Toxicological Responses of Red-Backed Salamanders (<Emphasis Type="Italic">Plethodon cinereus</Emphasis>) to Soil Exposures of Copper

Copper (Cu) has widespread military use in munitions and small arms, particularly as a protective jacket for lead projectiles. The distribution of Cu at many US military sites is substantial and sites of contamination include habitats in and around military storage facilities, manufacturing, load and packing plants, open burning/open detonation areas, and firing ranges. Some of these areas include habitat for amphibian species, which generally lack toxicity data for risk assessment purposes. In an effort to ascertain Cu concentrations in soil that are toxic to terrestrial amphibians, 100 red-backed salamanders (Plethodon cinereus) were randomly sorted by weight, assigned to either a control soil or one of four treatments amended with copper acetate in soil, and exposed for 28 days. Analytical mean soil concentrations were 18, 283, 803, 1333, and 2700 mg Cu/kg soil dry weight. Food consisted of uncontaminated flightless Drosophila melanogaster. Survival was reduced in salamanders exposed to 1333 and 2700 mg/kg by 55% and 100%, respectively. Mortality/morbidity occurred within the first 4 days of exposure. These data suggest that a Cu soil concentration of and exceeding 1333.3 ± 120.2 mg/kg results in reduced survival, whereas hematology analyses suggest that a concentration of and exceeding 803.3 ± 98.4 mg/kg might result in reduced total white blood cell count. No effects were observed at 283.3 ± 36.7 mg/kg.     

Toxicity of Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine (HMX) in Three Vertebrate Species

The explosive, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine or high-melting explosive (HMX), has been found in soils in areas used for testing and training by the military. Many of these areas contain habitat for valued wildlife species. In an effort to better understand the environmental consequences from exposure, a reptilian (western fence lizard [Sceloporus occidentalis]), an amphibian (red-backed salamander [Plethodon cinereus]), and a mammalian species (rabbit [Oryctolagus cuniculus]) were exposed to HMX under controlled laboratory conditions. Lizards and rabbits were exposed to HMX by way of corn oil through gavage, and salamanders were exposed to HMX in soil. Two deaths occurred from acute oral exposures to lizards to 5000 mg HMX/kg BW. Histological and gross pathologic assessment suggested gut impaction as a possible cause of death. Salamanders exposed to concentrations of HMX in soil ≤1970 mg HMX/kg soil for 10 days did not show adverse effects. Rabbits, however, showed neurologic effects manifested as hyperkinetic events with convulsions at >24 h after oral exposures. An LD₅₀ for rabbits was calculated as 93 mg/kg (95% confidence interval 76–117). A subacute 14-day testing regime found a lowest observed effect level of 10 mg/kg-d and a no observed adverse effect level of 5 mg/kg-d based on hyperkinesia and seizure incidence, although changes suggesting functional hepatic alterations were also found. These data suggest that physiologic differences between species, particularly in gastrointestinal structure and function, can affect the absorption of HMX and hence lead to marked differences in toxicity from exposure to the same compound.     

Transfer of Copper,Lead and Zinc in Soil–Grass Ecosystem in Aspect of Soils Properties,in Poland

The total metal concentrations in soil samples from polluted area (roadside soils) ranged from 13.87 to 195.76 mg/kg for Cu; 13.56–310.17 mg/kg for Pb and 18.43–894.11 mg/kg for Zn and they were, respectively about 5, 2 and 13 times above the corresponding values in soil samples from country area. The mean values of EDTA-extractable concentrations in soil samples at unpolluted sites were: 2.47 mg/kg for Cu, 6.33 mg/kg for Pb and 4.94 mg/kg for Zn. The highest concentrations of Cu, Pb and Zn in grass were measured in soils from polluted area. Higher values of proportions of EDTA-extractable metals (24% for Cu, 40% for Pb and 38% for Zn) indicate that anthropogenic metals were more mobile and bioavailable than the same metals in soils from unpolluted area (20, 16 and 20% for Cu, Pb and Zn, respectively). The availability of Cu, Pb and Zn are affected by soil properties such as pH, organic matter content and cation exchange capacity. Correlation between the EDTA-extractable forms concentrations of metals and the total concentration in the various soils was observed. The coefficients of determination (R²) varied between 0.809 for Cu; 0,709 for Pb and 0.930 for Zn in polluted soils and they are higher than corresponding values in unpolluted soils.     

