Sources and distribution of aliphatic and polyaromatic hydrocarbons in sediments from the Neuquen River, Argentine Patagonia.

Spatial distribution and probable sources of aliphatic and polyaromatic hydrocarbons (AHs, PAHs) were investigated in surface sediments collected along the bank of the Neuquen River, Argentina. Total concentrations of aliphatic hydrocarbons ranged between 0.41 and 125 µg/g dw. Six stations presented low values of resolved aliphatic hydrocarbons and the n-alkane distribution indexes applied suggested a clear biogenic source. These values can be considered the baseline levels of aliphatic hydrocarbons for the river sediments. This constitutes important information for the assessment of future impacts since a strong impulse in the exploitation of shale gas and shale oil in these zones is nowadays undergoing. For the other 11 stations, a mixture of aliphatic hydrocarbons of petrogenic and biogenic origin was observed. The spatial distribution reflects local inputs of these pollutants with a significant increase in concentrations in the lower course, where two major cities are located. The highest values of total aliphatic hydrocarbons were found in this sector which, in turn, was the only one where individual PAHs were detected.

Effects of azinphos methyl and carbaryl on Rhinella arenarum larvae esterases and antioxidant enzymes.

Organophosphate (OP) and carbamate pesticides are anticholinesterasic agents also able to alter antioxidant defenses in different organisms. Amphibian larvae are naturally exposed to these pesticides in their aquatic environments located within agricultural areas. We studied the effect of the carbamate carbaryl (CB) and the OP azinphos methyl (AM), compounds extensively used in Northern Patagonian agricultural areas, on reduced glutathione (GSH) levels and the activities of esterases and antioxidant enzymes of the toad Rhinella arenarum larvae. Larvae were exposed 48 h to AM 3 and 6 mg/L or CB 10 and 20 mg/L. Cholinesterase and carboxylesterases were strongly inhibited by CB and AM. In insecticide-exposed larvae, carboxylesterases may serve as alternative targets protecting cholinesterase from inhibition. GSH-S-transferase (GST) activity was significantly increased by CB and AM. Superoxide dismutase activity increased in tadpoles exposed to 6 mg/L AM. Conversely, catalase (CAT) was significantly inhibited by both pesticides. GSH levels, GSH reductase and GSH peroxidase activities were not significantly affected by pesticide exposure. GST increase constitutes an important adaptive response to CB and AM exposure, as this enzyme has been related to pesticide tolerance in amphibian larvae. Besides, the ability to sustain GSH levels in spite of CAT inhibition indicates quite a good antioxidant response. In R. arenarum larvae, CAT and GST activities together with esterases could be used as biomarkers of CB and AM exposure.

Evaluación de riesgo por plaguicidas sobre aguas superficiales de la región norpatagónica argentina / Assessing pesticide hazards on surface water from the northern patagonian region argentina

Aunque el manejo integrado de plagas se aplica en forma creciente en la Región Norpatagónica, todavía una amplia gama de plaguicidas es utilizada con el fin de controlar apropiadamente las principales plagas agrícolas. Otros agroquímicos también son aplicados en las actividades industriales asociadas. El objetivo del presente trabajo es evaluar el impacto potencial causado por estos plaguicidas sobre los organismos acuáticos y para ello se utilizan datos bibliográficos de toxicidad aguda y resultados analíticos locales. Se utilizó un procedimiento escalonado, permitiendo la selección de aquellos xenobióticos ambientales que justificarían un estudio de ecotoxicidad posterior. Los residuos máximos de metil azinfos (S-(3,4-dihydro-4-oxobenzo[d]-[1,2,3]-triazin-3-ylmethyl)O,O-dimethyl phosphordithioate), indican la probabilidad de efectos agudos en el 37% de las especies estudiadas en el río, principalmente peces y zooplancton. Este valor se incrementa en los drenajes hasta un 42%. En el caso del carbaril (1-napthylmethylcarbamate) los residuos encontrados en drenajes afectarían al 14% de las especies estudiadas, mientras que en el río el impacto es despreciable.

