Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 19.952
Filtrar
1.
Chemosphere ; 242: 125229, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896198

RESUMO

The objective was to determine the median lethal concentration (LC50) of nitrate for post-larvae and juveniles of Macrobrachium amazonicum exposed for 96 h, and to identify histopathological alterations in the gills of juveniles exposed to nitrate. Post-larvae and juveniles of M. amazonicum were exposed to seven different concentrations of nitrate (0, 50, 100, 500, 1000, 1500 and 2000 mg.L-1) with four replicates (n = 10 prawn/experimental unit). The degree of damage to the branchial structure of juveniles was evaluated using standard histological processing with hematoxylin and eosin (H&E), subjected to the Organ Index (Iorg). LC50 values at 24, 48, 72 were estimated by the Trimmed Spearman Karber Method software and were respectively 1574, 638, 237, and 194 mg.L-1 for post-larvae and 1070, 286, 185 and 155 mg.L-1 for juveniles, respectively. From these results, the safety level of nitrate was estimated at 157, 64, 24 and 19 mg.L-1 for post-larvae and 107; 27; 18 and 16 mg.L-1 for juveniles, respectively for 24 h, 48 h, 72 h and 96 h. Damage to the gills in treatments with 100% mortality for nitrate corresponded to the high occurrence of progressive, regressive, circulatory and inflammatory damages. The other treatments, which caused lower mortality, mainly resulted in inflammation and regressive damage, whose occurrence increased with increasing concentration of nitrate. However, in closed systems, the use of anaerobic denitrifying filters or aquatic macrophytes is necessary to provide suitable water quality for the best productive performance, avoiding the negative influence of the accumulated nitrate.


Assuntos
Nitratos/toxicidade , Palaemonidae/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Brânquias/patologia , Larva , Dose Letal Mediana , Testes de Toxicidade Aguda
2.
Chemosphere ; 242: 125293, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896202

RESUMO

The effects produced by the ethyl-carbamates: ethyl-4-bromophenyl carbamate (LQM 919) and ethyl-4-chlorophenyl carbamate (LQM 996) on the mortality and behavior of Apis mellifera were evaluated by the acute oral toxicity test and the acute contact toxicity test. The oral lethal dose, 50% of the ethyl-carbamates was >145.24 µg per bee, and the oral lethal dose, 50% of propoxur was 0.072 µg per bee. Therefore, according to the OECD criteria, the ethyl-carbamates were classified as relatively nontoxic orally; meanwhile, propoxur was classified as highly toxic orally. In the contact test, lethal concentrations 50% of the ethyl-carbamates were 4.83 and 2.23 µg/cm2 for LQM 919 and LQM 996, respectively; therefore, they were at least 10-fold less lethal (p < 0.05) than propoxur (0.22 µg/cm2). The ethyl-carbamates reduced the activity of A. mellifera acetylcholinesterase by up to 30%. The ki and kd values of both ethyl-carbamates were lower (p < 0.05) than those of propoxur and indicated that they are weak inhibitors and with low affinity to A. mellifera acetylcholinesterase, which along with the absence of behavioral alterations suggests that the mortality caused by ethyl carbamates is not related to damage to the nervous system. According to these results, the evaluated ethyl-carbamates can be considered a low ecotoxic risk for A. mellifera.


Assuntos
Acetilcolinesterase/metabolismo , Abelhas/efeitos dos fármacos , Carbamatos/toxicidade , Poluentes Ambientais/toxicidade , Inseticidas/toxicidade , Animais , Abelhas/enzimologia , Comportamento Animal/efeitos dos fármacos , Exposição Dietética/efeitos adversos , Exposição Ambiental/efeitos adversos , Dose Letal Mediana , Testes de Toxicidade Aguda
3.
Rev Soc Bras Med Trop ; 53: e20190211, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31994661

RESUMO

INTRODUCTION: Anopheles stephensi is the main malaria vector in Southeast Asia. Recently, plant-sourced larvicides are attracting great interests. METHODS: The essential oil was extracted from the leaf of Cinnamomum camphora (L.), and a bioassay was conducted to determine the larvicidal efficacy. The chemical composition of the essential oil was determined by GC-MS analysis. RESULTS: The oil showed strong, dose-dependent larvicidal activities. The onset of larvicidal efficiency was rapid. The LC50 and LC95 were determined as 0.146% and 1.057% at 1 h, 0.031% and 0.237% at 12 h, 0.026% and 0.128% at 24 h, respectively. The oil contains 32 compounds. CONCLUSIONS: The essential oil of C. camphora leaf has an excellent larvicidal potential for the control of A. stephensi.


