Chronic toxicity of tire and road wear particles to water- and sediment-dwelling organisms

Tire and road wear particles (TRWP) consist of a complex mixture of rubber, and pavement released from tires during use on road surfaces. Subsequent transport of the TRWP into freshwater sediments has raised some concern about the potential adverse effects on aquatic organisms. Previous studies have shown some potential for toxicity for tread particles, however, toxicity studies of TRWP collected from a road simulator system revealed no acute toxicity to green algae, daphnids, or fathead minnows at concentrations up to 10,000 mg/kg under conditions representative of receiving water bodies. In this study, the chronic toxicity of TRWP was evaluated in four aquatic species. Test animals were exposed to whole sediment spiked with TRWP at concentrations up to 10,000 mg/kg sediment or elutriates from spiked sediment. Exposure to TRWP spiked sediment caused mild growth inhibition in Chironomus dilutus but had no adverse effect on growth or reproduction in Hyalella azteca. Exposure to TRWP elutriates resulted in slightly diminished survival in larval Pimephales promelas but had no adverse effect on growth or reproduction in Ceriodaphnia dubia. No other endpoints in these species were affected. These results, together with previous studies demonstrating no acute toxicity of TRWP, indicate that under typical exposure conditions TRWP in sediments pose a low risk of toxicity to aquatic organisms.     

Transfer modelling and toxicity evaluation of the effluent from an installation of cleansing and uranium recovery using a battery of bioassays

On July 7, 2008, a leak of effluent from an Installation of Cleansing and Uranium Recovery (Tricastin, France) led to the spillage of uranium in a stream. The acute toxicity of the effluent was evaluated, and compared to the toxicity of uranium nitrate in bioassays using several organisms: Chlamydomonas reinhardtii, Daphnia magna, Chironomus riparius and Danio rerio. A sediment bioassay was also performed on C. riparius using water and sediment sampled along the river. Results showed that effluent EC₅₀ 72 h was 0.65 mg U/l for algae and LC₅₀ 48 h was 1.67 mg U/l for daphnia, while values obtained for uranium nitrate were higher. The LC₅₀ 96 h of effluent to C. riparius was 22.7 mg U/l, similar to value for uranium nitrate; the sediment collected was not toxic to C. riparius larvae. The LOEC of effluent and uranium nitrate on HT₅₀ of D. rerio were similar (0.03 mg U/l), but larvae were more sensitive to uranium nitrate than to effluent. Our results suggest that other substances contained in the effluent could potentially be toxic to wildlife in association with uranium. In parallel, the modelling of the transfers based on uranium measurements in the surface water was used to fill data gaps and assess the impact along the river. These results provided an estimate of exposure conditions that occurred along the river. This approach allowed us to see that the risk to ecosystem during this incident was certainly low and concerned a short period of time, but it could have existed at least for some species.     

Classificatory and quantitative models of the relationship between the structures of chemical compounds and their toxicity for <Emphasis Type="Italic">Daphnia magna</Emphasis>

A structural similarity method was used to construct stable classificatory models for discriminating compounds with mechanisms of general toxicity to Daphnia magna compared with all other compounds with different actions, compounds with the polar narcosis mechanism compared with all others, compounds inhibiting cholinesterase compared with compounds with other mechanisms, and compounds with general toxic actions compared with substances with the polar narcosis mechanism. Simultaneous use of the classificatory and regression models allowed clear identification of substances acting via the general toxicity mechanism, with quantitative assessments of LC₅₀ values and analysis of contributions of steric interactions and hydrogen bonds to toxicity. Our own experimental data on the toxicities (LC₅₀) of 119 chemical compounds with different types of toxic actions to Daphnia magna are presented. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 42, No. 6, pp. 22–27, June, 2008.     

Toxicity analysis of leachates from hazardous wastes via microtox and daphnia magna

One of the most common ways of surface and ground water contamination from hazardous wastes is through its leachates. Toxicity is a meaningful parameter allowing an integrated evaluation of the potential danger of leachates. Two bioassays were considered for measuring toxicity: Microtox and Daphnia magna. The toxicity was measured on leachates obtained, using different leaching procedures, from wastes of a pesticide manufacturing industry and sludge from electroplating wastewater. Twenty-two tests were carried out, measuring IC50 for D. magna and EC50 for Microtox. Both bioassays were compared using three toxicity criteria. The first criterium is classification on toxic/non-toxic at 25 and 50% leachate concentration. The second criterium is classification on percent ranks, and the third on log ranks. Considering these criteria, the agreement between both bioassays is within a 75–85%. It is shown that both, Microtox and D. magna assays could be used as toxicity indicators for the wastes considered. The sensitivity of the bioassays is different depending on leachate composition. In all samples, the leachate concentration of chemicals was measured.     