Toxicological responses of red-backed salamanders (Plethodon cinereus) to subchronic soil exposures of 2,4,6-trinitrotoluene

Since World War I, trinitrotoluene (TNT) has been the most commonly used explosive. Environmental contamination associated with synthesis, manufacture of weapons, and use during training exercises has been extensive, with soil concentrations reaching 145,000 mg/kg. Some of these areas include habitats for amphibian species. Earlier studies have shown that salamanders dermally absorb TNT from soil. To ascertain what soil concentrations of TNT are toxic to amphibians, red-backed salamanders (Plethodon cinereus) were exposed to one of five concentrations of TNT in soil for 28 d and evaluated for indicators of toxicity. A total of 100 salamanders were randomly sorted by weight and assigned to target TNT concentrations in soil of either 3,000, 1,500, 750, 325, or 0 mg/kg dry weight. Food consisted of uncontaminated flightless Drosophila melanogaster. Survival was reduced in salamanders exposed to 1,500 and 3,000 mg/kg by 10 and 55%, respectively. Most mortality/morbidity occurred within the first week of exposure. Salamanders had a reduction in hemoglobin at 750 mg/kg or greater and a reduction in red blood cell concentration at 1,500 mg/kg or greater. Food consumption was affected in salamanders at 750 mg/kg or greater; a reduction in body mass and liver glycogen content also occurred at and above this concentration. Splenic congestion also was observed in salamanders from these groups. These data suggest that soil TNT concentrations of 373 +/- 41.0 mg/kg or greater result in reduced body mass, reduced feed intake, and hematological effects.     

Effect of soil properties on lead bioavailability and toxicity to earthworms

Soil properties are important factors modifying metal bioavailability to ecological receptors. Twenty-one soils with a wide range of soil properties (USA; http://soils.usda.gov/technical/classification/taxonomy/) were amended with a single concentration of Pb (2,000 mg/kg) to determine the effects of soil properties on Pb bioavailability and toxicity to earthworms. Earthworm mortality ranged from 0 to 100% acute mortality following exposure to the same total concentration of Pb (2,000 mg/kg) in amended field soils. Internal Pb concentrations in earthworms ranged from 28.7 to 782 mg/kg, with a mean of 271 mg/kg. Path analysis was used to partition correlations in an attempt to discern the relative contribution of each soil property. Results of path analysis indicated that pH was the most important soil property affecting earthworm mortality (p < 0.01) and internal Pb (p < 0.05). Soil pH was related inversely to mortality and internal Pb, soil solution Pb, and Pb bioavailability. The most important soil property modifying reproduction was amorphous iron and aluminum oxides (FEAL). Because FEAL is rich in pH-dependent cation-exchange sites, several soil properties, including pH, FEAL, and cation-exchange capacity, have a causal effect on Pb adsorption and soluble Pb. Path analysis is useful for assessing contaminated soils with a wide range of soil properties and can assist in ecological risk assessment and remediation decisions for contaminated sites. Soil properties are important factors modifying metal bioavailability and toxicity and should be considered during the ecological risk assessment of metals in contaminated soils.     

Subchronic Lead Feeding Study in Male Rats

This study was done to establish baseline information on the bioavailability of low levels of different species of lead by oral feeding in young rats and to compare this with lead-contaminated soils of similar dosage. These results can be used to help establish low-level risk assessments for lead exposure in children. Lead acetate was used in this study as a point of reference because it was considered to be 100% bioavailable. The required amounts of either lead acetate or lead nitrate were added to the control soil of 135 mg/kg lead to match the targeted test soil lead concentrations of 375, 750, 1500, and 3000 mg/kg lead. This lead-contaminated soil was mixed 5% (soil/diet) by weight with a semipurified lab chow diet, which resulted in final dietary lead concentrations of 6.75, 18.75, 37.5, 75, and 150 μg Pb/g diet. Results from this study indicated that (1) the dietary lead concentrations used did not result in any overt signs of lead toxicity (i.e., no significant effect on body weight gain, food consumption, or fecal output), (2) there were significant dose-dependent increases in fecal lead concentration and total fecal lead output, although there were no significant differences among study groups, (3) there was a time-dependent decrease in net whole-body lead uptake from a total group average of 65% at week 1 down to ∼40% by week 5, and (4) there were no significant differences in terminal blood lead levels among study groups. Results from this study demonstrated a significant dose-dependent increase in tissue lead concentrations (μg Pb per g tissue weight) for bone, kidney, and liver for all study groups. There were no significant differences between the lead acetate and the test soil study groups at any lead dosages; however, there was a significantly increased lead incorporation into the bones from the lead nitrate study group. In summary, these results demonstrate that rats metabolize and handle lead of relatively small particle size from different soils and from different sources in a similar manner, although the use of lead acetate as the standard for 100% bioavailability might need to be reevaluated. James B. Heneghan—Retired.     

Effect of Bauxite Mineralized Soil on Residual Metal Levels in Some Post Harvest Food Crops in Jamaica

The concentrations of nine residual metals in some Jamaican foods were determined using inductively coupled plasma mass spectrometry technique. Cadmium concentration was highest in yellow yam (0.21 mg/kg). Sweet potato had the highest concentrations of lead (0.31 mg/kg), arsenic (0.70 mg/kg) and mercury (0.35 mg/kg). Samples from Grove Place exceeded the regulatory limits of 0.1 mg/kg for cadmium, lead and arsenic and 0.05 mg/kg for mercury. Significant correlations were found between soil and agricultural produce concentrations for cadmium and lead (r² ≥ 0.5). These results suggest that the elements were available in soluble forms in the soil for absorption by food crops.     

Trace Metal Content in Mussels, Perna viridis L., Obtained from Selected Seafood Markets in a Metropolitan City

Mussels, Perna viridis L., obtained from three selected seafood markets in Metro Manila, were tested for metal content including cadmium, copper, lead, and zinc through atomic absorption spectrophotometry. Water samples from Bacoor Bay, Cavite, which supplies mussels to the market, were likewise subjected to similar metal analyses. Of the metals analyzed in the soft tissues of mussels, only copper and lead with highest obtained values of 10.4 mg/kg and 2.3 mg/kg, respectively exceeded the PEMSEA guideline for safe human consumption. Water samples collected from the harvest sites in Bacoor Bay showed high concentrations of cadmium (0.023 mg/L) and lead (0.25 mg/L) that exceeded the standards of DENR, ASEAN, and US EPA. Zinc, though detected in relatively high concentrations in both water (0.03 mg/L) and soft tissues (12.16–14.43 mg/kg) of mussels remained below the criteria set by the above-mentioned agencies. Overall, the present study indicates that mussels being sold in selected Metro Manila seafood markets were contaminated with metals, notably Cu and Pb, at concentrations that are unsafe for human consumption and thus, represents a health risk.     

Solid-Phase Control on Lead Bioaccessibility in Smelter-Impacted Soils

The goal of this work was to identify the solid-phase control on lead (Pb) bioaccessibility in soils impacted by smelter activities in the city of San Luis Potosi, in north-central Mexico. Total Pb concentrations in 30 ha of soil terrain from a residential area adjacent to the smelter showed levels above the 400-mg/kg intervention guideline dictated by Mexican Environmental regulations. These concentrations, although raising human health and environmental concerns, showed low water-soluble lead (<0.1 mg/L) and relatively low lead bioaccessibility (2.4–20.5%). X-ray diffraction and electron microscopy techniques showed, in addition to common Pb phases reported in similar contaminated environments [galena (PbS) and anglesite (PbSO₄)], the presence of a solid lead arsenate phase. The Pb solubility measured in soils agrees very well with the low solubility reported for the Pb minerals identified and explains the relatively low Pb bioaccessibility values measured, presumably from their low dissolution during passage through the gastrointestinal tract. The results reported are highly relevant for smelter-originated environmental contamination scenarios in general.     

Lead and Cadmium Accumulation in Medicinal Plants Collected from Environmentally Different Sites

Though use of herbal medicine is increasing dramatically worldwide, environmental pollution especially with heavy metals poses serious problem on quality of medicinal plants and their products. In Ethiopia, where more than 85% of the population relies on traditional medicine, data on heavy metals level of plants is unavailable. The purpose of this study was to assess Pb and Cd in plants grown in different parts of Ethiopia. Out of 26 samples analyzed, four for lead (15.4%; 11.56 ± 1.07 to 98.19 ± 1.05 mg/kg) and seventeen for cadmium (65.4%; 0.38 to 1.83 ± 0.06 mg/kg) were found to contain concentrations above WHO limits (10 mg/kg and 0.3 mg/kg respectively).     

Seasonal Variations in the Concentrations of Metals in Crassostrea corteziensis from Sonora, México

This study examines seasonal variations in the concentrations of Cd, Cu, Pb, and Hg in experimentally cultured Crassostrea corteziensis, an oyster species known to have high resistance to physical and chemical stressors. The highest levels of Cd (4.92 mg/kg), Cu (3.45 mg/kg), and Pb (0.67 mg/kg) were detected in oyster samples collected during the summer, while Hg concentrations were similar (0.03 to 0.04 mg/kg) throughout all seasons. Results indicate that except for Cd, Crassostrea corteziensis accumulates metals to levels below those recommended by the US. FDA and the Mexican government. For Cd, its concentration correlates more strongly with the temperature of the oyster’s environment rather than to the oyster growth cycle.     

Tungsten effects on survival, growth, and reproduction in the earthworm, Eisenia fetida

To provide basic toxicity data for formulating risk characterization benchmarks, the effects of tungsten on survival, growth, and reproduction were investigated in the earthworm Eisenia fetida. Parallel studies with lead as a reference toxicant also were conducted. Although sodium tungstate (Na2WO4) was less acutely toxic than lead nitrate (Pb(NO3)2) in 14-d spiked field soil acute toxicity assays (lethal concentrations for 50% of organisms: W, 6,250 mg/kg; Pb, 2,490 mg/kg), tungstate completely inhibited reproduction in 28- and 56-d assays at all tested tungsten concentrations (> or = 704 mg/kg). By comparison, cocoon production was not significantly reduced for lead concentrations until concentrations reached 766 mg/kg, and cocoon production was still observed at the highest concentration tested (1,650 mg/kg). These data indicate that tungsten is a reproductive toxicant for earthworms and that, by comparison, its sublethal toxicity is greater than that of lead. Toxicity data for other soil invertebrate species are required to fully establish benchmark levels/ecological soil screening levels for tungsten.     