Assuntos
Anopheles/efeitos dos fármacos , Cinnamomum camphora/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Óleos Voláteis/farmacologia , Animais , Anopheles/classificação , Bioensaio , Inseticidas/isolamento & purificação , Dose Letal Mediana , Mosquitos Vetores/classificação , Óleos Voláteis/isolamento & purificação
4.
Environ Pollut ; 256: 113398, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31662250

RESUMO

In aquatic environments, organisms such as freshwater mussels are likely exposed to complex contaminant mixtures related to industrial, agricultural, and urban activities. With growing interest in understanding the risk that chemical mixtures pose to mussels, this investigation focused on the effects of various waterborne contaminants (ammonia, chloride, copper, and potassium) and selected binary mixtures of these chemicals following a fixed-ratio design to Villosa iris glochidia and juvenile Lampsilis fasciola. In individual exposures, 48-h EC50 values were determined for V. iris glochidia exposed to ammonia chloride (7.4 [95% confidence interval (CI) 6.6-8.2] mg N/L), ammonia sulfate (8.4 [7.6-9.1] mg N/L), copper sulfate (14.2 [12.9-15.4] µg Cu2+/L), potassium chloride (12.8 [11.9-13.7] mg K+/L), potassium sulfate (10.1 [8.9-11.2] mg K+/L), and sodium chloride (480.5 [435.5-525.5] mg Cl-/L). The 7-d LC50 values for juvenile L. fasciola were determined for potassium sulfate (45.0 [18.8-71.2] mg K+/L), and sodium chloride (1738.2 [1418.6-2057.8] mg Cl-/L). In Ontario these waterborne contaminants have been reported to co-occur, with concentrations exceeding the EC10 for both life stages at some locations. Data from binary mixture exposures for V. iris glochidia (chloride-ammonia, chloride-copper, and copper-ammonia) and juvenile L. fasciola (chloride-potassium) were analyzed using a regression-based, dose-response mixture analysis modeling framework. Results from the mixture analysis were used to determine if an additive model for mixture toxicity [concentration addition (CA) or independent action (IA)] best described the toxicity of each mixture and if deviation towards dose-ratio (DR) or dose-level (DL) synergism/antagonism (S/A) occurred. For all glochidia binary mixture exposures, CA was the best fit model with DL deviation reported for the chloride-copper mixture and DR deviation reported for the copper-ammonia mixture. Using the model deviation ratio (MDR), the observed toxicity in all three glochidia mixture exposures were adequately described by both CA (mean = 0.71) and IA (mean = 0.97) whereas the juvenile mixture exposure was only adequately described by CA (mean = 0.64; IA mean = 0.05).


Assuntos
Unionidae/fisiologia , Poluentes Químicos da Água/toxicidade , Amônia/análise , Amônia/toxicidade , Animais , Bivalves/efeitos dos fármacos , Cloretos/análise , Cloro , Cobre/análise , Cobre/toxicidade , Água Doce/química , Larva/efeitos dos fármacos , Dose Letal Mediana , Minerais/análise , Ontário , Potássio/análise , Potássio/toxicidade , Alimentos Marinhos/análise , Cloreto de Sódio/análise , Unionidae/efeitos dos fármacos , Poluentes Químicos da Água/análise
5.
Chemosphere ; 241: 125089, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31629234

RESUMO

The Pantanal (Brazil) is a wetland region characterized by seasonal flooding. Hydrological cycles influence the water physicochemical parameters, causing seasonal variations in pH and nitrites. Thus, the objective of this study was to evaluate the effects of varying pH and nitrite concentrations on the toxicity of the cypermethrin-based pesticide Barrage®, considering both lethal (mortality) and sublethal endpoints (growth and development). Larvae of the endemic shrimp Macrobrachium pantanalense and of the estuarine Amazonian congener Macrobrachium amazonicum were exposed to cypermethrin (through Barrage®) under several pH levels (6.5, 7.5 and 8.5) or nitrite concentrations (0.1, 0.2 and 0.4 mg/L). The pH had direct effects on all the tested endpoints for both species. For M. pantanalense, the lethal effects of the cypermethrin formulation were more pronounced at low pH (96-h LC50 = 0.004 µg/L at pH 6.5, and 0.146 µg/L at pH 8.5). For M. amazonicum, an opposite response was observed, with increased toxicity of the formulation at high pH (96-h LC50 = 0.110 µg/L at pH 6.5 and 0.044 µg/L at pH 8.5). Variations in pH also seemed to modify the sublethal effects of the formulation on larval growth and development of M. pantanalense. Nitrite concentrations affected larval growth of both species, modifying also the effects of the cypermethrin formulation on the larval development of M. amazonicum. This work shows the importance of considering abiotic factors for risk assessment either due to possible direct effects on the physiology of organisms and/or due to interactions with other stressors, particularly in fragile biomes such as Pantanal.