Acute toxicity to Daphnia magna of effluents containing Cd,Zn, and a mixture Cd‐Zn,after metal removal by Chlorella vulgaris

Daphnia magna was used as a test organism for assessing the toxicity remaining in simulated effluents containing cadmium, zinc, and a cadmium‐zinc mixture, after these metals were removed with suspended and immobilized Chlorella vulgaris cultures. The percentage of removal was higher (84.7%) for cadmium in the metal mixture with immobilized cultures. The LC₅₀ value was lower for the residual cadmium (single and in the mixture) in the effluent after treatment with suspended cultures. The acute toxicity response observed in D. magna, indicates that zinc has an antagonistic effect on cadmium toxicity. According to the results, the treatment system can modify the Cd acute residual toxicity. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 160–164, 2000<     

Differentiation of the toxicities of silver nanoparticles and silver ions to the Japanese medaka (Oryzias latipes) and the cladoceran Daphnia magna

Abstract

Silver nanoparticles (AgNPs) are increasingly used in various fields. However, little is known about the environmental effects of widespread use of products containing AgNPs. The objective of this study was to determine the ecotoxicity caused by AgNPs. The 48-h effective concentration 50 (EC₅₀) values for Daphnia magna of suspensions of 60 nm and 300 nm AgNPs were 1.0 (95% confidence interval [CI] = 0.1–1.3) and 1.4 (95% CI = 0.3–2.1) μg Ag/l, respectively. The 96 h LC₅₀ values for Oryzias latipes of 60 nm and 300 nm AgNP suspensions were 28 (95% CI = 23–34) and 67 (95% CI = 45–108) μg Ag/l, respectively. To show that toxicity is caused only by Ag⁺ and not by AgNPs, Ag⁺ was adsorbed onto the synthesized sorbents packed in a column and D. magna was exposed to the column-passed-300 nm AgNP suspensions. There was no acute toxicity with the AgNP suspensions not containing Ag⁺.     

Toxicity assessment of Tehran water treatment sludges using bioassay tests

The 48-, 72- and 96-h acute toxicity and 14-d chronic toxicity of the sludge of treatment plant No. 1, 3 and 5 were examined based on the survival percentage and fertility changes of Daphnia magna and Eisenia fetida. The highest percentage of D. magna death in the acute toxicity test appeared in treatment plant No. 1 sludge sample. The 48-h and 72-h LC₅₀ of treatment plant No. 1 sludge on D. magna were calculated to be 86.81 and 44.307% volume of the sludge, respectively. The release of untreated sludge into the environment could adversely affect the life of organisms.     

Predicting toxicity in marine sediment in Taranto Gulf (Ionian Sea,Southern Italy) using Sediment Quality Guidelines and a battery bioassay

The goal of this study was to assess coastal marine pollution in the Mar Piccolo and Taranto Gulf (Ionian Sea, Southern Italy) by combining chemical and toxicological data in order to compare and integrate both approaches. Pollutants levels, traditionally, have limited ability to predict adverse effects on living resources. Moreover, in order to provide information on the ecological impact of sediment contamination on aquatic biota Numerical Sediment Quality Guidelines (SQGs) and sediment toxicity bioassays were carefully recommended. In this study ERL (effect range low)/ERM (effect range medium value) and TEL (threshold effect level)/PEL (probable effect level) guidelines have been used. Bioassays were performed with two species of amphipods Gammarus aequicauda and Corophium insidiosum, one species of isopod Idotea baltica and bivalve Mytilus galloprovincialis larvae. The TEL/PEL analysis suggested that, especially for stations 1 and 2, sediments in Mar Piccolo should contain acutely toxic concentrations of metals. In particular Hg content, in station 1, was about 17 times PEL value. 96 h LC₅₀ and 48 h EC₅₀ values were estimated for cadmium, copper and mercury in these species using the static acute toxicity test. M. galloprovincialis larvae was more sensitive than other species to all the reference toxicants tested (EC₅₀ determined for cadmium copper and mercury were of 0.59, 0.11 and 0.01 mg/l respectively). Significant differences in sensitivity of species tested to all reference toxicants (ANOVA p < 0.001) were recorded. Bioassays with these species allowed to estimated sediment toxicity from the different studied sites. On the basis of results obtained a good agreement was reported between chemical data and response of the biological endpoints tested.     

Acute lethal toxicity of hydrocarbons and chlorinated hydrocarbons to two planktonic crustaceans: The key role of organism-water partitioning

The acute toxicities of 38 hydrocarbons and chlorinated hydrocarbons were determined for two planktonic crustaceans, freshwater Daphnia magna and saltwater Artemia. In both cases median lethal concentrations (LC₅₀ values) at 48 h and 24 h, respectively, were strongly correlated with aqueous solubility, there being little direct dependence on chemical structure. In the case of solid chemicals, it is suggested that the appropriate correlating solubility is that of the subcooled liquid chemical, not that of the solid. Many solids constrained by low water solubility are thus unable to achieve dissolved concentrations sufficient to cause acute toxicity to the test organisms. It is hypothesised that acute toxicity is non-selective and is controlled by organism-water partitioning so that each hydrocarbon group may contribute equally to toxicity and no single group of hydrocarbons is the dominant toxicant.The partitioning characteristics are expressed in two mathematical models which relate the LC₅₀ to the chemical properties of solubility and molar volume.     

The effects of elutriates from PAH and heavy metal polluted sediments on Crassostrea gigas (Thunberg) embryogenesis,larval growth and bio-accumulation by the larvae of pollutants from sedimentary origin

The release, bio-availability and toxicity of contaminants, when sediments are resuspended have been examined, studying concurrently their effects on the embryogenesis and on the larval growth of the Crassostrea gigas larvae and their bio-accumulation in those organisms. Three characteristic sediments have been selected (one contaminated by PAHs, a second by heavy metals and the last by the both pollutants). The organisms were directly exposed to elutriates obtained from each sediment or fed on algae (Isochrysis galbana) contaminated with the same elutriates. The elutriates used in this study show contamination levels similar to those observed in some polluted coastal and estuary environments. The larval growth test has appeared to be more sensitive that the embryotoxicity test. The biological effects and the contaminant bio-accumulation were more pronounced when larvae were directly exposed to different elutriates. In the case of PAHs, the contamination of algae was sufficient to lead to effect on the larval growth of the Crassostrea gigas. In all cases, a fraction of contaminants adsorbed on suspended particles was bio-available and accumulated by the larvae. This study has shown that resuspending polluted sediments constitutes a threat to pelagic organisms and than the C. gigas larval growth may be proposed as a test to protect the most sensitive areas.     

Ecotoxicity and Environmental Risk Assessment of Larvicides Used in the Control of Aedes aegypti to Daphnia magna (Crustacea,Cladocera)

Dengue transmitted by mosquitoes of the genus Aedes, species aegypti, is a major public health concern in Brazil. The chemical control of the mosquito larvae has been performed with the larvicide temephos since 1967. However, vector resistance was reported to temephos in several Brazilian states, and the Ministry of Health ordered the replacement of this larvicide by diflubenzuron (DFB), an inhibitor of chitin synthesis. Both insecticides are diluted in water with larvae and are able to reach aquatic environments in which they subsequently adversely damage nontarget organisms. The aims of this study were to (1) determine the acute toxicity (EC50) and environmental risk (RQ) of DFB and temephos to the microcrustacean Daphnia magna, and (2) evaluate the chronic toxicity (no-observed-effect concentration [NOEC] and lowest-observed-effect concentration [LOEC]) of these larvicides to D. magna. The experiments were performed according to a completely randomized design. The estimated 48-h EC₅₀ of temephos was 0.15 μg/L (lower limit = 0.1 and upper limit = 0.2 μg/L) and the 48-h EC₅₀ of DFB was 0.06 μg/L (lower limit = 0.03 and upper limit = 0.1 μg/L). RQ values were 4.166.7 to DFB and 6.666.6 to temephos. NOEC and LOEC values were respectively 2.5 and 5 ng/L for DFB, and respectively 6.2 and 12.5 ng/L for temephos. Thus, temephos and DFB are classified as highly toxic to Daphnia magna and pose a high environmental risk to this species. Mortality of D. magna was observed at concentrations lower than those used in the field to control A. aegypti larvae.     

