Acute Toxicity Bioassays Research Articles

Acute and Chronic Toxicity of Selected Pesticides Used in Strawberry Greenhouse to Honeybee (Apis mellifera) Larvae

Honey bee colonies have often collapsed when introduced in strawberry greenhouses for pollination. Toxicological risk assessments conducted to determine the likelihood how a given pesticide would impact honey bees primarily consider the survival of adult bees exposed to the pesticide. However, larvae are also exposed to pesticides as their diets can contain contaminated nectar and pollen collected by foragers. To understand the effect of pesticides in greenhouses on honey bee larvae, we investigated the effects of some insecticides used in strawberry greenhouse on A. mellifera larvae, by acute and chronic toxicity bioassay. Commercial formulations were serially diluted from the recommended concentration to 10SUP-6/SUP times. For acute toxicity, 30 μL of desired concentration of pesticides in diet C were fed to the three-day-old larvae. Mortality of larvae was monitored until the 6th day. For chronic exposure of larvae toxicity, residue level concentrations of pesticides were exposed from 2SUPnd/SUP to the 5SUPth/SUP days. Our results show toxicity order of emamectin benzoate, lufenuron, fluxametamide, acequinocyl, and Acetamiprid with LDSUB50/SUB values 0.000, 0.4, 8.1, 10 and 982.3 ㎍/larvae respectively. Among the two pesticides tested chronically, honey bee larvae were highly sensitive to emamectin benzoate that killed more than 50% in the 6SUPth/SUP day at 35, and 73 ppb. These results show that exposure of larvae to emamectin benzoate results in negative effects on the survival of bees, possibly compromising the dynamics of the colony, contributing to the decline of bee populations.

A mechanism-based approach unveils metabolic routes potentially mediating chlorantraniliprole synergism in honey bees, Apis mellifera L., by azole fungicides.

BACKGROUNDAlmond production in California is an intensively managed agroecosystem dependent on managed pollination by honey bees, Apis mellifera L. A recent laboratory study reported synergism in honey bees between chlorantraniliprole, a common diamide insecticide used in almond orchards, and the fungicide propiconazole. Indeed, there is an emerging body of evidence that honey bee cytochrome P450 monooxygenases of the CYP9Q subfamily are involved in the detoxification of insecticides across a diverse range of chemical classes. The objective of the present study was to unveil the molecular background of the described synergism and to explore the potential role of CYP9Q enzymes in diamide detoxification.RESULTSOur study confirmed the previously reported synergistic potential of propiconazole on chlorantraniliprole in acute contact toxicity bioassays, whereas no synergism was observed for flubendiamide. Fluorescence‐based biochemical assays revealed an interaction of chlorantraniliprole, but not flubendiamide, with functionally expressed CYP9Q2 and CYP9Q3. These findings were validated by an increased chlorantraniliprole tolerance of transgenic Drosophila lines expressing CYP9Q2/3, and an analytically confirmed oxidative metabolism of chlorantraniliprole by recombinantly expressed enzymes. Furthermore, we showed that several triazole fungicides used in almond orchards, including propiconazole, were strong nanomolar inhibitors of functionally expressed honey bee CYP9Q2 and CYP9Q3, whereas other fungicides such as iprodione and cyprodinil did not inhibit these enzymes.CONCLUSIONHoney bee CYP9Q enzymes are involved in chlorantraniliprole metabolism and inhibited by triazole fungicides possibly leading to synergism in acute contact toxicity bioassays. Our mechanistic approach has the potential to inform tier I honey bee pesticide risk assessment.

Development of an in vivo acute bioassay using the marine medaka Oryzias melastigma.

To determine whether the marine medaka Oryzias melastigma is a suitable model organism for in vivo acute toxicity bioassay in seawater, we first determined whether there were differences in the concentrations of chemicals that were toxic to marine medaka (O. melastigma) and freshwater medaka (O. latipes). We performed in vivo acute toxicity bioassay with 3-chloroaniline, triclosan, 3,4-dichloroaniline, fenitrothion, and pyriproxyfen on larvae of both species. Although the concentrations of 3-chloroaniline and fenitrothion that were lethal to the larvae were identical for both species, the toxic concentrations of triclosan, 3,4-dichloroaniline, and pyriproxyfen were lower for O. melastigma than for O. latipes. We then used an in vivo acute toxicity bioassay to monitor the quality of coastal seawater in Akita, Japan. No lethal effects were observed in the harbor and canal in 2019. O. melastigma could be used to monitor the quality of seawater with salinities in the range 2-25. Our findings suggest that O. melastigma can be used as the test fish for in vivo acute toxicity bioassay intended for water quality monitoring.

