Multiple pesticides occurrence, fate, and environmental risk assessment in a small horticultural stream of Argentina

From degradation to detection: Assessing enantioselective behavior of chiral triazole fungicides in horticultural stream waters

Chiral pesticides constitute nearly 40 % of active ingredients used in agriculture, yet their enantioselective environmental behavior is often overlooked in risk assessments. This study examined the enantioselective degradation of three widely used triazole fungicides-cyproconazole, epoxiconazole, and tebuconazole-in surface water from horticultural streams, and assessed their enantiomeric distribution in environmental samples. Laboratory degradation experiments were conducted under light and dark conditions using racemic standards. Enantiomers were separated and quantified via LC-MS/MS using a Lux Cellulose-2 chiral column. Under light conditions, degradation followed simple first-order (SFO) kinetics, showing faster dissipation of the (+)-enantiomers compared to the (-)-enantiomers. For cyproconazole, DT50 values ranged from 2.64 to 2.74 days for (+)-enantiomers and 2.78-2.90 days for (-)-enantiomers; epoxiconazole and tebuconazole followed the same trend. The enantiomeric fraction (EF) increased over time in degradation assays, reaching values of up to 0.62 for cyproconazole and 0.73 for tebuconazole, confirming progressive enrichment of the (-)-enantiomers. In real surface water samples, EF values were >0.5 in 86 % (EFA) and 90 % (EFB) of detections for cyproconazole, 100 % for epoxiconazole, and 98 % for tebuconazole. These results represent the first EF data reported for cyproconazole in environmental waters and confirm the occurrence of enantioselective pollution. The consistent enrichment observed in both experimental and field data highlights the role of stereoselective degradation processes in shaping environmental profiles. Given the differential toxicity and persistence of individual enantiomers, these findings support the need for enantiomer-specific monitoring and risk assessment of chiral pesticides.

Nanopesticides ecotoxicity towards traditional ones: A case of study with Daphnia magna and λ-cyhalothrin

Nanotechnology has contributed to agriculture industry with novel products to improve the targeted delivery of active ingredients (a.i.), enable gradual release, avoid premature degradation, and increase efficacy. The properties of nanopesticides make their drift and environmental behavior more unpredictable than traditional formulations. Our aim was to compare the ecotoxicity of two insecticides with λ-cyhalothrin as a.i.: a nano-based one and a traditional emulsified, considering the incidence of temperature according to climate change prospections (20 and 24 °C). We evaluated their effects on Daphnia magna survival, body stores, and butyrylcholinesterase (BChE) activity. Although after 24 h the traditional formulation had greater lethality than the nanopesticide, after 48 h this pattern was reversed. At 24 °C the lethality of both pesticides increased. BChE activity was inhibited at 24 °C by both pesticides. In general, the increase in temperature negatively affected protein and glycogen content. The traditional formulation reduced glycogen content at 24 °C. A decrease in lipid content and the whole energy budget was observed in organisms exposed to the traditional formulation at both temperatures. Although the nano-based pesticide developed a delayed toxicity, it was more lethal than the traditional one in the long term. The temperature rise worsened the pesticides effects in terms of decreased survival, BChE activity inhibition, and energy reserves depletion. The development and regulation of new eco-safer nanopesticides needs to be complemented by their ecotoxicological assessment. It is imperative to analyze their impact in the context of climate change in order to develop mitigation and adaptation strategies.

The Sub-Acute Potential Risk of Oxamyl in Male Albino Rats

The current study aimed to investigate the sub-acute effects of oxamyl on male Albino rats following oral administration of either 0.031 or 0.31 mg/kg/day for 14 consecutive days. The findings demonstrated that oxamyl produced a significant impact on most of the examined blood profile and biomarkers, along with a significant progressive and discernible alterations in the histology of organs. According to the results obtained, the potential mechanisms by which oxamyl causes its toxic effects on rats are identified as the inflammation indices, the inhibition of transaminases, alkaline phosphatase, and antioxidant enzymes, as well as the production of thiobarbituric acid reactive substances (TBARs) in organs following oxamyl treatment based on histopathological examinations. Due to the substantial genetic similarities between rats and humans, it is therefore anticipated that oxamyl will have comparable detrimental effects on humans.

Lambda-Cyhalothrin Effect on the Swimming Behavior of Boana pulchella (Anura: Hylidae) Tadpoles

Boana pulchella is an anuran species widely distributed in Neotropical South America and commonly abundant in the Argentine Pampas. The aim of this study was to evaluate the effects of the commonly used insecticide lambda-cyhalothrin on the swimming performance of B. pulchella tadpoles exposed to environmentally relevant concentration in a laboratory bioassay. Mean velocity was measured in two treatments of 1.5 and 10 µg/L and a control, after 2-h and 96-h exposures. The mean speed displacement was estimated using the video analysis software Tracker®. No mortality was detected. However, tail flexion was observed in all tadpoles in both treatments throughout the entire exposure period, which was not observed in the controls. Swimming velocity was significantly lower in the exposed treatments compared to the control, and lower at the higher concentration exposure. It is concluded that exposure to field-relevant lambda-cyhalothrin concentrations affects the morphology and swimming behavior of B. pulchella, thus influencing its competitive fitness and potentially affecting non-target amphibian assemblages.

Toxicity of pesticide cocktails in amphibian larvae: understanding the impact of agricultural activity on aquatic ecosystems in the Salado River basin, Argentina

Aquatic communities are increasingly exposed to complex mixtures of contaminants, mainly pesticides due to the impact of agricultural activity. The aim of this study was to evaluate the toxicity of an eight-pesticide cocktail on larvae of the South American common toad, Rinella arenarum. The cocktail represents a realistic mixture of insecticides (cypermethrin, chlorpyrifos and lambda-cyhalothrin), herbicides (glyphosate, glufosinate ammonium, prometryn and metolachlor), and a fungicide (pyraclostrobin) previously found in aquatic organisms (Prochilodus lineatus) from the Salado River Basin, an area with strong agricultural pressure. Computational simulations through the Density Functional Tight-Binding method indicated a strong spontaneous trend toward the formation of the cocktail, suggesting that it may act as a novel xenobiotic entity in the environment. The cocktail effects were evaluated in early-developing and premetamorphic larvae, at feasible concentrations found in real scenarios. The mixture led to high mortality and teratogenicity in early-developing larvae. Premetamorphic larvae showed endocrine disruption, oxidative stress, and impairments in detoxification and hepatic functioning. Neurotoxicity, genotoxicity, cardiotoxicity and high mortality under stress conditions were also observed in exposed larvae. This novel evaluation highlights the ecotoxicological risk for aquatic organisms exposed to complex mixtures and underscores the need to consider cocktail effects in studies regarding ecosystems health.