The mysid <Emphasis Type="Italic">Siriella armata</Emphasis> as a model organism in marine ecotoxicology: comparative acute toxicity sensitivity with <Emphasis Type="Italic">Daphnia magna</Emphasis>

Siriella armata (Crustacea, Mysidacea) is a component of the coastal zooplankton that lives in swarms in the shallow waters of the European neritic zone, from the North Sea to the Mediterranean. Juveniles of this species were examined as standard test organisms for use in marine acute toxicity tests. The effects of reference toxicants, three trace metals (Copper, Cadmium and Zinc), and one surfactant, sodium dodecyl sulfate (SDS) were studied on S. armata neonates (<24 h) reared in the laboratory. Acute toxicity tests were carried out with filtered sea water on individual chambers (microplate wells for metals or glass vials for SDS) incubated in an isothermal room at 20°C, with 16 h light: 8 h dark photoperiod for 96 h. Each neonate was fed daily with 10–15 nauplii of Artemia salina. Acute (96 h) LC₅₀ values, in increasing order, were 46.9 μg/L for Cu, 99.3 μg/L for Cd, 466.7 μg/L for Zn and 8.5 mg/L for SDS. The LC₁₀, NOEC and LOEC values were also calculated. Results were compared with Daphnia magna, a freshwater cladoceran widely used as a standard ecotoxicological test organism. Acute (48 h) LC₅₀ values were 56.2 μg/L for Cu, 571.5 μg/L for Cd, 1.3 mg/L for Zn and 27.3 mg/L for SDS. For all the reference toxicants studied, the marine mysid Siriella armata showed higher sensitivity than the freshwater model organism Daphnia magna, validating the use of Siriella mysids as model organisms in marine acute toxicity tests.     

Effect of culture conditions and mother’s age on the sensitivity of Daphnia magna Straus 1820 (Cladocera) neonates to hexavalent chromium

Daphnia magna is a freshwater cladoceran used worldwide as test organism in aquatic toxicity assays. In Mexico there is a test protocol for this species; nevertheless, some aspects of the controlled neonate production, as well as the possible consequences of the reproducers’ culture conditions on the response of neonates to the toxic substance, are not completely known. In the present study, we evaluated the effect of temperature and photoperiod on the acute toxicity of Cr(VI) in D. magna neonates, aimed at providing useful information on the Median Lethal Concentration (LC₅₀) to this heavy metal, which is used as reference toxicant in some laboratories. D. magna was cultured at 20 and 25°C, in combination with two photoperiod values: 16:8 and 12:12 (light:dark) during 40 days; the green microalga Ankistrodesmus falcatus (4×10⁵ cells ml⁻¹) was supplied as food. Once the reproduction began, the neonates were removed and acute toxicity bioassays at 20 and 25°C were performed, by exposing them to hexavalent chromium. We also determined changes in neonates’ size at 20 and 25°C. Chromium toxicity increased along with increasing temperatures, and LC₅₀ values were slightly lower for the first and last clutches in the observed period, but these findings are not conclusive because of the large variability recorded. The average LC₅₀’s were 0.2076±0.0164 mg l⁻¹ (at 20°C) and 0.1544±0.0175 mg l⁻¹ (at 25°C). The reproducers’ culture temperature had no effect on neonates’ sensitivity to chromium, in spite of performing the tests at temperatures either lower or higher than those at which the neonates had been obtained. The length of neonates produced during the first two clutches (<1.25 mm) was significantly lower than that measured in neonates of following reproductions (>1.3 mm), and were smaller at 25°C; however, this did not seem to affect their sensitivity to chromium.     

Single and Combined Effects of Sediment-Associated PAHs on Three Species of Freshwater Macroinvertebrates

Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous pollutants of sediments. Sediment quality criteria often use toxicity data for individual PAHs. However, PAHs always occur in field sediments as a complex mixture of compounds. In this study, the toxicity of phenanthrene (P), fluoranthene (FLA) and benzo(k)fluoranthene (B), alone or in combination, was assessed using monospecific sediment tests of acute toxicity (between 24h and 14 days). The test sediments were spiked formulated sediments. Toxicity of PAHs was determined on a freshwater pelagic organism, Daphnia magna, on an epibenthic organism, Hyalella azteca, and on a benthic organism, Chironomus riparius. The phototoxicity of fluoranthene and phenanthrene was verified. Benzo(k)fluoranthene was not phototoxic and presented no toxicity for the three organisms tested up to 300mg/kg, concentration rarely found in the environment. For all PAHs, the toxicity towards Daphnia magna was two-fold higher in the sediment toxicity tests than in the water-only standard tests, probably due to suspended contaminated particles and contact of daphnids with sediment. For phenanthrene, the LC50s found were 50, 15 and 20mg/kg dry weight sediment, respectively for Daphnia magna, Hyalella azteca and Chironomus riparius. The bioassays on fluoranthene yielded LC50s of 10, 5 and 15mg/kg dw respectively for Daphnia magna, Hyalella azteca and Chironomus riparius. LC50s of the PAHs mixture (1/3 of each compound by weight) were around 10mg/kg dry weight sediment for Hyalella azteca and 20mg/kg for Chironomus riparius. The effects of PAHs in the mixture seemed to be synergistic. This study gives new data about PAH toxicity and showed that the additivity of PAH effects could be inadequate to assess the environmental risk.     

