Paper spray ionization-high-resolution mass spectrometry (PSI-HRMS) of peroxide explosives in biological matrices.

Mitigation of the peroxide explosive threat, specifically triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), is a priority among the law enforcement community, as scientists and canine (K9) units are constantly working to improve detection. We propose the use of paper spray ionization-high-resolution mass spectrometry (PSI-HRMS) for detection of peroxide explosives in biological matrices. Occurrence of peroxide explosives and/or their metabolites in biological samples, obtained from urine or blood tests, give scientific evidence of peroxide explosives exposure. PSI-HRMS promote analysis of samples in situ by eliminating laborious sample preparation steps. However, it increases matrix background issues, which were overcome by the formation of multiple alkali metal adducts with the peroxide explosives. Multiple ion formation increases confidence when identifying these peroxide explosives in direct sample analysis. Our previous work examined aspects of TATP metabolism. Herein, we investigate the excretion of a TATP glucuronide conjugate in the urine of bomb-sniffing dogs and demonstrate its detection using PSI from the in vivo sample.

In vitro metabolism of HMTD and blood stability and toxicity of peroxide explosives (TATP and HMTD) in canines and humans.

Triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) are prominent explosive threats. Mitigation of peroxide explosives is a priority among the law enforcement community, with canine (K9) units being trained to recognise the scent of peroxide explosives. Herein, the metabolism, blood distribution, and toxicity of peroxide explosives are investigated.HMTD metabolism studies in liver microsomes identified two potential metabolites, tetramethylene diperoxide diamine alcohol aldehyde (TMDDAA) and tetramethylene peroxide diamine dialcohol dialdehyde (TMPDDD).Blood stability studies in dogs and humans showed that HMTD was rapidly degraded, whereas TATP remained for at least one week.Toxicity studies in dog and human hepatocytes indicated minimum cell death for both TATP and HMTD.

Safety Study of Single-Dose Intravenously Administered DOTA-Siglec-9 Peptide in Sprague Dawley Rats.

The peptide-based radioactive compound [68Ga]Ga-DOTA-Siglec-9 is a novel agent for imaging of inflammation with positron emission tomography. The drug target of [68Ga]Ga-DOTA-Siglec-9 is vascular adhesion protein 1. Previous studies have obtained promising results with [68Ga]Ga-DOTA-Siglec-9 in experimental animals. However, before taking this novel imaging agent into clinical trials, safety and toxicological studies need to be performed with the nonradioactive precursor compound DOTA-Siglec-9. This extended single-dose toxicity study was designed to provide information on the major toxic effects of DOTA-Siglec-9 and to indicate possible target organs after a single intravenous (iv) injection in rats. The study was performed using 60 adult Hsd: Sprague Dawley rats and included a control group and a treatment group to investigate the toxicity of DOTA-Siglec-9 solution at a final concentration of 0.2 mg/mL after a single iv injection of 582 µg/kg. The maximum dose tested was 1,000-fold the clinical dose on a mg/kg basis as indicated in European Medicines Agency International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guideline M3(R2). The planned human clinical dose is approximately 0.582 µg of DOTA-Siglec-9 per kg of body mass. This study demonstrates that iv administration of DOTA-Siglec-9 at a dose of 582 µg/kg was well tolerated in rats and did not produce toxicologically significant adverse effects.

Preclinical assessment of 68 Ga-PSMA-617 entrapped in a microemulsion delivery system for applications in prostate cancer PET/CT imaging.