Pesticides in fish from the Uruguay River and markets in Argentina and health risk assessment

Organochlorine, organophosphate, triazole, and strobilurin pesticides were determined in fish samples. Relative standard deviations lower than 9.3% were obtained for organochlorine pesticides and 10.8% for other pesticides. Accuracy ranged from 73% to 119% for organochlorine pesticides and 80.4% to 116% for organophosphate, triazole, and strobilurin pesticides. A total of 28 pesticides were analysed and 7 of them were detected (exceeding 10 µg/kg) in some samples, with the highest concentration recorded at 68.5 µg/kg, corresponding to heptachlor epoxide A. The pesticide most frequently detected was β HCH, found in 30 of the 100 analysed samples. Hazard Quotient values were estimated for men, women, and children. These values exceeded 1 for heptachlor epoxide in women and children, as well as for endrin in children. These findings emphasise the need for stricter controls to reduce fish contamination and mitigate health risks.

Basal levels of biochemical biomarkers in the freshwater prawn Palaemon argentinus and their alterations due to the exposure of both insecticides cypermethrin and spirotetramat

The aim of this study was to evaluate the sensitivity of the prawn Palaemon argentinus to the pyrethroid cypermethrin (CYP) and the tetramic acid spirotetramat (STM). These treatments were compared with prawns collected at a reference site to define their basal physiological state. Initially, physicochemical parameters and several pollutants at the selected site were analyzed. The LC50-96 h was determined in adult prawns. Then, prawns were exposed for 96 h to sublethal concentrations of CYP (0.0005 μg/l) and STM (0.44 mg/l) to evaluate the effects on some biochemical endpoints. A treatment combining both pesticides was also added at 5 % of these values. Controls with and without solvent (acetone) were included. The LC50-96 h values were 0.005 μg/l and 4.43 mg/l for CYP and STM, respectively. Moreover, some biomarkers linked to oxidative and energy metabolism were analyzed in the hepatopancreas and muscle of both essayed prawns and those at the basal state. The STM caused a significant decrease in total protein content (32 %) in contrast to the increase of protein carbonyl content (71 %) (p < 0.05). Also, glutathione S-transferase (52 %) and catalase (61 %) activities in the hepatopancreas of exposed prawns were higher compared to both the control and state basal groups (p < 0.05). In muscle, only a significant decrease in the lactate content (69 %) was caused by STM (p < 0.05). In addition, CYP caused a significant increase in the lactate dehydrogenase activity (110 %) in muscle and triacylglycerol content (73 %) in the hepatopancreas (p < 0.05). The integrated biomarker index (IBRv2) analysis showed that STM caused greater damage than CYP. Besides, the combined treatment showed an antagonistic interaction between both insecticides. The differential response of biomarkers to both CYP and STM exposure with respect to their basal levels shows a high sensitivity of P. argentinus demonstrating its potential role as a bioindicator organism.

A promising alternative for sustainable remediation of carbendazim in aquatic environments

The treatment of carbendazim-contaminated effluents is a challenge because of its complex composition and toxicity. A promising solution lies in biodegradation and the fungus Actinomucor elegans LBM 290 shows significant potential in this regard. Thus, the aim of this study was to biodegrade MBC by A. elegans LBM 290 in a liquid medium addressing the changes in the fungal morphology and protein production. The fungus A. elegans LBM 290 efficiently remove the fungicide carbendazim, with 86.6% removal within 8 days. This degradation is a combination of biodegradation (24.54%) and adsorption (62.08%). Exposure to carbendazim negatively affected the fungus, causing a decrease in biomass and morphological changes. Proteomic analysis revealed the fungal response to carbendazim stress through increased production of Cu-Zn superoxide dismutase, an antioxidant enzyme that combats oxidative stress, and the presence of a G protein subunit, suggesting participation in stress signaling pathways. These findings contribute to understanding the strategies of A. elegans LBM 290 to cope with carbendazim exposure in aquatic environments.

Biomarkers at the Individual and Biochemical Level: Effects of Pure and Formulated Lambda-Cyhalothrin in Boana pulchella Tadpoles (Duméril and Bibron, 1841)

We compared the effects of lambda-cyhalothrin as the pure active ingredient and as a formulated product (Zero®), on the larval stage of the autochthonous species Boana pulchella. We evaluated ecotoxicological endpoints, behavioral and developmental alterations, and the biochemical detoxifying, neurotoxic, and oxidative stress responses, covering a wide concentration range from environmental to high application levels. Both pyrethroid preparations displayed similar ecotoxicity (median lethal concentration of ~0.5 mg/L), with the lethal effect of Zero® being more pronounced than that of the active ingredient. Sublethal behavioral alterations in natatory activity were observed at 1000 times lower concentrations, indicating the ecological hazard of tadpole exposure to this pyrethroid at environmentally relevant concentrations. Biochemical endpoints in B. pulchella larvae showed significant responses to lambda-cyhalothrin in the ng/L range; these responses were different for the pure or the formulated product, and they were variable at higher concentrations. Principal components analysis confirmed the prevalence of biochemical responses as early endpoints at the lowest lambda-cyhalothrin concentrations; the Integrated Biomarker Response Index proportionally increased with pyrethroid concentration in a similar way for the pure and the formulated products. We conclude that lambda-cyhalothrin is of concern from an environmental perspective, with particular emphasis on autochthonous anuran development. The battery of biochemical biomarkers included in our study showed a consistent integrated biomarker response, indicating that this is a potent tool for monitoring impacts on amphibians. Environ Toxicol Chem 2024;43:2134-2144. © 2024 SETAC.