Although the Integrated Pest Management (IPM) is increasingly being applied in the Northern Patagonia Region, different pesticides are still used in order to properly control agricultural pests. Other agrochemicals are also applied in the agriculture associated activities like conservation and packaging industries. The potential impact caused by these pesticides on aquatic organisms is assessed in the present study by means of acute toxicity data available in the literature and local analytical results. A tiered procedure was used allowing the selection of those environmental xenobiotics that need further ecotoxicity studies. The observed maximum residues of azinphos-methyl, (S-(3,4-dihydro-4-oxobenzo[d]-[1,2,3]-triazin-3-ylmethyl) O,O-dimethyl phosphordithioate), indicate the probability of acute effects in 37 % of the studied species in the river, mainly fish and zooplankton.This value increased in drainage channels samples up to 42 %. Additionally, carbaryl (1-napthylmethylcarbamate) residues foundin drainage channels affect 14 % of the studied species, while in the river samples the impact was negligible.

Enhanced esterase activity and resistance to azinphosmethyl in target and nontarget organisms.

The organophosphorous compound azinphosmethyl (AzMe) is applied extensively in northern Patagonia (southern Argentina) to manage codling moths (Cydia pomonella). This area is irrigated by fast-flowing channels that provide a favorable habitat for many species, including amphipods (Hyalella curvispina) and a field-mixed population of black flies (Simulium bonaerense, Simulium wolffhuegeli, and Simulium nigristrigatum). In the present study, AzMe susceptibility and carboxylesterase (CarbE) activity from both insecticide-exposed and nonexposed field populations were studied. The median lethal dose determined in codling moths from an insecticide-treated orchard was significantly higher (3.48 microg/insect) than that observed in those from an untreated orchard (0.69 microg/insect). Similarly, the median lethal concentration (LC50) determined in black flies collected from the treated area (0.021 mg/L) was significantly higher than that recorded in those from the untreated site (0.011 mg/L). For amphipods, both a subpopulation susceptible to AzMe (LC50, 1.83 microg/L) and a resistant one (LC50, 390 microg/L) were found in the treated area. Both subpopulations were more resistant to AzMe than the population from the untreated site (LC50, 0.43 microg/L). Significant differences (p < 0.001) in CarbE activities were observed between populations from pesticide-treated and untreated areas. Mean activities +/- standard deviation from treated and untreated sites were 0.21 +/- 0.16 and 0.016 +/- 0.008 micromol/min/mg protein, respectively, for codling moths; 2.17 +/- 1.71 and 0.81 +/- 0.35 micromol/min/mg protein, respectively, for black flies; and 0.27 +/- 0.10 and 0.14 +/- 0.07 micromol/min/mg protein, respectively, for amphipods. The results suggest that enhanced CarbE activity is one of the mechanisms that provide AzMe resistance in H. curvispina, Simulium spp., and C. pomonella populations from the insecticide-treated areas.

Muscular and brain cholinesterase sensitivities to azinphos methyl and carbaryl in the juvenile rainbow trout Oncorhynchus mykiss.

The organophosphate azinphos methyl (AzMe) and the carbamate carbaryl are the insecticides mostly used in the irrigated valley of Río Negro and Neuquén, Patagonia, Argentina. Juvenile rainbow trout were exposed to AzMe and carbaryl and the sensitivity of skeletal muscular cholinesterase (ChE) and the time course of inhibition and recovery were evaluated. EC50 values demonstrated that AzMe was a stronger in vivo inhibitor of muscular ChE (1.05+/-0.23 microg/L) than carbaryl (270+/-62.23 microg/L). Muscular ChE was significantly less sensitive to both insecticides than brain ChE. EC50 values obtained for muscular ChE were closer than those for brain ChE to the respective pesticide lethal concentrations, pointing out the relevance of the muscular enzyme in determining acute toxicity. The recovery process of ChE activity after carbaryl exposure (500 microg/L) was fast, whereas no significant recovery was observed with AzMe (1 microg/L) after 21 days in uncontaminated media. Brain and muscular ChE were inhibited and showed a significant but not complete recovery after three consecutive 48-h exposures to AzMe (1 microg/L) followed by a recovery period of 7 days. This scheme mimics the periodical application of the insecticides in the region and suggests a certain probability of a sustained ChE inhibition under field conditions, affecting fish development and survival.

