Assessment of insecticide contamination in runoff and stream water of small agricultural streams in the main soybean area of Argentina

Aquatic macroinvertebrate assemblages are affected by insecticide applications on the Argentine Pampas

Agriculture intensification in Argentina has increased agrochemicals consumption in the last decades and might represent an environmental risk for adjacent water bodies. The objective of the present work was to assess the effect of land use on water quality and invertebrate assemblages in the Argentine Pampas streams. Eight streams were sampled on 4 occasions during the 2013/14 growing season. Three streams are located within a biosphere reserve, two drain basins with extensive livestock fields, and three run through intensively cultivated plots; one of them contained a 30m wide uncultivated grass-covered strip between the crop and the stream. Macroinvertebrates were sampled from emergent vegetation by means of a D-net with a 500µm pore size, and 30cm diameter. Higher nutrient concentrations were measured in the agricultural streams. Endosulfan was measured in sediments of the agricultural streams, concentrations being significantly lower in the stream with the buffer strip. Invertebrate assemblages in the cropped streams were significantly different from those in the livestock and reserve streams, those in the latter not being different from each other. Ampullaridae (Pomacea canaliculata) and Planorbidae (Biomophalaria peregrina) were the taxa best represented in the agricultural streams. Hyalellidae (Hyalella curvispina), Zygoptera and Planorbidae (B. peregrina) were the taxa best represented in the reserve and livestock streams. Present evidence suggests that the observed differences in the invertebrate composition in the agricultural streams were related with the impact of agrochemicals and that buffer strips represent a useful attenuation practice. Cattle breeding on natural pastures represented a land use with low impact on the invertebrate assemblages.

Chlorpyrifos interacts with other agricultural stressors to alter stream communities in laboratory microcosms

Chlorpyrifos is one of the most widely used agricultural insecticides in the world, but to date there is limited empirical information about its potential to interact with other common agricultural stressors. We conducted a 15-d, community-level, microcosm experiment evaluating individual and combined effects of chlorpyrifos, nutrient enrichment, and sedimentation on stream invertebrate communities (abundance, biomass, richness, size structure, composition) and ecosystem processes (primary productivity and leaf decomposition). We found that sedimentation was the most detrimental stressor, with significant negative impacts on most invertebrate community and ecosystem function variables. Even though chlorpyrifos did not cause significant invertebrate mortality in the microcosms, it still altered ecosystem function by lowering leaf decomposition rates, probably through sublethal inhibition of invertebrate shredders. Furthermore, we observed a significant reversal interaction between chlorpyrifos and sediment for small-sized invertebrates collected in gravel (abundance in sediment × insecticide microcosms was 2.4 times lower than predicted by additivity), as well as an antagonistic interaction with nutrients on invertebrate richness in the same microhabitat (richness in nutrient × insecticide microcosms was 1.6 times higher than predicted by additivity). Our results suggest that chlorpyrifos has the potential to alter freshwater ecosystem function and interact non-additively with other common agricultural stressors. These findings are in keeping with a growing body of research highlighting that multiple stressor interactions and ecosystem processes should be considered when evaluating the impacts of organic toxicants on freshwater ecosystems.

Cypermethrin: Oxidative stress and genotoxicity in retinal cells of the adult zebrafish

Cypermethrin (CM), widely used for control of indoor and field pests, is one of the most common contaminants in freshwater aquatic systems. We evaluated CM genotoxicity and the activities of superoxide dismutase (SOD) and catalase (CAT) in retinal cells of adult zebrafish. Histological and immunofluorescence techniques show the presence of apoptotic cells in the zebrafish retina after 9 d of treatment with 0.6 μg/L CM. Histone γ-H2AX, a marker of DNA damage, was detected in both outer and inner nuclear layers; caspase-3, an apoptotic marker, was detected in the outer nuclear layer. In the comet assay, the cells were sensitive to hydrogen peroxide-induced DNA damage, showing a dose-dependent response. We observed a positive comet assay response to CM that was dose- and time-dependent. Following exposure to CM, SOD and CAT enzyme activities, and sod and cat mRNA levels, increased. These results indicate that CM causes DNA damage and oxidative stress and can induce apoptosis in retinal cells.

Spatial and temporal trends and flow dynamics of glyphosate and other pesticides within an agricultural watershed in Argentina

In the present study, we evaluated the spatial and temporal trends of current-use pesticides in surface water and sediments as well as their relationship with hydrological stream dynamics within the agricultural watershed of El Crespo stream (Buenos Aires Province, Argentina). We sampled 2 contrasting sites: site 1 (upstream), surrounded by agricultural lands, and site 2 (downstream), surrounded by natural grasslands. Most of the applied pesticides (glyphosate, 2,4-D, atrazine, tebuconazole, and imidacloprid) were detected at high frequencies in surface water samples at both sites. However, only glyphosate and aminomethylphosphonic acid (AMPA) were present at high concentrations and had a significant spatial-temporal trend. The highest concentrations were found during spring 2014 at site 1, in association with the intense rains that occurred in that season. The fact that glyphosate and AMPA concentrations were higher than the rest of the studied compounds is closely related to the land use within the watershed, as glyphosate was the most applied herbicide during the fallow period of glyphosate-resistant crops (soybean, maize). The pesticide mixture had a significant spatial-temporal trend, reaching the highest levels during storm flow events in spring 2014. The intensive rains in spring 2014 could be the main factor influencing stream hydrology and pesticide behavior at El Crespo watershed. The estimated annual pesticide losses were 3.11 g/ha at site 1 and 0.72 g/ha at site 2. This result indicates that an attenuation process could be decreasing pesticide loads during downstream transport from site 1 to site 2. Environ Toxicol Chem 2017;36:3206-3216. © 2017 SETAC.

Environmental relevant concentrations of a chlorpyrifos commercial formulation affect two neotropical fish species, Cheirodon interruptus and Cnesterodon decemmaculatus

The increase of cultivated areas together with the intensive use of pesticides have greatly contributed to impair the quality of aquatic systems along different areas of South America. The main goal of the present study was to assess the effects of a commercial formulation of chlorpyrifos at environmentally relevant concentrations on two native fish species, Cheirodon interruptus and Cnesterodon decemmaculatus. Adult individuals were exposed during 48 h to the following concentrations: 0.084 nl/l (Ci-Cf 1) and 0.84 nl/l (Ci-CF 2) in C. interruptus (Ci) of Clorfox (CF), and 0.84 nl/l (Cd-CF 1) and 8.4 nl/l (Cd-CF 2) in C. decemmaculatus (Cd). Fish behavior was evaluated through locomotor activity and space usage variables. The activity of acetylcholinesterase (AChE) in brain and muscle, catalase (CAT) and glutathione-S-transferase (GST) in brain, liver, muscle and gills, and aspartate amino-transferase (AST), alanine amino-transferase (ALT), AST/ALT ratio and alkaline phosphatase (ALP) in liver, were measured. Both locomotor activity and space usage varied between the two species studied and between CF treatments. The enzyme activities showed significant variations in CAT for C. interruptus and in CAT, GST, AChE, AST, and AST/ALT for C. decemmaculatus under the exposure conditions. Given that both species responded to CF and the concentrations we tested are environmentally relevant, the presence of this pesticide in freshwater systems could impose a risk for populations of both native fish studied at field.

Pesticide impact study in the peri-urban horticultural area of Gran La Plata, Argentina

Vegetable production systems are characterized by intense pesticide use, yet the effects on the surrounding environment are largely unknown and need to be studied. Given this knowledge gap, the objective of this work is to determine the impact of horticulture on a representative watercourse by conducting an integrated study of the occurrence and concentration of pesticides in bottom sediments and their relation to lethal and sublethal effects on benthic fauna. Two sampling campaigns were conducted during seasons of low and high pesticide application in five sites along the Carnaval creek, located in the peri-urban area of La Plata City (Buenos Aires, Argentina). The samples were tested for 36 pesticide compounds by GC-MS and LC-MS, and whole-sediment laboratory toxicity tests were performed using the native amphipod Hyalella curvispina. The results showed a general but variable distribution in the concentrations detected along the stream. For each sampling campaign (first/second), the total pesticide loads, measured as the sum of herbicides, insecticides and fungicides, were 1080/2329, 3715/88, and 367/5ngg^-1 dw, respectively. Lethal and sublethal effects were observed in both sampling campaigns. In order to correlate both sets of results, data were assessed by multivariate analysis, including principal component analysis. The observed toxicity was considered to be mainly due to insecticides; thus, horticultural practices have an impact on nearby watercourses and can potentially endanger the benthic fauna. This is the first study in Argentina to assess the impact of pesticides on aquatic environments close to horticultural production areas.