Cellular Responses Induced by Zinc in Zebra Mussel Haemocytes. Loss of DNA Integrity as a Cellular Mechanism to Evaluate the Suitability of Nanocellulose-Based Materials in Nanoremediation.

Zinc environmental levels are increasing due to human activities, posing a threat to ecosystems and human health. Therefore, new tools able to remediate Zn contamination in freshwater are highly recommended. Specimens of Dreissena polymorpha (zebra mussel) were exposed for 48 h and 7 days to a wide range of ZnCl2 nominal concentrations (1–10–50–100 mg/L), including those environmentally relevant. Cellulose-based nanosponges (CNS) were also tested to assess their safety and suitability for Zn removal from freshwater. Zebra mussels were exposed to 50 mg/L ZnCl2 alone or incubated with 1.25 g/L of CNS (2 h) and then removed by filtration. The effect of Zn decontamination induced by CNS has been verified by the acute toxicity bioassay Microtox®. DNA primary damage was investigated by the Comet assay; micronuclei frequency and nuclear morphological alterations were assessed by Cytome assay in mussels’ haemocytes. The results confirmed the genotoxic effect of ZnCl2 in zebra mussel haemocytes at 48 h and 7-day exposure time. Zinc concentrations were measured in CNS, suggesting that cellulose-based nanosponges were able to remove Zn(II) by reducing its levels in exposure waters and soft tissues of D. polymorpha in agreement with the observed restoration of genetic damage exerted by zinc exposure alone.

Acartia tonsa Dana 1849 as a Model Organism: Considerations on Acclimation in Ecotoxicological Assays.

The copepod Acartia tonsa was standardized as model organism in acute toxicity bioassays due to its key position in coastal food chains and high sensitivity. Once bioassays are performed according to a protocol their results may become tools for the protection of aquatic ecosystems. However, there are divergences in bioassays methods using A. tonsa. This study aimed to investigate: (i) the need for acclimation of A. tonsa collected from the environment for use in acute toxicological bioassays; and (ii) differences in sensitivity between copepods collected from the environment and laboratory-grown copepods. Laboratory-grown copepods are more sensitive to SDS thanA. tonsa from theenvironment. The acclimation time of 30h helped organisms to recover from stress of collection/handling and changing environment/conditions. Therefore, laboratory-grown copepods showed to be more sensitive than organisms from environment; and for ecotoxicological bioassays acclimating A. tonsa collected from the environment for 30h can be adopted.

Effects of spirotetramat insecticide on life history traits and population growth of Encarsia formosa (Hymenoptera: Aphelinidae)

ABSTRACT Sublethal effects of a spirotetramat insecticide on life history traits and population growth of two local Serbian populations (Bujanovac and Negotin) and one commercial Dutch population (the Dutch strain) of Encarsia formosa Gahan (Hymen.: Aphelinidae) were evaluated in laboratory bioassays. Median lethal concentrations of spirotetramat estimated in the acute toxicity bioassay with adults (250 mg/l for Bujanovac and Negotin populations, and 225 mg/l for the Dutch population), significantly reduced the longevity of adult wasps exposed for 48 h to fresh residues by 1.6–2.8 days. Total parasitism of exposed adults, adult emergence in the F1 generation, and the instantaneous rate of increase of surviving wasp populations were significantly reduced (<30%). When applied to pupae within parasitised hosts (at LC50s estimated in the acute toxicity bioassay with pupae; 700 mg/l for Bujanovac and 600 mg/l for the Negotin and Dutch populations), the spirotetramat significantly extended the development of juveniles (by 1–1.4 days), and significantly reduced longevity (by 0.7 days) and the instantaneous rate of increase for the Bujanovac wasps, by 6.1%. According to the estimated acute toxity for both adults and pupae of E. formosa and taking into account the reduction of reproductive and demographic parameters (<30% in bioassays with adults and <10% in bioassays with pupae), spirotetramat can be classified as compatible with E. formasa in integrated whitefly management.

