Static-renewal Tests Research Articles

Marsh frog response to urea fertilizer during the embryonic, larval, and metamorphosis stages: a new perspective into urea toxicity on amphibians.

Amphibian populations are declining worldwide. These declines are caused by a variety of factors, one of which is the use of fertilizers in agriculture. This is especially true for tadpoles, which may develop in fertilizer-polluted agricultural water bodies. Nevertheless, there is little data on the toxicological consequences of fertilizers on amphibians. The goal of this study was to determine the acute and chronic toxicity of urea fertilizer on marsh frogs' (Pelophylax sp.) embryonic, larval, and metamorphic stages. For this purpose, in a static-renewal test, individuals were exposed to twelve nominal concentrations (0 to 15000mg/L) of urea for 122days to determine hatching success, survival, growth, development, and metamorphic traits, as well as histological consequences. Based on the results, at concentrations greater than 500mg/L, no hatching occurred. Survivorship was unaffected for the first 72hours, but it reached 0% on day 26 at concentrations greater than 150mg/L. Survival and development rates decreased significantly in 100 and 150mg/L treatments after a longer duration (day 86). Growth was reduced as well, but it was only significant at 150mg/L. Metamorphosis time and percentage were significantly impacted, but not metamorphosis size. Increased urea fertilizer concentrations had significant histopathological consequences for the skin, gills, liver, kidneys, and striated muscles. Our results suggest that urea fertilizer, at concentrations commonly found in agroecosystems, may pose a serious threat to temperate anuran species inhabiting these conditions.

Adult corals are uniquely more sensitive to manganese than coral early-life stages.

Manganese is an essential element and generally considered to be one of the least toxic metals to aquatic organisms, with chronic effects rarely seen at concentrations below 1000 µg/L. Anthropogenic activities lead to elevated concentrations of manganese in tropical marine waters. Limited data suggests that manganese is more acutely toxic to adult than to early life-stages of scleractinian corals in static renewal tests. However, to enable the inclusion of sufficient sensitive coral data in species sensitivity distributions to derive water quality guideline values (GVs) for manganese, we determined the acute toxicity of manganese to the adult scleractinian coral, Acropora muricata, in flow-through exposures. The 48-h EC50 was 824 µg Mn/L (based on time-weighted average, measured, dissolved manganese). The endpoint was tissue sloughing, a lethal process by which coral tissue detaches from the coral skeleton. Tissue sloughing was unrelated to superoxidase dismutase activity in coral tissue, and occurred in the absence of bleaching, i.e., toxic effects were observed for the coral host, but not for algal symbionts. We confirm that adult scleractinian corals are uniquely sensitive to manganese in acute exposures at concentrations 10 to 340 times lower than those reported to cause acute or chronic toxicity to coral early life stages, challenging the traditional notion that early life stages are more sensitive than mature organisms. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2023;00:0-0. © 2023 SETAC.

Histopathology of Brain and Spleen of Freshwater Teleost Anabas testudineus (Bloch, 1792) Induced by Organochlorine Insecticide Endosulfan

Endosulfan is an important environmental pollutant that is a pesticide of organochlorine. The 24, 48, 72 and 96h median lethal concentrations of endosulfan (35 EC) were assessed by an acute static renewal test. The sublethal concentration taken for the present study is one-tenth of the 96h LC50 and fish were exposed to that concentration (1.69 ppb) for 30 days. The histopathological observations revealed the presence of catecholamine neurons in the optic tectum and severe depletion of the layer stratum grisum periventricular. An altered pattern of neurons as an “interrupted string of pearls” was noticed in the posterior tuberal nucleus. From the present study, we could conclude that endosulfan is a serious toxicant that even affects the vital organs like the brain of vertebrates. Histology of the spleen showed necrosis in red pulp, hyperplasia and exudate in white pulp and an increased number of melanomacrophage centers (MMC) of the exposed fish species. Based on the results of this study, it is concluded that endosulfan is highly toxic to edible freshwater fish Anabas testudineus. Subsequently, damage to the structures of cells and tissues and histopathology of target organs comprise a significant parameter to be considered in evaluating the toxic possibility of contaminations on living organisms in various environmental conditions and represent the time exposure to which organisms are subjected.

