RESUMO
Agrochemicals cause diverse effects on aquatic communities, and amphibian species are particularly threatened due the high susceptibility to contamination. Present study evaluates the toxicity of a widely used fungicide tebuconazole (Trigal®) by the assessment of mortality and developmental alterations at acute, subchronic, and chronic exposure during the embryo-larval development of the South American toad Rhinella arenarum. Also, the sensitivity of the different embryonic stages was evaluated with 24-h pulse exposure treatments. The results demonstrated that larvae were more sensitive than embryos at acute exposure (LC50-24 and 96 h = 74.62, 31.92 mg/L and 24.27, 16.81 mg/L for embryos and larvae, respectively). Nevertheless, embryos toxicity increased significantly achieving a sensitivity very similar to larvae at chronic exposure (LC50-168 and 504 h = 13.31, 4.35 mg/L and 14.47, 6.83 mg/L for embryos and larvae, respectively). Embryos exhibited several sublethal effects from 5 mg/L at 96 h onwards, such as delayed development, reduce body size, edemas, tail/axial flexures, weakness, and absence of movements. The teratogenic index at 96 h was 10.13, indicating the severe teratogenic potential of the fungicide. 24-h pulse exposure treatments showed an increased sensitivity in intermediate stages as S.11, S.18, S20, and S.23 (NOEC-96 h = 100, 200, 75, and 20 mg/L, respectively), while stage S.25 was the most sensitive to the fungicide (NOEC-96 h = 5 mg/L). About metamorphic process, tebuconazole caused an acceleration of metamorphosis at the lowest concentration (0.001 mg/L), but also an increase in mortality and in addition, significant differences in the weight in all treatments. The results obtained throughout this work indicate that tebuconazole cause several adverse effects in Rhinella arenarum embryo-larval development.
Assuntos
Fungicidas Industriais , Triazóis , Poluentes Químicos da Água , Animais , Fungicidas Industriais/toxicidade , Bufo bufo , Embrião não Mamífero , Bufonidae , Bufo arenarum , Larva , América do Sul , Poluentes Químicos da Água/toxicidadeRESUMO
Among the factors implicated in amphibian global decline, agrochemicals have been gaining increasing attention. In order to evaluate the toxicity of a dimethoate-based insecticide on the early development of an autochthonous amphibian, Rhinella arenarum, continuous and 24 h pulse exposure bioassays were carried out. Lethal and sublethal effects, neurotoxicity and the ecological risk were assessed. Results demonstrate that larvae were more sensitive than embryos with 504 h-LC50 of 12.82 and 16.38 mg L-1, respectively. 24 h pulse experiments showed a high toxicity increment at early embryonic stages, while the sensitivity at later stages was high and constant. Dimethoate caused teratogenesis and several sublethal effects as morphological and behavioral alterations but also disruption in the metamorphic process. About neurotoxicity, dimethoate inhibited the activity of butyrylcholinesterase at 0.5 and 1 mg L-1 exposed larvae. The results obtained in this study as the risk assessment revealed that dimethoate represents a hazard on Rhinella arenarum survival and development but also a potential risk for the continuity of the populations of this species in agroecosystems.
Assuntos
Dimetoato , Praguicidas , Animais , Bufo arenarum , Butirilcolinesterase , Dimetoato/toxicidade , Embrião não Mamífero , Larva , Praguicidas/toxicidadeRESUMO
There is a great concern worldwide about the global decline of amphibians, particularly by agrochemical pollution. The aim of this study was to assess oxidative stress and genotoxicity of a commercial formulation of the insecticide dimethoate in Rhinella arenarum larvae, using sublethal biomarkers. The 24- and 96-h LC50 values of dimethoate to R. arenarum were 48.81 and 38.86 mg L-1, while the 96-h no observed effect concentration (NOEC) value was 20 mg L-1. For sublethal biomarker assays, R. arenarum larvae were exposed to 1.25, 2.5, and 5% of the 96-h NOEC (0.25, 0.5, and 1 mg L-1 dimethoate, respectively). After 96 h of exposure, inhibition of catalase (CAT) and glutathione S-transferase (GST) activities were registered. Also, an increased superoxide dismutase (SOD) activity was observed in larvae exposed to the highest concentration (1 mg L-1). Lipid peroxidation by increased thiobarbituric acid reactive substance levels in larvae exposed to 0.5 and 1 mg L-1 was detected. No differences in micronuclei frequency between treatments and negative control were observed. These results demonstrate the oxidative toxicity of dimethoate at sublethal concentrations in Rhinella arenarum larvae. The disruption of defense mechanisms may contribute to a deleterious impact on amphibian populations from habitats exposed to this organophosphorus insecticide.