Simultaneous electrochemical detection of ciprofloxacin and Ag(I) in a silver nanoparticle dissolution: Application to ecotoxicological acute studies

The combination of the indiscriminate use of antibiotics such as ciprofloxacin (CIP) and the recent use of biocides such as silver nanoparticles (AgNPs) that are eventually disposed of in the environment can negatively impact on aquatic biota. This work aims to develop a simple electrochemical method to detect CIP, AgNPs, and their mixtures (CIP–AgNPs) concentrations and to correlate them with the ecotoxicological effects in acute toxicity bioassays (48 h) using the microcrustacean Ceriodaphnia dubia as a test organism. The simultaneous electrochemical detection of CIP and Ag(I) in AgNP dissolution was performed by square wave anodic stripping voltammetry (SWASV) using a bismuth film electrode (BiFE). The analytical performance in the linear range was from 8 to 200 ng L−1 (R2 = 0.993) for CIP and from 104 to 3300 ng L−1 (R2 = 0.995) for Ag(I). The limits of detection (LODs) were 3 and 34 ng L−1 for CIP and Ag(I), respectively. The method was applied to the measurements of Ag(I) in the supernatant of AgNP suspensions and the study of the stability of CIP and Ag(I) from AgNPs during acute tests of C. dubia at 48 h. The median lethal concentration (LC50) of C. dubia in the presence of CIP, AgNPs, and CIP–AgNPs was calculated, and the toxicity decreased as follows: AgNPs > CIP–AgNP mixture > CIP. The lower toxicity of AgNPs in mixture with CIP could be explained by the complexation of metal ions with quinolones, decreasing their interaction with the test organisms. The stabilities of CIP and Ag(I) from AgNPs in ecotoxicology assays were estimated by measuring their concentrations by SWASV, and their values ranged from 80% to 120% from the nominal values, according to the OECD recommendation. As a perspective, the results of the work showed that the simultaneous use of stripping voltammetry and toxicity tests could be applied to the study of natural water samples and potentially to the monitoring of environmental quality. The relevance of electrochemical and ecotoxicology approaches as useful tools to contribute knowledge to preserve environmental health is highlighted.

Prescribing sea water quality criteria for arsenic, cadmium and lead through species sensitivity distribution

Water quality standards are essential for regulation of contaminants in marine environment. Seawater quality criteria (SWQC) for arsenic (As), cadmium (Cd) and lead (Pb) have not been developed for India. The aim of this study is to derive the SWQC for the metals based on Species Sensitivity Distribution (SSD). Eight species of sensitive marine organisms belonging to five phyla were assessed for their sensitivity to toxicity of As, Cd and Pb. Median effective concentrations (EC50) and Median Lethal Concentrations (LC50) were derived from the acute toxicity bio-assays. No Observed Effect Concentrations (NOEC), Lowest Observed Effect Concentrations (LOEC) and chronic values were derived from chronic toxicity bio-assays. Diatoms were more sensitive to As with 96 h EC50 of 0.1 mg/l and copepods were more sensitive to Cd and Pb with 96 h EC50 of 0.019 mg/l and 0.05 mg/l respectively. Estimated NOECs ranged from 4.87 to 21.55 µg/l of As, 1.0 to 120 µg/l of Cd and 5.67 to 91.67 µg/l of Pb. Similarly, chronic values (µg/l) were in the range of 6.71–26.1, 1.38–170, and 7.67–91.67 of As, Cd and Pb respectively. The Criterion Maximum Concentration (CMC), Criterion Continuous Concentration (CCC) and Predicted No Effect Concentration (PNEC) values were prescribed as SWQC. The CMC (µg/l) of 19, 1.7 and 17 for As, Cd, and Pb were derived respectively for acute exposure during accidental marine outfalls. The CCC (µg/l) for As was 4.6, 1.1 for Cd and 5.9 for Pb are recommended as SWQC for protection of 95% of marine organisms. PNEC (µg/l) of 3.8 for As, 0.92 for Cd and 4.3 for Pb are suggested for highly disturbed ecosystems, shell fishing and mariculture uses of water bodies. These values are recommended as a baseline for site specific water quality criteria for the coastal waters of the country.