Assessment of sulfonamide contamination in aquatic environments: A first report for Argentina and environmental risk assessment

The global surge in pharmaceutical consumption, driven by increasing population and the demand for animal proteins, leads to the discharge of diverse pollutants, including antibiotic residues, into water bodies. Sulfonamides, being water-soluble compounds, can readily enter surface run-off, posing potential risks to non-target species despite their low environmental concentrations. Latin America has implemented intensive production systems highly dependent on antimicrobials for productivity and animal health, yet there is a paucity of information regarding their concentration in the region. The objective of this study was to evaluate the presence of sulfonamides in water and sediment samples and assess their potential ecological risks through an environmental risk assessment. The Río de la Plata basin collects the waters of the Paraguay, Paraná, and Uruguay rivers, together with their tributaries and various wetlands, passing through the provinces in Argentina known for their significant animal husbandry production. Two sampling campaigns were carried out for sediment, while only one campaign was conducted for surface waters. The samples were analyzed by high performance liquid chromatography tandem mass-spectrometry (HPLC-MS/MS). None of the examined sulfonamide antibiotics were detected in the sediment samples from both sampling campaigns. In contrast, sulfadiazine (95 %), sulfamethoxazole (91 %), and sulfathiazole (73 %) were detected in the water samples. Sulfadiazine was found in the concentration range of 8 to 128 ng/L, while sulfamethoxazole and sulfathiazole were observed at concentrations ranging from 3.0 to 32.5 ng/L and 2.9 to 8.1 ng/L, respectively. Based on the environmental risk assessment conducted using the sulfonamide concentrations, most samples indicated a medium risk for aquatic biota, with only one sample surpassing the high-risk threshold. This study represents the first report presenting data on the presence of sulfonamide antibiotics in the aquatic environment of Argentina.

Multi-biomarker approach to evaluate the toxicity of chlorpyrifos (active ingredient and a commercial formulation) on different stages of Biomphalaria straminea

Biomphalaria straminea is a freshwater gastropod native to South America and used in toxicological assessments. Our aim was to estimate 48 h-LC50 and sub-chronic effects after the exposure to low concentrations of chlorpyrifos as commercial formulation (CF) and active ingredient (AI) on B. straminea adult, embryos and juveniles. Concentrations between 1 and 5000 μg L-1 were chosen for acute exposures and 0.1 and 1 μg L-1 for the sub-chronic one. After 14 days biochemical parameters, viability and sub-populations of hemocytes, reproductive parameters, embryotoxicity and offspring' survival were studied. Egg masses laid between day 12 and 14 were separated to continue the exposure and the embryos were examined daily. Offspring' survival and morphological changes were registered for 14 days after hatching. 48 h-LC50, NOEC and LOEC were similar between CF and AI, however the CF caused more sub-lethal effects. CF but not the AI decreased carboxylesterases, catalase and the proportion of hyalinocytes with respect to the total hemocytes, and increased superoxide dismutase and the % of granulocytes with pseudopods. Also CF caused embryotoxicity probably due to the increase of embryos' membrane permeability. Acetylcholinesterase, superoxide dismutase, hemocytes sub-populations, the time and rate of hatching and juveniles' survival were the most sensitive biomarkers. We emphasize the importance of the assessment of a battery of biomarkers as a useful tool for toxicity studies including reproduction parameters and immunological responses. Also, we highlight the relevance of incorporating the evaluation of formulations in order to not underestimate the effects of pesticides on the environment.

Distribution and risk assessment of pesticide pollution in small streams adjoining paddy fields

The present investigation was planned to bridge the knowledge gap on spatiotemporal variations of pesticide pollution in small streams adjacent to paddy fields, and to visualize the associated risks in the aquatic ecosystems. We screened 106 pesticides using GCMSMS and LCMSMS from 10 small streams (n = 212, surface water samples) adjacent to paddy fields over seven months. Fifty-five pesticides were detected across different streams and months. The highest mean concentration was detected for fenobucarb (272 ng L-1), followed by thiamethoxam (199 ng L-1). The highest maximum concentration was detected for thiamethoxam ( 13,264 ng L-1), followed by triflumezopyrim ( 11,505 ng L-1). The highest detection frequency was recorded for fenobucarb (80.00%), followed by pretilachlor (79.00%). Out of the ten streams, Attabira stream had the highest mean number of pesticides detected in each sample. Maximum number of pesticides were detected in October followed by September. Pesticides namely, hexaconazole, pretilachlor, tricyclazole, fenobucarb and thiamethoxam were consistently detected across all streams. The risk assessment against the fishes, micro-invertebrates and algae were measured by risk quotient index (RQ). Twenty-five pesticides out of the detected pesticides (n = 55) had risk quotient values greater than 1. The highest RQmax values were observed in case of fenpropathrin followed by cyfluthrin-3. The highest RQmean value was observed in case of cyfluthrin, indicating its higher toxicity to fishes. The present study reveals that small streams are polluted with pesticides and there is a need to develop strategies and policy interventions in regularizing the pesticide uses for reducing the pesticide pollution in aquatic systems.

Analyzing the impact of pesticides on the indus river: contamination levels in water, sediment, fish, and associated human health risks

Pesticides are frequently used to protect crop yields and manage malaria vectors; however, their inadvertent transport into aquatic habitats poses a significant concern. Various anthropogenic activities influence the Indus River in Pakistan. This study aimed to assess the presence of eight pesticide residues at three different sites (Kalabagh, Kundian, and Chashma) in water, sediment, and the fish species (Labeo rohita) during both dry and wet seasons to measure the intensity of this pressure. Pesticide analysis was carried out using gas chromatography equipped with an electron capture detector. The results revealed the highest concentrations of pesticides during both dry and wet seasons at all sites, measuring 0.83 and 0.62 μg/l (water), 12.37 and 9.20 μg/g/dw (sediment), and 14.27 and 11.29 μg/g/ww (L. rohita), respectively. Overall, pesticide concentrations were higher in the dry season than in the wet season across all study sites. Based on detection frequency and concentration in both seasons at all sites, dominant pesticides included cypermethrin and carbofuran (in water), as well as endosulfan and cypermethrin (in sediment and fish tissue). Levels of endosulfan and cypermethrin exceeded standard limits. Moreover, principal component analysis (PCA) indicated no correlation among pesticides in fish tissue, sediment, and water. However, pesticides exhibited different behavior in different seasons. Furthermore, endosulfan and triazophos impose great human health risk, as indicated by the THQ value (> 1). The overall HI value was greater for site 1 in the dry season (8.378). The study concluded that the presence of agricultural pesticides in the Indus River poses a risk to aquatic life and has the potential to disrupt the entire food chain. This highlights the importance of sustainable practices for the study area and Pakistan overall agricultural and environmental sustainability. It is further recommended to strengthen regulations for reduced pesticide use and promote eco-friendly pest management.