Assuntos
Água Doce/química , Palaemonidae/efeitos dos fármacos , Praguicidas/toxicidade , Piretrinas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Ecotoxicologia , Feminino , Água Doce/análise , Concentração de Íons de Hidrogênio , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Dose Letal Mediana , Mortalidade , Nitritos/análise , Nitritos/química , Palaemonidae/crescimento & desenvolvimento , Praguicidas/química , Piretrinas/química , Especificidade da Espécie , Testes de Toxicidade Aguda , Áreas Alagadas
6.
Chemosphere ; 241: 125100, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31629240

RESUMO

The most existing studies on the toxicity of antimony (Sb) were performed in limited types of soil and after short aging time. Effects of soil properties and long aging time on chronic toxicity of Sb(III) and Sb(V) to model organism Folsomia candida were studied in the laboratory studies. The results showed that after the Sb(V)-treated soils were aged for 365 d, the Sb exhibited no toxicity to survival and reproduction even at the nominal highest concentration of 12,800 mg kg-1 in ten types of soils with distinct differences in soil properties. In the Sb(III)-treated ten soils aged only for 30 d, the concentrations causing 50% mortality (LC50) and concentrations inhibiting 50% reproduction (EC50) were 1288-3219 mg kg-1 and 683-1829 mg kg-1, respectively. The LC50 were higher than the highest test concentration and the EC50 significantly increased by 2.24-6.16 fold after the Sb(III)-treated soils were aged for 150 d, and soil pH was the most important single factor explaining the variance in aging effects. After the aging time was 365 d, similar with Sb(V)-treated soils, no toxicity were observed in the most Sb(III)-treated soils, indicating the increasing aging effects with aging time. Regression analysis indicated that the OM and pH were the most important single factor predicting Sb toxicity to reproduction in Sb(III)-treated soils aged for 30 and 150 d, respectively.


Assuntos
Antimônio/toxicidade , Artrópodes/efeitos dos fármacos , Poluentes do Solo/toxicidade , Solo/química , Animais , Concentração de Íons de Hidrogênio , Dose Letal Mediana , Modelos Animais , Reprodução/efeitos dos fármacos , Poluentes do Solo/farmacologia , Fatores de Tempo
7.
Exp Parasitol ; 208: 107802, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31730782

RESUMO

In insects, diet plays an important role in growth and development. Insects can vary their diet composition based on their physiological needs. In this study we tested the influence of diet composition involving varying concentrations of macronutrients and zinc on the immune-tolerance following parasite and pathogen exposure in Spodoptera litura larvae. We also tested the insecticidal potential of Mesorhabditis belari, Enterobacter hormaechei and its secondary metabolites on Spodoptera litura larvae. The results shows macronutrient composition does not directly affect the larval tolerance to nematode infection. However, Zinc supplemented diet improved the immune tolerance. While larvae exposed to bacterial infection performed better on carbohydrate rich diet. Secondary metabolites from bacteria produced an immune response in dose dependent mortality. The study shows that the larvae maintained on different diet composition show varied immune tolerance which is based on the type of infection.


Assuntos
Enterobacter/fisiologia , Controle Biológico de Vetores , Rhabditoidea/fisiologia , Spodoptera/imunologia , Análise de Variância , Animais , Bioensaio , Carboidratos/administração & dosagem , Cromatografia Líquida de Alta Pressão , Dieta , Enterobacter/imunologia , Enterobacter/patogenicidade , Cromatografia Gasosa-Espectrometria de Massas , Tolerância Imunológica , Larva/imunologia , Dose Letal Mediana , Proteínas/administração & dosagem , Rhabditoidea/imunologia , Rhabditoidea/patogenicidade , Espectroscopia de Infravermelho com Transformada de Fourier , Spodoptera/fisiologia , Simbiose , Virulência , Zinco/administração & dosagem
8.
Aquat Toxicol ; 218: 105363, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31783302

RESUMO

The aquatic environment is continuously under threat because it is the final receptor and sink of waste streams. The development of industry, mining activities and agriculture gave rise to an increase in metal pollution in the aquatic system. Thus a wide occurrence of metal mixtures exists in the aquatic environment. The assessment of mixture stress remains a challenge considering that we can not predict the toxicity of a mixture on the basis of single compounds. Therefore the analysis of the effects of environmentally relevant waterborne mixtures is needed to improve our understanding of the impact of metal pollution in aquatic ecosystems. Our aim was to assess whether 10 % of the concentration of the 96 h LC50 (the concentration that is lethal to 50 % of the population in 96 h) of individual metal exposures can be considered as a "safe" concentration when applied in a trinomial mixture. Therefore, common carp were exposed to a sublethal mixture of Cu 0.07 ±â€¯0.001 µM (4.3 ±â€¯0.6 µg/L), Zn 2.71 ±â€¯0.81 µM (176.9 ±â€¯52.8 µg/L) and Cd 0.03 ±â€¯0.0004 µM (3.0 ±â€¯0.4 µg/L) at 20 °C for a period of one week. Parameters assessed included survival rate, bioaccumulation and physiological biomarkers related to ionoregulation and defensive mechanisms such as MT induction. Our results showed a sharp increase in Cu and Cd concentration in gills within the first day of exposure while Zn levels remained stable. The accumulation of these metals led to a Na drop in gills, liver and muscle as well as a decreased K content in the liver. Biomarkers related to Na uptake were also affected: on the first day gene expression for H+-ATPase was transiently increased while a concomitant decreased gene expression of the Na+/H+ exchanger occurred. A fivefold induction of metallothionein gene expression was reported during the entire duration of the experiment. Despite the adverse effects on ionoregulation all fish survived, indicating that common carp are able to cope with these low metal concentrations, at least during a one week exposure.