Application of Dispersive Liquid-Liquid Microextraction Followed by High-Performance Liquid Chromatography/Tandem Mass Spectrometry Analysis to Determine Tetrabromobisphenol A in Complex Matrices.

An accurate and sensitive ultrasound-dispersive liquid-liquid microextraction technique followed by high-performance liquid chromatography separation coupled with electrospray ionization tandem mass spectrometry detection method to determine the presence of tetrabromobisphenol A (TBBPA) in complex environmental matrices is proposed. The miniaturized procedure was used to extract and quantify the analyte in domestic sewage, anaerobic sludge, and the aquatic test organism species Daphnia magna and Chironomus sancticaroli, which are standardized organisms for ecotoxicity bioassays. Limits of detection of 2 ng L-1 (domestic sewage), 2 ng g-1 (anaerobic sludge), 0.25 ng g-1 (D. magna), and 5 ng g-1 (C. tentans) were obtained. The presence of TBBPA was determined in domestic sewage and anaerobic sludge from an anaerobic batch bioreactor at a concentration of 0.2 ± 0.03 μg L-1 and 507 ± 79 ng g-1 , respectively. In D. magna and C. sancticaroli exposed to TBBPA in an acute toxicity bioassay, the micropollutant accumulated at 3.74 and 8.87 μg g-1 , respectively. The proposed method is a simple and cost-effective tool to determine TBBPA environmental occurrence and biomagnification potential compared with conventional extraction methods. To the best of our knowledge, this is the first liquid-liquid miniaturized extraction method to be applied to D. magna and C. sancticaroli. Environ Toxicol Chem 2020;39:2147-2157. © 2020 SETAC.

Biodiscoloration, Detoxification and Biosorption of Reactive Blue 268 by Trametes sp. M3: a Strategy for the Treatment of Textile Effluents

The concern with the environment and the depletion of natural resources has aroused the interest for the rational use and recycling of water. Therefore, this study evaluated the capacity of the Trametes sp. M3 isolate in the bioremediation of Reactive Blue (RB) 268 dye and its potential for use as an adsorbent in the treatment of textile effluents. In a solid medium containing RB 268, the discoloration rate was 1.00 and the growth rate was 1.4 cm/day. When evaluated in the in vivo biodiscoloration process, 100% of the dye lost its color after 120 h. The oxidative enzyme laccase was found in cultures containing the dye with high activity, indicating that it underwent induction. The chromatogram after cultivation of the fungus showed that there was a change in the structure of RB 268. The mycelium of the culture with the dye was analyzed by FTIR, pointing to an adsorption of RB 268 or its metabolites despite the absence of the color. In the biosorption, the best results were obtained when the mycelium was treated with HCl. The toxicity of the medium decreased after the cultivation of the fungus allowing the survival of the microcrustaceans in the acute toxicity bioassay.

IMIDACLOPRID TOXICITY AND ITS ATTENUATION BY AQUEOUS EXTRACT OF MORINGA OLEIFERA LEAF IN ZEBRA FISH, DANIO RERIO

Objective: Imidacloprid (IMC) is a systemic chloro-nicotinyl insecticide that is applied in crop fields to control a wide variety of harmful insects and pests. The objective of the present study was to evaluate the mitigating effects of Moringa leaf extract (MLE) against Imidacloprid (IMC) induced mortality after acute toxicity bioassay in zebrafish, Danio rerio.&#x0D; Methods: The fishes were exposed to various concentrations of IMC to estimate the LC50 values at different exposure periods using the probit analysis.&#x0D; To assess the attenuating effect on mortality fishes were exposed to different concentrations of MLE along with 24 and 96 h LC50 of IMC. Mortality rate of fishes was recorded during all experimental periods.&#x0D; Results: The LC50 values were found to be 0.423, 0.352, 0.297 and 0.270 ml/l after 24, 48, 72 and 96 h respectively. The upper confidence limits were 0.491, 0.408, 0.334 and 0.302 ml/l and lower confidence limits were 0.355, 0.296, 0.260 and 0.238 ml/l for 24, 48, 72 and 96 h respectively.&#x0D; The fishes remain alive at 12 ml/l and 10 ml/l of MLE against 24 and 96 h LC50 respectively. Some behavioral responses such as violent, sluggish and erratic movement, respiratory distress, mucous secretion all over the body, discoloration were also observed in IMC treated fishes in comparison to MLE treated fishes.&#x0D; Conclusion: These findings demonstrated that MLE has mitigating effects against the toxic influence of IMC on mortality in zebra fishes which is attributed to its antioxidant effects.