Acute toxicity of Phytolacca dodecandra (Endod-S) and Niclosamide to snails,Schistosoma mansoni cercaria,Tilapia fish,and soil microorganisms

The acute toxicity of two molluscicides, the extract of the plant Phytolacca dodecandra (Endod-S) and Niclosamide, was determined using the following test species: The snails Biomphalaria glabrata (albino) and Biomphalaria pfeifferi, Schistosoma mansoni cercaria, and Tilapia nilotica fish. Endod-S showed a 24-h LC₅₀ of 2.57 and 5.37 mg/L for B. glabrata (albino) and B. pfeifferi respectively. Niclosamide produced a 24-h LC₅₀ of 0.063 mg/L and 0.049 mg/L for B. glabrata (albino) and B. pfeifferi, respectively. The 4-h LC₅₀ for S. mansoni cercaria was 2.92 mg/L for Endod-S and 0.0008 mg/L for Niclosamide. The 24-h LC₅₀ for Tilapia nilotica was 1.82 mg/L for Endod-S and 0.21 mg/L for Niclosamide. The toxicity of Endod-S and Niclosamide to a mixed population of soil microorganisms was measured using oxygen uptake and growth as measured by turbidity. Endod-S was not toxic to the microorganisms. The average Niclosamide toxic end point (IC₅₀) for these bacteria was 450 mg/L.     

Acaricidal activities of essential oils against two-spotted spider mite,Tetranychus urticae Koch

Eleven essential oils (EOs) were screened for their fumigant and repellent activity against two-spotted spider mite, Tetranychus urticae Koch (Acarina: Tetranychidae) under laboratory conditions. Results showed that, in fumigant toxicity assay, Mentha longifolia L. showed more toxic to T. urticae (LC₅₀?=?11.08?mg?L^?1 air) and was followed by Mentha piperita L. (LC₅₀?=?15.86?mg?L^?1 air), Cymbopogon flexuosus (Nees ex Steud.) W. Watson (LC₅₀?=?17.23?mg?L^?1 air) and Chrysopogon zizanioides (L.) (LC₅₀?=?18.82?mg L^?1 air). In repellent activity test, Acorus calamus (L.), M. piperita and C. flexuosus showed 100% repellent activity to T. urticae as compared to Cedrus deodara (Roxb.) and Aegle marmelos (L.) (76.67%).     

Multilaboratory evaluation of 15 bioassays for (eco)toxicity screening and hazard ranking of engineered nanomaterials: FP7 project NANOVALID

Within EU FP7 project NANOVALID, the (eco)toxicity of 7 well-characterized engineered nanomaterials (NMs) was evaluated by 15 bioassays in 4 laboratories. The highest tested nominal concentration of NMs was 100?mg/l. The panel of the bioassays yielded the following toxicity order: Ag?>?ZnO?>?CuO?>?TiO_2?>_?MWCNTs?>?SiO_2?>_?Au. Ag, ZnO and CuO proved very toxic in the majority of assays, assumingly due to dissolution. The latter was supported by the parallel analysis of the toxicity of respective soluble metal salts. The most sensitive tests/species were Daphnia magna (towards Ag NMs, 24-h EC_50?=_?0.003?mg Ag/l), algae Raphidocelis subcapitata (ZnO and CuO, 72-h EC_50?=_?0.14?mg Zn/l and 0.7?mg Cu/l, respectively) and murine fibroblasts BALB/3T3 (CuO, 48-h EC_50?=_?0.7?mg Cu/l). MWCNTs showed toxicity only towards rat alveolar macrophages (EC_50?=_?15.3?mg/l) assumingly due to high aspect ratio and TiO₂ towards R. subcapitata (EC_50?=_?6.8?mg Ti/l) due to agglomeration of TiO₂ and entrapment of algal cells. Finally, we constructed a decision tree to select the bioassays for hazard ranking of NMs. For NM testing, we recommend a multitrophic suite of 4 in vitro (eco)toxicity assays: 48-h D. magna immobilization (OECD202), 72-h R. subcapitata growth inhibition (OECD201), 30-min Vibrio fischeri bioluminescence inhibition (ISO2010) and 48-h murine fibroblast BALB/3T3 neutral red uptake in vitro (OECD129) representing crustaceans, algae, bacteria and mammalian cells, respectively. Notably, our results showed that these assays, standardized for toxicity evaluation of “regular” chemicals, proved efficient also for shortlisting of hazardous NMs. Additional assays are recommended for immunotoxicity evaluation of high aspect ratio NMs (such as MWCNTs).     

