Nitroaromatic Munition Compounds: Environmental Effects and Screening Values

Talmage, Sylvia S.; Opresko, Dennis M.; Maxwell, Carlos; Welsh, Chris J.E.; Cretella, F. M.; Reno, P. H.; Daniel, F. Bernard

doi:10.1007/978-1-4757-6427-7_1

Cited by 243 publications

(365 citation statements)

References 121 publications

(238 reference statements)

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“…While conjugates 2 and 3 were detected in the liquid culture experiments, in the raft-based system no such derivatives were identified in medium or plant extracts. Military training ranges often have areas of contamination containing between 100 and 1,000 mg kg 21 explosive pollutants (Talmage et al, 1999;Jenkins et al, 2006), although the majority are usually below this level. To test the detoxification abilities of the GST-U24 and GST-U25 overexpression lines in a soil-based system, we chose TNT concentrations of 25, 50, and 100 mg kg 21 (levels that unmodified Arabidopsis plants could tolerate while still being representative of the amounts found on training ranges).…”

Section: Overexpressing Gst-u24 and Gst-u25 Arabidopsis Linesmentioning

confidence: 99%

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

et al. 2014

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The explosive 2,4,6-trinitrotoluene (TNT) is a major worldwide military pollutant. The presence of this toxic and highly persistent pollutant, particularly at military sites and former manufacturing facilities, presents various health and environmental concerns. Due to the chemically resistant structure of TNT, it has proven to be highly recalcitrant to biodegradation in the environment. Here, we demonstrate the importance of two glutathione transferases (GSTs), GST-U24 and GST-U25, from Arabidopsis (Arabidopsis thaliana) that are specifically up-regulated in response to TNT exposure. To assess the role of GST-U24 and GST-U25, we purified and characterized recombinant forms of both enzymes and demonstrated the formation of three TNT glutathionyl products. Importantly, GST-U25 catalyzed the denitration of TNT to form 2-glutathionyl-4,6-dinitrotoluene, a product that is likely to be more amenable to subsequent biodegradation in the environment. Despite the presence of this biochemical detoxification pathway in plants, physiological concentrations of GST-U24 and GST-U25 result in only a limited innate ability to cope with the levels of TNT found at contaminated sites. We demonstrate that Arabidopsis plants overexpressing GST-U24 and GST-U25 exhibit significantly enhanced ability to withstand and detoxify TNT, properties that could be applied for in planta detoxification of TNT in the field. The overexpressing lines removed significantly more TNT from soil and exhibited a corresponding reduction in glutathione levels when compared with wild-type plants. However, in the absence of TNT, overexpression of these GSTs reduces root and shoot biomass, and although glutathione levels are not affected, this effect has implications for xenobiotic detoxification.The containment and cleanup of environmental pollutants is increasingly both a legal requirement and a responsible action in many developed countries. The most commonly used explosives in military weapons are 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and their continual use, along with production and decommissioning, are progressively contaminating millions of hectares of military land . Bioremediation of TNT is particularly challenging, as the electron-withdrawing properties of the three nitro groups render the aromatic ring particularly resistant to oxidative attack and ring cleavage by microbial oxygenases, which in the environment are normally central to the biodegradation of aromatic compounds (Qasim et al., 2007). In the United States, the Environmental Protection Agency and the military are addressing methods by which toxic TNT and RDX can be contained and detoxified on active military training ranges. One way this problem might be tackled is through the use of plants that are adapted to detoxify these compounds. This could be achieved either by traditional breeding programs or by genetic modification, as has been demonstrated previously for both RDX and TNT (Hannink et al., 2001;Rylott et al., 2006;Jackson et al., 2007).In t...

