Abstract  Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a widely used explosive that is present in soils at a number of military sites, including training and testing ranges. Because of its relatively weak adsorption to soil, RDX frequently migrates through the unsaturated zone and causes groundwater contamination. In the environment, RDX can transform to produce mono-, di-, and tri-nitroso derivatives (MNX, DNX, and TNX) and the ring cleavage products methylenedinitramine (MEDINA) and 4-nitro-2,4-diazabutanal (NDAB). The present study was undertaken to analyze RDX and its products in groundwater samples taken from various US military sites. The stability of some of the common transformation intermediates of RDX, including the nitroso derivatives, NDAB and MEDINA, under typical conditions in a groundwater aquifer is not well understood, and appropriate preservation methods for these compounds have not been established. Therefore, we studied the inherent stability of these compounds in deionized water and in groundwater, and evaluated various preservation techniques, including adjustment of pH, temperature, and salinity. NDAB and nitroso derivatives were stable under typical ambient environmental conditions, but MEDINA was highly unstable. The addition of sea salts (10% w/v) was found to stabilize MEDINA when the samples were stored at 4 °C. Using appropriate preservation techniques, we detected nitroso derivatives and NDAB, but no MEDINA, at some of the sites investigated. Stabilizing RDX intermediate products in field samples to allow detection is important because the presence of any of these chemicals can indicate past contamination by RDX and provide insight into the occurrence of in situ natural attenuation.

Abstract  Trinitrotoluene (TNT) and related compounds were tested for induction of mutation in the CHO-hprt mutation assay. The parent compound, TNT, was consistently found to be mutagenic at concentrations above 40 microg ml(-1), whether or not S9 activating enzymes were added. Five TNT metabolites gave statistically significant but small increases in mutation frequency over solvent controls: 4-amino-2,6 dinitrotoluene, 2,4',6,6'-tetranitro-2',4-azoxytoluene, 2,2',6,6'-tetranitro-4,4'-azoxytoluene, 2',4,6,6'-tetranitro-2,4'-azoxytoluene and triaminotoluene. Clear dose-response relationships could not be established for the mutagenic response of these compounds. They are considered as very weak mutagens in this mammalian test system. Five compounds did not produce statistically significant mutation frequencies at the levels tested: 2-amino-4,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene, 1,3,5-trinitrobenzene, 2,6-diamino-4-nitrotoluene and 4,4',6,6'-tetranitro-2,2'-azoxytoluene. The results indicate that none of the TNT metabolites tested pose a significant mutational health risk, at least as judged by the CHO-hprt assay.

Abstract  1,2,5-trinitro-1,3,5-triazine, commonly known as RDX, is a military explosive that has been extensively used by the U.S. Military since the late 1930's and has been reported to cause convulsions in military field personnel and munition workers during use and manufacture. In addition, military bases across the United States have been contaminated due to the testing and disposal of RDX. Thus, human exposure is possible both during remediation processes and through groundwater contamination. This report outlines a progressive series of three oral toxicity studies on RDX that were designed to identify effect levels, define target organs, support regulatory actions, and provide risk assessment information. Male and femal Fischer 344 rats were dosed 7 days a week for a period of 13 weeks at dosages of 0, 4, 8, 10, 12, and 15 mg/kg/day. The RDX was suspended in a solution of 1% Methylcellulose/0.2% Tween 80 in distilled water. Male and female dose dependent mortality, as well as other measured parameters, was observed at dosages of 8 mg/kg/day and above. The No Observed Adverse Effect Level for this study was 4 mg/kg/day, based on mortality.

Abstract  A database on the health and environmental aspects of munition production waste products is presented. Information on production processes and waste treatement methods is also presented.