Biomarcadores para el monitoreo de la exposición intrauterina a plaguicidas en comunidades rurales / Biomarkers for monitoring in utero exposure to pesticides in a rural community

La prevención del daño por exposición acontaminantes ambientales requiere identificar biomarcadores que representen una medida del proceso toxicológico antes de la manifestación de daños irreversibles. Considerando la alta vulnerabilidad del período de gestación, este trabajo fue diseñadopara evaluar el impacto de la exposición in utero a plaguicidas organofosforados (OP) y la utilidad de biomarcadores de exposición/efecto en tejidos fácilmente accesibles. Se entrevistaron 342 embarazadas del área frutícola del Alto Valle de Río Negro y Neuquén donde se alternan períodos de 6 meses de fumigación y receso. Se registraron características, hábitos y lugar de residencia materna, parámetros del neonato y de la placenta a término. Los estudios analíticos incluyeron colinesterasas sanguíneas, hemograma de las embarazadas y enzimas placentarias. Los datos fueron analizados por ANOVA regresión y correlación. La actividad de colinesterasa plasmática en época de fumigación disminuyó significativamente (18 %) y presentó asociacióncon la duración de la exposición. Tanto la actividad de acetilcolinesterasa (AChE) como catalasa (CAT) placentariaaumentaron en dicho período (40%) y la edad gestacional disminuyó en dos semanas. El perímetro cefálico aumentó por la residencia rural materna y por la fumigación en el hogar. Este parámetro se asoció con la actividad de CAT. Estos resultados indican que el uso combinado de la AChE y CAT placentarias, enzimas involucradas en eventos adaptativos, serían herramientas útiles en programas de monitoreo ambiental. Asimismo, corroboran que este tejido, el más accesible de la tríada madre – placenta– feto, muestra efectos acumulativos que reflejan el ambiente intrauterino.

Improvement of children’s health requires preventing environmental exposures and identifying predictive biomarkers that represent the toxicological process before irreversibleinjury appears. Considering the high vulnerability of the intrauterine development, this study was designed to investigate the impact of in utero exposure to organophosphate pesticides and biomarkers of early effects in easily asequible tissues. A cohort of 342 women living in the agricultural area of High Valley of Río Negro and Neuquén, where 6 month spraying and non spraying periods are alternated, were interviewed in order to characterize their demographic characteristics and lifestyle habits. Morphometric information about the offspring and placentas were recorded. The analytical studies included pregnant womenhemogram, blood cholinesterases as well as placental enzymes activities. Data were analyzed by ANOVA, regression and correlation. During spraying season plasma cholinesterase diminished significantly (18%) and was associated to exposure length. Inthis period, placental acetylcholinesterase (AChE) and catalase (CAT) increased in a similar extent (40%) and gestational agediminished in two weeks. An increase in cephalic circumference was observed in newborns from women residents in rural areas and also in ones having indoors fumigation habits. This parameter was associated to CAT activity. These results indicate that the combined use of the placental AChE and CAT, enzymes involved in adaptative events, seems to be a useful tool in environmentalmonitoring programmes. Also, they corroborate that this tissue, the most accessible and available component of the triad mother-infant-placenta shows cumulative effects that reflect the intrauterine environment in which the newborn was developed.

Modeling lead bioavailability and bioaccumulation by Lumbriculus variegatus using artificial particles. Potential use in chemical remediation processes.