Tissue-specific bioconcentration and biotransformation of cypermethrin and chlorpyrifos in a native fish (Jenynsia multidentata) exposed to these insecticides singly and in mixtures

The aim of the present study was to evaluate the accumulation of cypermethrin and chlorpyrifos when the fish Jenynsia multidentata was exposed to these pesticides singly and in technical and commercial mixtures. Adult female fish were exposed over 96 h to 0.04 μg/L of cypermethrin; 0.4 μg/L of chlorpyrifos; 0.04 μg/L of cypermethrin + 0.4 μg/L of chlorpyrifos in a technical mixture; and 0.04 μg/L of cypermethrin + 0.4 μg/L of chlorpyrifos in a mixture of commercial products. Fish exposed to cypermethrin accumulated this compound only in muscle, probably because of the low biotransformation capacity of this organ and the induction of cytochrome P4501A1 (CYP1A1) expression in the liver. The accumulation of chlorpyrifos occurred in fish exposed to the insecticide (intestine > liver > gills) even when these fish had higher gluthatione-S-transferase (GST) activity in gills and P-glycoprotein (P-gp) expression in the liver, compared with the control. Fish exposed to the technical mixture showed cypermethrin accumulation (liver > intestine > gills) with higher levels than those measured in fish after only cypermethrin exposure. Higher expression levels of CYP1A1 in the liver were also observed compared with the Control. Fish exposed to the commercial mixture accumulated both insecticides (cypermethrin: intestine > gills and chlorpyrifos: liver > intestine > gills > muscle). In the organs where accumulation occurred, biotransformation enzymes were inhibited. Consequently, the commercial formulation exposure provoked the highest accumulation of cypermethrin and chlorpyrifos in J. multidentata, possibly associated with the biotransformation system inhibition. Environ Toxicol Chem 2017;36:1764-1774. © 2016 SETAC.

Histopathological effects of chlorpyrifos on the gills, hepatopancreas and gonads of the freshwater crab Zilchiopsis collastinensis. Persistent effects after exposure

Sublethal effects of the pesticide chlorpyrifos were evaluated in the crab Zilchiopsis collastinensis (Decapoda, Trichodactylidae). Crabs were exposed to high concentrations of chlorpyrifos at the beginning of the experiment and controlled dilution, under natural light and temperature conditions. A control and three concentrations (22.4, 41.25 and 61.4µg chlorpyrifos L^-1) were evaluated in triplicate. Nine crabs per concentration and day were used. The gills, hepatopancreas and ovaries were sampled before pesticide exposure (day 0) and 8, 15 and 22 days later, when concentrations were diluted and below the detection limits. The histopathological effects and their variations in time were observed and quantified. In gills, hyperplasias were observed in several cases, mainly in crabs exposed to chlorpyrifos. The number of collapsed lamellae and the number of affected lamellae quickly increased in exposed crabs, as effects were observed on day 8 and remained until day 22. In hepatopancreas there was an increase in the number of F and B -cells and affected tubules, especially after 22 days of exposure (p<0.05). In ovaries, there were no effects on gonadosomatic indexes or oocyte volume, but there was a significant increase in the atretic oocyte proportion related to pesticide exposure (p<0.05). The histopathological effects on the gills, hepatopancreas and ovaries were observed after exposure and persist even after dilution, and might be related to earlier exposures. Thus, these histopathological effects might be used as pesticide biomarkers even after the pesticide is not detected by chemical methods.

Species at Risk (SPEAR) index indicates effects of insecticides on stream invertebrate communities in soy production regions of the Argentine Pampas

We investigated relationships among insecticides and aquatic invertebrate communities in 22 streams of two soy production regions of the Argentine Pampas over three growing seasons. Chlorpyrifos, endosulfan, cypermethrin, and lambda-cyhalothrin were the insecticides most frequently detected in stream sediments. The Species at Risk (SPEAR) pesticide bioassessment index (SPEARpesticides) was adapted and applied to evaluate relationships between sediment insecticide toxic units (TUs) and invertebrate communities associated with both benthic habitats and emergent vegetation habitats. SPEARpesticides was the only response metric that was significantly correlated with total insecticide TU values for all three averaged data sets, consistently showing a trend of decreasing values with increasing TU values (r2=0.35 to 0.42, p-value=0.001 to 0.03). Although pyrethroids were the insecticides that contributed the highest TU values, toxicity calculated based on all insecticides was better at predicting changes in invertebrate communities than toxicity of pyrethroids alone. Crustaceans, particularly the amphipod Hyalella spp., which are relatively sensitive to pesticides, played a large role in the performance of SPEARpesticides, and the relative abundance of all crustaceans also showed a significant decreasing trend with increasing insecticide TUs for two of three data sets (r2=0.30 to 0.57, p-value=0.003 to 0.04) examined. For all data sets, total insecticide TU was the most important variable in explaining variance in the SPEARpesticides index. The present study was the first application of the SPEAR index in South America, and the first one to use it to evaluate effects of pesticides on invertebrate communities associated with aquatic vegetation. Although the SPEAR index was developed in Europe, it performed well in the Argentine Pampas with only minor modifications, and would likely improve in performance as more data are obtained on traits of South American taxa, such as pesticide sensitivity and generation time.

Micronuclei and other nuclear abnormalities on Caiman latirostris (Broad-snouted caiman) hatchlings after embryonic exposure to different pesticide formulations

This study aimed to evaluate the embryotoxicity and genotoxicity of pesticide commercial formulations widely used in soybean crops through the Micronucleus (MN) test and other Nuclear Abnormalities (NAs) in erythrocytes of broad-snouted caiman (Caiman latirostris), exposed by topical application through the eggshell. Embryos were exposed (during all incubation: 70 days approximately) to sub-lethal concentrations of two glyphosate formulations PanzerGold® (PANZ) and Roundup® Full II (RU) (500, 750, 1000µg/egg); to the endosulfan (END) formulation Galgofan® and the cypermethrin (CYP) formulation Atanor® (1, 10, 100, and 1000µg/ egg). Blood samples were taken at the moment of hatching from the spinal vein for the application of the MN test and analysis of other NAs in erythrocytes, as markers of genotoxicity. Results indicated a significant increase in the frequency of MN for PANZ1000, END 10, CYP 1 and CYP 100 (p<0.05), and in the frequency of other NAs including Buds: END 100, 1000 and CYP 10 (p<0.05), eccentric nuclei: END 1, 10, 1000, CYP 10, 100, 1000 (p<0.01) and END 100 (p<0.05), notched nuclei: END 1, 10 (p<0.01) and END 1000, CYP 10, 100,1000 (p<0.05), and total nuclear abnormalities: END 1, 10, 100, 1000, CYP 10, 100 and 1000 (p<0.01), and the positive control (PC) (p<0.05), compared with the negative control. It was demonstrated a concentration dependent-effect in MN frequency only for PANZ (R2=0.98; p<0.01). Our study demonstrated that commercial formulations of pesticides induced genotoxic effects on C. latirostris, and NAs are a good indicator of genotoxicity in this specie.