Assuntos
Bioacumulação , Cádmio/toxicidade , Carpas/metabolismo , Cobre/toxicidade , Poluentes Químicos da Água/toxicidade , Zinco/toxicidade , Animais , Bioacumulação/genética , Biomarcadores/metabolismo , Cádmio/metabolismo , Carpas/genética , Cobre/metabolismo , Ecossistema , Eletrólitos/metabolismo , Expressão Gênica/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Dose Letal Mediana , Metalotioneína/genética , ATPases Translocadoras de Prótons/genética , Poluentes Químicos da Água/metabolismo , Zinco/metabolismo
9.
Int J Radiat Biol ; 96(1): 67-80, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30433842

RESUMO

Purpose: The aim of our work was to develop an approach to account for the impact of age at exposure on acute radiation lethality risk for the purpose of improving casualty estimation tools when applied to a diverse population.Materials and Methods: Age-dependent radiation lethality data were collected from published animal studies. The 50% lethal dose responses (LD50) were extracted, grouped according to developmental stages in humans and average LD50 values calculated for select age categories. Dose modification factors (DMFs) were developed by dividing LD50 values of non-young, adult groups to the reference adult category within each study. DMFs were combined across each age group to provide a DMF for each age category.Results: Data from 12 studies with age-dependent LD50 values from 5 species (>21,000 animals) demonstrate increased sensitivity to acute radiation in elderly and young animals compared to young adults. DMFs were developed for infant (0.80), juvenile (0.86), late adult (0.86), and elderly (0.71) populations.Conclusions: Animal and human data support increased radiosensitivity in infants, juveniles, and aging adults. DMFs provide a mechanism to account for age-dependent variability in health effects models and to determine the impact of age on casualty estimates.


Assuntos
Exposição à Radiação/efeitos adversos , Medição de Risco , Adolescente , Adulto , Fatores Etários , Idoso , Animais , Criança , Pré-Escolar , Humanos , Recém-Nascido , Dose Letal Mediana , Adulto Jovem
10.
Vet Parasitol ; 277: 109011, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31841946

RESUMO

In the present study, the tick isolates were collected from Assam state, of northeastern region (NER) and characterized using in vitro bioassay, biochemical and molecular assays. Comparing LC50 value of susceptible IVRI-I and larvae of field isolates, revealed that RF against deltamethrin was highest for Morigaon (MGN = 21.8) and lowest for Sonitpur (SNP = 3.3) isolate. The RF against cypermethrin was highest for Nagaon (NGO = 5.0) and lowest for Barpeta (BPT = 1.2) isolate. Against coumaphos, the highest RF of 4.5 was calculated for BPT (4.5) and lowest for NGO (1.3) isolate. While using adults based assay, highest RF of 24.68 against deltamethrin and lowest RF of 4.96 was determined for MGN and SNP isolate, respectively. In contrast to the results obtained using larvae, against cypermethrin, highest RF was recorded for Kamrup Metropolitan (KMP) while it was NGO isolate using larvae. In case of coumaphos, both larvae and adults of BPT isolate were also highly resistant and lowest RF was detected in SNP (2.30) isolate. All the isolates were susceptible to ivermectin. A significant correlation (p < 0.01) between deltamethrin resistance and higher expression of glutathioneS-transferase was observed while no correlation with esterase and monooxygenase enzymes activity was noted. For the development of possible ecofriendly control measure, different accessions of Argemone mexicana and Datura metel plant species were collected, extracted and screened against adult ticks. Two accessions, NEA-03 and NED-06 collected from Amlighat and Diphu (East Karbi Anglong) were more than 90 % effective. Further dose response study of these accessions determined the LC50 values of 4.86 and 3.96 %, respectively.The resistance status of the collected tick isolates was compared with the data generated from other regions having higher livestock population and possibility of exploitation of identified plant species for the development of natural antitick product is discussed.