Abstract  Toxicokinetic studies on the explosive RDX were conducted to develop environmental and health effects criteria. The absorption, distribution and elimination of 14C RDX were studies in rats following intratracheal administration. Rats were treated with 14C RDX (15 mg/kg, 5-6 microCi) in 1% carboxymethylcellulose suspension and placed in glass metabolism cages. Urine and feces were collected at 6-12 hr and 24 hr intervals, respectively, and radioactivity determined in a liquid scintillation counter. About 10% of the radioactivity appeared in the urine in 24 hr. In the first 4 and 6 days, respectively, females and males had eliminated 23% and 26% of the radioactive label via urine; in the same periods, excretion via the feces was 3% and 5%, respectively. After sacrifice of the rats at 4 or 6 days, the plasma levels of radioactivity were 0.02%/ml. The radioactive residues were 0.1%/g in liver, kidneys and lung, whereas brain and adipose tissus showed only 0.02%/g. The results indicate that a sizable fraction of RDX is eliminated in the urine, although considerable radioactive residues were detected in the liver, kidney, and lunug tissues after 4-6 days.

Abstract  The objective of this study was to perform a literature review on the transport and transformation processes that may affect the environmental fate of 11 munition wastewater constitutents. Estimates of kinetic rate constants for volatilization, sediment adsorption, biodegredation, photolysis, chemical oxidation were made from available literature data. Recommendations for the further elucidation of environmental fate are made to fill the gaps identified in the literature review.

Abstract  Composition C-4 is the most common plastic explosive employed by the military in Vietnam. Ingestion is followed in a few hours by multiple generalized seizures, hematuria, severe nausea and vomiting, muscle twitching, and mentation changes. Six patients requiring hospitalization were treated by gastric lavage, maintenance of airway, control of seizures, monitoring of urine volume, and maintenance of fluid and electrolyte balance. No fatalities were observed.

Abstract  At military training sites, a variety of pollutants such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), may contaminate the area originating from used munitions. Studies investigating the mechanism of toxicity of RDX have shown that it affects the central nervous system causing seizures in humans and animals. Environmental pollutants such as RDX have the potential to affect many different species, therefore it is important to establish how phylogenetically distant species may respond to these types of emerging pollutants. In this paper, we have used a transcriptional network approach to compare and contrast the neurotoxic effects of RDX among five phylogenetically disparate species: rat (Sprague-Dawley), Northern bobwhite quail (Colinus virginianus), fathead minnow (Pimephales promelas), earthworm (Eisenia fetida), and coral (Acropora formosa). Pathway enrichment analysis indicated a conservation of RDX impacts on pathways related to neuronal function in rat, Northern bobwhite quail, fathead minnows and earthworm, but not in coral. As evolutionary distance increased common responses decreased with impacts on energy and metabolism dominating effects in coral. A neurotransmission related transcriptional network based on whole rat brain responses to RDX exposure was used to identify functionally related modules of genes, components of which were conserved across species depending upon evolutionary distance. Overall, the meta-analysis using genomic data of the effects of RDX on several species suggested a common and conserved mode of action of the chemical throughout phylogenetically remote organisms.

Abstract  The report by Cholakis et al. (1980) presents methods and results of a total of nine toxicology studies with RDX. As per instructions, the acute toxicity studies and the two genotoxicity studies (Ames test and Dominant lethal mutation test) were not considered in this review. Overall, the tests, which were carried out during the period 1978-1980, can be considered acceptable even at the light of specific guidelines (from EPA and OECD) which were published about a decade later. Minor omissions in experimental design, testing or reporting are indicated below in the answers to the posed questions. In a few instances reporting and/or interpretation of findings is unclear.

Abstract  The role of a number of processes (photodegradation, hydrolysis, biodegradation, and sorption to sediment) which may affect the environmental fate of RDX was examined under laboratory conditions. Photodegradation of RDX appears to be a fairly rapid process (half-life of 9-13 hours) and one ofthe intermediate photolysis product may be a nitrosamine. RDX does not hydrolyze in an aqueous solution at a pH range normally formed in natural waters. RDX does not sorb significantly to the sediment. Following a lag period of 2:3 weeks, biodegradation of RDX (half-life about 7 days) occurs in Holston River water supplemented with sediment. Sorption of TNT to sediment is relatively low after 24 hours. TNT degrades in the presence of sediment and the products of degradation appear to bind strongly to sediment with time.