Assuntos
Dimetoato , Inseticidas , Animais , Dimetoato/toxicidade , Glutationa Transferase/metabolismo , Inseticidas/toxicidade , Larva/metabolismo , Compostos Organofosforados , Estresse OxidativoRESUMO
The toxicity of a commercial formulation of the fungicide chlorothalonil in sensitive stages of the native amphibian Rhinella arenarum (Ra) was assessed by means continuous treatments from embryo and larval development and 24-h pulse exposures evaluating acute and chronic lethal and sublethal effects and stage-dependent sensitivity. A risk assessment of chlorothalonil in Ra development also was performed. The results of continuous exposure in embryos showed a significant toxicity increase with exposure time, whereas sensitivity of larvae remained relatively constant through time (24 and 504-h LC50 = 0.86 and 0.04 mg L-1, and 0.37 and 0.34 mg L-1 for embryos and larvae respectively). Embryos exhibited several sublethal effects, such as delayed development, tail/axial flexures, edemas, and behavioral alterations. The 96-h NOEC values for lethal and sublethal effects were 0.025 and 0.01 mg L-1 respectively, so the 96-h Teratogenic Index was 2.5, which indicates the severe teratogenic potential of the fungicide. For 24-h pulse exposure experiments, S.21 and S.23 were the most sensitive stages for lethality (504-h NOEC = 0.05 mg L-1), whereas earlier stages exhibited severe morphological alterations. The results obtained in this study and the ecological risk evaluation highlight the severe toxicity of chlorothalonil threatening the continuity of Ra populations.
Assuntos
Fungicidas Industriais , Animais , Bufo arenarum , Embrião não Mamífero , Fungicidas Industriais/toxicidade , Larva , NitrilasRESUMO
The employ of nanomaterials (NMs) has exponentially grown due to the large number of technological advances in industrial, pharmaceutical and medical areas. That is the case of alumina (Al) nanoparticles which are extensively employed as support in heterogeneous catalysis processes. However, these NMs can cause great toxicity because of their ubiquitous properties, such as extremely small size and high specific surface area. So, it is required to assess the potential deleterious effects of these NMs on living organisms. In the present study, we analyze the oxidative stress and genotoxic potential of a nanoceramic catalyst Ni/
Assuntos
Óxido de Alumínio/toxicidade , Bufo arenarum , Cerâmica/toxicidade , Larva/efeitos dos fármacos , Mutagênicos/toxicidade , Nanopartículas/toxicidade , Níquel/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Animais , Testes para MicronúcleosRESUMO
Agricultural activity, especially the increasing use of pesticides, is considered one of the main reasons for the decline of amphibian populations. Mancozeb (MCZ) is one of the most used fungicides worldwide, despite its ancient use and toxicity demonstrated in different taxa. However, there is limited information about the effects of MCZ in amphibians, which are keystones of riparian ecosystems. For species conservation purposes, it is essential to identify the most sensitive developmental period(s) of a given species to a xenobiotic. We evaluated the toxicity of a commercial fungicide of mancozeb, (80% active ingredient) on the early development of the common South American toad Rhinella arenarum (Anura, Bufonidae). Embryos from early blastula (S.4) and larvae from complete operculum (S.25) stages were exposed to a wide range of MCZ concentrations during acute, subchronic and chronic exposure (up to 504 h) periods. The toxicity profiles for lethal and sublethal effects were performed. At all exposure times, MCZ was more toxic to embryos, for instance, NOEC 504 h were 0.01 and 0.05 mg MCZ/L for embryos and larvae, respectively. Thus, embryo sensitivity was 5-fold higher than larvae. A Teratogenic Index of 14 indicated the significant teratogenic potential of this fungicide. Among sublethal effects, embryos exhibited a wide range of abnormalities with high incidence. The ecological risk assessment demonstrated that the estimated Risk Quotient value for Rhinella arenarum embryos at chronic exposure was higher than the Level of Concern value, which warns about the potential risk of MCZ for this native species.