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Section: Overexpressing Gst-u24 and Gst-u25 Arabidopsis Linesmentioning

confidence: 99%

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

et al. 2014

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“…These authors reported that up to 3886 mg RDX/kg and 50 mg HMX/kg were measured in ryegrass tissue and calculated bioconcentration factors (BCF) ranging from 2 to 58 for RDX, and from 1 to 3 for HMX. Investigations of the effects of plant exposures to greater concentrations of explosives are necessary to better assess the ecological risks at explosives-contaminated sites, which were reported to contain RDX concentrations up to 74 000 mg/kg or HMX concentrations up to 5700 mg/kg (Best et al, 2006;Talmage et al, 1999). Information on the potential environmental impacts of CL-20 on plants is more limited.…”

Section: Introductionmentioning

confidence: 99%

Toxicity and uptake of cyclic nitramine explosives in ryegrass Lolium perenne

Rocheleau

Lachance

Kuperman³

et al. 2008

Environmental Pollution

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Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1, 3,5,3,5, and 2,4,6,8,10,4,6,8,10, are cyclic nitramines used as explosives. Their ecotoxicities have been characterized incompletely and little is known about their accumulation potential in soil organisms. We assessed the toxicity and uptake of these explosives in perennial ryegrass Lolium perenne L. exposed in a Sassafras sandy loam (SSL) or in a sandy soil (DRDC, CL-20 only) containing contrasting clay contents (11% and 0.3%, respectively). A 21-d exposure to RDX, HMX or CL-20 in either soil had no adverse effects on ryegrass growth. RDX and HMX were translocated to ryegrass shoots, with bioconcentration factors (BCF) of up to 15 and 11, respectively. In contrast, CL-20 was taken up by the roots (BCF up to 19) with no translocation to the shoots. These studies showed that RDX, HMX, and CL-20 can accumulate in plants and may potentially pose a risk of biomagnification across the food chain.

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“…RDX has been found in environmental media only in the vicinity of such sites. Explosives-contaminated soil concentrations are extremely heterogeneous, ranging from 0.7 to 74 000 mg kg À1 for RDX, and from 0.7 to 5700 mg kg À1 DW for HMX, and from 0.08 to 87 000 mg kg À1 for TNT, respectively (Talmage et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Effects, transfer, and fate of RDX from aged soil in plants and worms

et al. 2006

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The objectives of this study were to provide data that can be used to predict exposure-based effects of RDX in aged soil on multiple endpoint organisms representing two trophic levels. These data can be used for defining criteria or reference values for environmental management and conducting specific risk assessment. Dose-response experiments formed the basis for the evaluation of toxic effects and transfer of contaminants from soil into two trophic levels. Long-term exposure tests were conducted to evaluate chronic, sublethal, toxicity and transfer of aged soil-based explosives, with RDX as main contaminant. In these tests, plants were exposed for 55 days in the greenhouse, biomass was determined and residues of explosives parent compounds and RDX metabolites were analyzed using HPLC techniques. Worms were exposed for 28 days (Eisenia fetida) and 42 days (Enchytraeus crypticus) in the laboratory, biomass and number were determined, and tissues were analyzed for explosives compounds. The plants tolerated concentrations up to 1540 mg RDX kg À1 soil-DW. Biomass of Lolium perenne was not significantly related to soil-RDX concentration, while biomass of Medicago sativa significantly increased. No screening benchmark for RDX in soil for plants was calculated, since concentrations up to 1540 mg kg À1 soil failed to reduce biomass by 20% as required for a LOEC. RDX, RDX-metabolite MNX, and accompanying HMX concentrations in plants were significantly related to concentrations in soil after 55 days of exposure (RDX: R 2 = 0.77-0.89; MNX R 2 = 0.53-0.77; HMX: R 2 = 0.67-0.71). The average bioconcentration factors (BCF) were for RDX 17 in L. perenne and 37 in M. sativa, and for HMX 2 in L. perenne and 44 in M. sativa. The worms also tolerated concentrations up to 1540 mg RDX kg À1 soil-DW. Biomass of E. fetida adults decreased with soil-RDX concentration, and a LOEC of 1253 mg kg À1 soil-DW was estimated. RDX concentrations in E. fetida were significantly related to concentrations in soil after 28-day exposure (R 2 = 0.88). The average BCF in E. fetida for RDX was 1. Because in response to exposure to RDX-contaminated soil the RDX concentrations in plants increased initially and decreased subsequently, while those in worms increased continuously, RDX in worm tissues may accumulate to higher concentrations than in plant tissues, regardless of the low average BCF for worms.

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Nitroaromatic Munition Compounds: Environmental Effects and Screening Values

Cited by 243 publications

References 121 publications

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

Toxicity and uptake of cyclic nitramine explosives in ryegrass Lolium perenne

Effects, transfer, and fate of RDX from aged soil in plants and worms

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