Comparison of acetaminophen degradation in UV-LED-based advance oxidation processes: Reaction kinetics, radicals contribution, degradation pathways and acute toxicity assessment

Ultraviolet light emitting diode (UV-LED)-based advanced oxidation processes (AOPs) including UV-LED/chloramine (UV-LED/NH2Cl), UV-LED/hydrogen peroxide (UV-LED/H2O2) and UV-LED/persulfate (UV-LED/PS), were adopted for acetaminophen (AAP) removal. Results showed that AAP could be effectively degraded by the hybrid processes compared to solely using with UV irradiation and oxidants. The AAP degradation in the three UV-LED-based AOPs were in the order of UV-LED/PS > UV-LED/H2O2 > UV-LED/NH2Cl and followed a pseudo-first-order kinetics. The degradation rate constant (kobs) increased with increasing oxidant dosage, whereas overdosing lowered the AAP degradation. The second-order rate constants of HO, SO4−, and Cl with AAP were calculated as 5.15 × 109, 7.66 × 109 and 1.08 × 1010 M−1 s−1, respectively. Under neutral conditions, the contributions of UV-LED, HO, and Cl to AAP degradation were 4.21%, 60.15% and 35.64% in the UV-LED/NH2Cl system, whereas the respective contributions of UV-LED, HO and SO4− to AAP degradation were 2.09%, 22.84% and 75.07% in UV-LED/PS system, respectively. Meanwhile, the corresponding contributions of the involved reactive species were found to be pH-dependence. The natural organic materials (NOM) inhibited the AAP degradation, and the presence of Cl−, HCO3−, and NO3− had different effects on AAP degradation in the three hybrid processes. The AAP degradation was significantly inhibited in the three UV-LED-based AOPs in real water. In addition, the intermediate products were also identified, and possible degradation pathways were proposed in the three UV-LED-based AOPs. The acute toxicity bioassay using bacterium Vibrio fischeri suggested that the UV-LED/PS process was more effective than the UV-LED/H2O2 and UV-LED/NH2Cl processes in reducing the acute toxicity of the reacted AAP solution. Among the three UV-LED-based AOPs, the UV-LED/PS was found to be the most efficient process for AAP degradation.

New aluminum mesh from recyclable material for immobilization of TiO2 in heterogeneous photocatalysis

AbstractThis study presents a new aluminium mesh made out of soda can rings as a support for titanium dioxide (TiO2) in the degradation of the synthetic dyes Bordeaux Red (BR) and Tartrazine (TT). Three pre‐treatments including calcination and acidification steps were investigated in order to select the most efficient immobilization procedure for photocatalysis application. Raw and titania‐aluminum meshes were characterized by scanning electron microscopy, x‐ray diffraction, diffuse reflectance, and Fourier transform infrared spectroscopy. The material presented itself as a suitable alternative in the immobilization of titania for wastewater treatment. Preliminary tests selected H2O2/TiO2(suspension) oxidation systems under natural sunlight and germicidal lamps (UVC) exhibiting 97.2% and 99.5% of degradation in 180 minutes, respectively. Immobilized TiO2 systems reached high degradation rates (&gt;99%) after 180 minutes in both UVC and solar light‐based processes. An experimental planning study was carried out for the processes in order to find the best operational conditions and pseudo‐first‐order model fit well the removal data (discolouration rates of in the order of 0.0274 and 0.0145 min−1 for UVC and solar light systems, respectively). Parameters such as TOC, COD, and turbidity, revealed a great improvement in the environmental quality of the water after the treatment and acute toxicity bioassays demonstrated a significant decrease in toxicity for both systems after the treatments. The TiO2‐meshes demonstrated high performance in the removal after five cycles of operation. Therefore, the new immobilization procedure demonstrated that the TiO2‐aluminum mesh is a feasible option for wastewater treatment and photocatalysis.