Occurrence and fate of pesticides in the Argentine stretch of the Paraguay-Paraná basin

The Argentine stretch of the del Plata basin crosses regions devoted to extensive and intensive agriculture mostly with chemical pest control. The utilization of pesticides in the region has increased 900% in the last two decades associated with the introduction of biotech crops and direct-seeding techniques. Our objective was to study the occurrence, concentration, and fate of pesticides in surface water and bottom sediments of the principal tributaries and main watercourse of the Paraguay-Paraná River. We sampled 22 sites in the distal positions of the main affluents and main watercourse of the Paraná and report here results from two monitoring campaigns (2010-2012). Surface water and bottom sediments were analyzed according to standardized methods by matrix-solid-phase dispersion and liquid-liquid extraction, respectively. Twenty-three pesticide compounds were analyzed by gas chromatography. The results from both campaigns indicated a generalized but variable distribution in the concentrations detected throughout the basin. The ranges of total measured pesticide concentrations in water and sediments were, respectively, 0.004-6.62 μg/l and 0.16-221.3 μg/kg dry weight. Endosulfans, cypermethrin, and chlorpyrifos were ubiquitous compounds in both environmental compartments and quantitatively the most relevant. All concentrations detected in water were over the recommended guidelines for the protection of aquatic biota. The partitioning indicated a higher affinity for the sediments. Agricultural activity is the source of pesticide-pollution loads, transported by tributaries that reach the main watercourse and alter the quality of the aquatic ecosystem.

Effect of diet on carboxylesterase activity of tadpoles (Rhinella arenarum) exposed to chlorpyrifos

An outdoor microcosm was performed with tadpoles (Rhinella arenarum) exposed to 125μgL^-1 chlorpyrifos and fed two types of food, i.e., lettuce (Lactuca sativa) and a formulated commercial pellet. Acetylcholinesterase (AChE) and carboxylesterase (CbE) activities were measured in liver and intestine after 10 days of pesticide exposure. Non-exposed tadpoles fed lettuce had an intestinal AChE activity almost two-fold higher than that of pellet-fed tadpoles. No significant differences were observed, however, in liver AChE activity between diets. Likewise, intestinal CbE activity - measured using two substrates, i.e. 1-naphthyl acetate (1-NA) and 4-nitrophenyl valerate (4-NPV) - was higher in tadpoles fed lettuce than in those fed pellets. However, the diet-dependent response of liver CbE activity was opposite to that in the intestine. Chlorpyrifos caused a significant inhibition of both esterase activities, which was tissue- and diet-specific. The highest inhibition degree was found in the intestinal AChE and CbE activities of lettuce-fed tadpoles (42-78% of controls) compared with pellet-fed tadpoles (<60%). Although chlorpyrifos significantly inhibited liver CbE activity of the group fed lettuce, this effect was not observed in the group fed pellets. In general, intestinal CbE activity was more sensitive to chlorpyrifos inhibition than AChE activity. This finding, together with the high levels of basal CbE activity found in the intestine, may be understood as a detoxification system able to reduce intestinal OP uptake. Moreover, the results of this study suggest that diet is a determinant factor in toxicity testing with tadpoles to assess OP toxicity, because it modulates levels of this potential detoxifying enzyme activity.

Monitoring and distribution patterns of pesticide residues in soil from cotton/wheat fields of Pakistan

The excessive use of hazardous pesticides for massive cotton and wheat production has deteriorated the quality of Okara district's soil. Thus, in order to sustain the production of good-quality food, it is essential to determine the residue levels of pesticides in the agricultural soil and define their possible sources. Thus, the present study focused on the determination of selected pesticides in the soil samples obtained from cotton/wheat fields by using the modified multi-residue pesticide analysis method based on GCMS and HPLC-UV. Most of soil samples were found to be highly contaminated with imidacloprid, chlorpyrifos, and α-cypermethrin residues. Selected pesticides were significantly correlated with each other at p < 0.05 except imidacloprid, which was negatively correlated with triazophos, MCPA methyl ester, selected pyrethroid pesticides, and their metabolite. Soil pH and phosphate levels were significantly positively correlated while sulfate content was negatively correlated with most of selected pesticides. The varimax normalized factor analysis divides the selected pesticides to the two major factors that explained 87.19% of the total variance which evidenced that pesticide in the same cluster shared a common source in the soil. A significant negative correlation of chlorpyrifos in the second factor pointed towards a source different from other pesticides. Factor and cluster analysis indicated that sulfate levels of soil positively affected the persistence/ mobility of imidacloprid.

Human health risk assessment of organophosphorus pesticide in rice crop from selected districts of Anzali International Wetland basin, Iran

Low fertility in rice caused by Chilo suppressalis has led to the use of diazinon to control this pest. Residue of pesticide could penetrate products and also food which can affect public health. The aim of this research was to determine health risk assessment of organophosphorus (OP) pesticide in rice, a strategic crop in Iran. Ninety rice samples were collected from 30 points during harvesting seasons from Rasht Area, Guilan Province, Iran from which 30 samples were prepared. The concentration of diazinon, the most common pesticide used in the study area, was determined by high-performance liquid chromatography. The result indicated that the total average of diazinon in rice samples (31.91 mg/kg) is by far higher than the maximum residue limit recommended by the European Union. According to the results, EDAI was 0.051 mg/kg day, while health risk index in rice was 10.2. Results showed that there is a health risk associated with the lifetime consumption of rice polluted by OP pesticide in the study area.

Reproductive toxicity of chlorpyrifos tested in zebrafish (Danio rerio)

This study was carried out to find out whether exposure to environmentally relevant concentration of chlorpyrifos (CP) modulates reproductive competence. To understand this, eight adult male and eight adult female zebrafish ( Danio rerio) were exposed to 200 µg/L of CP for 24, 48, 72, and 96 h. Vitellogenin levels did not show much change in female fish, whereas in male the levels increased with increasing exposure time thereby indicating estrogenecity of the toxicant. Attenuation of serum 11-ketotestosterone in male and serum 17β-estradiol in female was noticed in the exposed fish and thus signified interference of CP in the reproductive endocrine system. Structural damage common to both the gonads was vacuolization. Elongation of seminiferous tubules in testes and atretic follicles in ovary was also observed.

Behavioral swimming effects and acetylcholinesterase activity changes in Jenynsia multidentata exposed to chlorpyrifos and cypermethrin individually and in mixtures

The pesticides cypermethrin (CYP) and chlorpyrifos (CPF) were found together in water bodies located in agricultural and urban areas. However, the impact to non-target biota from exposure to mixtures has received little attention. In the current study, we evaluated changes in swimming behavior and cholinesterase enzymes activity in Jenynsia multidentata, to investigate the possible effects of these insecticides individually and in mixtures. Moreover, differences between technical and commercial mixtures of the pesticides were evaluated. Females of J. multidentata were exposed over 96-h to CYP (0.04 and 0.4µgL(-1)), CPF (0.4 and 4µgL(-1)), individually and in a technical and commercial mixtures. Swimming behavior was recorded after 24h and 96h of exposure. Also, we measured cholinesterase enzymes activity in brain and muscle after 96h of exposure. Exposure to CYP increased the exploratory activity of J. multidentata in the upper area of the aquarium. Fish exposed to CPF (4µg L(-1)) showed a decrease in swimming activity and an increase in the time spent at the bottom of the aquarium. Interestingly, fish exposed to the technical and commercial mixture of CYP and CPF displayed a different behavior based on the concentration of exposure. Low concentration of pesticides elicited an increase in J. multidentata swimming activity with preference for the upper area of the aquarium, and high concentrations caused decrease in swimming activity with preference for the bottom area of the aquarium. Based on the response of cholinesterase enzymes, acetylcholinesterase in muscle was more sensitive to exposure to CYP, CPF and their mixtures than in brain. A decrease in swimming behavior correlates significantly with the inhibition of acetylcholinesterase activity in muscle of J. multidentata exposed to high concentrations of pesticides. These results draw attention to the need of more studies on the potential ecotoxicological impact of pesticides and its mixtures at environmental relevant concentrations.

