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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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