Artificial particles, specifically a diverse selection of chromatographical resins, have been recommended and used as a useful experimental model to predict the bioavailability and bioaccumulation of sediment-bound organic chemicals. In this work the same experimental model was adopted to investigate the bioavailability and bioaccumulation of lead by the freshwater oligochaete Lumbriculus variegatus. Particle-water partition coefficients were also determined. Sand particles and the anionic exchange resin promoted a similar uptake and bioaccumulation of lead. Instead, in the presence of the cationic exchanger the metal was not detected in the animals. For neutral particles, the uptake and accumulation depended on the chemistry of the functional groups at the active sites. In addition, a significant negative correlation was found between bioaccumulation and the particle-water partition coefficients. These studies may help to develop alternative methods for chemical remediation of lead-contaminated aquatic systems.

Organophosphorous and organochlorine pesticides affect human placental phosphoinositides metabolism and PI-4 kinase activity.

The objective of this work was to describe the effect of organophosphorous and organochlorine pesticides on phosphoinositides metabolism in human placenta. Pesticides concentration (10 microM) was used for in vitro incubations of cell-free homogenates labelled with (32)P orthophosphate. Heptachlor (HC) and dichloro-diphenyl-trichloroethane (o-p' DDT) increased phosphatidyl-inositol, phosphatidylinositolphosphate, and phosphatidyl-inositolbiphosphate phosphorylation while azinphosmethyl (AM) increased phosphatidylinositolbiphosphate labeling. Decreased (32)P incorporation in phosphatidylinositol was found with phosmet (PM), AM, and chlorpyriphos (CHL). The effects of these xenobiotics on PI4-kinase activity using different subcellular fractions were also examined. Both type of pesticides affected the postmembrane supernatant enzyme activity. A biphasic effect on membrane and nuclear PI4-kinase activity was seen with HC. The strongest effect found was seen with o-p' DDT in nuclear kinase activity while substantial changes were also observed in membrane. These data demonstrate the sensitivity of human placental PI4-kinase to pesticides currently found in human tissues and suggest deleterious consequences in different processes regulated by 4-phosphoinositides.

Different susceptibility of two aquatic vertebrates (Oncorhynchus mykiss and Bufo arenarum) to azinphos methyl and carbaryl.

We studied the effect of two insecticides azinphos methyl and carbaryl on two resident aquatic species (Oncorhynchus mykiss and Bufo arenarum). Juvenile trout and larval stages of toad were used for exposure and recovery assays. O. mykiss was more sensitive to azinphos methyl exposure than B. arenarum larvae, with a mean 96-h LC50 of 0.007 mg/l. Carbaryl is markedly less toxic than the organophosphate and the differences in potency, expressed as LC50, for both species varies only by five-fold. The relationship between cholinesterase (ChE) inhibition and lethality is not straightforward: O. mykiss survives with an almost complete inhibition of the brain enzyme when exposed to azinphos methyl and carbaryl. Their IC50 values are one or two orders of magnitude lower than the corresponding 96-h LC50 value. In B. arenarum larvae, the IC50 values for azinphos methyl and carbaryl are one half and one third of their 96-h LC50s, respectively. The time courses of enzyme inhibition and recovery also points out differences between both types of pesticides and species. Identifying the key features conferring species selectivity can be exploited to minimize the incidence and severity of intoxication of non-target organism. The data presented here highlight the necessity of including several species and endpoint analyses in the pesticide risk evaluations of aquatic ecosystems.

Biomarkers of effect in toads and frogs.