Effects of chlorpyrifos on life cycle parameters, cytochrome P450S expression, and antioxidant systems in the monogonont rotifer Brachionus koreanus

Chlorpyrifos is a widely used organophosphorus insecticide for controlling diverse insect pests of crops. In the monogonont rotifer Brachionus koreanus, population growth retardation with the inhibition of lifespan, fecundity, and individual body size of ovigerous females was shown over 10 d in response to chlorpyrifos exposure. At the molecular and biochemical levels, the rotifer B. koreanus defensome, composed of cytochrome P450 complements, heat shock protein 70, and antioxidant enzymatic systems (i.e., glutathione, glutathione peroxidase, glutathione reductase, and glutathione S-transferase), was significantly induced in response to different concentrations of chlorpyrifos. Thus, chlorpyrifos strongly induced a defensome system to mitigate the deleterious effects of chlorpyrifos at in vivo and in vitro levels as a trade-off in fitness costs. Environ Toxicol Chem 2016;35:1449-1457. © 2015 SETAC.

Insecticide concentrations in stream sediments of soy production regions of South America

Concentrations of 17 insecticides were measured in sediments collected from 53 streams in soy production regions of South America (Argentina in 2011-2014, Paraguay and Brazil in 2013) during peak application periods. Although environmental regulations are quite different in each country, commonly used insecticides were detected at high frequencies in all regions. Maximum concentrations (and detection frequencies) for each sampling event ranged from: 1.2-7.4 ng/g dw chlorpyrifos (56-100%); 0.9-8.3 ng/g dw cypermethrin (20-100%); 0.42-16.6 ng/g dw lambda-cyhalothrin (60-100%); and, 0.49-2.1 ng/g dw endosulfan (13-100%). Other pyrethroids were detected less frequently. Banned organochlorines were most frequently detected in Brazil. In all countries, cypermethrin and/or lambda-cyhalothrin toxic units (TUs), based on Hyalella azteca LC50 bioassays, were occasionally>0.5 (indicating likely acute toxicity), while TUs for other insecticides were <0.5. All samples with total insecticide TU>1 were collected from streams with riparian buffer width<20 m. A multiple regression analysis that included five landscape and habitat predictor variables for the Brazilian streams examined indicated that buffer width was the most important predictor variable in explaining total insecticide TU values. While Brazil and Paraguay require forested stream buffers, there were no such regulations in the Argentine pampas, where buffer widths were smaller. Multiple insecticides were found in almost all stream sediment samples in intensive soy production regions, with pyrethroids most often occurring at acutely toxic concentrations, and the greatest potential for insecticide toxicity occurring in streams with minimum buffer width<20 m.

Barrage fishponds: Reduction of pesticide concentration peaks and associated risk of adverse ecological effects in headwater streams

Constructed wetlands have been suggested as pesticide risk mitigation measures. Yet, in many agricultural areas, ponds or shallow lakes are already present and may contribute to the control of non-point source contamination by pesticides. In order to test this hypothesis, we investigated the influence of extensively managed barrage fishponds (n = 3) on the dissolved concentrations of 100 pesticides in headwater streams over the course of a year. Among the 100 pesticides, 50 different substances were detected upstream and 48 downstream. Highest measured concentration upstream was 26.5 μg/L (2-methyl-4-chlorophenoxyacetic acid, MCPA) and 5.19 μg/L (isoproturon) downstream. Fishponds were found to reduce peak exposure levels as high pesticide concentrations (defined here as ≥ 1 μg/L) generally decreased by more than 90% between upstream and downstream sampling sites. The measured concentrations in the investigated streams were compared to laboratory toxicity data for standard test organisms (algae, invertebrates and fish) using the toxic unit approach. When considering the threshold levels set by the European Union within the first tier risk assessment procedure for pesticide registration (commission regulation (EU) N° 546/2011), regulatory threshold exceedances were observed for 22 pesticides upstream from fishponds and for 9 pesticides downstream. Therefore, the investigated barrage fishponds contributed to the reduction of pesticide peak concentrations and potential risk of adverse effects for downstream ecosystems.

Combined endosulfan and cypermethrin-induced toxicity to embryo-larval development of Rhinella arenarum

The combined effects of two widely used pesticides, endosulfan and cypermethrin, on survival of embryo-larval development of the South American toad (Rhinella arenarum) were examined. The toxicity bioassays were performed according to the AMPHITOX test. Embryos and larvae were exposed to mixtures of these pesticides at equitoxic ratios from acute or chronic exposure to evaluate interaction effects. The results were analyzed using both Marking's additive index and combination index (CI)-isobologram methods. Acute (96-h) and intermediate (168-h) toxicity of endosulfan-cypermethrin mixtures remained almost constant for larvae and embryos, but when exposure duration was increased, there was a significant elevation in toxicity, obtaining chronic (240-h) no-observed-effect concentrations (NOEC) values of 0.045 and 0.16 mg/L for embryos and larvae, respectively. These are environmentally relevant concentrations that reflect a realistic risk of this pesticide mixture to this native amphibian species. The toxicity increment with the exposure duration was coincident with the central nervous system development on embryos reaching the larval period, the main target organ of these pesticides. The interactions of the pesticide mixtures at acute and chronic exposure were antagonistic for embryo development (CI > 1), and additive (CI = 1) for larvae, while chronic exposure interactions were synergistic (CI < 1) for both developmental periods. Data indicated that endosulfan-cypermethrin mixtures resulted in different interaction types depending on duration and developmental stage exposed. As a general pattern and considering conditions of overall developmental period and chronic exposure, this pesticide mixture usually applied in Argentine crop fields is synergistic with respect to toxicity for this native amphibian species.

Pesticide chlorpyrifos acts as an endocrine disruptor in adult rats causing changes in mammary gland and hormonal balance

Endocrine disruptors (EDs) are compounds that interfere with hormone regulation and influence mammary carcinogenesis. We have previously demonstrated that the pesticide chlorpyrifos (CPF) acts as an ED in vitro, since it induces human breast cancer cells proliferation through estrogen receptor alpha (ERα) pathway. In this work, we studied the effects of CPF at environmental doses (0.01 and 1mg/kg/day) on mammary gland, steroid hormone receptors expression and serum steroid hormone levels. It was carried out using female Sprague-Dawley 40-days-old rats exposed to the pesticide during 100 days. We observed a proliferating ductal network with a higher number of ducts and alveolar structures. We also found an increased number of benign breast diseases, such as hyperplasia and adenosis. CPF enhanced progesterone receptor (PgR) along with the proliferating cell nuclear antigen (PCNA) in epithelial ductal cells. On the other hand, the pesticide reduced the expression of co-repressors of estrogen receptor activity REA and SMRT and it decreased serum estradiol (E2), progesterone (Pg) and luteinizing hormone (LH) levels. Finally, we found a persistent decrease in LH levels among ovariectomized rats exposed to CPF. Therefore, CPF alters the endocrine balance acting as an ED in vivo. These findings warn about the harmful effects that CPF exerts on mammary gland, suggesting that this compound may act as a risk factor for breast cancer.

Comparative sensitivity among early life stages of the South American toad to cypermethrin-based pesticide

Cypermethrin is one of the most widely used pesticides due to its low mammalian and bird toxicity, but it is extremely toxic to aquatic organisms. The aim of the present study was to evaluate the toxicity of a commercial formulation of cypermethrin on the embryo-larval development of Rhinella arenarum. An ecological risk assessment based on the hazard quotient (HQ) approach was performed. The results showed that cypermethrin toxicity was stage-dependent and dramatically increased during the larval period. Thus, larvae were more sensitive than embryos, obtaining at the end of the experiment a 336-h median lethal concentration (LC50) of 0.65 μg cypermethrin/L. Cypermethrin exposure caused morphological abnormalities such as general underdevelopment, edema, gill malformations, and behavioral alterations as hyperkinesia and spasmodic contractions. The 168-h teratogenic index was 5, implying a high risk for embryos to be malformed in the absence of significant embryonic lethality. Based on the results of the toxicity effects and the ecological risk assessed (HQ for chronic exposure >  level of concern), this pesticide should be considered as a direct (effects on survival) or indirect (severe sublethal effects) risk for conservation purposes of this amphibian in agroecosystems.

