Inhibitory effect of triclosan and nonylphenol on respiration rates and ammonia removal in activated sludge systems

The toxic effects of triclosan (TCS) and nonylphenol (4-n-NP) on activated sludge heterotrophic and autotrophic microorganisms were evaluated. Toxicity experiments with specific oxygen uptake rate (SOUR) and ammonia uptake rate (AUR) revealed that TCS was much more toxic to heterotrophic and autotrophic microorganisms than 4-n-NP. In experiments with heterotrophic biomass, increase of sludge age (theta(c)) from 5 to 15 days resulted in a decrease of median effective concentrations (EC(50)) of TCS from 38.2 to 9.97 mg l(-1) and in an increase of EC(50) values of 4-n-NP from 441 to 649 mg l(-1). In experiments with autotrophic biomass and sludge age of 15 days, significantly lower EC(50) values were obtained for both compounds, indicating the higher sensitivity of nitrifiers to TCS and 4-n-NP. To compare toxicity of TCS and 4-n-NP towards single species and mixed wastewater cultures, experiments were performed using marine bacterium Vibrio fischeri. EC(50) values of 0.22 and 3.51 mg l(-1) were estimated for TCS and 4-n-NP, respectively, indicating the higher sensitivity of this bioassay to toxicants. According to the levels of tested compounds commonly found in influent wastewater and the results of this study, there is a possible risk for deterioration of nitrification in activated sludge systems due to the presence of TCS.     

Assessing the Toxicity of Chemical Compounds Associated With Land-Based Marine Fish Farms: The Sea Urchin Embryo Bioassay With Paracentrotus lividus and Arbacia lixula

In aquaculture, disinfection of facilities, prevention of fish diseases, and stimulation of fish growth are priority goals and the most important sources of toxic substances to the environment, together with excretory products from fish. In the present study, embryos of two species of sea urchin (Paracentrotus lividus and Arbacia lixula) were exposed to serial dilutions of six antibiotics (amoxicillin (AMOX), ampicillin, flumequine (FLU), oxytetracycline (OTC), streptomycin (ST), and sulfadiazine [SFD]) and two disinfectants (sodium hypochlorite (NaClO) and formaldehyde [CH(2)O]). Alterations in larval development were studied, and the effective concentrations (ECs) were calculated to evaluate the toxicity of the substances. Both species showed similar sensitivities to all substances tested. Disinfectants (EC(50) = 1.78 and 1.79 mg/l for CH(2)O; EC(50) = 10.15 and 11.1 mg/l for NaClO) were found to be more toxic than antibiotics. AMOX, OTC, and ST caused <20 % of alterations, even at the highest concentrations tested. FLU was the most toxic to P. lividus (EC(50) = 31.0 mg/l) and SFD to A. lixula (EC(50) = 12.7 mg/l). The sea urchin bioassay should be considered within toxicity assessment-monitoring plans because of the sensitivity of larvae to disinfectants.     

Assessment of the toxicity of triasulfuron and its photoproducts using aquatic organisms

The toxicological effects of the sulfonylurea herbicide triasulfuron and its photoproducts were assessed on four aquatic organisms. Toxicity varied with tested organism and with triasulfuron irradiation time. Triasulfuron and its photoproducts had no significant effects on the crustacean (Cladocera) Daphnia magna (causing 50% effective concentration [EC50] [48 h] = 49 +/- 1 mg/L) and the marine bacteria Vibrio fischeri (EC50 [30 min] > 100 mg/L). In contrast, primary producers (the duckweed Lemna minor, the microalgae Pseudokirchneriella subcapitata, and Chlorella vulgaris) were very sensitive to triasulfuron (EC50s < 11 microg/L). For these organisms, triasulfuron photoproducts were less toxic than the parent compound but the residual toxicity observed still represented a potential environmental hazard.     