Pila virens as sentinel of silica nanoparticles toxicity induced oxidative stress

The aquatic ecosystem is under threat due to the continuous inlet of various emerging contaminants affecting the inhabiting organisms. The Silica nanoparticles (SiNPs) are among the most abundantly produced nanoparticles globally posing a threat to the aquatic organisms because of their entry into aquatic ecosystem through various point and nonpoint sources. In this work, we report the toxicological impacts of SiNPs on fresh water snail Pila virens (P.virens) as a biomonitor. The acute toxicity of SiNPs on P. virens was performed in a 96 h static renewal tests. The median lethal concentration of SiNPs for 96 h on P. virens is 366.92 µg/L. The P. virens were exposed to 165 µg/L for 24 and 48 h respectively shown a significant increase in lipid peroxidation, protein carbonyl, superoxide dismutase and reduction in total glutathione content in comparison to their controls. The fresh water edible snail P. virens serve as model organisms for other engineered nanomaterials toxicity.

Toxicological impacts of herbicide paraquat dichloride on histological profile (gills, liver, and kidney) of freshwater fish Channa punctatus (Bloch).

Paraquat dichloride is a broad-spectrum herbicide used worldwide. It is very fast acting and used to kill a wide range of grasses and broad-leaved weeds. Paraquat dichloride gets run off to aquatic water bodies, and its presence has been reported by various researchers, where its effect is certain on aquatic organisms. Fish are vulnerable to aquatic pollutants as they are in direct contact with their environment. Therefore, our study was designed to evaluate the effects of herbicide paraquat dichloride on histology of vital organs (gills, liver, and kidney) of the fresh water fish Channa punctatus (Bloch). Toxicity effects are evaluated under static renewal test conditions, and histological alterations were detected microscopically. Fish were exposed to acute dose (96hLC50/2 = 32.93mg/L) for 96h of paraquat dichloride. Simultaneous control was also maintained. Principal histopathological alterations in gills during acute exposure showed curling of secondary lamellae, aneurysm, gill bridging, and enlargement of the cartilaginous core. The tissue damages like melanomacrophage centers, pyknotic nucleus, large sinusoidal congestion, and cell fusion are some histological alterations observed in the liver after acute exposure. The changes in histoarchitecture observed in the kidney include an increase in Bowman's space, necrosis of glomeruli, and damage to collecting duct at acute exposure. The histopathological changes were more prominent with the duration of exposure in the experimental groups. The present study demonstrated that the vital organs exhibited significant damage, among all gill histology specifically got altered being directly exposed to paraquat dichloride. Paraquat dichloride exposure affects the histology of gills, liver, and kidney, thus impairing the vital functions like respiration, excretion, and metabolic regulation which in turn will affect the fish health and is a serious threat. Histopathological alteration in gills, liver, and kidney can be regarded as sensitive biomarkers of paraquat dichloride toxicological manifestations and thus can be utilized for ecotoxicological biomonitoring of aquatic bodies. Graphical abstract.

Improved prediction of sediment toxicity using a combination of sediment and overlying water contaminant exposures

The choice of sediment quality assessment methodologies can strongly influence assessment outcomes and management decisions for contaminated sites. While in situ (field) methods may potentially provide greater realism, high costs and/or complex logistics often prevent their use and assessment must rely on laboratory-based methods. In this study, we utilised static-renewal and flow-through ecotoxicology tests in parallel on sediments with a wide range of properties and varying types and concentrations of contaminants. The prediction of chronic effects to amphipod reproduction was explored using multiple linear regression (MLR). The study confirmed the considerable over-estimation of the risk of toxicity of contaminated sediments in field locations when assessments rely on the results of laboratory-based static and static-renewal tests. Improved prediction of toxicity risks was achieved using a combination of contaminant exposure measures from sediment and overlying water. Existing sediment and water quality guideline values (GVs) were effective for predicting risks posed by sediments containing mixtures of common metal and organic contaminants. For 17 sediments with paired data sets from static-renewal and flow-through tests, the best prediction of toxicity to reproduction was achieved using a 2-parameter MLR that included hazard quotients for sediment contaminants and toxic units for dissolved metals (r2 = 0.892). The inclusion of particle size, organic carbon and acid-volatile sulfide did not improve toxicity predictions, despite these parameters being recognised as modifying contaminant bioavailability. The use of dilute-acid-extractable metal concentrations in place total recoverable metal concentrations did not improve the predictions. The study also confirmed that sediments existing within the estuarine and marine bays of Sydney Harbour pose significant risks of adverse effects to benthic organisms.