Abstract  1. PURPOSE. This study was conducted to assess the feasibility of using exhaled breath condensate as a non-invasive sampling method for measuring biomarkers ofRDX exposure in Yorkshire pigs. A secondary objective was to assess the absorption and distribution of a single oral dose ofRDX throughout the body. 2. CONCLUSION. Breath sampling of juvenile swine was considered technically feasible for this kind of study while simultaneous sampling of blood from the ear permitted monitoring of RDX absorption over time. This model can be used again for this kind of study. 3. RECOMMENDATION. Use this model to continue studies on breath analysis of swine with modifications and more effective trapping of breath.

Abstract  A number of nitroaromatic explosives and related compounds were examined for mutagenic activity with the Salmonella/mammalian microsome test. 9 of 11 nitroaromatics tested were mutagenic, including 2,4,6-trinitrotoluene, the most widely produced military explosive. All the nitroaromatics, except 2,4,6-trinitrophenol and 2,3,5-trinitroresorcinol, were at least an order of magnitude more mutagenic than 3 dinitrotoluene (DNT) isomers. The most active compound was 2,3,5-trinitronaphthalene, which was approximately 5000 times more mutagenic than DNT isomers. These compounds induced predominantly frameshift mutations. The mutagenic activity did not require S9 activation, but was largely dependent on the presence of an intact nitroreductase capability in the test bacteria. This implied that reduced metabolites, possibly hydroxylamines, are the proximal mutagenic intermediates.

Abstract  The accidental or intentional ingestion of toxic substances frequently results in life threatening complications of various types. Frequently, the nature of the offending substance is unknown to the physician who must care for the critically ill or potentially critically ill patient. The following case reports describe two patients who, while intoxicated with ethanol, ingested unknown quantities of Composition C-4, a plastic-type explosive. This substance is widely available in Vietnam. Since there have been no previous reports in the literature of ingestion of this substance, the two cases are reported in some detail. Comments are made about the composition and chemical structure of C-4 together with a brief discussion of known toxic effects of some of its breakdown products.

Abstract  This project is the first to investigate RDX metabolism in human liver. RDX metabolism was screened in human liver tissues including S9 preparations, microsomes, hepatocytes and several recombinant CYP450 isoforms under aerobic, anaerobic and oxygen reduced conditions. RDX metabolism was also conducted in several animal liver microsomes to compare with hum an liver microsomes. loss of the parent compound (RDX) was determined at 30 and 180 minutes of the incubation and ranked as human (46.6% & 51.8%)> rat (40.1% & 47.2%)> monkey (34.6% & 35.7%)> Pig (25.5% & 33.7%)> rabbit (11.6% & 18.0). The data is used to establish Physiologically-based pharm acokinetic (PBPK) models for human useful in risk assessment. Further characterization of the profiles of RDX in vitro metabolism in human and animal liver tissues is proposed. This study developed an in vitro metabolic model which mimics in vivo physiological condition and will be useful in the evaluation of human metabolic fate for novel energetics such as replacement formulations for RDX and for other toxic TICs/TIMs.

Abstract  Hexahydro-1,3,5-trinitro-1,3,5-triazine (Royal Demolition Explosive or RDX) is an explosive nitroamine widely used in military and industrial applications. Contamination with RDX has been identified at areas of explosive manufacturing, processing, storage, and usage. Thus, the potential exists for explosure to humans. To determine a neurotoxic developmental effect the compound must first be transferred from themother to the offspring during gestation. This study was designed to determine if RDX would be passsed to the offspring during gestation as well as during lacatation. Female Sprague Dawley rats were dosed with RDX, 6 mg/kg on gestation day (GD) 6 through postnatal day (PND) 10. At PND 0, 3, 5, and 10 dams and pups were tested for RDX in the milk and brain, respectively. The results indicated that there was a significant amount of RDX present in the brain of the pups following parturition. RDX was also found in significant amounts in the milk during lactation. Given these data further studies evaluated the neurotoxic and developmental effects of RDX should be conducted.