Comparative deterministic and probabilistic approaches for assessing the aquatic ecological risk of pesticides in a mixed land use basin: A case study in Uruguay

Environmental concentrations of 25 pesticides in superficial water were employed to conduct an ecological risk assessment (ERA) in a mixed land-use basin utilized as a drinking water source. A deterministic risk assessment (RQ) was utilized to evaluate the chronic risk to aquatic biota, while a probabilistic risk assessment (PRA) approach was applied to assess the acute and chronic risk in the most sensitive species and at the community level. A high risk was identified for insecticides (pyrethroids, organophosphates and organochlorines). RQs ranged from 4.0e-4 (2,4-D) to 105.3 (ethion) considering median concentrations and from 8.0e-4 (2,4-D) to 230 (p,p'-DDT) considering extreme concentrations. Temporal variation in ΣRQs showed the highest risk during spring and summer months, which is related to the crop calendar and land use in the Laguna del Cisne basin. For PRA, the probability of exceeding the hazardous concentration HC5 (5th percentile) was higher for the most sensitive species in chronic exposure, especially for cypermethrin (38.9 %), permethrin (25.6 %), and chlorpyrifos (16.6 %). In the case of acute exposures, the probability of surpassing HC5 was higher for the entire freshwater biota, with the highest values observed for bifenthrin (28.3 %), cypermethrin (25.5 %), permethrin (11.75 %), and ethion (11.1 %). The advantages and disadvantages of PRA for assessing pesticide ecological risk were compared with the conventional deterministic RQs approach, highlighting that PRA offers improvements over the deterministic risk assessment, especially for organophosphate pesticides. Additionally, PRA provides a more comprehensive evaluation of risk for both short and long-term exposure, has the potential to incorporate others available toxicity data (e.g., LD50, Daily Intake), and utilizes different hazardous concentrations, such as HC5, HC10, and HC50. Our findings emphasize the urgent need to establish a national regulatory framework to evaluate and mitigate pesticide risks in aquatic ecosystems, especially in drinking water source like Laguna del Cisne.

Whole-sediment toxicity bioassays with Hyalella curvispina as a valuable bioanalytical tool for assessing pesticide risks in watercourses with different types of agro-productive activities

The current Argentine agricultural production model is dependent on agrochemicals such as fertilizers and pesticides. Extensive agriculture and horticulture are the two major productive activities that use copious amounts of pesticides. Extensive agriculture is characterized by areas of 50 to 100 ha of a single crop, while peri-urban horticulture is characterized by intense land use, with farms ranging from 1 to 3 ha cultivated with a variety of vegetables. Despite the relevance of pesticides, data on their effects on the biota associated with nearby watercourses are scarce. Given this paucity of knowledge, the objective of the present work was to assess the relative impact of extensive agriculture and horticulture on sediment quality in representative watercourses by conducting whole-sediment toxicity bioassays with the native amphipod Hyalella curvispina. The lower Gualeguay Basin, in the Province of Entre Ríos, was selected as a representative watercourse impacted by extensive agriculture, and the Carnaval Creek, on the periphery of La Plata, Province of Buenos Aires, was selected as a horticulture-impacted watercourse. Growth inhibition (sublethal effect) was observed in both systems, whereas mortality (lethal effect) was largely observed in horticulture. The observed effects were integrated with pesticide concentrations in the same sediments and correlated by multivariate analysis, revealing that toxicity was mainly due to insecticides, particularly λ-cyhalothrin. Therefore, horticultural practices and their associated pesticide use could potentially endanger the benthic fauna of nearby watercourses.

Single and joint toxicity of azoxystrobin and cyproconazole to Prochilodus lineatus: Bioconcentration and biochemical responses

Fungicides are widely used across the world to protect crops and their presence in freshwater systems is increasing. However, the evaluation of their potential impacts on non-target organisms is in the minority of studies related to pesticides. In the current research, the single and joint toxicity of azoxystrobin (AZX) and cyproconazole (CYP) was investigated in juvenile fish Prochilodus lineatus. In particular, we evaluated bioconcentration and biochemical responses following a short-term exposure to environmentally relevant concentrations of the fungicides (alone and in mixture). We also determined interactions between the biological responses when the two compounds were used in mixture. Our results demonstrate that AZX and CYP pose a risk to native freshwater fish by causing deleterious effects. Both compounds, alone and in mixture, bioaccumulated in P. lineatus and triggered neurotoxicity and changes in oxidative stress biomarkers in several organs. Moreover, muscle was a target tissue for these fungicides and a synergistic interaction was observed for the mixture. Due to the lack of studies in fish assessing the effects following exposure to AZX-CYP mixtures and considering a realistic exposure situation in agriculture-impacted water bodies, these findings provide new and relevant information for future studies.

First Report of the Joint Exposure to Glyphosate and Glufosinate of a Male Population in the Province of Córdoba (Argentina)

Despite potential health implications, data on the presence of Glyphosate (GLY) and other non-GLY herbicides in human matrices remain scarce. This study aimed to develop a simple and cost-effective methodology for detecting and quantifying GLY, its primary biodegradation product; aminomethylphosphonic acid (AMPA); and glufosinate (GLU) in plasma and urine of environmentally and occupationally exposed populations from the province of Córdoba (Argentina). Different alternatives of pre-treatment, derivatization with FMOC-Cl, solid phase extraction, and final sample conditioning steps were evaluated to improve the quantification of the herbicides by a high-performance liquid chromatography system coupled to a triple-quadrupole mass spectrometer. Recoveries ranged from 39 to 84% in both matrices, while limits of quantification were 3, 1, and 0.3 ng/mL and 3.6, 5.1, and 0.3 ng/mL for AMPA, GLY, and GLU in plasma and urine, respectively. In plasma samples, GLY was the most frequently detected analyte (32%), followed by GLU (10%). In urine samples, GLU was the most frequently detected herbicide (13%), followed by GLY (6%). No differences between group or matrix correlations were found. This study is the first report of GLU in human biological matrices and should be used to establish baseline values for future surveillance systems.

Toxicity of glyphosate and aminomethylphosphonic acid (AMPA) to the early stages of development of Steindachneridion melanodermatum, an endangered endemic species of Southern Brazil

This study aimed to evaluate glyphosate (GLY) and aminomethylphosphonic acid (AMPA) toxicity at 65, 650, and 6500 μg L-1 to the initial stages of development of Steindachneridion melanodermatum, an endangered endemic species from the Iguaçu River, assessing hatching, survival, total larval length, deformities, oxidative stress biochemical biomarkers, and neurotoxicity. Overall, looking at the sum of responses through the integrated biomarker response, the species was more sensitive to AMPA than GLY, especially at the lower concentration of 65 μg L-1, which induced mortality, deformities, underdevelopment, and oxidative stress. Considering the risk of exposure and the importance of conservation of the highly endemic ichthyofauna of this basin, it is urgent to investigate and regulate both GLY and AMPA levels at the Iguaçu River to protect not only this species, but the entire ecosystem.

Benzene Sulfonyl Linked Tetrasubstituted Thiacalix[4]arene for Selective and Sensitive Fluorometric Sensing of Sulfosulfuron along with Theoretical Studies

Herein, we designed two fluorescent tetrasubstituted benzene sulfonyl appended Thiacalix[4]arene receptors named L1 and L2, which sensitively and selectively detect Sulfosulfuron among other herbicides and pesticides. The detection limit (LOD) was found to be 0.21 ppm and 0.35 ppm, and the enhancement constant (Ks) was determined to be 7.07 X 104 M-1 and 5.55 X 104 M-1 for L1 and L2, respectively. Using the non-linear regression method, the association constant was obtained as 2.1 X 104 M-1 and 2.23 X 104 M-1 whereas, the binding ratio was found to be 1:1 for both L1 and L2, respectively. Additionally, the interference studies show the selective nature of receptors for Sulfosulfuron among its sulfonylurea family. To further confirm the interaction mechanism, 1H-NMR spectroscopy, and a computational investigation were carried out, which validates the 1:1 binding ratio. The receptors were found to be recyclable in nature with simple acid-base treatment. This new approach of using supramolecules as fluorescent probes for sensitive and selective detection of herbicides is rare in the literature.

Risk evaluation and prioritization of contaminants of emerging concern and other organic micropollutants in two river basins of central Argentina

A research gap exists in baseline concentrations of organic micropollutants in South American rivers. Identification of areas with different degrees of contamination and risk to the inhabitant biota is needed to improve management of freshwater resources. Here we inform the incidence and ecological risk assessment (ERA) of current used pesticides (CUPs), pharmaceutical and personal care products (PPCPs) and cyanotoxins (CTX) measured in two river basins from central Argentina (South America). Risk Quotients approach was used for ERA differentiating wet and dry seasons. High risk was associated to CUPs in both basins (45 % and 30 % of sites from Suquía and Ctalamochita rivers, respectively), mostly in the basins extremes. Main contributors to risk in water were insecticides and herbicides in Suquía river and insecticides and fungicides in Ctalamochita river. In Suquía river sediments, a very high risk was observed in the lower basin, mainly from AMPA contribution. Additionally, 36 % of the sites showed very high risk of PCPPs in Suquía river water, with the highest risk downstream the wastewater treatment plant of Córdoba city. Main contribution was from a psychiatric drug and analgesics. In sediments medium risk was observed at the same places with antibiotics and psychiatrics as main contributors. Few data of PPCPs are available in the Ctalamochita river. The risk in water was low, with one site (downstream Santa Rosa de Calamuchita town) presenting moderated risk caused by an antibiotic. CTX represented in general medium risk in San Roque reservoir, with San Antonio river mouth and the dam exit showing high risk during the wet season. The main contributor was microcystin-LR. Priority chemicals for monitoring or further management include two CUPs, two PPCPs, and one CTX, demonstrating a significant input of pollutants to water ecosystems from different sources and the need to include organic micropollutants in current and future monitoring.

Mammary Gland Development in Male Rats Perinatally Exposed to Propiconazole, Glyphosate, or their Mixture

This study aimed to assess whether perinatal exposure to propiconazole (PRO), glyphosate (GLY) or their mixture (PROGLY) alters key endocrine pathways and the development of the male rat mammary gland. To this end, pregnant rats were orally exposed to vehicle, PRO, GLY, or a mixture of PRO and GLY from gestation day 9 until weaning. Male offspring were euthanized on postnatal day (PND) 21 and PND60. On PND21, GLY-exposed rats showed reduced mammary epithelial cell proliferation, whereas PRO-exposed ones showed increased ductal p-Erk1/2 expression without histomorphological alterations. On PND60, GLY-exposed rats showed reduced mammary gland area and estrogen receptor alpha expression and increased aromatase expression, whereas PRO-exposed ones showed enhanced lobuloalveolar development and increased lobular hyperplasia. However, PROGLY did not modify any of the endpoints evaluated. In summary, PRO and GLY modified the expression of key molecules and the development of the male mammary gland individually but not together.

Lethality and Acetylcholinesterase Inhibition in a Native Invertebrate Species Exposed to Water Samples of an Impacted Stream (Reconquista River Basin, Argentina)

The study of multiple biomarkers in bioindicator species is a useful tool to evaluate water quality in addition to physicochemical analysis. The aim of this work was to study the toxicity of water samples from two sites with different anthropogenic impacts (R: near a residential area and FP: close to horticultural farms and industrial waste treatment plants) from Las Catonas sub-basin (Reconquista River basin) in the native gastropod Biomphalaria straminea. Some physicochemical parameters and chlorpyrifos concentration were measured in water samples. Snails were exposed in laboratory conditions 48 h to the water samples and neurotoxicity, behavior, lethality and acetylcholinesterase, carboxylesterase, glutathione S-transferase, glutathione reductase and catalase activities were measured. In water from FP, chlorpyrifos was detected and conductivity and pH were higher than in R. Lethality (60%) and a decrease (30%) in acetylcholinesterase were observed in snails exposed to FP indicating that water contamination causes high toxicity in B. straminea.

Pesticides bioassays using neotropical aquatic species: Trends during the last twenty years and future challenges in Argentina

The presence of pesticides in aquatic ecosystems is one of the most relevant stressors which biota usually face. Laboratory tests using model organisms for pesticides toxicity assessment are employed worldwide. The use of these species has been encouraged in the scientific community due to their advantageous features and their acceptation by regulatory and standardization organizations. However, non-model species as well as those belonging particular ecosystems could contribute in the laboratory-field toxicity extrapolation. In this context, this work aims on exploring the state of the ecotoxicological studies of pesticides in neotropical aquatic species, focusing on bioassays performed in Argentina over the last 20 years as a case of study. Furthermore, we analyzed the possible advantages and disadvantages of these studies, possible differential sensitivities among native and model species, and future challenges to be faced. The analysis of more than 150 publications allowed identify the chemical identity of tested compounds, organisms used for the bioassays, characteristics of the experimental designs, and the toxicity endpoints. Particularly, the studied cases showed that the tested chemicals are related to those most used in the agricultural activity in Argentina, the predilection for particular species in some taxonomic groups (e.g. amphibians), and the wide election of biochemical biomarkers in the studies. Regarding the sensitivity comparison between native and non-native species, the amount of data available indicates that there is not a clear difference beyond some particular cases. However, deeper understanding of toxic effects of pesticides on non-model species could help in a more comprehensive ecological risk assessment in different ecosystems.

Dissipation kinetics of chlorpyrifos and 3,5,6 trichloro-2-pyridinol under vegetation of different aromatic grasses: Linkage with enzyme kinetics and microbial community of soil

The dissipation of chlorpyrifos (CP) and its hydrolytic metabolite 3,5,6-trichloro-2-pyridinol (TCP) in the soil is crucial for safe agriculture. However, there is still lacking relevant information about its dissipation under different vegetation for remediation purposes. In the present study, evaluation of dissipation of CP and TCP in non-planted and planted soil with different cultivars of three types of aromatic grass viz Cymbopogon martinii (Roxb. Wats), Cymbopogon flexuosus, and Chrysopogon zizaniodes (L.) Nash was examined in light of soil enzyme kinetics, microbial communities, and root exudation. Results revealed that the dissipation of CP was well-fitted into a single first-order exponential model (SFO). A significant reduction in the half-life (DT₅₀) of CP was observed in planted soil (30-63 days) than in non-planted soil (95 days). The presence of TCP in all soil samples was observed. The three types of the inhibitory effect of CP i.e. linear mixed inhibition (increase in enzyme-substrate affinity (Km) and decrease in enzyme pool (Vmax), un-competitive inhibition (decrease in Km and Vmax), and simple competitive inhibition were observed on soil enzymes involved in mineralization of carbon, nitrogen, phosphorus, and sulfur. The improvement in the enzyme pool (Vmax) was observed in planted soil. Streptomyces, Clostridium, Kaistobacter, Planctomyces, and Bacillus were the dominant genera in CP stress soil. CP contamination in soil demonstrated a reduction of richness in microbial diversity and enhancement of functional gene family related to cellular process, metabolism, genetic, and environmental information processing. Among all the cultivars, C. flexuosus cultivars demonstrated a higher dissipation rate of CP along with more root exudation.

Glyphosate affects the susceptibility of non-target native plant species according to their stage of development and degree of exposure in the landscape

Unsustainable agriculture is producing a great socio-ecological transformation in Latin America because it has expanded into areas occupied by native forests. Glyphosate is the most widely used herbicide, with severe ecotoxicological effects on non-target organisms. The aim of this study was to determine the effects of glyphosate on seedlings of 24 non-target herbaceous and non-herbaceous plant species present in forest relicts of Argentine Chaco. The effects of a gradient of glyphosate doses (525, 1050, 2100, 4200, and 8400 g ai/ha) were measured in seedlings of each species under greenhouse conditions. Seedlings were grown from seeds collected from native forest fragments of different sizes (assuming three different degrees of historical exposure to glyphosate in the landscape). Doses were applied at different stages of seedling development (five- and ten-weeks after emergence), and phytotoxicity, growth reduction, and sensitivity were measured. Glyphosate produced lethal or sublethal effects in all 24 species, some of which were very sensitive (>60 % of the species presented strong to severe growth reduction with ¼ of the dose used on crops). The greatest toxicological effects were related to early stage of development, herbaceous species, and low historical exposure to glyphosate. According to the species sensitivity distribution, the drift-dose to protect 95 % of the plant species that occur in larger forest fragments should not exceed 5 % of the dose commonly used on crops. These results suggest that the current weed management linked to glyphosate-resistant crops could lead to a gradual loss of biodiversity in the landscape. Concurrently, selection of glyphosate-tolerant biotypes in some non-target species could represent a very problematic cycle for the current model of industrial agriculture. Some alternatives for weed control are proposed.

Developing a glyphosate-bioremediation strategy using plants and actinobacteria: Potential improvement of a riparian environment

Glyphosate (Gly) and its principal degradation product, the aminomethylphosphonic acid (AMPA) were found in soils from a riparian environment in Argentina. Sixty-five actinobacteria were isolated from these soils, rhizosphere, and plants (Festuca arundinacea and Salix fragilis). The isolate Streptomyces sp. S5 was selected to be used as bioinoculant in a greenhouse test, in which plants, actinobacteria, and their combinations were assessed to bioremediate the riparian soil. The dissipation of both compounds were estimated. All treatments dissipated similarly the Gly, reaching 87-92 % of dissipation. AMPA, dissipation of 38 % and 42 % were obtained by Salix and Festuca, respectively, while they increased to 57 % and 70 % when the actinobacterium was added to each planted system. Regarding the total dissipation, the higher efficiencies for both compounds were achieved by the non-planted soils bioaugmented with the actinobacterium, with 91 % of Gly dissipated and 56 % for AMPA. According to our study, it could be suggested which strategy could be applied depending on the bioremediation type needed. If in situ bioremediation is necessary, the combination of phytoremediation and actinobacteria bioaugmentation could be convenient. On the other hand, if ex situ bioremediation is needed, the inoculation of the soil with an actinobacterium capable to dissipate Gly and AMPA could be the more efficient and easier alternative.