Short-Term Guideline Values for Chlorine in Marine Waters.

Chlorination is commonly used to control biofouling organisms, but chlorine rapidly hydrolyzes in seawater to hypochlorite, which undergoes further reaction with bromide, and then with organic matter. These reaction products, collectively termed chlorine-produced oxidants (CPOs), can be toxic to marine biota. Because the lifetime of the most toxic forms is limited to several days, appropriate guideline values need to be based on short-term (acute) toxicity tests, rather than chronic tests. Flow-through toxicity tests that provide continuous CPO exposure are the most appropriate, whereas static-renewal tests generate variable exposure and effects depending on the renewal rate. There are literature data for acute CPO toxicity from flow-through tests, together with values from 2 sensitive 15-min static tests on 30 species from 9 taxonomic groups. These values were used in a species sensitivity distribution (SSD) to derive guideline values that were protective of 99, 95, and 90% of species at 2.2, 7.2, and 13 µg CPO/L respectively. These are the first marine guideline values for chlorine to be derived using SSDs, with all other international guideline values based on the use of assessment factors applied to data for the most sensitive species. In applying these conservative guideline values in field situations, it would need to be demonstrated that concentrations of CPOs would be reduced to below the guideline value within an acceptable mixing zone through both dilution and dissociation. Environ Toxicol Chem 2020;39:754-764. © 2020 SETAC.

Acute and chronic toxicity of neonicotinoid and butenolide insecticides to the freshwater amphipod, Hyalella azteca

Neonicotinoids are the most widely used insecticides in the world. They are preferentially toxic to insects while displaying a low toxicity toward vertebrates, and this selective toxicity has resulted in the rapid and ubiquitous use of these compounds. However, neonicotinoids have been detected in agricultural surface waters and are known to cause adverse effects in non-target aquatic organisms. A wide range of toxicity has been reported for aquatic crustaceans, but most of the studies focus on the acute effects of imidacloprid, and few data are available regarding chronic effects of other neonicotinoids or neonicotinoid replacements (e.g., butenolides). The objective of this study was to assess the acute and chronic toxicity of six neonicotinoids (imidacloprid, thiamethoxam, acetamiprid, clothianidin, thiacloprid, and dinotefuran) and one butenolide (flupyradifurone) to the freshwater amphipod Hyalella azteca. Chronic (28-d), water-only, static-renewal tests were conducted. Survival was assessed weekly, and growth was measured at the end of the exposure. Effects of neonicotinoids varied depending on the compound. Acute (7-d) LC50s were 4.0, 4.7, 60, 68, 230, and 290 μg/L for clothianidin, acetamiprid, dinotefuran, thiacloprid, imidacloprid, and thiamethoxam, respectively. Chronic (28-d) survival and growth were reduced at similar concentrations to acute (7-d) survival for thiamethoxam, acetamiprid, clothianidin, and dinotefuran. However, chronic survival and growth of amphipods exposed to imidacloprid and thiacloprid were reduced at lower concentrations than acute survival, with respective 28-d LC50s of 90 and 44 μg/L, and EC50s of 4 and 3 μg/L. Flupyradifurone was intermediate in toxicity compared to the neonicotinoids: 7-d LC50, 28-d LC50, and 28-d EC50 were 26, 20, and 16 μg/L, respectively. The concentrations of imidacloprid and clothianidin reported for North American surface waters fall within the effect ranges observed in this study, indicating the potential for these compounds to cause adverse effects to indigenous populations of H. azteca.

Chronic toxicity of 6 neonicotinoid insecticides to Chironomus dilutus and Neocloeon triangulifer.

Neonicotinoid insecticides are frequently detected in surface waters near agricultural areas, leading to a potential for chronic exposure to sensitive aquatic species. The midge Chironomus dilutus and the mayfly Neocloeon triangulifer have been shown to be acutely sensitive to neonicotinoids. Previous studies have established chronic effects of some neonicotinoids on C. dilutus, but reproduction has not been studied. Toxic effects have not been assessed using N. triangulifer. We present the results of chronic, static-renewal tests for 6 neonicotinoids (acetamiprid, clothianidin, dinotefuran, imidacloprid, thiacloprid, and thiamethoxam) with C. dilutus (≤56-d in length) and N. triangulifer (≤32-d in length). Emergence was generally the most sensitive endpoint for both species across all neonicotinoids. Effect concentrations, 10% (EC10s; emergence) were 0.03 to 1.1 μg L-1 for acetamiprid, clothianidin, imidacloprid, and thiacloprid. Dinotefuran and thiamethoxam were less potent, with EC10s (C. dilutus) or median effect concentrations (EC50s; N. triangulifer) of 2.2 to 11.2 μg L-1 . Hazard was assessed through comparison of neonicotinoid environmental concentrations from agricultural surface waters in Ontario (Canada) with either the 5th percentile hazard concentration (for imidacloprid) or species-specific EC10s from the present study (for all remaining neonicotinoids). The resulting hazard quotients (HQs) indicated little to no hazard (HQ <1) in terms of chronic toxicity for acetamiprid, dinotefuran, thiacloprid, or thiamethoxam. A moderate hazard (HQ >1) was found for emergence of N. triangulifer for clothianidin, and a high hazard (HQ = 74) was found for imidacloprid. Environ Toxicol Chem 2018;37:2727-2739. © 2018 SETAC.

A comparison of electronic and traditional cigarette butt leachate on the development of Xenopus laevis embryos.

Potential developmental toxicities of three different cigarette butt leachates were evaluated using the frog embryo teratogenesis assay–Xenopus (FETAX). Xenopus laevis embryos were exposed to regular cigarette butt (RCB), menthol (MCB) and electronic (ECB) in concentrations ranging from 0 to 4 butts/l for RCB and MCB and 0–10 butts/l for ECB. The embryos were from stage 8 to 11 and were exposed for a 96-h period in static renewal test conditions. Median lethal concentration (LC50), malformation (EC50), non-observed adverse effect concentration (NOAEC), and lowest observed adverse effect concentration (LOAEC) were calculated. Results from these studies suggest that each tested leachate is teratogenic for X. laevis embryos. The lowest LC50 was determined for ECB exposure at 17.9 cigarette butts/L. The LC50 value was the highest with RCB and MCB having LC50 s of approximately 1 cigarette butt/L. There were notable EC50 differences with RCB having the highest and ECB the lowest. The NOAEC and LOAEC levels for RCB and MCB were below 1 cigarette butt/L for both mortality and malformations; over 8 butts/L for ECB mortality and over 4 butts/L for malformations. From these results, we conclude that RCB leachate is the most toxic compound, while MCB leachate has the higher teratogenicity. ECB leachate has the lowest toxic and teratogenic effects on embryos but there were still noticeable effects. The results confirmed that the FETAX assay can be useful in an integrated biological hazard assessment for the preliminary screening for ecological risks of cigarette butts, and electronic cigarettes, in aquatic environment.

Chronic Toxicity of Unweathered and Weathered Macondo Oils to Mysid Shrimp (Americamysis bahia) and Inland Silversides (Menidia beryllina).

Chronic, 21-28-day toxicity tests of Macondo source (Massachusetts, or MASS) and weathered Slick A (CTC) and Slick B (Juniper) oils field collected during the 2010 Deepwater Horizon (DWH) Incident in the Gulf of Mexico (GOM) were conducted using standardized procedures. Standard species, Americamysis bahia and Menidia beryllina, were evaluated for changes in survival and growth during daily static-renewal tests. Both species demonstrated an increased sensitivity to low-energy water accommodated fractions (WAFs) of un-weathered MASS oil, with growth and survival decreasing as oil loading rate increased from 0.01 to 1.0g/L. Survival and growth of mysid shrimp exposed to weathered oil (Slick A and Slick B) did not differ from that of test controls. In contrast, survival and growth of inland silversides declined relative to that of test controls at loading rates of 1g/L for both weathered oils. Based on the concentration of total polycyclic aromatic hydrocarbons (TPAH42), no observed effect concentrations were lower for inland silverside survival (5.00-7.61µg/L) and growth (<2.02 to <7.61µg/L) in chronic exposures to Slick B and Slick A weathered oils compared with mysids (4.75-17.9µg/L). Average TPAH concentrations in full strength WAFs followed the weathering trend, with 165±17.2, 17.9±0.480, and 4.75±0.521µg/L for MASS, Slick A, and Slick B oils, respectively. The effect (LOEC, IC25) and no-effect exposure concentrations (in TPAHs) from the standardized laboratory toxicity studies with un-weathered and weathered oils are discussed relative to the actual exposure concentrations in the GOM in 2010. The exposures evaluated in the laboratory toxicity tests represent the highest concentrations of total PAHs that were rarely observed in water column samples collected in the GOM during the release and post release periods of the DWH incident.

SEM study of ultrastructural changes in branchial architecture of Ctenopharyngodon idella (Cuvier &amp; Valenciennes) exposed to chlorpyrifos

We evaluated structural modifications in the branchial architecture of grass carp, Ctenopharyngodon idella, chronically exposed to chlorpyrifos (an organophosphate) using scanning electron microscopy (SEM). Static renewal tests were conducted for 96 h to determine the LC50 of chlorpyrifos to the fish. Physicochemical analysis of water was done using standard methods. To assess the effect of chronic toxicity, fish were exposed to two sublethal concentrations (1.44 ?g/L and 2.41 ?g/L) of chlorpyrifos for 15, 30 and 60 days, after which gills were examined by SEM, which revealed changes in gill ultrastructure. Branchial alterations included distorted secondary lamellae in the form of curling and shortening, erosion in a few primary filaments and a wrinkled and denuded epithelial surface. Excessive mucosal openings (mucoid hyperplasia) on the surface were observed in the gills of fish exposed to both concentrations of chlorpyrifos. Alteration in the microridge pattern of pavement cells and cracks on the gill rakers were also observed, and the intensity of the damage was found to be directly related to the toxicant concentration and exposure period. The present study revealed that the assessment of surface morphology can serve as a novel bioindicator of pollution, disease and toxicity.

Acute toxicity of Euphorbia turcomanica on Aphanius dispar

Piscicidal and molluscicidal activities of aqueous extracts of many members of the family Euphorbiaceae are well-known, but the toxicity potential of Euphorbia turcomanica was not yet studied on any aquatic animals. An acute toxicity test was performed by using a four-day static renewal test to determine the LC 50 value of dried powder of E. turcomanica for the euryhaline fish, Aphanius dispar . The LC 50 values at various exposure periods are 0.177±0.039 g/L for 24 hrs, 0.131±0.030 g/L for 48 hrs, 0.073±0.018 g/L for 72 hrs, and 0.052±0.013 g/L for 96 hrs. The toxicity of dried powder of E. turcomanica exhibits a positive correlation between fish mortality and exposure periods. As this is the first report about toxicity of E. turcomanica on A. dispar , the results could be only compared to that of other Euphorbiaceae as well as other fishes. It is concluded that the toxicity potential of E. turcomanica is comparable and close to that of well-documented Euphorbiaceae. It has been suggested that E. turcomanica products cannot be used directly in fish-inhabiting water reservoirs.

Long- and short-term effects of smothering and burial by drill cuttings on calcareous algae in a static-renewal test.

Discharge of drill cuttings into the ocean during drilling of offshore oil wells can impact benthic communities through an increase in the concentrations of suspended particles in the water column and sedimentation of particles on the seafloor around the drilling installation. The present study assessed effects of water-based drill cuttings, barite, bentonite, and natural sediments on shallow- and deep-water calcareous algae in short-term (30 d) and long-term (90 d) experiments, using 2 species from Peregrino's oil field at Campos Basin, Brazil: Mesophyllum engelhartii and Lithothamnion sp. The results were compared with the shallow-water species Lithothamnion crispatum. Smothering and burial exposures were simulated. Oxygen production and fluorescence readings were recorded. Although less productive, M. engelhartii was as sensitive to stress as Lithothamnion sp. Mesophyllum engelhartii was sensitive to smothering by drill cuttings, barite, and bentonite after 60 d of exposure and was similarly affected by natural sediments after 90 d. These results indicate that smothering by sediments caused physical effects that might be attributable to partial light attenuation and partial restriction on gas exchange but did not kill the calcareous algae in the long term. However, 1-mo burial by either natural sediments or drill cuttings was sufficient after 60 d for both species to reduce oxygen production, and the algae were completely dead under both sources of sediments.

Chronic toxicity of silver nanoparticles to Daphnia magna under different feeding conditions

Despite substantial information on the acute toxicity of silver nanoparticles (AgNP) to aquatic organisms, little is known about their potential chronic effects and the applicability of current test guidelines for testing nanomaterials. The purpose of this study was to study the influence of food availability on toxicity. This was done through a series of Daphnia magna 21-day reproduction tests (OECD 211) using 30nm citric acid stabilized AgNP aimed at studying the influence of food abundance on the reproductive toxicity of AgNP in D. magna. The experiments were carried out as static renewal tests with exposure concentrations from 10 to 50μgAg/L, and test animals were fed green algae Pseudokirchneriella subcapitata in low and high food treatments. The endpoints recorded were survival, growth of parent animals and number of live neonates produced. Detrimental effects of AgNP on survival, growth and reproduction were observed in concentrations higher than 10μgAg/L, whereas the animals exposed to 10μgAg/L had larger body length and produced more offspring than controls at both food treatments. High food treatment resulted in higher animal survival, growth and reproduction compared to result found for low food treatment.

Lethal and Sublethal Effects of Inorganic Nitrogen on Gladiator Frog Tadpoles (Hypsiboas faber,Hylidae)

Human activities dramatically increased the amount of reactive nitrogen in the environment through the widespread production and application of fertilizers, generation of human and livestock waste, and combustion of fossil fuels. This excessive nitrogen load eventually reaches water bodies and at circumneutral or acidic pH accumulates in the form of nitrate, nitrite, and ammonium. Our objective was to test if prolonged exposure to low and environmentally relevant concentrations of nitrate, nitrite, and ammonium could affect survivorship, growth, and behavior of tadpoles of a Brazilian amphibian species, the gladiator frog Hypsiboas faber. Tadpoles of H. faber were exposed to 0, 2.5, and 10 mg.L−1 of nitrogen as nitrate, nitrite, and ammonium in a 21-day static renewal test. We demonstrated that under prolonged exposure even relatively low concentrations of inorganic nitrogen can cause lethal and sublethal effects on anuran larvae. Nitrate, the most abundant form of nitrogen in nature, caused no effects even in the largest manipulated concentration. Tadpoles exposed to 10 mg.L−1 N-nitrite had decreased growth and survivorship relative to controls. However, such nitrite concentrations are uncommon and generally found only in highly polluted, anaerobic conditions. In turn, tadpoles exposed to 10 mg.L−1 N-ammonium (which is within the upper range of concentrations observed in nature) had reduced activity rates and survivorship relative to controls. Future studies that aim to assess the environmental risk of nitrogen contamination should expand monitoring of concentrations in natural habitats, assess ontogenetic variation in organismal sensitivity, and evaluate the effects of synergistic interactions between inorganic nitrogen and other physical, chemical, or biological stressors to amphibian larvae.

Toxicity and bioconcentration of the pharmaceuticals moxifloxacin, rosuvastatin, and drospirenone to the unionid mussel Lampsilis siliquoidea

Pharmaceuticals and personal care products (PPCPs) and their metabolites are continually released from wastewater treatment plants into the aquatic environment; however, their impact on aquatic biota is poorly understood. This study examined the toxicity and bioconcentration of three pharmaceuticals: moxifloxacin, rosuvastatin, and drospirenone to the unionid mussel Lampsilis siliquoidea. Effects of moxifloxacin and rosuvastatin were assessed through aqueous 21-d static-renewal tests using 2–year-old mussels, at 0.01, 0.1, 1, 10 and 100mg/L (nominal concentrations). Following exposure, survival, behavior, algal clearance rate, hemocyte viability and density, and glutathione S-transferase (GST) activity were assessed. In addition, the acute (48h) toxicity of moxifloxacin (0–100mg/L) and drospirenone (0–3mg/L) to glochidia (larval mussels) were examined. In 21day exposures (2-yr old mussels), there were no differences in survival, oxygen consumption, hemocyte density, or GST activity over the range of concentrations examined; however, the proportion of time mussels spent filtering, and consequently the algal clearance rate, decreased at the higher moxifloxacin and rosuvastatin concentrations. Bioconcentration factors (BCFs) ranged between 0.03 and 70 for moxifloxacin, and between 0 and 0.05 for rosuvastatin for exposures up to 100mg/L. The BCF for moxifloxacin at the highest exposure concentration was lower than that at the mid-level concentrations, likely due to decreased filtering activity at the higher exposure levels. The feeding rates declined and the amount of time the subadult mussels spent with their valves closed increased at the higher moxifloxacin and rosuvastatin exposures. Glochidia viability did not vary with exposure to drospirenone, but declined at the highest moxifloxacin concentration, resulting in an EC50 of 120mg/L. Overall, observed sublethal and lethal effects occurred at concentrations which exceed expected environmental concentrations through aqueous exposure, suggesting a low risk to freshwater mussels from these particular PPCPs.

Comparative acute toxicity of gallium(III), antimony(III), indium(III), cadmium(II), and copper(II) on freshwater swamp shrimp (Macrobrachium nipponense).

BackgroundAcute toxicity testing were carried out the freshwater swamp shrimp, Macrobrachium nipponense, as the model animal for the semiconductor applied metals (gallium, antimony, indium, cadmium, and copper) to evaluate if the species is an suitable experimental animal of pollution in aquatic ecosystem.ResultsThe static renewal test method of acute lethal concentrations determination was used, and water temperature was maintained at 24.0 ± 0.5°C. Data of individual metal obtained from acute toxicity tests were determined using probit analysis method. The median lethal concentration (96-h LC50) of gallium, antimony, indium, cadmium, and copper for M. nipponense were estimated as 2.7742, 1.9626, 6.8938, 0.0539, and 0.0313 mg/L, respectively.ConclusionsComparing the toxicity tolerance of M. nipponense with other species which exposed to these metals, it is obviously that the M. nipponense is more sensitive than that of various other aquatic animals.

The effects of zinc chloride during early embryonic development in zebrafish (Brachydanio rerio)

This study investigated the developmental toxicity of zinc chloride (ZnCl_{2}) in zebrafish embryos (Brachydanio rerio, Cyprinidae, Cypriniformes). Zebrafish embryos were exposed to 5 different concentrations of ZnCl_{2}, from the blastula stage, for 15 days under static renewal test conditions. As a result, the corresponding median lethal concentration (LC_{50}) value determined for ZnCl_2 exposure was 1.36 mg/L (0.65 mg/L as a lone Zn^{2+} ion). At 1.0 mg/L ZnCl_{2}, the exposed group's hatching began at 7 days instead of at 4 days, and most of the embryos died in the chorion without hatching at 11 and 12 days. Developmental deformities such as abnormal embryogenesis, low hatchability, delayed hatching, and reduction of newly hatched larvae, and a poor survival ratio (mortality ratio of 1.5 and 10 mg/L concentrations compared to control, P < 0.001), were observed during the embryo larval stage due to zinc exposure. Based on these results, we observed that critical and teratogenic effects of ZnCl_2 on embryonic development of zebrafish occurred at concentrations greater than 0.5 mg/L. Moreover, our results confirm that the zebrafish embryo teratogenesis assay can be a useful pretest for integrated biological hazard assessment of chemical agents used in industrial production and drug development technologies.

Evaluation of E330-induced developmental toxicity using FETAX

The present study evaluates the teratogenic and toxicological effects of citric acid (E330), a food additive, on Xenopus laevis embryos. The embryos were exposed to a range of E330 concentrations, from stage 8 to 11 of development, for 96 h under static renewal test conditions. The median lethal concentrations, no-observed adverse effect concentration (NOAEC), lowest observed adverse effect concentration (LOAEC), and minimum concentration to inhibit growth (MCIG) values were calculated. The lethal concentration (LC) values LC_{10}, LC_{20}, LC_{30}, LC_{40}, and LC_{50} determined for E330 exposure were 0.0113, 0.0117, 0.0119, 0.0122, and 0.0124 g/L, respectively. NOAEC and LOAEC values were calculated as 0.001 and 0.01 g/L. Since the effective concentration (EC_{50}) value could not be determined, the E330 teratogenic index (TI), which is LC_{50}/EC_{50}, was not calculated. MCIG was calculated to be 0.010 g/L. The anomaly rate in Xenopus embryos treated with E330 was quite low. Therefore, the endpoint for the Xenopus embryos was whether they were alive or dead at the end of the study. It can be concluded from these observations that using unlimited amounts of E330 may result in preterm birth or abortion in humans, and E330 usage must be reevaluated and, potentially, limited. Moreover, our results confirm that the Frog Embryo Teratogenesis Assay Xenopus (FETAX) can be a useful pretest for integrated biological hazard assessment.