Mercury Contamination in Idaho Bald Eagles, <Emphasis Type="Italic">Haliaeetus leucocephalus</Emphasis>

Because mercury contamination is potentially threatening to bald eagle (Haliaeetus leucocephalus) populations, we collected molted feathers at nests to determine the level of contamination in bald eagles in the state of Idaho, USA. Eagle feathers contained measurable amounts of cadmium (Cd), chromium (Cr), selenium (Se), lead (Pb), as well as mercury (Hg). Cadmium, Cr, Se, and Pb levels averaged 0.17, 4.68, 2.02, and 1.29 mg/kg dry weight, respectively, and were at or below concentrations indicated as causing reproductive failure in bald eagles. Mercury contamination was found to be the highest averaging 18.74 mg/kg dry weight. Although a concentration of only 7.5 mg/kg dry weight Hg in bird feathers can cause reduced productivity and even sterility, all of the eagles we sampled bred successfully and the population of bald eagles continues to grow annually throughout the state.     

Total and Methyl Mercury Contents and Distribution Characteristics in Cicada, Cryptotympana atrata (Fabricius)

Total and methyl mercury concentrations of cicada bodies, wings, and exuviae were investigated to study the mercury distribution characteristics. Results indicated that total and methyl mercury concentrations of cicada bodies were 2.64 mg/kg and 123.93 ng/g on average, respectively. In cicada tissues, total mercury concentrations were found to increase in the order of exuviae (0.50 mg/kg on average) < wings (0.98 mg/kg on average) < cicada bodies (2.64 mg/kg on average) and methyl mercury concentrations of cicada bodies were 123.93 ng/g on average and were the highest. Methyl mercury concentrations accounted for about 4.69% of total mercury in cicada bodies and most mercury was in inorganic forms in cicada. Sex differences of total mercury concentrations were significantly great (F = 8.433, p < 0.01) and total mercury concentrations of the males, which were 3.38 mg/kg on average, were much higher. Correlation analysis showed that neither total nor methyl mercury concentrations of cicada bodies was significantly related to the corresponding contents of soil (r = 0.0598, p > 0.05).     

Heavy Metals in the Farming Environment and in some Selected Aquaculture Species in the Van Phong Bay and Nha Trang Bay of the Khanh Hoa Province in Vietnam

Aquaculture is currently one of the most rapidly growing production sectors in Vietnam. This publication describes the concentrations of heavy metals in the farming environment and some aquaculture species in the Khanh Hoa Province in Vietnam. The concentration of total As in the sediments ranged from 0.07 to 0.64 mg/kg, whereas the concentration of Hg varied from <0.0005 to 0.56 mg/kg. The corresponding concentration span for Cd and Pb, were 0.001–0.069 and 0.016–0.078 mg/kg, respectively. The concentrations of As in the aquaculture organisms spanned from 0.14 to 1.03 mg/kg. For Hg the concentrations varied from 0.1 to 0.45 mg/kg, for Cd from 0.02 to 0.10 mg/kg and for Pb from 0.07 to 0.37 mg/kg.     

Toxic Exposure of Songbirds to Lead in the Southeast Missouri Lead Mining District

Mining and smelting in the Southeast Missouri Lead Mining District has caused widespread contamination of soils with lead (Pb) and other metals. Soils from three study sites sampled in the district contained from approximately 1,000–3,200 mg Pb/kg. Analyses of earthworms [33–4,600 mg Pb/kg dry weight (dw)] collected in the district showed likely high Pb exposure of songbirds preying on soil organisms. Mean tissue Pb concentrations in songbirds collected from the contaminated sites were greater (p < 0.05) than those in songbirds from reference sites by factors of 8 in blood, 13 in liver, and 23 in kidney. Ranges of Pb concentrations in livers (mg Pb/kg dw) were as follows: northern cardinal (Cardinalis cardinalis) = 0.11–3.0 (reference) and 1.3–30 (contaminated) and American robin (Turdus migratorius) = 0.43–8.5 (reference) and 7.6–72 (contaminated). Of 34 adult and juvenile songbirds collected from contaminated sites, 11 (32 %) had hepatic Pb concentrations that were consistent with adverse physiological effects, 3 (9 %) with systemic toxic effects, and 4 (12 %) with life-threatening toxic effects. Acid-fast renal intranuclear inclusion bodies, which are indicative of Pb poisoning, were detected in kidneys of two robins that had the greatest renal Pb concentrations (952 and 1,030 mg/kg dw). Mean activity of the enzyme delta-aminolevulinic acid dehydratase (ALAD) in red blood cells, a well-established bioindicator of Pb poisoning in birds, was decreased by 58–82 % in songbirds from the mining sites. We conclude that habitats within the mining district with soil Pb concentrations of ≥1,000 mg Pb/kg are contaminated to the extent that they are exposing ground-feeding songbirds to toxic concentrations of Pb.     