Combined effects of high temperature and pesticide mixture exposure on free-swimming behaviors and hepatic cytochrome P450 1A expression in goldfish, Carassius auratus

The synergy between multiple compounds and other stressors, including heat, creates volatility and greater unpredictability than standard single-chemical toxicity testing, especially in the case of pesticides and metabolites which might contain several noxious ingredients resulting in adverse ecological effects. To address this, the aim of this study was to examine the dose- and time-dependent effects of low- and high-dose pesticide mixture (metalachlor, linuron, isoproturon, tebucanazole, aclonifen, atrazine, pendimethalin, azinphos-methyl) and heat stress co-exposure (22°C control/32°C treatment for 4-week) on free-swimming behaviors and cumulative actionless time (CAT) of goldfish. Behavioral analysis showed a dose- and time-dependent decrease in distance swam, as well as a subsequent increase in CAT. Vertical and horizontal spatial behavioral use were affected under heat and pesticides co-exposure conditions. In 3- and 4-week(s) exposure groups, horizontal spatial behavioral use demonstrated elevated time spent in the lower third of the aquarium. Similarly, during 3- and 4-week(s) exposure (32°C control and 32°C high doses) vertical spatial behavioral use was found to increase time spent in the outermost edges of the aquarium. In all treatment groups, the final condition factor (KM) showed significant attenuation when compared to the initial KM. However, there was an unclear relationship between heat/pesticide co-exposure and growth most notably in 32°C high-dose groups. In addition, the expression of hepatic cytochrome P450 1A mRNA was significantly higher in pesticide-exposed groups. Taken together, data demonstrated that co-exposure with low- or high-dose pesticide mixture and heat stress significantly impacted natural swimming patterns, which over time might result in the broader population and ecological effects.

Postnatal exposure to a glyphosate-based herbicide interferes with the development and growth of the mammary gland of pre-pubertal Ewe lambs

The aim of the present study was to evaluate whether early postnatal exposure to a glyphosate-based herbicide (GBH) alters pre-pubertal mammary development in Friesian lambs. To this end, from postnatal day 1-14, ewe lambs were exposed subcutaneously or orally to GBH (2 mg/kg bw/day) or vehicle (control) and mammary gland biopsies were obtained at 45 days of age. GBH-exposed lambs exhibited larger mammary ducts and less area occupied by terminal duct lobular units than controls, accompanied by an increase in the area of adipocytes in the mammary stroma. Lambs subcutaneously exposed to GBH showed increased protein expression of estrogen receptor alpha; however, both GBH-exposed groups had decreased mRNA expression of this receptor. Control lambs showed nuclear progesterone receptor (PR) protein expression, whereas GBH-exposed animals showed cytoplasmic PR expression; both GBH-exposed groups exhibited decreased mRNA expression of PR. GBH-exposed lambs also had decreased epithelial cell proliferation. Regarding insulin-like growth factors, both groups showed similar IGF-1 mRNA and protein expression but decreased expression of its receptor, and increased IGFBP5 expression. In addition, phosphorylated AKT was only observed in the mammary gland of control lambs. Our results show that early postnatal exposure to GBH, regardless of the exposure route, affects the IGF-1 system and the AKT/protein kinase B pathway, interfering with steroid hormone receptor expression and cell proliferation. This consequently modifies the growth and development of the pre-pubertal mammary gland of Frisian lambs.

Occurrence, distribution, and driving factors of current-use pesticides in commonly cultivated crops and their potential risks to non-target organisms: A case study in Hainan, China

Multiple pesticides are heavily applied in crops grown in China's tropics due to the prevalence of diseases and pests, thus posing potential risks to nontarget organisms (e.g., honeybees, lacewings, ladybugs, and humans). However, there is little information on this topic. This study is the first assessment of the occurrence, driving factors, and ecological/human health risks of 32 current-use pesticides (CUPs) in 10 frequently-planted crops collected from practicing rice-vegetable rotation systems in Hainan, China. Of the 132 whole crop samples, 44 (33.3 %) residues from ≥8 pesticides were detected in 9.09 % of crop samples with concentrations ≥0.5 mg kg-1. Six pesticide residues, namely carbendazim, pyraclostrobin, acetamiprid, thiophanate methyl, phoxim, and imidacloprid, were detected in 72.7 % of samples, with concentrations ranging from 0.0021 to 13.5 (median = 0.032) mg kg-1. Among them, carbendazim, pyraclostrobin, and acetamiprid were the most common, contributions from 10.2 to 25.5 % and a detection frequency ranging from 25.6 to 56.1 %. The order of total concentration of 32 CUPs (∑32 CUP) concentrations during the year was January > May > November > August and vegetables > rice, being highly related with pesticides usage pattern, crop type, plant accumulation/dissipation and plant lipid contents. The ecological risk quotients (RQs) to four beneficial terrestrial organisms showed that 9.6-39.1 % of samples posed a potential medium or high ecological risk, with 13.6-65.9 % of samples at ∑RQ > 1 being highly affected by the residues of neonicotinoids and emamectin benzoate. Emamectin benzoate (8.9 %) and acetamiprid (5.6 %) exceeded the individual Maximum Residue Levels based on Chinese legislation (GB2763-2021). Moreover, cumulative dietary exposure presented a higher risk to humans in 11.0 and 22.0 % of the cases for acute and chronic, mainly originating from the higher concentration contributors of systemic pesticides in edible crops. Therefore, the regulation and monitoring of CUP residues is imperative for rice-vegetable rotation systems in tropical China to avoid negative effects on nontarget organisms.

How the exposure to environmentally relevant pesticide formulations affects the expression of stress response genes and its relation to oxidative damage and genotoxicity in Caiman latirostris

This study aimed to analyze the molecular stress responses thought the expression levels of catalase (cat), superoxide dismutase (sod) and heat shock protein 70 (hsp70) genes, and how these relate with cellular stress response considering oxidative damage to lipids, DNA and genotoxicity in blood of Caiman latirostris hatchlings exposed to pesticide formulations under ex situ conditions. Treatments were: negative control (NC-tap water), glyphosate 2% (GLY), cypermethrin 0.12% (CYP), chlorpyrifos 0.8% (CPF), and their ternary mixture (Mx3). The concentrations and schedule of application were those recommended in soybean crops. Soil and water showed pesticides residues in all exposed groups. Results showed a statistically significant increase in the micronucleus frequency and DNA damage, with an important oxidation in all exposed groups. The expression level of cat gene was significantly higher in CYP while the expression of hsp70 was significantly lower in GLY, CYP and Mx3, compared to NC. Pesticides tested showed alterations in expression levels, growth parameters, DNA damage and base oxidation under realistic exposure conditions, and can threaten, in the long term, the health status of wild populations.