Acute toxicity of oxytetracycline and florfenicol to the microalgae Tetraselmis chuii and to the crustacean Artemia parthenogenetica

Aquaculture systems are a potentially significant source of antibacterial agents to the aquatic environment. The antibacterials oxytetracycline (OTC) and florfenicol (FLO) have been widely used in aquaculture. These pharmaceuticals may cause deleterious effects on wild aquatic organisms accidentally exposed to them. Therefore, the objective of this study was to evaluate the acute toxicity of OTC and FLO to the microalgae Tetraselmis chuii and to the crustacean Artemia parthenogenetica, using culture growth inhibition and death, respectively, as effect criteria. OTC and FLO were found to inhibit the growth of T. chuii cultures, with 96 h IC(50) values of 11.18 and 6.06 mg/L, respectively. OTC 24 and 48 h LC(50) values for A. parthenogenetica were 871 and 806 mg/L, respectively. FLO did not cause mortality of A. parthenogenetica. These results indicate that OTC and FLO are considerably more toxic to T. chui than to A. parthenogenetica. They also indicate that the concentrations required to induce mortality to A. parthenogenetica only in exceptional conditions will occur in the environment.     

HPLC法测定蜂王浆冻干粉中的甲砜霉素、氟甲砜霉素及代谢物氟甲砜霉素胺

目的建立高效液相色谱方法测定蜂王浆冻干粉中的甲砜霉素、氟甲砜霉素及代谢物氟甲砜霉素胺的方法。方法采用乙酸乙酯-乙腈-氨水提取蜂王浆冻干粉中残留的化合物,凝胶渗透色谱净化,荧光检测器检测。结果平均回收率84.6%～99.1%,相对标准偏差(RSD)6.02%～9.81%;甲砜霉素、氟甲砜霉素在0.20～5.0mg/L氟甲砜霉素胺在0.1～4.0mg/L范围内有良好的线性关系,甲砜霉素与氟甲砜霉素的检测限达0.025mg/kg、氟甲砜霉素胺的检测限达0.015mg/kg。结论该方法快速、灵敏、准确,适用于分析蜂王浆冻干粉中的甲砜霉素、氟甲砜霉素及代谢物氟甲砜霉素胺含量。     

Effects of hydrogen sulfide to Vibrio fischeri, Scenedesmus vacuolatus, and Daphnia magna

The effects of hydrogen sulfide (H2S) were tested in three ecotoxicological tests in order to evaluate its confounding potential in assessment of pore water and groundwater toxicity. The luminescent bacteria Vibrio fischeri, the water flea Daphnia magna, and the microalgae Scenedesmus vacuolatus often are part of a biotest battery. A new technique for the synthesis of hydrogen sulfide solutions of defined concentrations using an electrochemical generator instead of sodium sulfide solutions was used. Because hydrogen sulfide is volatile, the loss rate of H2S was studied over time to enable estimation of the mean test concentrations over the whole test duration. Loss rates were calculated to be 13 +/- 6% after 30 min, and 39 +/- 11% and 43 +/- 16% after a 24- and 48-h exposure time, respectively. Sensitivities of the test organisms in terms of median effective concentration (EC50), corrected for the above loss rates, varied from 0.28 to 0.0036 and 0.055 mM for the luminescent bacteria, the crustacea, and the algae, respectively. A species-sensitivity distribution using EC and mean lethal concentration literature data for marine and freshwater crustaceans and phytoplankton showed a medium sensitivity of the water flea D. magna, though the bacteria V. fischeri and the algae S. vacuolatus were among the least-sensitive group of organisms. This demonstrates that only the algae and the bacteria are easy to use in the assessment of toxicity of matrices with H2S concentrations above 0.06 mM.     

Toxicity of mono- and diesters of o-phthalic esters to a crustacean, a green alga, and a bacterium

The degradation of phthalic acid diesters may lead to formation of o-phthalic acid and phthalic acid monoesters. The ecotoxic properties of the monoesters have never been systematically investigated, and concern has been raised that these degradation products may be more toxic than the diesters. Therefore, the aquatic toxicity of phthalic acid, six monoesters, and five diesters of o-phthalic acid was tested in three standardized toxicity tests using the bacteria Vibrio fischeri, the green algae Pseudokirchneriella subcapitata, and the crustacean Daphnia magna. The monoesters tested were monomethyl, monoethyl, monobutyl, monobenzyl, mono(2-ethylhexyl), and monodecyl phthalate, while the diesters tested were dimethyl, diethyl, dibutyl, butylbentyl, and di(2-ethylhexyl)phthalate, which were assumed to be below their water solubility. The median effective concentration (EC50) values for the three organisms ranged from 103 mg/L to >4.710 mg/L for phthalic acid, and corresponding values for the monoesters ranged from 2.3 mg/L (monodecyl phthalate in bacteria test) to 4,130 mg/L (monomethyl phthalate in bacteria test). Dimethyl and diethyl phthalate were found to be the least toxic of the diesters (EC50 26.2-377 mg/L), and the toxicity of the other diesters (butylbenzyl and dibutyl phthalate) ranged from 0.96 to 7.74 mg/L. In general, the phthalate monoesters (degradation products) were less toxic than the corresponding diesters (mother compounds).     

Development of flow cytometry-based algal bioassays for assessing toxicity of copper in natural waters

Copper toxicity to the freshwater algae Selenastrum capricornutum and Chlorella sp. and the marine algae Phaeodactylum tricornutum and Dunaliella tertiolecta was investigated using different parameters measured by flow cytometry: cell division rate inhibition, chlorophyll a fluorescence, cell size (i.e., light-scattering), and enzyme activity. These parameters were assessed regarding their usefulness as alternative endpoints for acute (1-24 h) and chronic (48-72 h) toxicity tests. At copper concentrations of 10 micrograms/L or less, significant inhibition (50%) of the cell division rate was observed after 48- and 72-h exposures for Chlorella sp., S. capricornutum, and P. tricornutum. Bioassays based on increases in algal cell size were also sensitive for Chlorella sp. and P. tricornutum. Copper caused both chlorophyll a fluorescence stimulation (48-h EC50 of 10 +/- 1 micrograms Cu/L for P. tricornutum) and inhibition (48-h EC50 of 14 +/- 6 micrograms Cu/L for S. capricornutum). For acute toxicity over short exposure periods, esterase activity in S. capricornutum using fluorescein diacetate offered a rapid alternative (3-h EC50 of 90 +/- 40 micrograms Cu/L) to growth inhibition tests for monitoring copper toxicity in mine-impacted waters. For all the effect parameters measured, D. tertiolecta was tolerant to copper at concentrations up to its solubility limit in seawater. These results demonstrate that flow cytometry is a useful technique for toxicity testing with microalgae and provide additional information regarding the general mode of action of copper (II) to algal species.     

Fuel oil effect on the population growth, species diversity and chlorophyll (a) content of freshwater microalgae

Fresh water algae were subjected to different concentrations (0.03, 0.07, 0.12, 0.25 and 0.5 g x l(-1)) of aqueous extract of reference fuel oil (EPA, USA, API Oil No. 2, 38% aromatic, 1274). Significant decrease in Chlorophyll. (a) was observed as the concentration of fuel oil was increased. The EC50 value of fuel oil after 7 days was 0.29 g x l(-1). Total algal counts and growth rate decreased in response to the studied fuel oil. High diversity values in diatoms were observed in all treated aqueous cultures. High concentrations of fuel oil significantly decreased carbohydrate and protein contents of algal cells.     

Heterocyclic compounds: toxic effects using algae, daphnids, and the Salmonella/microsome test taking methodical quantitative aspects into account

Heterocyclic aromatic hydrocarbons containing nitrogen, sulfur, or oxygen (NSO-HET), have been detected in air, soil, sewage sludge, marine environments, and freshwater sediments. Since toxicity data on this class of substances are scarce, the present study focuses on possible implications NSO-HET have for ecotoxicity (algae and daphnids) and mutagenicity (Salmonella/microsome test). A combination of bioassays and chemical-analytical quantification of the test compounds during toxicity assays should aid in determination of the hazard potential. Samples of the test concentrations of 14 NSO-HET were taken at the beginning and end of the bioassays; these samples were then quantified by high-performance liquid chromatography. The toxicity potential of the substances was evaluated and compared with the toxicity calculated with the nominal concentrations. Significantly different results were obtained primarily for volatile or highly hydrophobic NSO-HET. The concentration of heterocyclic hydrocarbons can change significantly during the algae and Daphnia test. The EC50 values (effective concentration value: the concentration of a chemical that is required to produce a 50% effect) calculated with the nominal concentrations underestimate the toxicity by a factor of up to 50. Prioritizing the tested compounds according to toxicity, the mutagenic and toxic compounds quinoline, 6-methylquinoline, and xanthene have to be listed first. The greatest ecotoxic potential on algae and daphnids was determined for dibenzothiophene followed by acridine. In the Daphnia magna immobilization test, benzofuran, dibenzofuran, 2-methylbenzofuran, and 2,3-dimethylbenzofuran and also carbazole are ecotoxicologically relevant with EC50 values below 10 mg/L. These substances are followed by indole with a high ecotoxic effect to daphnids and less effect to algae. Only minor toxic effects were observed for 2-methylpyridine and 2,4,6-trimethylpyridine.     