It has in recent years been reported that microemulsion (ME) delivery systems provide an opportunity to improve the efficacy of a therapeutic agent whilst minimising side effects and also offer the advantage of favourable treatment regimens. The prostate-specific membrane antigen (PSMA) targeting agents PSMA-11 and PSMA-617, which accumulate in prostate tumours, allow for [68 Ga]Ga3+ -radiolabelling and positron emission tomography/computed tomography (PET) imaging of PSMA expression in vivo. We herein report the formulation of [68 Ga]Ga-PSMA-617 into a ME ≤40 nm including its evaluation for improved cellular toxicity and in vivo biodistribution. The [68 Ga]Ga-PSMA-617-ME was tested in vitro for its cytotoxicity to HEK293 and PC3 cells. [68 Ga]Ga-PSMA-617-ME was administered intravenously in BALB/c mice followed by microPET/computed tomography (CT) imaging and ex vivo biodistribution determination. [68 Ga]Ga-PSMA-617-ME indicated negligible cellular toxicity at different concentrations. A statistically higher tolerance towards the [68 Ga]Ga-PSMA-617-ME occurred at 0.125 mg/mL by HEK293 cells compared with PC3 cells. The biodistribution in wild-type BALB/C mice showed the highest amounts of radioactivity (%ID/g) presented in the kidneys (31%) followed by the small intestine (10%) and stomach (9%); the lowest uptake was seen in the brain (0.5%). The incorporation of [68 Ga]Ga-PSMA-617 into ME was successfully demonstrated and resulted in a stable nontoxic formulation as evaluated by in vitro and in vivo means.

[Acute lethal effect of the commercial formulation of the insecticides Imidacloprid, Spinosad y Thiocyclam hidrogenoxalate in Bombus atratus (Hymenoptera: Apidae) workers]. / Efecto letal agudo de los insecticidas en formualción commercial Imidacloprid, Spinosad y Thiocyclam hidrogenoxalato en obreras de Bombus atratus (Hymenoptera: Apidae).

The effect of insecticides on bees has gained great attention, however, there are few studies that explore this issue on Neotropical bees. Bombus atratus is a neotropical species broadly distributed in Colombia and is considered an important pollinator of both Andean ecosystems and agroecosystems. However, as for many wild bees species, the effect of insecticides on B. atratus is unknow. In this study we determined the acute median lethal dose (LD50) of commercial formulations of insecticides Imidacloprid, Spinosad and Thiocyclam hydrogen oxalate, widely used in Colombia to control several pests of important crops. The LD50 was carried out by oral and contact routes, following and modifying the EPPO and OECD guidelines to perform LD50 on A. mellifera. We evaluated five doses for each route and insecticide, in a total of 25 medium-size workers for each dose by duplicate. Mortality was registered at 24, 48 and 72 hours after the experiment; and data were analyzed with the Probit regression model. For Imidacloprid, contacts and oral LD50 were 0.048 µg/bee and 0.010 µg/bee, respectively. For Thiocyclam hydrogen oxalate, topical and oral LD50 were 0.244 µg/bee and 0.056 µg/bee, respectively. For Spinosad, the oral LD50 corresponded to 0.28 µg/bee; it was not possible to establish the LD50 for the contact route. The Hazard Quotient (HQ) and Index of Relative Toxicity indicated that all three active ingredients are highly toxic. We discussed the risk of the insecticides use on B. atratus, considering their chemical nature.

Metal based imaging probes of DO3A-Act-Met for LAT1 mediated methionine specific tumors: synthesis and preclinical evaluation.

PURPOSE: Tumor cells are known to have an elevated requirement for methionine due to increased protein synthesis and trans-methylation reactions. A methionine based macrocyclic tumor imaging system, DO3A-Act-Met, has been designed to provide a novel platform for tumor imaging via modalities, PET/MRI using metal ions, (68)Ga and (157)Gd. METHODS: Synthesis of DO3A-Act-Met was confirmed through NMR and mass spectrometric techniques. Cytotoxicity of complexes was evaluated using MTT assay whereas receptor binding and trans-stimulation studies were performed on EAT and U-87 MG cell lines. Tumor targeting was assessed through imaging and biodistribution experiments on U-87 MG xenograft model. RESULTS: DO3A-Act-Met was synthesized and radiolabeled with (68)Ga in high radiochemical purity (85-92%). The receptor binding assay on EAT cells predicted high binding affinity with Kd of 0.78 nM. Efflux of (35)S-L-methionine trans-stimulated by extracellular DO3A-Act-Met on U-87MG cells suggested an L-system transport. MR studies revealed a longitudinal relaxivity of 4.35 mM(-1) s(-1) for Gd-DO3A-Act-Met and a 25% signal enhancement at tumor site. The biodistribution studies in U-87MG xenografts validated tumor specificity. CONCLUSION: DO3A-Act-Met, a methionine conjugated probe is a promising agent for targeted molecular imaging, exhibiting high specificity towards tumor owing to its essential role in proliferation of cancer cells mediated through LAT1.