Assuntos
Acaricidas/farmacologia , Resistência a Inseticidas , Extratos Vegetais/farmacologia , Rhipicephalus/efeitos dos fármacos , Animais , Bovinos , Índia , Resistência a Inseticidas/efeitos dos fármacos , Dose Letal Mediana , Estágios do Ciclo de Vida/efeitos dos fármacos
11.
Ecotoxicol Environ Saf ; 188: 109847, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31732268

RESUMO

Chlorothalonil is a fungicide present in antifouling paints and other formulations used in agriculture, although studies have shown this chemical to be toxic to fish species. To clarify the deleterious effects of chlorothalonil for these non-target organisms, the present study evaluated the toxic effects of this biocide for the estuarine guppy Poecilia vivipara in terms of an acute mortality test (96 h) and the analysis of biomarkers of oxidative stress, genotoxicity, and sperm quality. The LC50 calculated for P. vivipara was 40.8 µg/L of chlorothalonil. For the analysis of biomarkers, fish were exposed (96 h) to 1 and 10 µg/L of chlorothalonil. It was observed that chlorothalonil alters the levels of pro- and antioxidants towards oxidative stress. In the gills, a negative effect on total antioxidant capacity (ACAP) was detected, while there was a reduction in the activity of glutathione S-transferase (GST) in the liver. However, levels of glutathione (GSH) and the activity and glutamate-cysteine-ligase (GCL) increased in both tissues, as a possible detoxification response. Following chlorothalonil exposure, oxidative damage measured by lipoperoxidation (LPO) significantly increased at the cellular level only (red blood cells (RBCs) and sperm cells). An increase in fluidity of membranes, reactive oxygen species concentration and micronuclei (MNs) incidence were also seen in RBCs. In sperm cells, LPO increased, while membrane and mitochondrial functionality as well as sperm motility decreased. Based on these results, chlorothalonil can be considered as a toxic compound for fish, causing genotoxicity and affecting the RBCs physiology and the fertility of males of P. vivipara.


Assuntos
Biomarcadores/análise , Nitrilos/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Poecilia/fisiologia , Espermatozoides/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Dano ao DNA , Desinfetantes/toxicidade , Fungicidas Industriais/toxicidade , Dose Letal Mediana , Masculino , Poecilia/metabolismo , Espermatozoides/fisiologia
12.
Chemosphere ; 240: 124969, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726589

RESUMO

The objective of this work was to evaluate whether tetracycline (TC) in environmentally relevant concentrations was able to induce alterations to embryonic development and teratogenic effects in oocytes and embryos of Cyprinus carpio. For this purpose, an embryolethality study was conducted and the lethal concentration 50 (LC50) and effective concentration 50 of malformations (EC50) were calculated, and with these data the teratogenic index (TI) was determined. The main alterations to embryonic development and the teratogenic effects produced by TC on embryos of C. carpio were determined using the Kimmel and Hersem scale adapted for Cyprinus carpio. LC50 and EC50 were respectively 500.08 and 145.3 µg L-1.TC was shown to be teratogenic with teratogenic index of 3.44, and the main malformations identified in concentrations of 90-900 µg L-1 were malformation in tail, modified chorda structure, pericardical edema, scoliosis and malformations of the heart. A significant decrease in concentration-dependent in Kimmel and Hersem score was observed. The results allow us to conclude that TC at environmentally relevant concentrations is capable of inducing embryotoxic and teratogenic effects, generating risk in the integrity of the common carp C. Carpio.


Assuntos
Carpas/embriologia , Desenvolvimento Embrionário/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Teratogênios/farmacologia , Tetraciclina/toxicidade , Animais , Dose Letal Mediana , Teratogênese
13.
Exp Parasitol ; 209: 107825, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31877275

RESUMO

Ciliate ectoparasites are one of the most important groups of pathogens in fish culture, and the traditional treatments are sometimes harmful to the fish and the environment. Thus, the search for novel compounds that are effective at low concentrations and safe for fish are necessary to optimise treatments in aquaculture. The antiprotozoal capacity of silver nanoparticles (AgNPs) against the ciliate Tetrahymena has been documented; however, their toxicity may vary with the synthesis methodology and nanoparticle size. The objectives of this study were a) to evaluate the acute toxicity in vitro of two AgNPs (Argovit™ and UTSA) on Tetrahymena sp., a biological model for ciliated ectoparasites of fish and b) to test the safety of lethal and higher doses of UTSA AgNPs for ciliates on the fish C. estor. Light microscopy and scanning electron microscopy (SEM) were used to determine whether AgNPs affected the structure of the cell surface of Tetrahymena. The mortality, histopathological alterations and metagenomics of the fish were used to determine the major effects of UTSA AgNPs. In Tetrahymena, the median lethal concentration (LC50) for Argovit™ was 2501 ± 1717 ng/L at 15 min and 796 ± 510 ng/L at 60 min, while the LC50 for UTSA AgNPs was 4 ± 2 and 1 ± 0.6 ng/L at 15 min and 60 min, respectively. A concentration of 3300 ng/L Argovit™ and 10.6 ng/L UTSA AgNPs for 15 and 60 min, respectively, was 100% effective against Tetrahymena. After 60 min of exposure to 0.25 and 0.50 ng/L UTSA AgNPs, the number of cilia significantly reduced, there were small holes on the cell surface, and the cellular membrane was ruptured. In fish exposed to lethal (10.6 ng/L) and higher (31.8 and 95.4 ng/L) doses of UTSA, the AgNPs did not affect fish survival after 96 h, and there were no signs of histopathological damage or gut microbial changes. This study is the first report on microscopic and ultrastructural changes in Tetrahymena after exposure to significantly low concentrations of UTSA AgNPs with antiprotozoal efficacy without evidence of harmful effects on fish. These results provide the basis for further studies of both pet aquarium and commercial fish that may validate these findings at a larger experimental scale, taking into account AgNPs bioaccumulation, safety for human consumption and environmental impact.