Toxicological evaluation of nitrofurazone and furaltadone on Selenastrum capricornutum, Daphnia magna, and Musca domestica

Short-term toxicity of nitrofurans, nitrofurazone, furaltadone tartrate, and furaltadone chlorohydrate, was tested in the laboratory on two freshwater organisms, Selenastrum capricornutum (algae) and Daphnia magna (crustaceans). Toxicity studies with nitrofurazone were also carried out on larval development of the house fly Musca domestica L. Nitrofurazone was invariably the most toxic compound (the 96-hr EC50 of algal species was 1.45 mg/liters; the EC50 values for D. magna were 40.04 and 28.67 mg/liter after 24 and 48 hr, respectively) followed by furaltadone tartrate and furaltadone chlorohydrate. This study provides some evidence of the potential ecotoxicity of nitrofurans, indicating the need for further investigations.     

Comparison of four chronic toxicity tests using algae, bacteria, and invertebrates assessed with sixteen chemicals

The performances of four chronic toxicity tests, comprising the Daphnia magna 21-day (d) (crustacean), Brachionus calyciflorus 2-d (rotifer), Pseudokirchneriella subcapitata 72-h (green algae), and the Microtox chronic 22-h (bacteria) tests, were compared. Sixteen chemicals with toxicity covering 6 orders of magnitude were studied. Very high correlations were found between the NOEC/EC(10) Pseudokirchneriella 72-h, NOEC/EC(10) Brachionus 2-d, and the NOEC Daphnia 21-d tests. The toxicological response of rotifers and microalgae were within the same order of magnitude as the response of Daphnia in 80% of cases (13/16 chemicals). The Microtox chronic test also anticipated the overall results of the Daphnia 21-d test, but the prediction was rather imprecise, compared with microalgae and rotifers. The test measuring the algal growth inhibition of P. subcapitata after 72h was the most sensitive bioassay. Toxicity on microalgae after 72h could be estimated after 5h by measuring either the direct fluorescence of either photosynthetic pigments or fluorescein diacetate in 56 and 43% of cases, respectively. The median value of the ratio between EC(10) and EC(50) was 3.75, 2, and 1.5 with the algae, the rotifers, and the bacteria, respectively.     

The Effects of Dietary Silver on Larval Growth in the Echinoderm Lytechinus variegatus

Previous studies have demonstrated that the euryhaline copepod Acartia tonsa is extremely sensitive to dietborne silver (Ag) exposure, with a 20 % inhibition (EC(20)) of survival occurring when copepods are fed algae with 1.6 μg g(-1) dry weight (dw) Ag, corresponding to a waterborne Ag concentration of 0.46 μg l(-1) Ag. In contrast, 43 μg l(-1) Ag is required to elicit similar effects in copepods exposed to Ag by way of water. In the current study, we investigated whether another planktonic marine organism might also be sensitive to dietary Ag. Specifically, we tested larvae of the echinoderm, Lytechinus variegatus in an 18-day study in which larvae were continuously exposed to Ag-laden algae (Isochrysis galbana). After 7 days of exposure, no significant effects were observed on larval growth up to the highest concentration tested (10.68 μg g(-1) dw Ag in algae after exposure to 3.88 μg l(-1) waterborne Ag). After 18 days, significant effects were observed in all Ag treatments resulting in a lowest-observable effect concentration of 0.68 μg g(-1) dw Ag in algae and corresponding waterborne Ag concentration of 0.05-0.07 μg l(-1) Ag (depending on background Ag [see Results]). However, the dose-response relationship was quite flat with a similar level of growth inhibition (approximately 15 %) in all Ag treatments, resulting in an EC(20) of >10.68 μg g(-1) dw Ag in algae (>3.88 μg l(-1) Ag in water). This flat dose-response relationship is characteristic of dietary metal (silver, copper, cadmium, nickel, and zinc) toxicity to copepods as well, although the effect is slightly more robust (approximately 20-30 % inhibition of survival or reproduction). We conclude that echinoderm larvae may be similar to copepods in their sensitivity to dietary Ag, although a better understanding of the mechanisms underlying the apparent flat dose-response relationships is clearly needed.     