Structure-Activity Relationship of Antischistosomal Ozonide Carboxylic Acids.

Semisynthetic artemisinins and other bioactive peroxides are best known for their powerful antimalarial activities, and they also show substantial activity against schistosomes-another hemoglobin-degrading pathogen. Building on this discovery, we now describe the initial structure-activity relationship (SAR) of antischistosomal ozonide carboxylic acids OZ418 (2) and OZ165 (3). Irrespective of lipophilicity, these ozonide weak acids have relatively low aqueous solubilities and high protein binding values. Ozonides with para-substituted carboxymethoxy and N-benzylglycine substituents had high antischistosomal efficacies. It was possible to increase solubility, decrease protein binding, and maintain the high antischistosomal activity in mice infected with juvenile and adult Schistosoma mansoni by incorporating a weak base functional group in these compounds. In some cases, adding polar functional groups and heteroatoms to the spiroadamantane substructure increased the solubility and metabolic stability, but in all cases decreased the antischistosomal activity.

Nonenolides and cytochalasins with phytotoxic activity against Cirsium arvense and Sonchus arvensis: a structure-activity relationships study.

A structure-activity relationships study was conducted assaying 15 natural analogues and derivatives belonging to two groups of organic compounds, nonenolides and cytochalasins, for their toxicity against the composite perennial weeds Cirsium arvense and Sonchus arvensis occurring through the temperate region of world. The toxic nonenolides (stagonolide, putaminoxin, pinolidoxin) and cytochalasins (deoxaphomin, cytochalasins A, B, F, T, Z2 and Z3) were isolated from phytopathogenic Stagonospora, Phoma and Ascochyta spp. The pinolidoxin (7,8-O,O'-diacetyl- and 7,8-O,O'-isopropylidene-pinolidoxin) and cytochalasins B (21,22-dihydro-, 7-O-acetyl- and 7,20-O,O'-diacetyl-cytochalasin B) derivatives were obtained by chemical modifications of the corresponding toxins. Among the 15 compounds tested, stagonolide and deoxaphomin proved to be the most phytotoxic to C. arvense and S. arvensis leaves, respectively. The tested phytotoxic nonenolides were stronger inhibitors of photosynthesis in C. arvense leaves than cytochalasines A and B. Stagonolide had less effect on membrane permeability in C. arvense leaves than cytochalasin B. Significant changes of light absorption by C. arvense leaves in visible and infrared spectra were caused by stagonolide. The functional groups and the conformational freedom of the ring, appear to be important structural features for the nonenolides toxicity, whereas and the presence of the hydroxy group at C-7, the functional group at C-20 and the conformational freedom of the macrocyclic ring are important for the cytochalasins toxicity.

Constraining the Teratogenicity of Pesticide Pollution by a Synthetic Nanoreceptor.

The teratogenicity of the pesticide nereistoxin (NTX) and its derivative thiocyclam (THI) towards aquatic life was dramatically constrained by a synthetic nanoreceptor, cucurbit[7]uril, through selective encapsulation of the pesticides (KCB[7]-NTX of 3.24(±0.31)×106 m-1 and KCB[7]-THI of 7.46(±0.10)×105 m-1 ), as evidenced by the rate of hatchability, morphology development, and tyrosinase activity of zebrafish larvae incubated with the pesticides (3-300 µm) in the absence and in the presence of 300 µm cucurbit[7]uril, demonstrating the significant potential of the nanoreceptor in managing ecological pollution of these pesticides.

Explosives: fate, dynamics, and ecological impact in terrestrial and marine environments.