Massive airborne Endosulfan inputs related to intensive agriculture in Argentina's Pampa

In order to evaluate the impact of intensive agriculture on air quality in the most productive and populated Argentina's Pampas, a comprehensive assessment of airborne Endosulfan (∑Endo) was performed using polyurethane passive samplers deployed from 2010 to 2013 covering the critical period of Endosulfan restrictions at twenty nine sites in the Rural Pampa and Great Buenos Aires Metropolitan Area (GBA: Horticultural and Urban subareas). ∑Endo concentrations were very high and variable (0.01-63 ng m(-3)), exceeding worldwide reported maxima at Horticultural GBA and Rural Pampa with lowest values at Urban GBA (geometric means: 3.1, 1.1 and 0.53 ng m(-3), respectively). The composition was relatively fresh with strong predominance of Endo I (72 ± 18%) over Endo II (23 ± 15%) and Endo SO4 (5 ± 10%). Airborne ∑Endo was significantly correlated to annual soybean crop in Rural Pampa. ∑Endo concentrations showed a temporal pattern defined by consistent peaks enriched in Endo I during summer application periods, cold temperature minima with higher proportions of Endo SO4 and a general exponentially declining trend over time related to incipient control policies.

Omega-3 and alpha-tocopherol provide more protection against contaminants in novel feeds for Atlantic salmon (Salmo salar L.) than omega-6 and gamma tocopherol

Extended use of plant ingredients in Atlantic salmon farming has increased the need for knowledge on the effects of new nutrients and contaminants in plant based feeds on fish health and nutrient-contaminant interactions. Primary Atlantic salmon hepatocytes were exposed to a mixture of PAHs and pesticides alone or in combination with the nutrients ARA, EPA, α-tocopherol, and γ-tocopherol according to a factorial design. Cells were screened for effects using xCELLigence cytotoxicity screening, NMR spectroscopy metabolomics, mass spectrometry lipidomics and RT-qPCR transcriptomics. The cytotoxicity results suggest that adverse effects of the contaminants can be counteracted by the nutrients. The lipidomics suggested effects on cell membrane stability and vitamin D metabolism after contaminant and fatty acid exposure. Co-exposure of the contaminants with EPA or α-tocopherol contributed to an antagonistic effect in exposed cells, with reduced effects on the VTG and FABP4 transcripts. ARA and γ-tocopherol strengthened the contaminant-induced response, ARA by contributing to an additive and synergistic induction of CYP1A, CYP3A and CPT2, and γ-tocopherol by synergistically increasing ACOX1. Individually EPA and α-tocopherol seemed more beneficial than ARA and γ-tocopherol in preventing the adverse effects induced by the contaminant mixture, though a combination of all nutrients showed the greatest ameliorating effect.

Acute Toxicity of Endosulfan to the Non-target Organisms Hyalella curvispina and Cnesterodon decemmaculatus

Pesticide consumption in Argentina has steadily increased over the last two decades, while one of these compounds, namely endosulfan, is commonly found in environmental samples. Also the fish Cnesterodon decemmaculatus and the amphipod Hyalella curvispina are widely distributed in agricultural areas of southern South America. The aim of the present contribution was therefore to determine the acute toxicity of endosulfan to both organisms, and compare it with species sensitivity distributions (SSD) and measured field concentrations. The 48 h-LC50 (with 95 % confidence limits) were 1.8 (1.6-2.1) µg/L for C. decemmaculatus and 16.4 (15.1-17.7) µg/L for H. curvispina. C. decemmaculatus was more sensitive than 74 % of fish based on the SSD. Endosulfan concentrations in stream water reported in the literature were often higher than the C. decemmaculatus LC50. It may hence be concluded that C. decemmaculatus is a suitable sentinel organism for ecotoxicological risk assessment in South America.

Endosulfan affects GnRH cells in sexually differentiated juveniles of the perciform Cichlasoma dimerus

Endosulfan (ES) is an organochlorine pesticide widely used in agriculture despite its high toxicity towards non-target organisms such as fish. It has been demonstrated that ES can cause negative effects on aquatic animals, including disruption of hormonal systems. However, the alterations produced by this pesticide on the reproductive axis of fish prior to sexual maturity, as well as possible modes of action have hardly been studied. This study aimed at assessing the effect of waterborne exposure to the pesticide ES on the reproductive axis during sexual differentiation of juveniles of the South American freshwater cichlid fish Cichlasoma dimerus. No mortality was observed due to ES subchronic exposure (90 days post-fertilization). Exposure to ES did not affect body weight nor morphometric parameters, indicating that larvae nutritional state was not affected. Timing of sexual differentiation, gonadal morphology and sex ratio were likewise not altered by ES. However, ES acted as an endocrine disrupting chemical in this species as the morphometry of gonadotropin-releasing hormones (GnRH) producing cells was altered. Exposure to ES altered nuclear area, cell area and nucleus/cytoplasm ratio of GnRH II neurons, and cell and nuclear area and diameter of GnRH III neurons. Interestingly, in our previous study, exposure before sex differentiation (30 day exposure) caused no alteration to GnRH II and III, and did alter GnRH I and FSH cells. These alterations could lead to changes in circulating hormone levels, especially when fish are exposed for prolonged periods, ultimately impairing reproductive fitness. C. dimerus juveniles can be an interesting biological model to perform toxicological studies with the intent to assess early disruption endpoints in the reproductive axis during development.

Application of species sensitivity distribution in aquatic probabilistic ecological risk assessment of cypermethrin: a case study in an urban stream in South China

A tiered ecological risk assessment was applied to quantitatively refine the overall probabilistic risk of cypermethrin, a pyrethroid insecticide, to aquatic organisms. These results were then validated through the bioassays using field water from an urban stream, Chebei Creek in Guangzhou, South China. Seventeen water samples were collected along Chebei Creek for evaluation. In total, 71% of the field waters were acutely toxic to Hyallela azteca and 24% of the waters caused 100% mortality. Toxic unit evaluation suggested that cypermethrin was one of the main contributors to toxicity. The tiered ecological risk assessment approach (deterministic quotient method and probabilistic methods, including joint probability curve and Monte Carlo Simulation) suggested that cypermethrin posed significant threats to aquatic ecology in this stream. The overall probabilistic risk of cypermethrin to aquatic species in Chebei Creek reached 66% when acute-to-chronic ratios were set at 125. An exceedance probability of cypermethrin in Chebei Creek that affected H. azteca as modeled using the joint probability curve method was 88%, suggesting that most sites were at risk due to cypermethrin exposure. This value was similar to the results obtained from acute toxicity tests (71% of field water samples were acutely toxic to H. azteca), indicating the effectiveness of the tiered approach to assess risk of cypermethrin in urban waterways. To the authors' knowledge, the present study is the first to provide a focused probabilistic evaluation of ecological risk for cypermethrin in a complex urban waterway environment. Despite uncertainties existing in the ecological risk assessment procedure, this approach provides a comprehensive assessment of ecological risk of cypermethrin, and subsequently, a foundation for further risk diagnosis and management in urban waterways.

Histopathological effects of endosulfan to hepatopancreas, gills and ovary of the freshwater crab Zilchiopsis collastinensis (Decapoda: Trichodactylidae)

In this work, the effects of a pulse exposure of endosulfan on hepatopancreas, gills and ovary of the burrowing crab Zilchiopsis collastinensis were evaluated. The crabs were exposed to three sublethal concentrations in a pulse system with controlled dilutions. Water samples for pesticide concentrations measurements and crab tissue samples were taken when applications were made and 2, 8, 15 and 22 days after administering the pesticide. The exposure to endosulfan caused an increase in B cell number and a decrease in F and R cell number (p<0.05). Necrotic tubules, abnormal lumen and other histopathologies were observed in the hepatopancreas of crabs exposed to endosulfan. There was an increase in the proportion of collapsed gills caused by endosulfan effects. Other effects as hyperplasia were also observed. There were no changes in the gonadosomatic index of exposed crabs; however there were changes in the volume of oocytes of exposed crabs in certain days (p<0.05). The increase in B cell number and the consequent reduction in F cell number may be related to the detoxification processes. The changes in cell number within the hepatopancreas and the histopathologies observed both in hepatopancreas and gills might be used as endosulfan exposure indicators.