Assuntos
Ectoparasitoses/veterinária , Doenças dos Peixes/tratamento farmacológico , Nanopartículas Metálicas/toxicidade , Prata/farmacologia , Tetrahymena/efeitos dos fármacos , Animais , Aquicultura , Ectoparasitoses/tratamento farmacológico , Ectoparasitoses/parasitologia , Doenças dos Peixes/parasitologia , Peixes , Água Doce , Microbioma Gastrointestinal , Humanos , Dose Letal Mediana , Metagenômica , Nanopartículas Metálicas/química , Microscopia Eletrônica de Varredura/veterinária , Prata/química , Prata/toxicidade , Tetrahymena/ultraestrutura
14.
Sci Total Environ ; 700: 134500, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31627045

RESUMO

Flumethrin is a typical pyrethroid varroacide widely used for mite control in beekeeping worldwide. Currently, information on the toxicological characteristics of flumethrin on bees at sublethal concentrations is still lacking. To fill this gap in information, we performed a 48-h acute oral and 14-day chronic toxicity testing of flumethrin in newly emerged adult honey bees under laboratory conditions. Results showed that flumethrin had high acute toxicity to honey bees with a 48-h LD50 of 0.47 µg/bee (95% CI, 0.39 ∼ 0.57 µg/bee), which is higher than that of many other commercial pyrethroid insecticides, but lower than that of tau-fluvalinate. After 14 days of chronic exposure to flumethrin at 0.01, 0.10, and 1.0 mg/L, significant antioxidant response, detoxification, immune reaction, and apoptosis were observed in the midguts. These findings indicated that flumethrin had potential risks to bees, and it can disturb the homeostasis of bees at sublethal concentrations under longer exposure conditions. Flumethrin is highly lipophilic and easy to accumulate in beeswax; thus, careless practices might pose risks to colony development in commercial beekeeping and native populations. This laboratory study can serve as an early warning, and further studies are required to understand the real residual level of flumethrin in bees and the risks of flumethrin in field condition.


Assuntos
Abelhas/fisiologia , Inseticidas/toxicidade , Piretrinas/toxicidade , Animais , Criação de Abelhas , Dose Letal Mediana , Testes de Toxicidade Crônica
15.
Ecotoxicol Environ Saf ; 188: 109945, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31753309

RESUMO

Cyanobacterial harmful algal blooms dominated by Microcystis frequently produce microcystins, a family of toxins capable of inflicting harm to pelagic and benthic freshwater invertebrates. Research on the effect of microcystins on invertebrates is inconclusive; from one perspective, studies suggest invertebrates can coexist in toxic blooms; however, studies have also measured negative food-associated effects from microcystins. To test the latter perspective, we examined the reproduction, growth, and survival of laboratory-cultured Ceriodaphnia dubia, Daphnia magna, and Hexagenia spp. exposed to cell-bound microcystins through a series of life-cycle bioassays. Test organisms were exposed to a concentration gradient ranging from 0.5 µg L-1 to 300 µg L-1 microcystins, which corresponds to values typically found in freshwaters during bloom season. Lethal concentrations in C. dubia (LC50 = 5.53 µg L-1) and D. magna (LC50 = 85.72 µg L-1) exposed to microcystins were among the lowest recorded to date, and reproductive effects were observed at concentrations as low as 2.5 µg L-1. Length of D. magna was significantly impacted in microcystin treatments great than 2.5 µg L-1. No lethality or growth impairments were observed in Hexagenia. This information will improve our understanding of the risks posed by microcystins to food webs in freshwaters.