Animal Health Problems Attributed to Environmental Contamination in Lake Nakuru National Park,Kenya: A Case Study on Heavy Metal Poisoning in the Waterbuck <Emphasis Type="Italic">Kobus ellipsiprymnus defassa</Emphasis> (Ruppel 1835)

A study was conducted in which samples of soil, forage, as well as serum, bone, kidney, and liver of waterbuck were collected from Lake Nakuru National Park. The objective was to determine the ecosystem health status in order to establish the causes of animal health problems previously recorded in some sections of the Park. Trace element analysis in serum indicated occurrence of copper (Cu) deficiency in the north and eastern sections of the Park where mean values were marginal (range: 0.36–0.81, mean: 0.62 mg/l) compared to concentrations recorded in the western part of the Park (range: 0.69–1.48, mean: 1.22 mg/l). Bone analysis on dry matter basis (DM) indicated higher (p < 0.01) levels of cadmium (Cd, 0.437 mg/kg), fluoride (F, 3178 mg/kg), and lead (Pb, 20.62 mg/kg) in animals from the east compared to those from the west (0.002, 1492, 4.87 mg/kg, respectively), suggesting heavy exposure. In addition, samples from the east had much lower than normal calcium (Ca)-to-phosphorus (P) ratios (mean: 1.9:1) compared to those recorded in the west (2.2:1), suggesting poor bone mineralization. There was a higher concentration of Cd in the kidney (16.24 mg/kg, p < 0.05) and Pb in the liver (58.3 mg/kg, p < 0.01) in animals from the east compared to those in the west (12.92 and 36.2 mg/kg, respectively), but the converse was true of Cu. The liver Cu status was better in animals from the west with, concentrations (mean: 21.7 mg/kg) being about twice those recorded in the east (11.9 mg/kg DM). Forage analysis revealed prospects of Ca, P, and Cu deficiencies in the entire Park. However, in the northeastern section of the Park (measuring 50 ha) where waterbuck residence times are high, forage concentrations of Cd (0.31 mg/kg DM), molybdenum (Mo, 7.20 mg/kg DM), Pb (2.88 mg/kg DM), and zinc (Zn, 126 mg/kg DM) were an order of magnitude greater (p < 0.01) than the levels recorded in the rest of the Park (ranges: 0.133–0.165, 3.69–5.61, 0.485–0.621, 11.6–17.4 mg/kg DM, respectively). These disparities were attributed to a higher soil concentration of Cd (2.77 mg/kg DM), Pb (85.1 mg/k DM) and Zn (1414 mg/kg DM) in this section compared to the rest of the Park (ranges: 0.10–0.15, 5.02–6.26, 1.49–5.44 mg/kg DM, respectively), and strongly suggest heavy metal contamination as the source of animal health problems in the Park.     