Abstract  The PWG was convened to review selected H & E-stained liver sections from a two-year chronic study of hexahydro-1,3,5-trinitro-1,3.5-triazine (RDX) administered in the diet. The following is a summary of review findings. - A number of liver lesions were downgraded from tumor to non-tumor status. As a result of these changes there are four less hepatocellular tumors in Group 3, two less hepatocellular tumors in Group 4, and two less hepatocellular tumors in Group 5. - A number of lesions were downgraded from malignant to benign status. As a result of these changes there are three less hepatocellular carcinomas in Group 2, three less hepatocellular carcinomas in Group 4, and one less hepatocellular carcinomas in Group 5. - Two new non-tumor diagnoses were added. As a result of these changes there are two additional non-tumor hepatocellular lesions in Group 2. - The PWG review altered the numerical incidence of hepatocellular lesions in all dose groups except the controls. The general incidence pattern persisted in Groups 1 through 4, but the previously noted linear increase in liver tumor incidence in all treated groups was no longer evident in Group 5.

Abstract  The consideration of multiple or cumulative sources of exposure to a chemical is important for adequately protecting human health. This assessment demonstrates one way to consider multiple or cumulative sources through the development of a relative source contribution (RSC) factor for the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), using the Exposure Decision Tree approach (subtraction method) recommended by the U.S. Environmental Protection Agency. The RSC factor is used to ensure that the concentration of a chemical allowed by a regulatory criterion or multiple criteria, when combined with other identified sources of exposure common to the population of concern, will not result in unacceptable exposures. An exposure model was used to identify relevant potential sources for receptors. Potential exposure pathways include ingestion of soil, water, contaminated local crops and fish, and dermal contact with soil and water. These pathways are applicable only to areas that are in close proximity to current or former military bases where RDX may have been released into the environment. Given the physical/chemical properties and the available environmental occurrence data on RDX, there are adequate data to support a chemical-specific RSC factor for RDX of 50% for drinking water ingestion.

Abstract  The U.S. Environmental Protection Agency’s (EPA) National Center for Environmental Assessment (NCEA) is currently developing a human health assessment of 1,3,5-trinitro-1,3,5-hexahydrotriazine (RDX) CAS No. 121-82-4. The study reports by Levine et al. (1983) entitled “Determination of the Chronic Mammalian Toxicological Effects of RDX: Twenty-Four Month Chronic Toxicity/Carcinogenicity Study of Hexahydro-1,3,5-trinitro-1,3,5- triazine (RDX) in the Fischer 344 Rat,” and Crouse et al. (2006) entitled “Subchronic Oral Toxicity of RDX in Rats” are being considered for the development of an oral toxicity value for RDX. Additionally, the study report by Lish et al. (1984) entitled “Determination of the Chronic Mammalian Toxicological Effects of RDX: Twenty-Four Month Chronic Toxicity/ Carcinogenicity Study of Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in the B6C3F1 Hybrid Mouse” is being considered in the development of a cancer assessment for RDX in conjunction with a reevaluation of the incidence of hepatocellular adenomas and carcinomas (Parker et al. 2006). The reports of Levine et al. (1983) and Lish et al. (1984) are on the effects from chronic oral (dietary) exposure to RDX in Fischer 344 (F344) rats and B6C3F1 mice. Crouse et al. (2006) describe effects from a 90-day gavage exposure to RDX in F344 rats. The primary reports and the associated necropsy and histopathology reports have not been subjected to a formal peer review process. Such a peer review process is important in establishing the appropriateness, validity, robustness of the study design, conduct, and findings of the reported investigation. The purpose of the requested peer review was for EPA to receive written comments from individual experts.

Abstract  Two cases of hexogen-induced seizures after occupational exposure in a French explosive factory are described. The workers were hand-sieving large amounts of dry hexogen powder, for 4 and 6 hours respectively. Recurrent seizures occurred despite anticonvulsant therapy, 6 and 2 hours after admission, respectively. E.E.G., C.T. scan and M.R.I. were normal in the first patient as was E.E.G. in the second; both recovered uneventfully. Previous cases were found after a retrospective study of the factory's medical records. The available toxicological data on this rare occupational poisoning are reviewed.