Amphibians are good bioindicators of environmental pollution due to their susceptibility to chemicals during their freshwater cycles. The effects of environmental pollution, together with changes in human activity and climate, have contributed to the reduction in the amphibian population over recent decades. However, toxicological research on amphibians has been rather scarce compared with that on other vertebrates. In this article we review the biochemical alterations underlying xenobiotic action and/or the detoxifying responses described for anuran species, with the aim of establishing possible biomarkers of effect. During the embryonic development of anurans, morphological and behavioural alterations are the effects most frequently cited in connection with chemical exposures. However, such biomarkers have a low sensitivity and are unspecific compared with biochemical alterations. Some primary pesticide targets, in particular cholinesterases for organophosphates and carbamates, have been evaluated. Esterases change seasonally and with the stage of development, and their sensitivity to anticholinesterase agents varies between species. Thus their use as biomarkers in anurans must be carefully analysed. Enzymes and endogenous compounds related to oxidative metabolism may also be used as biomarkers of effect. Glutathione pool, glutathione-S-transferases and metallothioneins respond in different ways to pesticides and heavy metals in anuran embryos and tadpoles. Mixed-function oxidases, in turn, are less developed in amphibians, and show a reduced induction in response to pesticide exposures. Endogenous polyamine levels are also proposed as good age-related biomarkers of damage. Finally, molecular biomarkers related to receptor binding, signal transduction and genetic response have gained increasing relevance, as they have been implicated in the fertilisation process and the earliest events in anuran development. The identification of transcription factors associated with the exposure of amphibians to xenobiotics as well as other alterations in hormone signalling appears highly promising. However, these techniques are likely to complement other methods. In conclusion, the use of several biomarkers with multiple endpoints is needed to link exposure to response and to provide better predictive tools for the environmental protection of endangered anuran species.

Alteration of thrombine-signaling mechanism by heptachlor in human platelets.

Heptachlor is a persistent organochlorine insecticide that has been detected in human tissues and fluids. The ability of heptachlor to interfere with platelet phosphoinositides metabolism and related signaling events stimulated by thrombin was evaluated. In vitro incubations with a concentration range of 1-100 microM heptachlor, prior to platelets activation, were performed. Experiments showed that 10 microM increased protein Kinase C (PKC) activity and phosphatidylinositolbiphosphate and phosphatidic acid phosphorylation. Simultaneously phosphatidylcholine and phosphatidylethanolamine breakdown were prevented. Similar effects were observed with HC 1 microM. However, heptachlor 100 microM increased phosphatidylinositolbiphosphate phosphorylation but reduced serine/threonine kinases activity. We propose that signal transduction steps downstream phospholipase C (PLC) are unphysiologically activated by heptachlor and facilitated by the increase in phosphatidylinositolbiphosphate, the substrate for PLC activity, thus producing an accumulation of phosphatidic acid. The elevated level of this compound itself or the transient increase in diacylglycerol produced may cause calcium mobilization and the activation of PKC. In contrast with the alterations observed in phospholipids and protein phosphorylation, no changes in aggregation properties were observed.

Distribución de Paratión y Mercurio y Biomarcadores de efecto en la exposicióon de Cyprinus Carpio a concentraciones subletales / Distribution of parathion and mercury and biomarkers of effect in Cyprinus carpio exposed to sublethal concentrations

Se avaluó la distribución de mercurio y paration en carpa (Cyprinus carpio), y su efectos sobre biomarcadores en el hígado y el cerebro en la exposición a niveles subletales; constituye este trabajo una primera aproximación al estudio de la exposición a múltilples contaminantes en los cursos de agua de la región Comahue (Agentina). El insecticida paratión marcado co C se distribuyó en forma órgano-rspecífica en el hígado, con con concerntraciones 6 veces más altas que en otros órganos, mientras que la cumulación de mercurio se produjo más lentamente, principalmente en el hígado y el riñón. El paratión no afectó el índice hepatosomático, los niveles de glutatión, ni la producción de peróxidos lipidsicos; sin embargo, provocó una caída significativa del contenido de proteínas totales en el hígado. La aceticolinesterasa cerebral registró una inhibición pronunciada y significativa a las 24 horas de exposición (86 por ciento). Luego de 96 horas de exposición a mercurio solo se registró un 25 por ciento de inhibición de acetilcolisterasa cerebral. Estos resultados sugiere que si bien la exposición a niveles subletales de ambos tóxicos conduce a una concentración preferencial rn órganops críticos, los parámetros biomarcadores se ven afectados en los órganos diana. Esta situación se manisfesto en la acción neurotóxica de ambos compuestos y corrobora la evidencia de que la inhibición de la aceticolinesterasa no es prpducida solamente por insecticidas anticolinesterásicos, sino que metales tóxicos, como el mercurio, tambien pueden hacerlo.

Plaguicidas en aguas subterraneas en el valle del rio Neuquen

Se llevo a cabo un monitoreo sistematico de 30 freatimetros en la zona de produccion fruticola en la prov. de Neuquen,en el periodo octubre 1995-marzo 1997,no existiendo en la zona antecedentes de un relevamiento de la calidad del agua subterranea a pesar de ser de uso frecuente,la utilizacion de plaguicidas en zonas frutihorticolas.En el estudio se detecto con mayor frecuencia el Metil Azinfos,detectandose en algunos freatimetros la presencia de mas de un contaminante.Asimismo se evidenciaron asociaciones de interes entre la presencia de plaguicidas en al agua subterranea y algunos factores relacionados,tales como el clima,uso quimico y el tipo de suelo

Analisis del riesgo potencial para la salud y el medio ambiente derivado de la disposicion clandestina de agroquímicos en El Cuy, Provincia de Río Negro, Argentina / Environmental and health effects arising from two clandestine agrochemical waster buried in El Cuy, Río Negro (Argentina)

En el presente trabajo se exponen los resultados obtenidos de las pericias realizadas en la causa judicial originada en una denuncia por delitos contra el medio ambiente. La mismas conciernen al enterramiento clandestino de residuos de agroquímicos en un paraje semidesértico de la Provincia de Río Negro, Argentina. Un total de dieciocho muestras representativas de lo encontrado en las excavaciones se analizó por cromatografía gaseosa- espectrometría de masas (GC/MS). En todos los casos se constató la presencia de plaguicidas parcialmente degradados junto con sustanciaspropias de la formulación del producto técnico. En ninguno se observó la presencia de metales pesados. Por otra partese realizaron mediciones de residuos de plaguicidas sobre tierra de los pozoz y el área circundante, con el objeto de monitorear el proceso de limpieza y descontaminación del área (ánalisis de algunos plaguicidas organofosforados por GC con detección NOD). En base a datos geológicos e hidrográficos de la zona, se analizó el riesgo potencial para la salud y el medio ambiente

Analisis del riesgo potencial para la salud y el medio ambiente derivado de la disposicion clandestina de agroquímicos en El Cuy, Provincia de Río Negro, Argentina / Environmental and health effects arising from two clandestine agrochemical waster buried in El Cuy, Río Negro (Argentina)

En el presente trabajo se exponen los resultados obtenidos de las pericias realizadas en la causa judicial originada en una denuncia por delitos contra el medio ambiente. La mismas conciernen al enterramiento clandestino de residuos de agroquímicos en un paraje semidesértico de la Provincia de Río Negro, Argentina. Un total de dieciocho muestras representativas de lo encontrado en las excavaciones se analizó por cromatografía gaseosa- espectrometría de masas (GC/MS). En todos los casos se constató la presencia de plaguicidas parcialmente degradados junto con sustanciaspropias de la formulación del producto técnico. En ninguno se observó la presencia de metales pesados. Por otra partese realizaron mediciones de residuos de plaguicidas sobre tierra de los pozoz y el área circundante, con el objeto de monitorear el proceso de limpieza y descontaminación del área (ánalisis de algunos plaguicidas organofosforados por GC con detección NOD). En base a datos geológicos e hidrográficos de la zona, se analizó el riesgo potencial para la salud y el medio ambiente(AU)