Chlorpyrifos inhibits cell proliferation through ERK1/2 phosphorylation in breast cancer cell lines

It is well known the participation of oxidative stress in the induction and development of different pathologies including cancer, diabetes, neurodegeneration and respiratory disorders among others. It has been reported that oxidative stress may be induced by pesticides and it could be the cause of health alteration mediated by pollutants exposure. Large number of registered products containing chlorpyrifos (CPF) is used to control pest worldwide. We have previously reported that 50 μM CPF induces ROS generation and produces cell cycle arrest followed by cell death. The present investigation was designed to identify the pathway involved in CPF-inhibited cell proliferation in MCF-7 and MDA-MB-231 breast cancer cell lines. In addition, we determined if CPF-induced oxidative stress is related to alterations in antioxidant defense system. Finally we studied the molecular mechanisms underlying in the cell proliferation inhibition produced by the pesticide. In this study we demonstrate that CPF (50 μM) induces redox imbalance altering the antioxidant defense system in breast cancer cells. Furthermore, we found that the main mechanism involved in the inhibition of cell proliferation induced by CPF is an increment of p-ERK1/2 levels mediated by H2O2 in breast cancer cells. As PD98059 could not abolish the increment of ROS induced by CPF, we concluded that ERK1/2 phosphorylation is subsequent to ROS production induced by CPF but not the inverse.

Pesticide effects on crabs: how environmental concentrations of endosulfan and chlorpyrifos affect embryos

The objectives of this work were to evaluate the effects of environmentally relevant chlorpyrifos and endosulfan, concentrations in the incubation period, effective hatching and survival of embryos and neonates of the freshwater burrowing crab, Zilchiopsis collastinensis (Decapoda, Trichodactylidae). Both pesticides were prepared from commercial and technical grade products. The exposure to about 100, 200, and 400 ng endosulfan L(-1), and 48, 240, and 1,200 ng chlorpyrifos L(-1) did not cause differences in the incubation period or in effective hatching but decreased survival of neonates, especially in the concentrations prepared from the technical grade product. Even if these concentrations are below the median lethal concentration (LC50) values for embryos, these caused a significant decrease in the survival of neonates, i.e. when crabs are outside the egg and not protected by chorion. The decrease in the neonate population caused by these concentrations, which could be found in the environment, might impact aquatic communities.

The impact of Eskoba, a glyphosate formulation, on the freshwater plankton community

This study analyzed the acute effects of a glyphosate-based herbicide (Eskoba) on the microalgae Chlorella vulgaris, the cladoceran Simocephalus vetulus, and the copepod Notodiaptomus conifer, and evaluated the recovery ability of the surviving micro-crustaceans. Survival, age of first reproduction, and fecundity were used as endpoints for S. vetulus, while survival and time to reach the adult stage were used as endpoints for N. conifer. The registered order of sensitivity was S. vetulus (48-hour effective concentration [EC50]: 21 mg/L) > C. vulgaris (72-hour EC50: 58.59 mg/ L) > N. conifer (48-hour EC50: 95 mg/L). Despite the growth of C. vulgaris stimulated after 24 hours of exposure to the commercial formulation of glyphosate Eskoba, it was inhibited after 48 hours by all the concentrations tested. In postexposure experiments, microcrustaceans reduced their life expectancy, S. vetulus decreased its fertility, and N. conifer inhibited its sexual maturity. In summary, it was demonstrated that these species lost their recovery ability.

Synergy between glyphosate- and cypermethrin-based pesticides during acute exposures in tadpoles of the common South American toad Rhinella arenarum

The herbicide glyphosate and the insecticide cypermethrin are key pesticides of modern management in soy and corn cultures. Although these pesticides are likely to co-occur in ephemeral ponds or aquatic systems supporting amphibian wildlife, the toxicological interactions prevailing in mixtures of these two pesticides have been little studied. The current study evaluated the toxicity of equitoxic and non-equitoxic binary mixtures of glyphosate- and cypermethrin-based pesticides to tadpoles of the common South American toad, Rhinella arenarum. Two different combinations of commercial products were tested: glyphosate Glifosato Atanor®+cypermethrin Xiper® and glyphosate Glifoglex®+cypermethrin Glextrin®. When tested individually, the formulations presented the following 96 h-LC50s: Glifosato Atanor® 19.4 mg ae L(-1) and Glifoglex 72.8 mg ae L(-1), Xiper® 6.8 mg L(-1) and Glextrin® 30.2 mg L(-1). Equitoxic and non-equitoxic mixtures were significantly synergic in both combinations of commercial products tested. The magnitude of the synergy (factor by which toxicity differed from concentration addition) was constant at around twofold for all tested proportions of the glyphosate Glifoglex®+cypermethrin Glextrin® mixture; whereas the magnitude of the synergy varied between 4 and 9 times in the glyphosate Glifosato Atanor®+cypermethrin Xiper® mixture. These results call for more research to be promptly undertaken in order to understand the mechanisms behind the synergy observed and to identify and quantify the extent of its environmental impacts.

Comparative toxicity of pyrethroid insecticides to two estuarine crustacean species, Americamysis bahia and Palaemonetes pugio

Pyrethroid insecticides are widely used on agricultural crops, as well as for nurseries, golf courses, urban structural and landscaping sites, residential home and garden pest control, and mosquito abatement. Evaluation of sensitive marine and estuarine species is essential for the development of toxicity testing and risk-assessment protocols. Two estuarine crustacean species, Americamysis bahia (mysids) and Palaemonetes pugio (grass shrimp), were tested with the commonly used pyrethroid compounds, lambda-cyhalothrin, permethrin, cypermethrin, deltamethrin, and phenothrin. Sensitivities of adult and larval grass shrimp and 7-day-old mysids were compared using standard 96-h LC50 bioassay protocols. Adult and larval grass shrimp were more sensitive than the mysids to all the pyrethroids tested. Larval grass shrimp were approximately 18-fold more sensitive to lambda-cyhalothrin than the mysids. Larval grass shrimp were similar in sensitivity to adult grass shrimp for cypermethrin, deltamethrin, and phenothrin, but larvae were approximately twice as sensitive to lambda-cyhalothrin and permethrin as adult shrimp. Acute toxicity to estuarine crustaceans occurred at low nanogram per liter concentrations of some pyrethroids, illustrating the need for careful regulation of the use of pyrethroid compounds in the coastal zone.

Toxicological effect of single contaminants and contaminant mixtures associated with plant ingredients in novel salmon feeds

Increasing use of plant feed ingredients may introduce contaminants not previously associated with farming of salmonids, such as pesticides and PAHs from environmental sources or from thermal processing of oil seeds. To screen for interaction effects of contaminants newly introduced in salmon feeds, Atlantic salmon primary hepatocytes were used. The xCELLigence cytotoxicity system was used to select optimal dosages of the PAHs benzo(a)pyrene and phenanthrene, the pesticides chlorpyrifos and endosulfan, and combinations of these. NMR and MS metabolic profiling and microarray transcriptomic profiling was used to identify novel biomarkers. Lipidomic and transcriptomic profiling suggested perturbation of lipid metabolism, as well as endocrine disruption. The pesticides gave the strongest responses, despite having less effect on cell viability than the PAHs. Only weak molecular responses were detected in PAH-exposed hepatocytes. Chlorpyrifos suppressed the synthesis of unsaturated fatty acids. Endosulfan affected steroid hormone synthesis, while benzo(a)pyrene disturbed vitamin D3 metabolism. The primary mixture effect was additive, although at high concentrations the pesticides acted in a synergistic fashion to decrease cell viability and down-regulate CYP3A and FABP4 transcription. This work highlights the usefulness of 'omics techniques and multivariate data analysis to investigate interactions within mixtures of contaminants with different modes of action.

Predator-prey imbalances due to a pesticide: density and applicability timing as determining factors for experimental assessments

Predator-prey relationships are determining factors in sustaining community structure but xenobiotics, including pesticides, have the potential to alter them, causing imbalances at the ecosystem level. Although invertebrate predation on zooplankton is of high importance in shallow lakes, there is still little information regarding disturbances on this trophic interaction. This work assessed the potential effects of a chlorpyrifos-based pesticide (CLP) on the interaction between prawns Macrobrachium borellii and cladocerans Ceriodaphnia dubia, taking into account prey densities, specific time of exposure and contamination level. The analysis was focused on the specific sensitivity of both species and, especially, on the predation rate of M. borellii on C. dubia. The latter was evaluated through different treatments that combined predator and/or prey exposure to the insecticide, before (lapse of 12 h) or during the interaction. Under low prey density, when prawns were previously exposed to the insecticide, their consumption rate was lower than that of controls. Conversely, when cladocerans or both species were previously exposed, the prawns' feeding rate was higher. Under high prey density, there were no substantial differences among treatments. Comparatively, cladocerans were significantly more consumed when the exposure of both species was performed before rather than during the interaction. From the results obtained, it can be assumed that the trophic interaction under study is sensitive to CLP and that individual density and specific time of exposure are important variables to be considered in similar studies in order to obtain realistic results.

The effect of cypermethrin, chlorpyrifos, and glyphosate active ingredients and formulations on Daphnia magna (Straus)

Acute effects of active ingredients (a.i.) and formulations (F) of widely used pesticides were assessed by means of the Daphnia magna toxicity test. Studied pesticides were the insecticides, cypermethrin and chlorpyrifos, and the herbicide, glyphosate. Results were analyzed and compared according to statistical endpoints (LCx) and log-probit regressions of toxicity data. The potency of acute toxicity followed the order: chlorpyrifos F > chlorpyrifos a.i. > cypermethrin F > cypermethrin a.i. ≫ glyphosate F > glyphosate a.i. Three to five orders of magnitude differences between the toxicity (µg/L to mg/L) of insecticides and the herbicide were observed. A pairwise comparison between a.i. and F indicated that all formulations were more potent. Additionally, for the case of glyphosate, evidence suggests that the adjuvant contributes to formulation toxicity rather than to the enhancement of a.i. potency.

Genetic and biochemical biomarkers in the macrophyte Bidens laevis L. exposed to a commercial formulation of endosulfan

Previous studies in the wetland macrophyte Bidens laevis L have demonstrated that the insecticide endosulfan induces a high frequency of somatic chromosome aberrations in anaphase-telophase (CAAT) but no DNA changes as determined by the single cell gel electrophoresis (Comet) assay. Thus, cytogenetic biomarkers appear to be more sensitive to the toxic effects of the insecticide than the DNA molecule in the studied species. For this reason, the goals of this study were to use cytogenetic biomarkers--CAAT and abnormal metaphase--and defense biomarkers such as the activity of the antioxidant enzymes--guaiacol peroxidases (POD), glutathione reductase, and microsomal and cytosolic (m- and c-) glutathione-S-transferase (GST)--to evaluate in B. laevis effects caused by a commercial formulation of endosulfan. The frequency of CAAT was increased at 5, 10, 50, and 100 μg/L endosulfan with respect to the negative controls by 3.1, 2.5, 2.5, and 3.2-fold, respectively while the frequency of abnormal metaphases was also increased at the same concentrations by 3.5, 2.8, 3.2, and 11.3-fold, respectively. In addition to these aneugenic effects, other abnormalities such as C-mitosis and chromosome clumping were observed at 10 μg/L endosulfan. On the other hand, POD induction at 0.02, 0.5, 5, and 10 μg/L and m-GST inhibition at 0.5, 10, and 50 μg/L in plants exposed during 24 h to endosulfan were observed but all of these responses were highly variable. In conclusion, only cytogenetic biomarkers like CAAT in B. laevis can serve potentially as early warning systems to detect environmentally relevant concentrations of endosulfan in aquatic ecosystems.

Multimatrix measurement of persistent organic pollutants in Mar Chiquita, a continental saline shallow lake

RAMSAR sites are determined by specific characteristics of the environment in terms of ecological productivity as well services for human development, but they are also one of the most threatened ecosystems. Thus, the objective of this work was to evaluate the dynamic of Persistent Organic Pollutants (POPs) in different biotic and abiotic matrixes of the RAMSAR site (wetlands with international importance), Mar Chiquita Lake. Sampling was performed according to land use (agricultural, urban, and industrial) at two stations: Laguna del Plata and Campo Mare. POPs were analyzed in superficial water (Sw), suspended particulate material (SPM), bottom sediment (Bs) and fish tissues (Odontesthes bonariensis). Organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were analyzed by GC-ECD. HCHs, Endosulfans, DDTs, PCBs and PBDEs were found in all matrixes at both stations. The high persistence and transport processes are responsible for the occurrence of HCHs, DDTs and PCBs in Bs, SPM and fish tissues, even many years after their prohibition. PBDEs showed lower levels according to the scarcity of punctual sources in the area. Endosulfan showed variable amounts in agreement with application periods since this pesticide was used until a few years ago in this area. Finally, PCB levels overpassed the acceptable daily intake for human consumption being a risk for human health Thus, the present report confirms the occurrence of POPs in Mar Chiquita lake, alerting on the contribution of agricultural and urban pollutants in a RAMSAR site. Current results also raise concerns on biomagnification processes through the food web.

Presence of pesticides in surface water from four sub-basins in Argentina

Argentina has 31 million hectares given over to agriculture comprising 2.2% of the world's total area under cultivation (Stock Exchange of Rosario, Argentina). Despite the intensity of this agricultural activity, data on pesticide pollution in surface water are rather scarce. In this sense, the aim of this work is to determine the presence of pesticides in surface water of four agricultural sub-basins of Argentine. An environmental monitoring was carried out to determine the impact of twenty-nine pesticides used in agricultural activities on the surface water quality of agricultural areas within the San Vicente, Azul, Buenos Aires southeast and Mista stream sub-basins. The samples were analyzed by solid-phase extraction (SPE) using OASIS HLB 60 mg cartridges and ultra-high-pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC/MSMS) that provided good analytical quality parameters. The southeast of Buenos Aires was the site with the highest frequency of pesticides detection, followed by Azul and San Vicente microbasins. The most detected pesticides, considering all surface water samples, were atrazine, tebuconazole and diethyltoluamide with maximum concentration levels of 1.4, 0.035, and 0.701 μg L(-1), respectively. The results obtained for all basins studied show the presence of residual pesticides in surface waters according the different agricultural activities developed.

Acute toxicity of chlorpyrifos to the non-target organism Cnesterodon decemmaculatus

Chlorpyrifos is the most used insecticide in Argentina. Cnesterodon decemmaculatus is a widely distributed, endemic fish from Neotropical America. It attains high densities in the shallow water assemblages of Argentina and Brazil. The aim of this study was to assess the acute toxicity of chlorpyrifos to C. decemmaculatus. The mean 96-h LC50 of three independent determinations was 105.3 (± 3.1) μg/L. Sublethal effects were observed. Swimming behavioral changes at each chlorpyrifos exposure concentration were reported. C. decemmaculatus represents a good model for ecotoxicological risk assessment.

Biomonitoring toxicity of natural sediments using juvenile Hyalella curvispina (Amphipoda) as test species: evaluation of early effect endpoints

The utility of early effect endpoints as biomarkers of ecotoxicity of natural sediments in water-sediment static system was investigated. The particular goal was to evaluate the ecotoxicity of the sediment samples from La Choza stream, located in upper basin of the Reconquista river, the second most polluted river of Argentina. Native juveniles Hyalella curvispina were used as test organisms evaluating survival, growth, oxidative stress parameters (SOD; CAT, TBARS) and the electron transport system (ETS) activity as early toxic effect. This study used methodologies and techniques that allow the assessment of sediment pollution with a native species as test organism and provided data to discuss the viability of sublethal endpoints as tools for freshwater sediment assessment. In spring and in summer two ten-day series of whole-sediment assays were conducted simultaneously: (a) standard assays and (b) biomarkers assays. A control sediment was ran simultaneously in which no--effect on survival was measured. In summer there was a significant increase in length and biomass in both exposed and control groups. In spring an inhibitory effect on growth and an increase in oxidative damage with a concomitant rise in antioxidant defenses, was observed in animals exposed to La Choza sediment. ETS measurement indicated a significant depression of metabolic activity of amphipods exposed to contaminated sediments. The measured biomarkers represent the first record for juvenile H. curvispina exposed to polluted natural sediments under standardized laboratory conditions. The used bioanalytical tools demonstrated higher sensitivity and a more accurate assessment of the effects than those obtained by the standard tests of survival and growth. We propose their adoption in biomonitoring of freshwater sediment toxicity.