Assuntos
Bufo bufo , Fungicidas Industriais/toxicidade , Maneb/toxicidade , Zineb/toxicidade , Animais , Bufo arenarum , Bufonidae , Ecossistema , Embrião não Mamífero , Larva , Medição de RiscoRESUMO
Alumina nanoparticles (NP-Al2O3) are widely used but their environmental effects are unknown, so they can become potentially dangerous. The aim of this study was to evaluate the toxicity of a nanoceramic catalyst Ni/γ-Al2O3 (NC) and NPs involved in their synthesis, γ-Al2O3 support (SPC) and NiO/γ-Al2O3 precursor (PC) on Rhinella arenarum embryo-larval development. The NPs toxicity significantly increased over time obtaining a similar sensitivity to PC and NC (336 h-LC50 = 4.03 and 5.11 mg/L respectively) and very low sensitivity to SPC (336 h-LC50 = 90.83 mg/L). Embryos exposed to SPC and PC exhibited general underdevelopment, axial flexures and behavioral alterations. Pharyngeal and intestinal epithelia alterations at the level of cell surface as dissociation, apoptosis and numerous lysosomes were observed at light and transmission electronic microscopy. Images of scanning electron microscope with backscattered electron detector revealed the presence of nickel in the intestinal epithelium. The increased toxicity of PC could be due to the presence of Ni as oxide which could interfere with vital functions such as breathing and feeding. Taking into account the exponential production and use of these NPs it is expected that their pollution levels will considerably increase and amphibians will be more exposed and at higher risk.
Assuntos
Óxido de Alumínio/toxicidade , Bufonidae , Cerâmica/toxicidade , Nanoestruturas/toxicidade , Níquel/toxicidade , Teratogênicos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Embrião não Mamífero/efeitos dos fármacos , Desenvolvimento Embrionário/efeitos dos fármacos , Larva/efeitos dos fármacos , Síndromes Neurotóxicas/etiologia , Síndromes Neurotóxicas/veterináriaRESUMO
Agricultural fungicide application in Argentina has increased twice since 2008, with Maxim® XL (2.5% fludioxonil +1% metalaxyl-M) as one of the most used fungicide formulation. The toxicity of this pesticide on Rhinella arenarum was assessed by means of continuous (from embryo and larval development) and 24-h pulse exposure standardized bioassays. Lethality was concentration- and exposure time-dependent. Maxim® XL caused a progressive lethal effect along the bioassays with higher toxicity on embryos than larvae, obtaining 50% lethal concentrations at 96, 336, and 504 h of 10.85, 2.89, and 1.71 mg/L for embryos, and 43.94, 11.79, and 5.76 mg/L for larvae respectively. Lethal 504-h no observed effect concentration values for embryos and larvae were 1 and 2.5 mg/L respectively. A stage-dependent toxicity of Maxim® XL was also demonstrated within the embryo development, with early stages more sensitive than the later ones, and blastula as the most sensitive developmental stage. The risk quotients obtained for chronic risk assessment determined a potential threat for the survival and continuity of R. arenarum populations under these conditions. The results indicate that the levels of the fungicide reaching amphibian habitats could be risky for the early development of this amphibian species. This study also emphasizes the necessity to evaluate the chronic effects of fungicides in pesticide risk assessment.