Accumulation of Some Heavy Metals Seasonally in Hysterotylacium aduncum (Nematoda) and Its Host Red Sea Bream,Pagellus erythrinus (Sparidae) from Gulf of Iskenderun (North-Eastern Mediterranean)

The Red Sea Bream’s nematode and Sparus aurata, sampled from the Iskenderun Bay, North-eastern Mediterranean in March 2008 were analysed by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) for their some heavy metal (Cd, Cr, Cu, Fe, Hg, Mn, Mg, Pb and Zn) levels. The metal concentrations of the parasites were compared to different organs (liver, muscle, swimbladder, intestine and skin) of the fish hosts. The highest Cd (0.303 mg/kgg ww) concentrations were found in the muscle, highest Cr (4.932 mg/kg ww), Hg (2.350 mg/kg ww) Pb (22.82 mg/kg ww) concentrations were found in the parasite, highest Cu (7.608 mg/kg ww) and Fe (176.7 mg/kg ww) concentrations were found in the liver, highest Mn (31.24 mg/kg ww) Zn (78.51 mg/kg ww) concentrations were found in the swimbladder for parasitized fish. The highest Cd (0.612 mg/kg ww), Cu (8.261 mg/kg ww) Fe (261.1 mg/kg ww) concentrations were found in the liver, highest Cr (6.123 mg/kg ww) and Pb (9.125 mg/kg ww) concentrations were found in the intestine, highest Hg (2.013 mg/kg ww) Zn (83.30 mg/kg ww) and Mn (41.24 mg/kg ww) concentrations were found in the swimbladder for un-parasitized fish.     

Wild Boar Tissue Levels of Cadmium, Lead and Mercury in Seven Regions of Continental Croatia

Concentrations of cadmium, mercury and lead were analysed by atomic absorption spectrometry in the kidney and muscle of free-living wild boar (n = 169) from hunting grounds in seven counties of continental Croatia. Mean levels of metals (mg/kg) in muscle and kidney of boars ranged as follows: Cd: 0.005–0.016 and 0.866–4.58, Pb: 0.033–0.15 and 0.036–0.441, Hg: 0.004–0.012 and 0.04–0.152. In all seven regions, concentrations exceeded the permitted values (muscle and kidney mg/kg: cadmium 0.05/1; lead 0.1/0.5; mercury 0.03/0.1) in 13.6% and 71.6% of samples (muscle and kidney, respectively) for cadmium; 13.6% and 8.9% for lead; 19.5% and 2.4% for mercury. There were significant differences among the regions. Vukovar-Srijem and Virovitica-Podravina Counties were highly contaminated with cadmium, Sisak-Moslavina and Virovitica-Podravina Counties with lead and Brod-Posavina County had highest mercury concentrations. These results suggest a detailed investigation of physiological and environmental factors contributing to accumulation of metals in boars.     

Toxicologic and Histopathologic Response of the Terrestrial Salamander <Emphasis Type="Italic">Plethodon cinereus</Emphasis> to Soil Exposures of 1,3,5-Trinitrohexahydro-1,3,5-Triazine

Red-backed salamanders (Plethodon cinereus) were exposed to four different concentrations of 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX) in soil under controlled laboratory conditions for 28 days. Wild-caught P. cinereus (N = 20/treatment) were exposed to target concentrations of 5,000, 1000, 100, 10, and 0 mg RDX/kg soil (dry wt) using a microcosm design. Animals were fed 5 to 10 uncontaminated mutant Drosophila flies every 3 days and monitored daily. Animals were weighed 1 day before being placed in treatment and weekly thereafter. RDX concentrations in soil were analytically determined after the compound was added and mixed at the beginning, the midpoint, and the end of exposure. RDX soil concentrations were relatively stable throughout the exposure period. Signs of overt toxicity were observed primarily in the highest exposure group. Salamanders exposed to 5,000 mg RDX/kg soil exhibited signs of neuromuscular effects (lethargy, gaping, hypersensitivity, tremors) and exhibited significant weight loss. A single moribund animal from this group lost >20% of its original body weight and was killed. Animals in this exposure group also lost weight relative to animals in other treatments. Histopathologic evaluations, including an evaluation of melanomacrophage parameters, indicated no strong treatment-related findings. This study provided information regarding the effects from subchronic dermal exposure of a terrestrial amphibian species to RDX in soil and provides a microcosm approach to the evaluation of toxicity of contaminants in soil to a terrestrial vertebrate.