Variations in lethal and sublethal effects of cypermethrin among aquatic stages and species of anuran amphibians

Despite the use of model species to predict the effects of chemicals in the environment, unpredicted variation in levels of risk to organisms from xenobiotics can be observed. Physiological and morphological differences between species and life stages may lead to differences in sensitivity, while seasonal and spatial variation in pesticide concentrations may affect the level of risk faced by organisms in the environment. Because anurans breed in aquatic habitats subject to contamination by runoff and spraying, they are particularly vulnerable to pesticides. In the present study, embryos, newly hatched larvae, and larvae with limb buds of 3 anuran amphibian species--Pseudacris regilla, Rana cascadae, and Rana aurora--were exposed for 48 h to either 0.5 µg/L or 5.0 µg/L cypermethrin under laboratory conditions. The authors monitored hatching success, larval survival, and measured growth. Additionally, they assayed avoidance behavior 2 wk after exposure or 2 wk after hatching for individuals exposed as embryos. Hatching and survival were not affected in animals of any species exposed as embryos. After exposure as embryos and as newly hatched larvae, however, P. regilla displayed behavioral abnormalities in response to prodding. Cypermethrin increased mortality in P. regilla exposed in both larval stages. Cypermethrin also increased mortality in larval R. cascadae when exposed at the early stage. These results indicate variation in sensitivity to environmentally relevant concentrations of cypermethrin among anuran species and life stages.

Dynamics of organochlorine contaminants in surface water and in Myriophyllum aquaticum plants of the River Xanaes in central Argentina during the annual dry season

The dynamics of organochlorine pesticides (OCPs) and their major metabolites were studied in surface waters and plants of the River Xanaes (province of Córdoba, Argentina) during the annual dry season. The results of the 5-month monitoring study (April to August 2010) showed similar low contamination levels in nonagricultural mountain and agricultural areas in both water and plants. The concentrations of compounds detected in the surface water were <4.5 ng L(-1), whereas concentrations of these substances in Myriophyllum aquaticum plants were <5 μg kg(-1) (dry weight) with the exception of trans-permethrin (17.6 μg kg(-1), dry weight). Because no notable differences in the contamination level between samples from the mountain and the agricultural area were observed, it was assumed that OCPs may not play an important role in today's pesticide use in this area. Furthermore, the concentration-time trends for OCPs in the submerged plants showed a generally similar elimination behaviour independent of compound and sampling site, thus indicating an integral rather then a substance-specific process, such as partitioning between the plant and the ambient water. As known, rooted macrophytes can take up contaminants by way of roots, so sediments may be the principal source. To understand the dynamics of these compounds in the river area more deeply, thus further research should include study of the river sediment.

Nutrient concentrations in a Pampasic first order stream with different land uses in the surrounding plots (Buenos Aires, Argentina)

The objective of this study was to assess the effect of land use on nutrient concentrations in a Pampasic stream. Soluble reactive phosphorus (SRP) concentrations in the stream were higher at a site surrounded by fertilized double-cropped wheat/soybeans than at unfertilized soybeans plots. Nitrate and SRP concentrations in the stream were lower at sites surrounded by soybeans than livestock. It is suggested that crop fertilization and cattle manure increased nutrients loads released to the stream. It is suggested that preservation and restoration of riparian habitats may benefit water quality by decreasing nutrient loads.

Short and long-term effects of three neurotoxic insecticides on biological and behavioural attributes of the orb-web spider Alpaida veniliae (Araneae, Araneidae): implications for IPM programs

Soybean pest control in Argentina is done just by chemical control using broad-spectrum pesticides. Alpaida veniliae (Araneae, Araneidae) is one of the most abundant spider species of the orb web weaver guild in soybean, and it is considered a very important polyphagous predator, attacking different insects' families. The objective of this study was to determine if neurotoxic insecticides commonly used in soybean crops and a new active ingredient registered in Argentina (spinosad) adversely affected survival, prey consumption, mating behaviour, web building and reproductive capacity of A. veniliae females, under standard laboratory conditions. Spinosad was the most harmful insecticide due to high acute toxicity, even at lower concentrations than those registered for its field use and for its sublethal effects also. Cypermethrin caused several sublethal effects although its acute toxicity on spider was lower than other insecticides. It reduced prey consumption, affected web building, caused abnormalities in eggs sacs and decreased drastically the fecundity and fertility at sublethal concentrations. Endosulfan did not reduce prey consumption but it affected web building, caused abnormalities in eggs sacs and egg masses, and decreased the fecundity and fertility. Spinosad was also the compound with the most drastic effect on web building, it did not reduce prey consumption and fecundity, but fertility was reduced and abnormalities in egg sacs and egg masses were observed. The use of these insecticides in IPM programs according to their potential toxicity on spider communities is discussed.

Probabilistic risk assessment of insecticide concentrations in agricultural surface waters: a critical appraisal

Due to the specific modes of action and application patterns of agricultural insecticides, the insecticide exposure of agricultural surface waters is characterized by infrequent and short-term insecticide concentration peaks of high ecotoxicological relevance with implications for both monitoring and risk assessment. Here, we apply several fixed-interval strategies and an event-based sampling strategy to two generalized and two realistic insecticide exposure patterns for typical agricultural streams derived from FOCUS exposure modeling using Monte Carlo simulations. Sampling based on regular intervals was found to be inadequate for the detection of transient insecticide concentrations, whereas event-triggered sampling successfully detected all exposure incidences at substantially lower analytical costs. Our study proves that probabilistic risk assessment (PRA) concepts in their present forms are not appropriate for a thorough evaluation of insecticide exposure. Despite claims that the PRA approach uses all available data to assess exposure and enhances risk assessment realism, we demonstrate that this concept is severely biased by the amount of insecticide concentrations below detection limits and therefore by the sampling designs. Moreover, actual insecticide exposure is of almost no relevance for PRA threshold level exceedance frequencies and consequential risk assessment outcomes. Therefore, we propose a concept that features a field-relevant ecological risk analysis of agricultural insecticide surface water exposure. Our study quantifies for the first time the environmental and economic consequences of inappropriate monitoring and risk assessment concepts used for the evaluation of short-term peak surface water pollutants such as insecticides.

Abnormalities in amphibian populations inhabiting agroecosystems in Northeastern Buenos Aires Province, Argentina

The occurrence of abnormalities in amphibians has been reported in many populations, and its increase could be related to environmental pollution and habitat degradation. We evaluated the type and prevalence of abnormalities in 5 amphibian populations from agroecosystems with different degrees of agricultural disturbance (cultivated and reference areas). We detected 9 types of abnormalities, of which the most frequent were those occurring in limbs. The observed prevalence of abnormality in assessed populations from cultivated and reference areas was as follows: Rhinella fernandezae (37.1 and 10.2%, respectively), Leptodactylus latrans adults (28.1 and 9.2%) and juveniles (32.9 and 15.3%), and Hypsiboas pulchellus (11.6 and 2.8%). Scinax granulatus populations did not show abnormalities. Pseudis minuta, which was only detected in the reference area, exhibited a prevalence of 13.3%. For R. fernandezae, L. latrans, and H. pulchellus, generalized linear mixed models showed that prevalence of abnormalities was significantly higher (p < 0.05) in cultivated than in reference areas. L. latrans juveniles were more vulnerable to abnormalities than adults (p < 0.05). The presence of abnormalities in some species inhabiting different agroecosystems suggests that environmental stress factors might be responsible for their occurrence. While we detected pesticides (endosulfan, cypermethrin, and chlorpyrifos) and lower dissolved oxygen levels in ponds of the cultivated area, no data are currently available on how other factors, such as injuries from predators and parasite infections, vary by land use. Further research will be necessary to evaluate possible causes of abnormalities detected in the present study mainly in the context of factor interactions.