Seasonal variations in the dose-response relationship of acetylcholinesterase activity in freshwater fish exposed to chlorpyrifos and glyphosate

The herbicide glyphosate [N- (phosphonomethyl) glycine; PMG] and the insecticide chlorpyrifos [O, O-diethyl O- (3,5,6-trichloro-2-pyridinyl) -phosphorothioate, CPF] are widely used in agricultural practices around the world and can reach aquatic environments. Therefore, it is necessary to characterize the toxicity of these pesticides on non-target species. The use of biomarkers as a tool to assess responses of organisms exposed to pollutants requires the understanding of their natural fluctuation and the dose-response relationship. In the present work, the effect of the exposure to PMG and CPF on the acetylcholinesterase activity (AChE, biomarker of neurotoxicity) in Cnesterodon decemmaculatus, a native teleost, was evaluated in different environmental conditions. Semi-static bioassays of acute toxicity were carried out under controlled conditions during the four weather seasons of the year using animals of homogeneous size. Circannual rhythms in the basal levels of AChE activity in homogenates of the anterior section were confirmed. Statistically significant average inhibition of AChE activity (47.1 ± 0.7% for 1 μg CPF × L−1; 69.7 ± 2.5% for 5 μg CPF × L−1; 23.1 ± 1.1% for 1 mg PMG × L−1 and 32.9 ± 3.3% for 10 mg PMG × L−1) was determined during summer, winter and spring weather seasons. Interestingly, animals exhibit an increased susceptibility to exposure during the autumn season (inhibition of 55.4 ± 0.6% for 1 μg CPF × L−1; 81.9 ± 3.3% for 5 μg CPF × L−1; 41.4 ± 1.7% for 1 mg PMG × L−1 and 61.1 ± 0.3% for 10 mg PMG × L−1). A different sensitivity of the enzyme between seasons was evaluated by in vitro tests. The inhibition pattern for chlorpyrifos-oxon (CPF-oxon, the active metabolite of CPF) was not affected when test was performed using homogenates of unexposed specimens of summer or autumn. Otherwise, PMG in vitro inhibitory effect was not observed in a wide range of concentrations.The results confirm that AChE activity is a sensitive biomarker for exposure to CPF and PMG, even at environmentally relevant concentrations. Finally, this work highlights the existence of seasonal variations in the dose-response relationship, which could be due to variations in the metabolism of the pollutants.

Effects of Lambda Cyhalothrin on the behaviour and histology of gills of Sarotherodon melanotheron in brackish water

Abstract Pyrethroids like Lambda Cyhalothrins, are synthetic insecticides that contaminate and modify the physico-chemical integrity of receiving water bodies and are toxic to the resident life forms. When applied at a given site may find their way into natural water bodies through leaching, precipitation, percolation, drift, or runoff. The aim of this study was to determine the acute toxicity, behavioural effects and histopathological effects on gills of Sarotherodon melanotheron exposed to Lambda Cyhalothrin (LCT) in brackish water. Four hundred and sixty (460) fingerlings of Sarotherodon melanotheron (mean length – 8.0 cm) and (mean body weight – 8.9 g) were exposed to various concentrations (3, 5, 7, 9, 11 and 13 mg/L) of a pyrethroid insecticide – Lambda Cyhalothrin in brackish water in the Marine Pollution Monitoring Laboratory in the University of Port Harcourt, Nigeria. An acute toxicity bioassay (96 h) was carried out to determine the LC50 of the toxicant. The histopathological effects of the toxicant on the gills and behaviour of fish were recorded. Physico-chemical parameters of the test solution were measured. At the end of the test period, fish from each concentration was dissected and the gills removed for histological studies following standard methods. The results revealed a 96 h LC50 of 9 mg/L. The behavioural-somatic responses include: erratic swimming, surfacing, hyperventilation, loss of reflex, skin (scale) discolourations, caudal bending, etc. These aberrations were seen to have increased with corresponding increase in the concentrations of the toxicant and length of exposure. There were pathological alterations such as cellular infiltrations, fusion of the lamellar, hyperplasia, tissue inflammations, vacuolation, tissue degeneration and necrosis that appeared more severe with increasing concentrations. The observed behavioural and histopathological alterations at the various test concentrations were indications that the toxicant may have impaired their normal physiological integrity. The findings also showed that LCT although toxic to Sarotherodon melanotheron in brackish water, required high concentrations. The use of LCT in brackish water, fish farms or zones close to aquatic water systems should be discouraged.