Effect-directed investigation and interactive effect of organic toxicants in landfill leachates combining Microtox test with RP-HPLC fractionation and GC/MS analysis

Landfill leachates contain a large amount of unknown harmful compounds derived from domestic and industrial sources. A toxicity effect-directed approach was used to identify biologically active compounds in three landfill leachate samples (S1–S3) by combining the Microtox test with reverse-phase high performance liquid chromatography (RP-HPLC) fractionation and gas chromatography/mass spectrometry (GC/MS) analysis. Organic toxicants were recovered from coarse fractions only in S1 and in S2. Fine fractionation exhibited a somewhat different toxicity pattern in S1 and S2. GC/MS analysis positively identified Bisphenol A (BPA) and 4-t-butylphenol (4-t-BP) in both samples, N-ethyltoluenesulfoneamide (NETSA) was detected only in S1. However, their concentrations were not high enough to be responsible for the observed toxicity in original samples. A synergistic effect among detected organic compounds (BPA, NETSA, and 4-t-BP) was demonstrated. Each compound present at 1/7 of its individual EC₅₀, might lead to undesirable mixture toxicity, which indicated that interactive effects may, to a certain extent, play a role in landfill leachates with complex matrices. The results from further hydrophobicity analysis and estrogen receptor (ER) competitive binding assays of fraction 13 of both samples gave evidence that some possible toxicants that failed to be identified by GC/MS might be endocrine disrupting chemical(s) (EDC) with a log K _ow range of 3.5–3.7 in both samples.     

Volatile,non-volatile composition and insecticidal activity of Eupatorium adenophorum Spreng against diamondback moth,Plutella xylostella (L.), and aphid,Aphis craccivora Koch

Essential oil (EO) from aerial parts of Eupatorium adenophorum Spreng was extracted by steam distillation and characterized by Gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). α-epi-cadinenol (16.63%), O-cymene (13.54%), bornyl acetate (7.70%), β-phellandrene (7.46%), and σ-2-carene (5.77%) were the major terpenoids. The EO showed promising toxicity (median lethal concentration, LC₅₀?=?3176.54?mg?L^?1) and repellent activity (median repellent concentration, RC₅₀?=?2070.99?mg L^?1) to larvae of Plutella xylostella within 24?h. Among fractions, hexane fraction was more effective to P. xylostella (LC₅₀?=?5056.74?mg L^?1), whereas methanol fraction to Aphis craccivora (LC₅₀?=?1175.83?mg L^?1).     

Azadirachtin,a neem‐derived biopesticide,impairs behavioral and hematological parameters in carp (Cyprinus carpio)

Azadirachtin (Aza) is a promisor biopesticide used in organic production and aquaculture. Although this compound is apparently safe, there is evidence that it may have deleterious effects on fish. Behavioral and hematological tests are grouped into a set of parameters that may predict potential toxicity of chemical compounds. Here, we investigate the effects of Aza, in the commercial formulation Neenmax^?, on carp (Cyprinus carpio) by defining LC₅₀ (96 h), and testing behavioral and hematological parameters. In our study, LC₅₀ was estimated at 80 μL/L. We exposed carp to Aza at 20, 40, and 60 μL/L, values based on 25, 50, and 75% of LC₅₀, respectively. At 60 μL/L, Aza promoted significant changes in several parameters, increasing the distance traveled and absolute turn angle. In addition, the same concentration decreased the time spent immobile and the number of immobile episodes. Hematological parameters, such as hematocrit, hemoglobin, hematimetrics index, and red cell distribution, were decreased at 60 μL/L Aza exposure. In conclusion, our study demonstrates that 60 μL/L Aza altered locomotor activity, motor pattern, and hematological parameters, suggesting potential toxicity to carp after acute exposure. In addition, this is the first report that evaluates the actions of a chemical contaminant using automated behavioral tracking of carp, which may be a useful tool for assessing the potential toxicity of biopesticides in conjunction with hematological tests. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1381–1388, 2016.