Assuntos
Alanina/análogos & derivados , Bufo arenarum/embriologia , Bufo arenarum/crescimento & desenvolvimento , Dioxóis/toxicidade , Fungicidas Industriais/toxicidade , Pirróis/toxicidade , Alanina/administração & dosagem , Alanina/toxicidade , Animais , Blástula/efeitos dos fármacos , Dioxóis/administração & dosagem , Relação Dose-Resposta a Droga , Ecotoxicologia/métodos , Embrião não Mamífero/efeitos dos fármacos , Feminino , Fungicidas Industriais/administração & dosagem , Larva/efeitos dos fármacos , Mortalidade , Pirróis/administração & dosagem , Testes de Toxicidade CrônicaRESUMO
The increasing application of nanoparticles (NPs) to a variety of new technologies has become a matter of concern due to the potential toxicity of these materials. Many questions about the fate of NPs in the environment and the subsequent impact on ecosystems need to be answered. The aim of this work was to evaluate the ecotoxicity of two alumina-based nanoceramics, γ-Al2O3 (NC) and Ni/ γ-Al2O3 (NiNC) by means of three different standardized tests: Biochemical Oxygen Demand (BOD5), bioassay with luminescent bacteria (Vibrio fischeri; Microtox), and bioassay on amphibian larvae (Rhinella arenarum) (AMPHITOX). BOD5 values of a very biodegradable mixture (glucose/glutamic acid) decreased with the addition of NiNC(43.8%) and NC (31.6%) with respect to control samples (52.9%). Microtox test results indicated that NiNC presents higher toxicity than NC, with EC50s values of 16.1% and 29.9% respectively; a reduced toxicity was observed, however, in presence of organic matter, thus obtaining EC50s of 37.8% and 19.4%. The results of AMPHITOX test showed a significant increase in the toxicity of both substances over time, the NiNC toxicity being greater than that of NC. The values of 96h-LC50 and 504h-LC50 determined for NiNC were 1.58 and 0.83mg/L, respectively, and 14.5 and 10.5mg/L for NC samples. Amphibian larvae exhibited collapsed cavities, edema, axial flexures, and behavioral alterations as hyperkinesia and reduced movements. These results evidence the vulnerability of wildlife to xenobiotics and the need to develop specific standardized ecotoxicity tests in order to help environmental sustainability and natural species conservation.
Assuntos
Aliivibrio fischeri/efeitos dos fármacos , Óxido de Alumínio/toxicidade , Monitoramento Ambiental/métodos , Larva/efeitos dos fármacos , Nanopartículas/toxicidade , Níquel/toxicidade , Animais , Bioensaio , Análise da Demanda Biológica de Oxigênio , Bufo marinus , Ecotoxicologia , Propriedades de Superfície , XenobióticosRESUMO
Bisphenol A diglycidyl ether (BADGE) is used in packaging materials, in epoxy adhesives, and as an additive for plastics, but it is also a potential industrial wastewater contaminant. The aim of the present study was to evaluate the adverse effects of BADGE on Rhinella arenarum by means of standardized bioassays at embryo-larval development. The results showed that BADGE was more toxic to embryos than to larvae at all exposure times. At acute exposure, lethality rates of embryos exposed to concentrations of 0.0005 mg/L BADGE and greater were significantly higher than rates in the vehicle control, whereas lethality rates of larvae were significantly higher in concentrations of 10 mg/L BADGE and greater. The toxicity then increased significantly, with 96-h median lethal concentrations (LC50s) of 0.13 mg/L and 6.9 mg/L BADGE for embryos and larvae, respectively. By the end of the chronic period, the 336-h LC50s were 0.04 mg/L and 2.2 mg/L BADGE for embryos and larvae, respectively. This differential sensitivity was also ascertained by the 24-h pulse exposure experiments, in which embryos showed a stage-dependent toxicity, with blastula being the most sensitive stage and S.23 the most resistant. The most important sublethal effects in embryos were cell dissociation and delayed development, whereas the main abnormalities observed in larvae related to neurotoxicity, as scare response to stimuli and narcotic effect. Environ Toxicol Chem 2016;35:3031-3038. © 2016 SETAC.