Acute and sub-chronic toxicity bioassays of Olive Mill Wastewater on the Eastern mosquitofish Gambusia holbrooki

Olive oil production generates large volumes of wastewaters mostly in peri-Mediterranean countries with adverse impacts on the biota of the receiving aquatic systems. Few studies have however documented its toxicity on aquatic species, with an almost total lack of relative studies on fish. We assessed the acute and sub-chronic OMW toxicity, as well as the acute and sub-chronic behavioural, morphological and biochemical effects of OMW exposure on the mosquitofish Gambusia holbrooki. LC50 values of the acute bioassays ranged from 7.31% (24 h) to 6.38% (96 h). Behavioural symptoms of toxicity included hypoactivity and a shift away from the water surface, coupled with a range of morphological alterations, such as skin damage, excessive mucus secretion, hemorrhages, fin rot and exophhalmia, with indications also of gill swelling and anemia. Biochemical assays showed that OMW toxicity resulted in induction of catalase (CAT) and inhibition of acetylcholinesterase (AChE) activities. The implications of our results at the level of environmental policy for the sustainable management of the olive mill industry, i.e. the effective restriction of untreated OMW disposal of in adjacent waterways, as well as the implementation of new technologies that reduce their impact (detoxification and/or revalorization of its residues) are discussed.

Toxicity assessment of arsenic on common carp (Cyprinus carpio) and development of natural sorbents to reduce the bioconcentration by RSM methodology

The objective of the present study was firstly acute toxicity bioassay of arsenic on common carp (Cyprinus carpio) and then the development of natural sorbent beds (clinoptilolite and pumice) to reduce bioconcentration of arsenic in muscle tissue were considered in comparative evaluation. In this regard, the acute toxicity of arsenic on juvenile fish was assessed according to the OECD guideline (No. 203). Moreover, the efficacy of clinoptilolite and pumice as natural sorbents was assessed to reduce bioconcentration of arsenic in the fish muscle tissue during a 21 day by response surface methodology (RSM) under central composite design (CCD). The most important point of this study was to evaluate the interactions between independent variables (clinoptilolite and pumice as sorbents and arsenic as pollutant) and arsenic bioconcentration in fish muscle tissue as a dependent variable (response). In these regards, a total of 24 sets of experiments (12 sets for clinoptilolite and pumice separately) were designed by the software to achieve the best adsorption conditions. According to the arsenic toxicity test, results as estimated by Probit method, the 96 h LC50 was 9.48 ± 1.01 mg/L. Analysis of variance (ANOVA) which was applied to modeling and optimization of response revealed that the predicted values were in relatively good agreement with the experimental data. Additionally, the obtained value for model desirability by clinoptilolite and pumice were 0.932 and 0.958, respectively. Overall, the obtained results indicate that both adsorbents reduced the bioconcentration of As (V) in the muscle tissue of common carp, but clinoptilolite was more effective.

Toxic and sublethal effects of buprofezin on the whitefly parasitoid Encarsia formosa Gahan