An explosive or energetic compound is a chemical material that, under the influence of thermal or chemical shock, decomposes rapidly with the evolution of large amounts of heat and gas. Numerous compounds and compositions may be classified as energetic compounds; however, secondary explosives, such as TNT, RDX, and HMX pose the largest potential concern to the environment because they are produced and used in defense in the greatest quantities. The environmental fate and potential hazard of energetic compounds in the environment is affected by a number of physical, chemical, and biological processes. Energetic compounds may undergo transformation through biotic or abiotic degradation. Numerous organisms have been isolated with the ability to degrade/transform energetic compounds as a sole carbon source, sole nitrogen source, or through cometabolic processes under aerobic or anaerobic conditions. Abiotic processes that lead to the transformation of energetic compounds include photolysis, hydrolysis, and reduction. The products of these reactions may be further transformed by microorganisms or may bind to soil/sediment surfaces through covalent binding or polymerization and oligomerization reactions. Although considerable research has been performed on the fate and dynamics of energetic compounds in the environment, data are still gathering on the impact of TNT, RDX, and HMX on ecological receptors. There is an urgent need to address this issue and to direct future research on expanding our knowledge on the ecological impact of energetic transformation products. In addition, it is important that energetic research considers the concept of bioavailability, including factors influencing soil/sediment aging, desorption of energetic compounds from varying soil and sediment types, methods for modeling/predicting energetic bioavailability, development of biomarkers of energetic exposure or effect, and the impact of bioavailability on ecological risk assessment.

Effects of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) exposure on reproduction and hatchling development in Northern bobwhite quail.

Adult Northern bobwhite quail (Colinus virginianus) were exposed via food to octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), an energetic compound found in soils at military training installations. Depuration of HMX into eggs was examined in an initial study, and effects on egg production, hatching, growth, development, and survival of chicks were examined in a follow-up study. HMX was readily and rapidly transferred from female quail into eggs. Marked weight loss was observed in quail exposed to 125 and 250 mg/kg HMX in food, likely due to reductions in food intake rather than a toxic mechanism. In the second study, significant alterations in body mass occurred among quail at concentrations >52.5 +/- 9.3 mg/kg but not at 12.3 +/- 1.1 mg/kg in food. Treatment-related reductions in food consumption and decreases in egg laying rates were observed. No HMX-related effects were found in chick growth or survival. Quail inhabiting HMX-contaminated sites could possibly be exposed to HMX and therefore deposition of HMX into eggs is also possible. However, results of these studies further suggest that the potential for reproductive toxicity of HMX to birds is low.

Food avoidance behavior to dietary octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) exposure in the northern bobwhite (Colinusvirginianus).

High-melting explosive (HMX; octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) is a widely utilized explosive component of munitions used by the military. Consequently, production and use through testing and training at military installations has resulted in deposition of HMX in soil. Since these areas are often used by birds, the oral toxicity of HMX exposure to northern bobwhite (Colinus virginianus) was evaluated. Attempts to determine the acute lethal dose were unsuccessful. Initially, 8 birds (1 male/1 female per dose group) were orally dosed at levels ranging from 125 to 2125 mg HMX/kg body weight. A single death at the midrange resulted in subsequent trials of oral doses up to 10,760 mg/kg body weight. Only a single death occurred at 7173 mg/kg. A subsequent 28-d feeding study was then conducted to evaluate the potential for toxicity resulting from repetitive oral exposures. Northern bobwhite were exposed to concentrations of HMX in feed of either 10000, 1000, 100, or 0 mg/kg. These exposures resulted in a clear concentration-related reduction in feed consumption and body mass. Reductions in egg production in females were correlated with changes in body mass and feed consumption. Other physiological indicators were consistent with a considerable reduction in feed intake. These results suggest that HMX concentration is responsible for intense feed aversion behavior and thus not likely a factor that would appreciably contribute to risk for wild birds at military ranges.

Survival and reproduction of enchytraeid worms, Oligochaeta, in different soil types amended with energetic cyclic nitramines.