Assuntos
Daphnia/efeitos dos fármacos , Ephemeroptera/efeitos dos fármacos , Água Doce/química , Microcistinas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Daphnia/crescimento & desenvolvimento , Ephemeroptera/crescimento & desenvolvimento , Cadeia Alimentar , Proliferação Nociva de Algas , Dose Letal Mediana , Estágios do Ciclo de Vida , Reprodução/efeitos dos fármacos
16.
Ecotoxicol Environ Saf ; 190: 109985, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31841893

RESUMO

Effort has been made to standardise regulatory ecotoxicity tests for engineered nanomaterials (ENMs), but the environmental realism of altered water quality and/or pulse exposure to these pollutants should be considered. This study aimed to investigate the relative toxicity to early life-stage zebrafish of CuO ENMs at acid pH and then under pulse exposure conditions, all compared to CuSO4. At all pH values, CuSO4 was more toxic to zebrafish than CuO ENMs. Additions of H+ were protective of CuSO4 toxicity, with median lethal concentrations LC50 (with 95% confidence intervals) of: 0.36 (0.33-0.40), 0.22 (0.20-0.24) and 0.27 (0.25-0.29) mg L-1 at pH 5, pH 6 and pH 7, respectively. In contrast, the toxicity of CuO ENMs increased with acidity; LC50 values were: 6.6 (4.5-8.5), 19.4 (11.6-27.2) and >100 mg L-1 at pH 5, pH 6 and pH 7, respectively. The increased toxicity of the CuO ENMs in acid water corresponded with greater dissolution of dissolved Cu from the particles at low pH, suggesting free Cu2+ ion delivery to the zebrafish was responsible for the pH-effect. In continuous 96 h exposures to the substances at the LC10 values and at pH 6, both CuSO4 and CuO ENMs caused Cu accumulation, inhibition of Na+/K+-ATPase and depletion of total glutathione in zebrafish. However, two 24 h pulses of CuSO4 or CuO ENMs at the same peak concentration caused similar effects to the continuous 96 h exposure, despite the shorter exposure durations of the former; suggesting that the pulses were more hazardous than the continuous exposure. In conclusion, the current water quality correction for pH with respect to Cu toxicity to freshwater fish should not be applied to the nano form. Crucially, CuO ENMs are more toxic in pulse than continuous exposure and new corrections for both water pH and the Cu exposure profile are needed for environmental risk assessment.


Assuntos
Sulfato de Cobre/toxicidade , Cobre/toxicidade , Nanoestruturas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Concentração de Íons de Hidrogênio , Dose Letal Mediana , Água/química , Peixe-Zebra/embriologia
17.
Food Chem Toxicol ; 135: 111053, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31857126

RESUMO

Chronic pain management has several adverse effects and research looking for new and effective pain management drugs posing lower undesirable effects is necessary. Given the above, the pharmacological investigation of medicinal plants significantly contributes to the dissemination of plant-derived therapeutics. The aim of this study was to evaluate the antinociceptive activity of the Psidium brownianum Mart ex DC. leaf essential oil (PBEO) and the participation of the opioid pathway in this effect in mice. Swiss Mus musculus male mice were tested using acute nociception models (acetic acid induced abdominal contortions, formalin, capsaicin and hot plate tests). The possible myorelaxant action of the PBEO was tested using the rotarod test. The essential oil reduced animal nociception in chemical and heat models, with this action being devoid of a myorelaxant effect. Naloxone (2 mg/kg, intraperitoneally - i.p.) partially antagonized the PBEO activity, possibly acting via opioid receptors. The results obtained provide evidence that the traditional Psidium brownianum use may be effective for pain treatment.


Assuntos
Analgésicos/farmacologia , Óleos Voláteis/farmacologia , Extratos Vegetais/farmacologia , Folhas de Planta/química , Psidium/química , Animais , Modelos Animais de Doenças , Dose Letal Mediana , Masculino , Camundongos , Nociceptividade/efeitos dos fármacos , Dor/tratamento farmacológico , Extratos Vegetais/uso terapêutico , Teste de Desempenho do Rota-Rod
18.
Ecotoxicol Environ Saf ; 187: 109709, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31654870

RESUMO

Among the most used chemicals in the world are nonionic surfactants. One of these environmental pollutants is nonylphenol ethoxylate (NP-9), also known as Tergitol, and its degradation product, nonylphenol (NP). The objective of this work was to determine the toxicity of NP and NP-9 in Caenorhabditis elegans. Wild-type L4 larvae were exposed to different concentrations of the surfactants to measure functional endpoints. Mutant strains were employed to promote the activation of toxicity signaling pathways related to mtl-2, gst-1, gpx-4, gpx-6, sod-4, hsp-70 and hsp-4. Additionally, stress response was also assessed using a daf-16::GFP transgenic strain. The lethality was concentration dependent, with 24-h LC50 of 122 µM and 3215 µM for NP and NP-9, respectively. Both compounds inhibited nematode growth, although NP was more potent; and at non-lethal concentrations, nematode locomotion was reduced. The increase in the expression of tested genes was significant at 10 µM for NP-9 and 0.001 µM for NP, implying a likely role for the activation of oxidative and cellular stress, as well as metabolism pathways. With the exception of glutathione peroxidase, which has a bimodal concentration-response curve for NP, typical of endocrine disruption, the other curves for this xenobiotic in the strains evaluated were almost flat for most concentrations, until reaching 50-100 µM, where the effect peaked. NP and NP-9 induced the activation and nuclear translocation of DAF-16, suggesting that transcription of stress-response genes may be mediated by the insulin/IGF-1 signaling pathway. In contrast, NP-9 induced a concentration-dependent response for the sod-4 and hsp-4 mutants, with greater fluorescence induction than NP at similar levels. In short, NP and NP-9 affect the physiology of C. elegans and modulate gene expression related to ROS production, cellular stress and metabolism of xenobiotics.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/efeitos dos fármacos , Disruptores Endócrinos/toxicidade , Poluentes Ambientais/toxicidade , Etilenoglicóis/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Fenóis/toxicidade , Animais , Animais Geneticamente Modificados , Caenorhabditis elegans/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Expressão Gênica/efeitos dos fármacos , Larva/metabolismo , Dose Letal Mediana , Locomoção/efeitos dos fármacos , Estresse Oxidativo/genética
19.
Ecotoxicol Environ Saf ; 187: 109849, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31677571

