ABSTRACT
Diazinon, an anti-cholinesterase organophosphate, is an extensively used pesticide. The main objective of this work was to assess the lethal and sublethal effects of Diazinon and its comparison with the uptake by embryos and larvae of the common South American toad Rhinella arenarum by means of standardized bioassays during acute (96 h), short-term chronic (168 h) and chronic (504 h) exposures. Toxicity resulted time- and stage-dependent, thus the lethal concentration 50 for 96 h, 168 h and 504 h were 27.2; 20.1 and 6.8 mg Diazinon L(-1) for embryos and 8, 6.7 and 1.9 mg Diazinon L(-1) for larvae. It is noteworthy the remarkable differences found in the concentration which caused lethality with those causing adverse effects on development such as malformations (teratogenic effects). Therefore, the teratogenic index from 144 h was greater than two; the main adverse effects were axial flexures, irregular borders, wavy tail, microcephaly, malformed mouth and adhesive structures, gut miscoiling, underdeveloped gills, cloacal edema, desquamation and severe hydropsy. Moreover, the characteristic sublethal effect of Diazinon on larvae was abnormal behavior related to neurotoxicity with a NOEC-168 h of 4.5 mg Diazinon L(-1). Diazinon contents in R. arenarum were time-dependent and significantly related to exposure concentration for both embryos and larvae. Diazinon contents were also stage-dependent, as it was up to 27 times higher for organisms exposed from blastula stage onwards than early larvae. These facts and the Hazard Quotients, a numerical expression of ecological risk, of 2.73, which is above USEPA's Level of Concern, showed the threat that Diazinon represents for R. arenarum populations.
Subject(s)
Bufonidae/embryology , Bufonidae/growth & development , Diazinon/metabolism , Diazinon/toxicity , Ecotoxicology , Embryo, Nonmammalian/drug effects , Animals , Biological Transport , Environmental Pollutants/metabolism , Environmental Pollutants/toxicity , Female , Larva/drug effects , Larva/growth & development , Lethal Dose 50 , Pesticides/metabolism , Pesticides/toxicityABSTRACT
The acclimation possibilities to copper in Bufo arenarum embryos was evaluated by means of three different low level copper exposure conditions during 14 days. By the end of the acclimation period the copper content in control embryos was 1.04 +/- 0.09 microg g(-1) (wet weight) while in all the acclimated embryos a reduction of about 25% of copper was found. Thus copper content could be considered as a biomarker of low level exposure conditions. Batches of 10 embryos (by triplicate) from each acclimation condition were challenged with three different toxic concentrations of copper. As a general pattern, the acclimation protocol to copper exerted a transient beneficial effect on the survival of the Bufo arenarum embryos. The acclimation phenomenon could be related to the selection of pollution tolerant organisms within an adaptive process and therefore the persistence of information within an ecological system following a toxicological stressor.
Subject(s)
Adaptation, Physiological , Amphibians , Anura , Bufo arenarum , Copper/toxicity , Embryo, Nonmammalian/drug effects , Environmental Exposure/adverse effects , Environmental Pollution/adverse effects , Animals , Biomarkers , Tissue Survival , Zinc/toxicityABSTRACT
Cu2+ and butylic ester of 2,4-Dichlorophenoxyacetic acid as Esternon Ultra (2,4-D) toxicity on Bufo arenarum embryos were evaluated by means of a short-term chronic toxicity test (AMPHITOX). The NOEC values for Cu and 2,4-D were 0.02 mg/L and 2 mg/L respectively. The toxicity profile curves for Cu and 2,4-D were reported. The interactions of the metal and the herbicide were evaluated by combined treatments with different concentrations of Cu and 2,4-D. Although in all cases, a synergistic effect between these chemicals was observed, the combination of concentrations exerting low level effects in isolated treatments resulted in more adverse embryonic survival. Considering that both products are extensively used in agroecosystems, this fact could be of concern for non target species like amphibians.
Subject(s)
2,4-Dichlorophenoxyacetic Acid/analogs & derivatives , Copper/toxicity , 2,4-Dichlorophenoxyacetic Acid/toxicity , Amphibians/embryology , Animals , Bufo arenarum , Drug Synergism , Embryo, Nonmammalian , Female , Toxicity TestsABSTRACT
La contaminación por metales representa una de las principales causas de deterioro en la calidad de las aguas debido a las importantes cantidades que se están acumulando en el medio ambiente, su alta toxicidad y persistencia. La protección de la vida silvestre requiere establecer concentraciones máximas admisible, especialmente para las sustancias con alto impacto ambiental como el níquel y el aluminio. El presente estudio confirma la elevada sensibilidad de los embriones de Bufo arenarum a la contaminación química aún para exposiciones agudas a los metales informados en este trabajo
Subject(s)
Water Quality , Water Pollution , Nickel , Aluminum , Zinc , Fauna , Toxicity , EnvironmentABSTRACT
La contaminación por metales representa una de las principales causas de deterioro en la calidad de las aguas debido a las importantes cantidades que se están acumulando en el medio ambiente, su alta toxicidad y persistencia. La protección de la vida silvestre requiere establecer concentraciones máximas admisible, especialmente para las sustancias con alto impacto ambiental como el níquel y el aluminio. El presente estudio confirma la elevada sensibilidad de los embriones de Bufo arenarum a la contaminación química aún para exposiciones agudas a los metales informados en este trabajo
Subject(s)
Aluminum , Fauna , Environment , Nickel , Water Pollution , Water Quality , Toxicity , ZincABSTRACT
Sostiene que el río Reconquista es considerado en la Argentina como uno de los cuerpos de agua "supercríticos" debido al grave deterioro en la calidad de sus aguas. En su cuenca de 1574 km2 viven más de 3.000.000 de habitantes y existen unas 12.000 industrias. Este estudio informa sobre la calidad del agua en seis estaciones de muestreo del río sobre la base del test de toxicidad. Afirma que casi en la totalidad de su curso, la toxicidad del agua resultó mayor que el nivel máximo de toxicidad admisible para efluentes industriales según la EPA. Señala que estos test parecen ser particularmente indicados para evaluar la contaminación y la calidad del agua, información esencial para objetivos de diagnóstico, protección de los servicios del ecosistema, monitoreo y para evaluar progresos en tareas de saneamiento
Subject(s)
Argentina , River Pollution , Water QualityABSTRACT
Sostiene que el río Reconquista es considerado en la Argentina como uno de los cuerpos de agua "supercríticos" debido al grave deterioro en la calidad de sus aguas. En su cuenca de 1574 km2 viven más de 3.000.000 de habitantes y existen unas 12.000 industrias. Este estudio informa sobre la calidad del agua en seis estaciones de muestreo del río sobre la base del test de toxicidad. Afirma que casi en la totalidad de su curso, la toxicidad del agua resultó mayor que el nivel máximo de toxicidad admisible para efluentes industriales según la EPA. Señala que estos test parecen ser particularmente indicados para evaluar la contaminación y la calidad del agua, información esencial para objetivos de diagnóstico, protección de los servicios del ecosistema, monitoreo y para evaluar progresos en tareas de saneamiento