Assessment of lead toxicity to the marine bacterium, Vibrio fischeri, and to a heterogeneous population of microorganisms derived from the Pearl River in Jackson, Mississippi, USA.

Microorganisms are known to be excellent test organisms because of the relative ease for handling and suitability for analysis related to their small size, large number and convenient growing conditions. In this research, we tested the toxic effects of lead against a marine bacterium (Vibrio fischeri), and a heterogeneous population of bacteria derived from the Pearl River in Jackson, Mississippi. Using the level of bioluminescence in the Microtox Assay (V. fischeri), and the kinetics of dissolved oxygen uptake and growth (mixed bacterial population) as measures of toxicity, lead concentrations effecting a 50% reduction in these parameters (EC50) were determined as the toxic end-points. The activity quotients were also computed to determine the degrees of toxicity. Optical density (measure of growth) and oxygen uptake were measured over an extended period of time (20 h). EC50 values of 0.34 +/- 0.03, 3.10 +/- 0.01, and 3.80 +/- 0.02 mg/L were recorded for bioluminescence, growth, and oxygen uptake, respectively. As expected, the results indicated that the sensitivity to lead toxicity of V. fischeri was about one order of magnitude (10 times) greater than that of the mixed population of Pearl River microorganisms. Reductions in bioluminescence, growth, and oxygen uptake were directly correlated to lead concentrations, with toxic levels ranging from slightly toxic in lower concentrations to extremely toxic in higher concentrations. Upon 20 h of exposure, the times required to produce 50% reduction in dissolved oxygen uptake were (TD50S) 8.01 +/- 0.44, 9.60 +/- 0.46, 11.29 +/- 0.46, 13.03 +/- 0.57, 17.32 +/- 0.95, and 20.00 +/- 0.00 h in 0, 1, 2, 3, 4, 5, and 6 mg/L of lead, respectively, indicating a time-response relationship with respect to lead toxicity.     

Cadmium-induced colony disintegration of duckweed (Lemna paucicostata Hegelm.) and as biomarker of phytotoxicity

The toxic effect of cadmium on Lemna paucicostata was investigated with hydroponic culture in a culture facility. Cadmium treatment (0.4-6.4 micromol L(-1) Cd) induced L. paucicostata to release daughter fronds from the mother frond before maturity, resulting in colony disintegration. The 8-h and 24-h EC(50) values for colony disintegration in L. paucicostata plants were 0.12 and 0.11 mg L(-1), respectively. The maximum permissible concentrations (MPCs) were 0.012 and 0.011 mg L(-1) accordingly (MPC = 10% x EC(50)). These values were lower than the values of most of these biomarkers in duckweed reported in the literature, suggesting that colony disintegration in L. paucicostata may serve as a sensitive biomarker for the phytotoxicity test. Nutrient concentrations (1/2, 1/10, 1/20, 1/40, and 0-fold concentrations of Hoagland's solution) and Cd salt form (CdCl(2) or CdSO(4)) did not have a significant effect on colony disintegration. In addition, resistance to Cd stress differed significantly among clones of the plants. Approximately 2% of colonies in the wild population of L. paucicostata were tolerant of cadmium. These results indicate that colony disintegration of L. paucicostata could be used as a sensitive, cost-effective, and valuable biomarker to assess the acute phytotoxicity of cadmium and other heavy metals.     