Acute toxicity of a buprofezin-based product (commercial product Elisa 440 SC) to pupae of the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae), and its effects on life history traits and population growth in F1 generation of a commercial strain (?Dutch? strain, D) and two local populations from Serbia (Bujanovac, B; Negotin, N) were examined in laboratory bioassays. All trials were carried out at 27?1?C temperature and 60?10% relative humidity, and under 16/8 h daylight/darkness photoperiod in four replications. In an acute toxicity bioassay, tobacco leaves carrying parasitoid pupae (20 pupae per replicate) were treated with a series of buprofezin concentrations covering a 10-90% mortality range, and mortality was calculated based on the number of emerging adults 9 days after treatment. The following LC50 (mg/l) estimates were obtained: 244.2, 281.5 and 199.5 (for B, N and D, respectively). The product based on buprofezin, applied to parasitoid pupae at concentrations within the LC50s and 95% confidence limits (264 mg/l for B and N; 220 mg/l for D), significantly prolonged the duration of juvenile development (2, 1.7 and 2.2 days for B, N and D, respectively, compared to control data). Females from all tested populations that emerged from the treated pupae and were exposed to the residual action of buprofezin lived shorter than control females (B, N and D by 1.5, 0.7 and 1.7 days, respectively). Also, females that emerged from the treated pupae achieved a significantly reduced level of parasitism (B, N and D by 11.7, 17.7 and 17.6 %, respectively), total adult emergence (B, N and D by 11.6, 17.8 and 17.8 %, respectively) and instantaneous rate of increase (B, N and D by 8.2, 6.8 and 12.5 %, respectively), compared to control. More precise determination of risks involved in the use of buprofezin requires its more detailed field testing.

Histological, Genotoxic, and Biochemical Effects on Cnesterodon decemmaculatus (Jenyns 1842) (Cyprinodontiformes, Poeciliidae): Early Response Bioassays to Assess the Impact of Receiving Waters.

In the present study, the toxicity of receiving waters from a highly polluted urban watercourse, the Reconquista River, Argentina, collected at a dam in the upstream part of the river was evaluated. Cnesterodon decemmaculatus, a widely distributed fish species in Pampasic rivers proposed for use in ecotoxicological evaluations, was used as a test organism. A 96-h acute toxicity bioassay with river water quality which has been characterized as moderately contaminated was performed. The treatment groups were (1) whole surface river water; (2) whole surface river water with 2 mg Cd/L added as a simulated metal contaminant pulse; (3) a negative control using reconstituted moderately hard water (MHW); (4) a metal positive control, MHW + 2 mg Cd/L; and (5) a positive genotoxicity control, MHW + 5 mg Cyclophosphamide/L (CP). The condition factor rate, micronuclei frequency, and comet assay from peripherical blood, structural changes of the gill arrangement by scanning electron microscope (SEM) analysis, histopathological changes in the liver and the glutathione-S-transferase, catalase, superoxide dismutase, glutathione, and protein content from the body midsection (viscera) were evaluated. According to our results, for short term exposure, SEM analyses of gills and liver histopathological analyses could be useful tools for the evaluation of target organ damage as well as comet assays for DNA damage. We propose that the 96-h laboratory bioassay protocol described is useful for monitoring the deterioration of water quality employing the teleost C. decemmaculatus and that the microscope analysis of gills and liver as well as the comet assay methodology could be sensitive endpoint indicators.

Optimization of microorganism preservation conditions for the development of an acute toxicity bioassay for biocides

Biocides, also referred to as ‘microbicides’ or ‘inhibitors’, are widely used in industrial processes (e.g. utility water in cooling towers) to control and/or eliminate the growth of microorganisms. Because of their inherent toxicity, their presence in various sources (e.g. river sediments, potable water) can negatively affect ecosystems. Currently available biocide detection techniques are not suitable for ‘point-of-use’ applications since they are tedious, complicated, and often require experienced personnel to operate. To address this concern, we sought to develop a simple-to-use toxicity bioassay based on a model microorganism (E. coli) after short (<30 min) exposure to known biocides that can be stored at room temperature (preferably) or in the fridge. Based on recent work and our expertise in polymer-based preservation of biomolecules, we leveraged this knowledge to improve E. coli preservation for biocide detection purposes. A design-of-experiments strategy was used to evaluate 16 different preservation conditions from 5 process parameters (i.e. 25−1 fractional factorial). It was found that pullulan, a sugar-based polymer, improved E. coli culturability by an order of magnitude after three months of storage. Also, it was found that storing E. coli in the fridge in Milli-Q water was favorable for maintaining a high level of culturability. Finally, the toxicity of three common biocides (Cetyltrimethylammonium bromide (CTAB), ProClin™ 300, and Grotan® BK) was evaluated using a fluorescence-based assay across all 16 preservation conditions. The response of the preserved E. coli was biocide specific and at certain conditions did not vary during the entire three-month storage period.