Evaluation of pesticide pollution in the Gualeguay Basin: An extensive agriculture area in Argentina

The current agricultural production model was established in the 1990s based on the use of genetically modified organisms and agrochemicals, mainly pesticides. Despite pesticide spread and prevalence, data on the associated concentrations in surface watercourses are comparatively scarce. The aim of this work was to evaluate to what extent the >20 years of agricultural activity with the use of pesticides has impacted on the Gualeguay-River basin, with respect to the different stream orders: the tributary streams and main channel. Thirteen sites within the lower Gualeguay basin were sampled once every season (autumn, winter, spring, and summer) in 2017-2018. The samples were analyzed by gas chromatography time-of-flight mass-spectrometry (GC-TOF-MS) and ultraperformance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS). The most frequently detected pesticide was glyphosate along with its metabolite (aminomethyl)phosphonic acid (AMPA), at 82 % and 71 % of surface water samples and 97 % and 92 % of bottom sediments, respectively; followed by atrazine in 73 % of the water samples. The concentrations of these compounds, each in their respective matrices, did not present sufficient statistically significant differences for differentiating a tributary stream from the main channel. Regardless of glyphosate's affinity for the suspended particulate and bottom sediments, over the entire basin the soluble fraction contributed on average to >80 % of the total concentration in surface water. Despite not being so frequently detected, certain insecticides, mostly deltamethrin, were likewise detected at concentrations above their water-quality guidelines for the protection of aquatic life, even in samples from the main channel. Upon comparison of the pesticide profiles of extensive- and horticultural-production systems in the country, atrazine emerged as a prime candidate to be used as a tracer of extensive agriculture contamination in the environment. Further research is required to establish to what degree pesticides used in agriculture and mobilized by watercourses have an impact on their associated wetland ecosystems.

Phosphate addition enhances alkaline extraction of glyphosate from highly sorptive soils and aquatic sediments

BACKGROUND

Analytical constraints complicate environmental monitoring campaigns of the herbicide glyphosate and its major degradation product aminomethylphosphonic acid (AMPA): their strong sorption to soil minerals requires harsh extraction conditions. Coextracted matrix compounds impair downstream analysis and must be removed before analysis.

RESULTS

A new extraction method combined with subsequent capillary electrophoresis-mass spectrometry for derivatization-free analysis of glyphosate and AMPA in soil and sediment was developed and applied to a suite of environmental samples. It was compared to three extraction methods from literature. We show that no extraction medium reaches 100% recovery. The new phosphate-supported alkaline extraction method revealed (1) high recoveries of 70-90% for soils and aquatic sediments, (2) limits of detections below 20 μg kg-1 , and (3) a high robustness, because impairing matrix components (trivalent cations and humic acids) were precipitated prior to the analysis. Soil and sediment samples collected around Tübingen, Germany, revealed maximum glyphosate and AMPA residues of 80 and 2100 μg kg-1 , respectively, with residues observed along a core of lake sediments. Glyphosate and/or AMPA were found in 40% of arable soils and 57% of aquatic sediment samples.

CONCLUSION

In this work, we discuss soil parameters that influence (de)sorption and thus extraction. From our results we conclude that residues of glyphosate in environmental samples are easily underestimated. With its possible high throughput, the method presented here can resolve current limitations in monitoring campaigns of glyphosate by addressing soil and aquatic sediment samples with critical sorption characteristics.

Microbiomes and glyphosate biodegradation in edaphic and aquatic environments: recent issues and trends

Glyphosate (N-(phosphonomethyl)glycine) has emerged as the top-selling herbicide worldwide because of its versatility in controlling annual and perennial weeds and the extensive use of glyphosate-resistant crops. Concerns related to the widespread use of glyphosate and its ubiquitous presence in the environment has led to a large number of studies and reviews, which examined the toxicity and fate of glyphosate and its major metabolite, aminomethylphosphonic acid (AMPA) in the environment. Because the biological breakdown of glyphosate is most likely the main elimination process, the biodegradation of glyphosate has also been the object of abundant experimental work. Importantly, glyphosate biodegradation in aquatic and soil ecosystems is affected not only by the composition and the activity of microbial communities, but also by the physical environment. However, the interplay between microbiomes and glyphosate biodegradation in edaphic and aquatic environments has rarely been considered before. The proposed minireview aims at filling this gap. We summarize the most recent work exploring glyphosate biodegradation in natural aquatic biofilms, the biological, chemical and physical factors and processes playing on the adsorption, transport and biodegradation of glyphosate at different levels of soil organization and under different agricultural managements, and its impact on soil microbial communities.

A comprehensive approach using multiple biomarkers to detect damage induced by pesticides in broad-snouted caiman (Caiman latirostris) under ex-situ conditions

Caiman latirostris is one of the two species of the order Crocodylia that inhabit Argentina and is considered a species of vital ecological and economic importance in the north-east of Argentina. In this region, pesticides are the most common contaminants in natural environments and wild caiman populations are subject to this contamination constantly. The aim of this study was to evaluate the effects the main pesticides used in the region: glyphosate (GLY), cypermethrin (CYP) and chlorpyrifos (CPF) -based formulations, as well as the mixture of them, on C. latirostris juveniles under semi-controlled condition of exposure (ex-situ) during 75 days. One hundred yearling caimans (10-month-old) were equally distributed into five experimental groups (20 animals per group): a negative control (NC -tap water), GLY 2% (Roundup® Full II formulation -RU), CYP 0.12% (Atanor® formulation), CPF 0.8% (Lorsban® formulation), and a mixture of the three pesticides (Mx3: GLY 2% + CYP 0.12% + CPF 0.8%). We applied early warning biomarkers to detect damage induced by these chemicals in peripheral blood: activity of the antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD), analysis of lipid peroxidation (LPO) by the thiobarbituric acid reactive substances (TBARS), DNA damage and specific base oxidation through the standard and modified comet assay (CA), chromosome damage by micronucleus (MN) test and other nuclear abnormalities (NAs), hematological and growth parameters. Results showed a statistically significant increase in MN and NAs frequency, DNA damage, with an important contribution of base oxidation for all exposed groups compared to the NC. Total white blood cells count (TWBCC), and growth parameters showed effects mainly at the Mx3. The principal component analysis (PCA) demonstrated more sensitivity for biomarkers associated to genetic damage, including base oxidation to DNA than LPO, antioxidant enzyme modulation, immunotoxicity or growth parameters, to detect pesticides effects, applied under conditions similar to that found in natural environments.