Hexanitrohexaazaisowurtzitane (CL-20), a new polycyclic polynitramine, has the same functional nitramine groups (N-NO2) as the widely used energetic chemicals hexahydro-1,3,5-trinitro-1,3,5-triazacyclohexane (royal demolition explosive [RDX]) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (high-melting explosive [HMX]). Potential impacts of CL-20 as an emerging contaminant must be assessed before its use. The effects of CL-20, RDX, or HMX on adult survival and juvenile production by potworms Enchytraeus albidus and Enchytraeus crypticus were studied in three soil types, including Sassafras sandy loam (1.2% organic matter [OM], 11% clay, pH 5.5), an agricultural soil (42% OM, 1% clay, pH 8.2), and a composite agricultural-forest soil (23% OM, 2% clay, pH 7.9) by using ISO method 16387 (International Standard Organization, Geneva, Switzerland). Results showed that CL-20 was toxic to E. crypticus with median lethal concentration values for adult survival ranging from 0.1 to 0.7 mg/kg dry mass (DM) when using the three tested soils. In addition, CL-20 adversely affected juvenile production by both species in all soils tested, with median effective concentration (EC50) values ranging from 0.08 to 0.62 mg/kg DM. Enchytraeus crypticus and E. albidus were similarly sensitive to CL-20 exposure in the composite agricultural-forest soil, which supported reproduction by both species and enabled comparisons. Correlation analysis showed weak or no relationship overall among the soil properties and reproduction toxicity endpoints. Neither RDX nor HMX affected (p > 0.05) adult survival of either species below 658 and 918 mg/kg DM, respectively, indicating that CL-20 is more toxic to enchytraeids than RDX or HMX. Examination of data shows that CL-20 should be considered as a potential reproductive toxicant to soil invertebrates, and that safeguards should be considered to minimize the potential for release of CL-20 into the environment.

Activity of selected neonicotinoids and dicrotophos on nontarget arthropods in cotton: implications in insect management.

Certain neonicotinoids are used in cotton, Gossypium hirsutum (L.), to control various piercing-sucking pests. We conducted field studies using three neonicotinoids (acetamiprid, thiamethoxam, and imidacloprid) and an organophosphate (dicrotophos) to assess the activity of these insecticides against nontarget arthropods, particularly predators, and to determine the potential economic consequences of such activity. Mortality among populations of the big-eyed bug, Geocoris punctipes (Say), and the red imported fire ant, Solenopsis invicta Buren, was highest after thiamethoxam and dicrotophos treatments. Numbers of arachnids were consistently lower after dicrotophos treatments, whereas none of the neonicotinoids caused appreciable mortality. Total predators in pooled data from five separate studies revealed that numbers, compared with untreated plots, were reduced by -75% in dicrotophos, 55-60% in thiamethoxam, and only 30% in both acetamiprid and imidacloprid plots. Acetamiprid and thiamethoxam exhibited significant mortality against field-deposited eggs of bollworm, Helicoverpa zea (Boddie). Both thiamethoxam and dicrotophos plots exhibited bollworm numbers that were approximately three times higher than treatment thresholds (three per 100 plants), whereas numbers in untreated plots were below threshold levels. In one study on Bt cotton, a significant negative correlation was observed between numbers of predators and bollworm larvae. Results demonstrated that neonicotinoids differ in activity against predaceous arthropods and bollworm eggs and that high predator mortality can result in resurgence of bollworm larvae and additional insecticide costs.

Cytotoxic and genotoxic effects of energetic compounds on bacterial and mammalian cells in vitro.

The mutagenicity and toxicity of energetic compounds such as 2,4, 6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), hexahydro-1,3, 5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3, 5,7-tetrazocine (HMX), and of amino/nitro derivatives of toluene were investigated in vitro. Mutagenicity was evaluated with the Salmonella fluctuation test (FT) and the V79 Chinese hamster lung cell mutagenicity assay. Cytotoxicity was evaluated using V79 and TK6 human lymphoblastic cells. For the TK6 and V79 assays, TNB and 2, 4,6-triaminotoluene were more toxic than TNT, whereas RDX and HMX were without effect at their maximal aqueous solubility limits. The primary TNT metabolites (2-amino-4,6-dinitrotoluene, 4-amino-2, 6-dinitrotoluene, 2,4-diamino-6-nitrotoluene and 2, 6-diamino-4-nitrotoluene) were generally less cytotoxic than the parent compound. The FT results indicated that TNB, TNT and all the tested primary TNT metabolites were mutagenic. Except for the cases of 4-amino-2,6-dinitrotoluene and 2,4-diamino-6-nitrotoluene in the TA98 strain, addition of rat liver S9 resulted in either no effect, or decreased activity. None of the tested compounds were mutagenic for the V79 mammalian cells with or without S9 metabolic activation. Thus, the FT assay was more sensitive to the genotoxic effects of energetic compounds than was the V79 test, suggesting that the FT might be a better screening tool for the presence of these explosives. The lack of mutagenicity of pure substances for V79 cells under the conditions used in this study does not preclude that genotoxicity could actually exist in other mammalian cells. In view of earlier reports and this study, mutagenicity testing of environmental samples should be considered as part of the hazard assessment of sites contaminated by TNT and related products.