Synthesis and leishmanicidal activities of 1-(4-X-phenyl)-N'-[(4-Y-phenyl)methylene]-1H-pyrazole-4-carbohydrazides

1H-pyrazole-4-carbohydrazides were synthesized and their leishmanicidal in vitro activities and cytotoxic effects were investigated. The drugs prototypes of these new compounds (ketoconazole, benznidazole, allopurinol and pentamidine) were also tested. It was found that among all the 1H-pyrazole-4-carbohydrazides derivatives examined, the most active compounds were those with X = Br, Y = NO2 (27) and X = NO2, Y = Cl (15) derivatives which showed to be most effective on promastigotes forms of L. amazonensis than on L. chagasi and L. braziliensis species. When tested against murine peritoneal macrophages as mammalian host cell controls of toxicity, 1-(4-Br-phenyl)-N'-[(4-NO(2)-phenyl)methylene]-1H-pyrazole-4-carbohydrazides (27) (EC50 = 50 microM l(-1)) and 1-(4-NO2-phenyl)-N'-[(4-Cl-phenyl)methylene]-1H-pyrazole-4-carbohydrazides (15) EC50 = 80 microM l(-1))] was reasonably toxic. However, both compounds were less toxic than pentamidine and ketoconazole. These results provide new perspectives on the development of drugs with activities against Leishmania parasite.     

Ecotoxicological evaluation of wastewater treatment plant effluent discharges: a case study in Prato (Tuscany, Italy)

Textile wastewaters, which contain numerous chemicals such as dyes, surfactants, solvents, organic and inorganic salts, can cause severe pollution problems for the receiving freshwaters. The ecotoxicity of wastewaters in Prato, where there are about 14,000 textile and related factories, was investigated from 1996-1999 by means of bioassays. 147 samples of reclaimed wastewater were collected at the outlets of 4 centralized wastewater treatment plants. The acute and chronic toxicity of the effluents was measured with bioassays using three different target organisms: green algae (Pseudokirchneriella subcapitata), crustaceans (Daphnia magna) and bioluminescent bacteria (Vibrio fischeri). Toxicity was expressed as Effective Concentration 50 (EC50) and Toxic Units (TU). The results indicated that the effluents did not have significant acute toxicity: only 2.74% (EC50<100%, TU>1) of the 146 samples tested with crustaceans and 6.52% (EC50<50%, TU>2) of the 78 tested with bioluminescent bacteria showed toxic effects. With algae, slight chronic toxicity was found in 49.33% (mean EC50 value=86.56%, mean TU=1.16) of the 140 samples tested. The highest relative response was found with the algal assay using Pseudokirchneriella subcapitata: 49.33% of 140 samples showed chronic toxicity at 96 hours (EC50<100%).     

The Ecotoxicity of Chlorate to Aquatic Organisms: A Critical Review

In order to assess the risk posed by chlorate in aquatic ecosystems, data on the effects of chlorate on aquatic organisms (microorganisms, algae, invertebrates, and fish) and mesocosm studies have been collated and critically reviewed. The geometric mean E(L)C₅₀ values for both freshwater and marine species were (as ClO₃⁻): microorganisms, 38,583 mg · liter⁻¹; microalgae, 563 mg · liter⁻¹ invertebrates, 2442 mg · liter⁻¹; fish, 3815 mg · liter⁻¹. Marine macro red algae were insensitive to chlorate, whereas marine macro brown algae (e.g., Fucus sp.) appeared to be exceptionally sensitive to chlorate, adverse long-term effects having been reported at concentrations as low as 0.015 mg ClO₃⁻ · liter⁻¹. Evidence for the mechanism by which chlorate is thought to be particularly toxic to these species is also reviewed. It is concluded that, based on the species reported, chlorate is nontoxic (acute toxicity >100 mg · liter⁻¹) to most of the freshwater and marine species examined. However, chlorate is highly toxic (acute toxicity <0.1 mg · liter⁻¹) to certain macro brown algal species. For macro brown algae, the NOEC after 6 months was reported to be approximately 0.005 mg ClO₃⁻ · liter⁻¹. It is also concluded that an improved understanding of the actual mode of action of chlorate in sensitive species is desirable. Together with further information on the environmental fate of chlorate, this will improve the risk assessment for chlorate in the aquatic environment.     

Toxicity of Euphorbia milii latex and niclosamide to snails and nontarget aquatic species

The toxicity of Euphorbia milii molluscicidal latex and niclosamide (NCL) to target snails (Biomphalaria glabrata and Biomphalaria tenagophila) and nontarget aquatic organisms is evaluated. Planorbidae snails were killed by very low concentrations of lyophilized latex (48-h LC(50), mg/L: B. glabrata, 0.12; B. tenagophila, 0.09; Helisoma duryi, 0.10). Latex was less toxic (48-h LC(50) or EC(50), mg/L) to oligochaeta (Tubifex tubifex, 0.31), planktonic crustacea (Daphnia similis, 0.38; C. dubia, 1.07; Artemia sp., 0.93), and fishes (Danio rerio, 0.96; Poecilia reticulata, 1. 39), and considerably less toxic to Ampullariidae snails (Pomacea sp. , 10.55) and frog tadpoles (Rana catesbeiana, 7.50). Latex (up to 100 mg/L) was not toxic to bacteria (P. putida and V. fischeri), algae (Selenastrum capricornutum and Chlorella vulgaris), and mosquito larvae (Anopheles albitarsis, Aedes aegypti, Aedes fluviatilis). NCL was very toxic (48-h LC(50) or EC(50), mg/L) to Planorbidae snails (B. glabrata, 0.15, B. tenagophila, 0.13; H. duryi, 0.10), T. tubifex (0.11), crustacea (D. similis, 0.19; Ceriodaphnia dubia, 0.47; Artemia sp. 0.18), fishes (D. rerio, 0.25; P. reticulata, 0.29), R. catesbeiana (0.16), and Pomacea sp. (0.76). NCL was toxic to bacteria, algae (96-h IC(50), mg/L: S. capricornutum, 0.34; C. vulgaris, 1.23) and slightly toxic to mosquito larvae. In conclusion, E. milii latex, as compared with the reference molluscicide niclosamide, presents a higher degree of selectivity toward snails which are intermediate hosts of Schistosoma trematodes.     

Upper body cooling during exercise-heat stress wearing the improved toxicological agent protective system for HAZMAT operations

This study compared endurance in a U.S. Army developmental Occupational Safety and Health Administration Level B personal protective equipment (PPE) system against the toxicological agent protective (TAP) suit, the Army's former standard PPE for Level A and Level B toxic environments. The developmental system consisted of two variations: the improved toxicological agent protective (ITAP) suit with self-contained breathing apparatus (ITAP-SCBA), weight 32 kg, and the ITAP with blower (ITAP-B), weight 21 kg. Both ITAP suits included the personal ice cooling system (PICS). TAP (weight 9.5 kg) had no cooling. It was hypothesized that PICS would effectively cool both ITAP configurations, and endurance in TAP would be limited by heat strain. Eight subjects (six men, two women) attempted three 2-hour treadmill walks (0.89 m/sec, 0% grade, rest/exercise cycles of 10/20 min) at 38 degrees C, 30% relative humidity. Metabolic rate for TAP (222+/-35 W) was significantly less than either ITAP-SCBA (278+/-27 W) or ITAP-B (262+/-24 W) (p<0.05). Endurance time was longer in ITAP-SCBA (85+/-20 min) and ITAP-B (87+/-25 min) than in TAP (46+/-10 min) (p<0.05). Heat storage was greater in TAP (77+/-15 W.m(-2)) than in ITAP-SCBA (51+/-16 W.m(-2)) (p<0.05), which was not different from ITAP-B (59+/-14 W.m(-2)). Sweating rate was greater in TAP (23.5+/-11.7 g/min(1)) than in either ITAP-SCBA (11.1+/-2.9 g/min) or ITAP-B (12.8+/-3.5 g/min) (p<0.05). Endurance in ITAP was nearly twice as long as in PPE with no cooling, even though the PICS, SCBA tanks, and new uniform itself all served to increase metabolic cost over that in TAP. PICS could also be used with civilian Levels A and B PPE increasing work time and worker safety.