially expressed metabolites (155 upregulated and 42 downregulated), and HMX induced 234 differentially expressed metabolites (132 upregulated and 102 downregulated). Of these differentially expressed metabolites, lipids and lipid-like molecules were the main metabolites induced by explosives poisoning. TNT mainly caused significant changes in the alanine, aspartate, and glutamate metabolism metabolic pathways, RDX mainly caused disorders in the arginine biosynthesis metabolic pathway, and HMX disrupted the oxidative phosphorylation metabolic pathway. Taken together, the results show that exposure to TNT, RDX, and HMX leads to imbalances in plant photosynthetic characteristics and antioxidant enzyme systems, changes the basic metabolism of plants, and has significant ecotoxicity effects.

Toxicity of trinitrotoluene to sheepshead minnows in water exposures

Lethal effects of trinitrotoluene (TNT) to juvenile sheepshead minnows (JSHM) ( Cyprinodon variegatus) were assessed in ten-day water exposures. Ten-day median lethal concentrations (LC50s) were 2.3 and 2.5 mg L −1, the 10-d median lethal residue value (LR50) was 26.1 μmol kg −1 wet weight (ww), and bioconcentration factors (BCFs) ranged from 0.7 to 2.4 L kg −1. The lethal effects of TNT and its transformation products 2-aminodinitrotoluene (2-ADNT), 2,4-diaminonitrotoluene (2,4-DANT) and trinitrobenzene (TNB) to JSHM were compared in 5-d static-renewal exposures. Nitroreduction decreased the toxicity of TNT to SHM, as the 5-d LC50 for 2-ADNT was 8.6 mg L −1 and the lowest lethal concentration of 2,4-DANT was 50.3 mg L −1. TNB (5-d LC50=1.2 mg L −1) was more toxic than TNT to SHM. The 5-d LR50s were 4.3 mg kg −1 ww (20.4 μmol kg −1) for SumTNT (TNT exposure) and 54.2 mg kg −1 ww (275.3 μmol kg −1) for 2-ADNT and significant mortality occurred at 47.4 mg kg −1 ww (283.6 μmol kg −1). The range of BCF values was from 1.8 to 2.4, 5.6 to 8.0, and 0.6 to 0.9 L kg −1 for TNT, 2-ADNT, and 2,4-DANT, respectively.

Comparative and Mixture Sediment Toxicity of Trinitrotoluene and Its Major Transformation Products to a Freshwater Midge

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.

A NEW TEST FOR THE DETECTION AND THE APPRAISAL OF EXPOSURE TO TRINITROTOLUENE

In the course of an experimental study of the toxicity of trinitrotoluene and the mechanism of its action, it was found that trinitrotoluene is partly reduced in the organism with the formation of amines. One of these is presumably 2,6-dinitro-4-aminotoluene. Although sufficient quantities for chemical identification have not been isolated from the urine so far, certain characteristics seem to favor this assumption. It appears very likely that other reduction products such as mononitrodiaminotoluene and dinitrohydroxylaminotoluene and its derivatives may be encountered, but so far none of these have been identified by us in urines of experimental animals and man. These studies are still in progress and will be reported at a later date together with a discussion of the pertinent literature, but a test developed for the determination of 2,6-dinitro-4-aminotoluene was applied to a large number of urines of workers exposed to trinitrotoluene and was found to be more sensitive