Chronic toxicity of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in soil determined using the earthworm (Eisenia andrei) reproduction test.

The sublethal and chronic effects of the environmental contaminant and explosive octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in artificial soil were assessed using the earthworm (Eisenia andrei). Based on various reproduction parameters (total and hatched number of cocoons, number of juveniles and their biomass), fecundity was reduced at the different concentrations of HMX tested (from 280.0 +/- 12.3 to 2502.9 +/- 230.0 mg kg-1 dry soil) in spiked artificial soil (LOEC: 280.0 +/- 12.3 mg kg-1 dry soil). The growth of adult E. andrei was also reduced at the different concentrations tested, though no mortality occurred, even at the highest tested concentrations. The number of juveniles produced was correlated with the number of total and hatched cocoons, and the biomass of juveniles was correlated with the number of cocoons. Pooled results of these and earlier studies on explosives (TNT, RDX) using the E. andrei reproduction test confirm that effects of HMX on cocoon production are indicative of some reproductive consequences (number of juvenile and their biomass), whereas adult growth, in general, does not correlate strongly with change in reproduction capacity.

Development of QSARs to investigate the bacterial toxicity and biotransformation potential of aromatic heterocylic compounds.

A series of aromatic heterocyclic and hydrocarbon compounds were tested for toxicity and biotransformation potential against two contrasting lux-marked whole-cell microbial biosensors. Toxicity was determined by inhibition of light output of a Pseudomonas fluorescens construct that expresses lux constitutively. Biotransformation was tested by increase in light output of P. fluorescens HK44 (pUTK21), which expresses lux when in the presence of a metabolic intermediate (salicylate). The data were then modelled against physical/chemical properties of the compounds tested to see if quantitative structure-activity relationships (QSARs) could be derived. Toxicity was found to be accurately predicted by log Kow (R2 = 0.95, Q2 = 0.88), with the basic (pyridine-ring containing) heterocycles modelled separately. The biotransformation data were best modelled using lowest unoccupied molecular orbital (LUMO) energies (R2 = 0.90, Q2 = 0.87).

Toxicity of sediment-associated nitroaromatic and cyclonitramine compounds to benthic invertebrates.

The toxicity of nitroaromatic (2,4-diaminonitrotoluene [2,4-DANT] and 1,3,5-trinitrobenzene [TNB]) and 14C-labeled cyclonitramine compounds (hexahydro-1,3,5-trinitro-1,3,5-triazine [RDX] and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine [HMX]) to the marine polychaete Neanthes arenaceodentata and the estuarine amphipod Leptocheirus plumulosus following 10- or 28-d exposures to spiked sediments was investigated. Organismal-level effects on survival, growth, and reproduction and cellular-level effects on apoptosis (programmed cell death) were evaluated. Because cyclonitramines have low affinity for sediment, overlying water was not exchanged in the RDX and HMX exposures. Nitroaromatics sorbed strongly to sediment, resulting in near complete resistance to solvent extraction. Cyclonitramines sorbed weakly to sediment, as more 14C-activity was found in the overlying water than in the sediment at exposure termination. No significant decrease in survival or growth was observed with cyclonitramines at initial sediment concentrations as high as 1,000 microg/g. Survival was significantly affected by nitroaromatics at nominal sediment concentrations as low as 200 microg/g, with L. plumulosus being more sensitive than N. arenaceodentata. Growth was significantly decreased at sublethal concentrations of 2,4-DANT for N. arenaceodentata. Reproduction, measured only with L. plumulosus, was significantly decreased only in the highest RDX treatment and also in the lower TNB treatment. However, no decrease was observed in higher concentrations of TNB. Body burden at exposure termination was below detection limit (1 microg/kg) for all compounds. Significant inhibition of apoptosis was not accompanied by significant decreases in growth or reproduction. Because of its critical function in many biological processes. alterations in this endpoint may result in adverse effects on the organism and could be used as an early indicator of toxicity.