RESUMO

Harmonia axyridis is an important predator of several pest species and is part of many Integrated Pest Management (IPM) programs. To assess the risks of pesticide application to H. axyridis, we studied the effects of sulfoxaflor on H. axyridis larvae. At 72 h after treatment, the acute toxicity LR50 was 311.9476 g a. i. ha-1 by the residual contact method. This result indicated low-contact toxicity against second-instar H. axyridis larvae. The LR50 of the F1 generation decreased from 69.96 to 36.41 g a. i. ha-1 in a long-term toxicity test. The daily hazard quotient (HQ) for H. axyridis larvae lowered the safety threshold value in the first 5 d. However, the HQ values were greater than 2 during days 6-18 after sulfoxaflor treatments. We determined the No Observed Effect Application Rates of sulfoxaflor on the survival (<11.25 g a. i. ha-1), duration of larval and pupal stages (45 g a. i. ha-1), adult stage (90 g a. i. ha-1), total pre-oviposition period, adult pre-oviposition period (45 g a. i. ha-1), and reproduction (11.25 g a. i. ha-1). Pupation, adult emergence, and eggs counts of H. axyridis were reduced after sulfoxaflor treatments. The predation ability and population demography parameters were significantly impaired by higher application rates. At 90 g a. i. ha-1 or less, sulfoxaflor was slightly harmful to H. axyridis but a rate of 180 g a. i. ha-1 was moderately harmful. These results demonstrated that sulfoxaflor is harmful to H. axyridis when applied at high application rates.


Assuntos
Besouros/efeitos dos fármacos , Larva/efeitos dos fármacos , Resíduos de Praguicidas/toxicidade , Pupa/efeitos dos fármacos , Piridinas/toxicidade , Compostos de Enxofre/toxicidade , Animais , Besouros/fisiologia , Relação Dose-Resposta a Droga , Feminino , Larva/fisiologia , Dose Letal Mediana , Controle de Pragas , Comportamento Predatório/efeitos dos fármacos , Pupa/fisiologia , Reprodução/efeitos dos fármacos , Testes de Toxicidade
20.
Chemosphere ; 239: 124799, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31518926

RESUMO

Terrestrial adult stages of freshwater insects may be exposed to pesticides by wind drift, over-spray, contact or feeding. However, studies addressing insecticide effects on freshwater invertebrates focus primarily on the impact of pesticides reaching the streams and potentially harming the aquatic juvenile stages. This is also reflected in the current risk assessment procedures, which do not include testing of adult freshwater insects. In order to assess the potential impact of insecticides on adult stages of freshwater insects, we exposed six common species to the insecticides Karate (lambda-cyhalothrin) and Confidor (imidacloprid). Dose-response relations were established, and LD50 estimates were compared to those of the honey bee, Apis mellifera L. (Hymenoptera: Apidae), which is the standard terrestrial test insect when pesticides are evaluated prior to commercial release. Generally, the tested species were more sensitive to the studied insecticides than the honey bee. In order to examine whether the sensitivity of adult stages of freshwater insects corresponds with the sensitivity of the juvenile stages of the same species, the ranking of the two life stages with respect to the toxicity of Karate was compared, revealing some correspondence, but also some dissimilarities. Our results strongly indicate that terrestrial adult stages of aquatic insects are not adequately protected by current risk assessment procedures.


Assuntos
Insetos/efeitos dos fármacos , Insetos/fisiologia , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrilos/toxicidade , Nitrocompostos/toxicidade , Piretrinas/toxicidade , Animais , Abelhas/efeitos dos fármacos , Dinamarca , Relação Dose-Resposta a Droga , Ecotoxicologia/métodos , Inseticidas/administração & dosagem , Dose Letal Mediana , Neonicotinoides/administração & dosagem , Nitrilos/administração & dosagem , Nitrocompostos/administração & dosagem , Piretrinas/administração & dosagem , Rios , Especificidade da Espécie , Poluentes Químicos da Água/toxicidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA