Metabolite Aminomethylphosphonic Acid Research Articles

Glyphosate resistance and biodegradation by Burkholderia cenocepacia CEIB S5-2.

Glyphosate is a broad spectrum and non-selective herbicide employed to control different weeds in agricultural and urban zones and to facilitate the harvest of various crops. Currently, glyphosate-based formulations are the most employed herbicides in agriculture worldwide. Extensive use of glyphosate has been related to environmental pollution events and adverse effects on non-target organisms, including humans. Reducing the presence of glyphosate in the environment and its potential adverse effects requires the development of remediation and treatment alternatives. Bioremediation with microorganisms has been proposed as a feasible alternative for treating glyphosate pollution. The present study reports the glyphosate resistance profile and degradation capacity of the bacterial strain Burkholderia cenocepacia CEIB S5-2, isolated from an agricultural field in Morelos-México. According to the agar plates and the liquid media inhibition assays, the bacterial strain can resist glyphosate exposure at high concentrations, 2000mg·L-1. In the degradation assays, the bacterial strain was capable of fast degrading glyphosate (50mg·L-1) and the primary degradation metabolite aminomethylphosphonic acid (AMPA) in just eight hours. The analysis of the genomic data of B. cenocepacia CEIB S5-2 revealed the presence of genes that encode enzymes implicated in glyphosate biodegradation through the two metabolic pathways reported, sarcosine and AMPA. This investigation provides novel information about the potential of species of the genus Burkholderia in the degradation of the herbicide glyphosate and its main degradation metabolite (AMPA). Furthermore, the analysis of genomic information allowed us to propose for the first time a metabolic route related to the degradation of glyphosate in this bacterial group. According to the findings of this study, B. cenocepacia CEIB S5-2 displays a great glyphosate biodegradation capability and has the potential to be implemented in glyphosate bioremediation approaches.

Gamma irradiation was able to degrade the glyphosate and aminomethylphosphonic acid (AMPA) from drinking water analyzed by LC-MS/MS

Glyphosate is the most widely used systemic herbicide in the world, applied post-emergence to control weeds and is non-selective. However, due to its toxicity to aquatic organisms and high persistence in water, it is necessary to conduct studies on the decontamination of water resources with glyphosate residues and its metabolite aminomethylphosphonic acid (AMPA). The objective of this study was to evaluate the degradation of glyphosate and AMPA in drinking water using gamma irradiation. First, the drinking water sample was found to be free of the herbicide and its metabolite, and then three concentrations of glyphosate and AMPA alone were added (0.5, 5.0, and 50.0 mg L−1). The samples were then exposed to different doses of gamma irradiation (0, 0.5, 1.0, 2.5, 5.0, and 10 kGy) in a cobalt-60 (60Co) source. The procedure was performed at room temperature with a dose of 0.08 kGy h−1 from the irradiator (source power: 215.95 Ci). Glyphosate and AMPA were quantified by Liquid Chromatography coupled to tandem Mass Spectrometry (LC-MS/MS). A pseudo-first order model was fitted from the kinetic study of the degradation of the chemicals. The irradiation doses required to degrade 50% of glyphosate (D0.5 = 8.97, 12.03, and 9.73 kGy) and the value for complete degradation (90%) of the herbicide (D0.9 = 29.82, 39.97, and 32.34 kGy), as the value of the dose constant (k), were 0.0772, 0.0576, and 0.0712 kGy−1 at concentrations of 0.5, 5.0, and 50.0 mg L−1, respectively. The increase in gamma irradiationgradually decreased of glyphosate and AMPA in drinking water. Thus, this study showed that the use of gamma irradiation can decontaminate drinking water with glyphosate and AMPA residues and be used in treatment plants, but it is necessary to use higher doses of radiation.

Low-background interference detection of glyphosate, glufosinate, and AMPA in foods using UPLC-MS/MS without derivatization.

The abuse of herbicides has emerged as a great threat to food security. Herein, a low-background interference detection method based on UPLC-MS was developed for the simultaneous determination of glufosinate, glyphosate, and its metabolite aminomethylphosphonic acid (AMPA) in foods. Initially, this study proposed a simple and rapid pretreatment method, utilizing water extraction and PRiME HLB purification to isolate glyphosate, glufosinate, and AMPA from food samples. After the optimization of pretreatment conditions, the processed samples are then analyzed directly by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) without pre-column derivatization. The method can effectively reduce interference from by-products of pre-column derivatization and background substrates of food sample, showing low matrix effects (ME) ranging from - 24.83 to 32.10%. Subsequently, the method has been validated by 13 kinds of food samples. The recoveries of the three herbicides in the food samples range from 84.2 to 115.6%. The limit of detection (LOD) is lower to 0.073mg/kg, 0.017mg/kg, and 0.037mg/kg, respectively. Moreover, the method shows an excellent reproducibility with relative standard deviations (RSD) within 16.9%. Thus, the method can provide high trueness, reproducibility, sensitivity, and interference-free detection to ensure human health safety.

Effect of glyphosate, its metabolite AMPA, and the glyphosate formulation Roundup® on brown trout (Salmo trutta f. fario) gut microbiome diversity.

Glyphosate is used worldwide as a compound of pesticides and is detectable in many environmental compartments. It enters water bodies primarily through drift from agricultural areas so that aquatic organisms are exposed to this chemical, especially after rain events. Glyphosate is advertised and sold as a highly specific herbicide, which interacts with the EPSP synthase, an enzyme of the shikimate metabolism, resulting in inhibition of the synthesis of vital aromatic amino acids. However, not only plants but also bacteria can possess this enzyme so that influences of glyphosate on the microbiomes of exposed organisms cannot be excluded. Those influences may result in subtle and long-term effects, e.g., disturbance of the symbiotic interactions of bionts with microorganisms of their microbiomes. Mechanisms how the transformation product aminomethylphosphonic acid (AMPA) of glyphosate might interfere in this context have not understood so far. In the present study, molecular biological fingerprinting methods showed concentration-dependent effects of glyphosate and AMPA on fish microbiomes. In addition, age-dependent differences in the composition of the microbiomes regarding abundance and diversity were detected. Furthermore, the effect of exposure to glyphosate and AMPA was investigated for several fish pathogens of gut microbiomes in terms of their gene expression of virulence factors associated with pathogenicity. In vitro transcriptome analysis with the fish pathogen Yersinia ruckeri revealed that it is questionable whether the observed effect on the microbiome is caused by the intended mode of action of glyphosate, such as the inhibition of EPSP synthase activity.

Validation of a Liquid Chromatography Coupled to Mass Spectrometry Method for Glyphosate and Aminomethylphosphonic Acid in Urine for Human Biomonitoring Using Combined Hybrid Anion-Exchange and Hydrophilic Interaction Liquid Chromatography

Glyphosate-based herbicides are the most widely used pesticides in the world; however, the toxicity of glyphosate (GlyP) toward humans, especially its carcinogenicity, is controversial. The aim of this work was to validate a rapid assay for measuring GlyP and its metabolite aminomethylphosphonic acid (AMPA) in urine for human biomonitoring. The analytes were purified via solid-phase extraction in the presence of isotopically labeled internal standards. An LC-MS/MS assay was developed using a column with a novel hybrid stationary phase combined with anion exchange and hydrophilic interaction liquid chromatography. Detection and quantification were performed using negative electrospray ionization in a hybrid triple quadrupole/linear ion trap mass spectrometer. The retention times for AMPA and GlyP were 1.44 and 7.24 min, respectively. Calibration curves showed a linear dynamic range of up to 40 µg/L, inter- and intra-run precisions <7.5%, and accuracies within 10% of the theoretical concentrations. The limits of quantification were 0.1 µg/L and 0.5 µg/L for GlyP and AMPA, respectively. The matrix effect bias was controlled using internal standards. Successful participation in external quality assurance exercises strengthens the validity of the method. The assay was applied to the measurement of GlyP and AMPA in the urine of 9 urban residents, 26 rural residents, and 12 agricultural workers; while AMPA was mostly not quantifiable, the median GlyP values were 0.1 and 0.34 µg/L in rural residents and workers, respectively. The assay is useful to assess GlyP and AMPA in human urine following different exposure scenarios.

Glyphosate-induced glioblastoma cell proliferation: Unraveling the interplay of oxidative, inflammatory, proliferative, and survival signaling pathways

The aim of the present study was to investigate the impacts of glyphosate herbicide on the survival and proliferation of glioblastoma cells and to explore the molecular mechanisms underlying such effects. For this, cultured human glioblastoma cell line, A172, was exposed to the glyphosate analytical standard, a glyphosate-based herbicide formulation (GBH), or the metabolite aminomethylphosphonic acid (AMPA). The three compounds induced A172 cytotoxicity after 24 h of exposure, with more prominent cytotoxic effects after 48 and 72 h of treatment. Further experiments were performed by treating A172 cells for 6 h with glyphosate, GBH, or AMPA at 0.5 mg/L, which corresponds to the maximum residue limits for glyphosate and AMPA in drinking water in Brazil. Colony forming units (CFU) assay showed that AMPA increased the number of CFU formed, while glyphosate and GBH increased the CFU sizes. The three compounds tested altered the cell cycle and caused DNA damage, as indicated by the increase in γ-H2AX. The mechanisms underlying the pesticide effects involve the activation of Akt and mitogen-activated protein kinases (MAPKs) signaling pathways, oxidative imbalance, and inflammation. Glyphosate led to NLRP3 activation culminating in caspase-1 recruitment, while AMPA decreased NLRP3 immunocontent and GBH did not alter this pathway. Results of the present study suggest that exposure to glyphosate (isolated or in formulation) or to its metabolite AMPA may affect cell signaling pathways resulting in oxidative damage and inflammation, giving glioblastoma cells an advantage by increasing their proliferation and growth.

Spatiotemporal patterns of multiple pesticide residues in central Argentina streams

Pollution of surface waters is a global threat, with particular concern about pesticides due to their severe negative effects on ecosystem functioning and human health. The aims of this study were to identify the spatiotemporal patterns of water and sediment quality, and the key variables related to the variation in pesticide pollution (122 compounds), in headwater streams (surrounding land uses: crop or mixed crop-livestock systems) and floodplain streams (surrounding land uses: urban development or natural wetland) of the Paraná River basin in the central area of Argentina. We found significant differences in water and sediment quality related to local land uses among headwater streams, but not among floodplain streams. These differences were more noticeable during spring than during autumn. Pesticides were widespread in all the streams, independently of the surrounding land use, reflecting the combination of local inputs and the role of floodplain hydrological connectivity in transporting pollutants from upstream sources. The most frequently detected compound was atrazine (75 %), whereas the highest concentration of an individual compound was observed for the glyphosate metabolite aminomethylphosphonic acid (AMPA, up to 4 μg L−1). The significant explanatory variables for pesticide pollution were turbidity, chromophoric dissolved organic matter (CDOM), sub-basin area, side slope of streams (positive relations), wetland cover, and precipitations (negative relations). Our results can be useful for the design of monitoring programs that capture the spatial and temporal variability of pesticide pollution.

P16-41: The Effects of Glyphosate and its Metabolite Aminomethylphosphonic Acid on Apoptosis and Epigenetic Mechanisms in HepG2 Cell Cultures

P16-41: The Effects of Glyphosate and its Metabolite Aminomethylphosphonic Acid on Apoptosis and Epigenetic Mechanisms in HepG2 Cell Cultures

Delineating the cascade of molecular events in protein aggregation triggered by Glyphosate, aminomethylphosphonic acid, and Roundup in serum albumins

The molecular basis of protein unfolding on exposure to the widely used herbicide, Glyphosate (GLY), its metabolite aminomethylphosphonic acid (AMPA), and the commercial formulation Roundup have been probed using human and bovine serum albumins (HSA and BSA). Protein solutions were exposed to chemical stress at set experimental conditions. The study proceeds with spectroscopic and imaging tools. Steady-state and time-resolved fluorescence (TRF) measurements indicated polarity changes with the possibility of forming a ground-state complex. Atomic force microscopy imaging results revealed the formation of fibrils from BSA and dimer, trimer, and tetramer forms of oligomers from HSA under the chemical stress of GLY. In the presence of AMPA, serum albumins (SAs) form a compact network of oligomers. The compact network of oligomers was transformed into fibrils for HSA with increasing concentrations of AMPA. In contrast, Roundup triggered the formation of amorphous aggregates from SAs. Analysis of the Raman amide I band of all aggregates showed a significant increase in antiparallel β-sheet fractions at the expense of α-helix. The highest percentage, 24.6%, of antiparallel β-sheet fractions was present in amorphous aggregate formed from HSA under the influence of Roundup. These results demonstrated protein unfolding, which led to the formation of oligomers and fibrils.

Dissipation of pesticides by stream biofilms is influenced by hydrological histories.

To evaluate the effects of hydrological variability on pesticide dissipation capacity by stream biofilms, we conducted a microcosm study. We exposed biofilms to short and frequent droughts (daily frequency), long and less frequent droughts (weekly frequency) and permanently immersed controls, prior to test their capacities to dissipate a cocktail of pesticides composed of tebuconazole, terbuthylazine, imidacloprid, glyphosate and its metabolite aminomethylphosphonic acid. A range of structural and functional descriptors of biofilms (algal and bacterial biomass, extracellular polymeric matrix (EPS) concentration, microbial respiration, phosphorus uptake and community-level physiological profiles) were measured to assess drought effects. In addition, various parameters were measured to characterise the dynamics of pesticide dissipation by biofilms in the different hydrological treatments (% dissipation, peak asymmetry, bioconcentration factor, among others). Results showed higher pesticide dissipation rates in biofilms exposed to short and frequent droughts, despite of their lower biomass and EPS concentration, compared to biofilms in immersed controls or exposed to long and less frequent droughts. High accumulation of hydrophobic pesticides (tebuconazole and terbuthylazine) was measured in biofilms despite the short exposure time (few minutes) in our open-flow microcosm approach. This research demonstrated the stream biofilms capacity to adsorb hydrophobic pesticides even in stressed drought environments.

Development of a specific and sensitive method for the detection of glyphosate pesticide and its metabolite in tea using dummy molecularly imprinted solid-phase extraction coupled with liquid chromatography-tandem quadrupole mass spectrometry

Glyphosate, a widely used herbicide, and its primary metabolite aminomethyl phosphonic acid have been found to cause environmental and ecological issues and threaten human health. The conventional pretreatment method was insufficient for the extraction, concentration, and enrichment of trace substances, resulting in poor specificity. Thus, our objective was to develop a method for glyphosate pesticide detection using dummy molecularly imprinted solid-phase extraction (DMI-SPE) combined with liquid chromatography-tandem quadrupole mass spectrometry (DMI-SPE-LC/MS/MS). The sol-gel method was used to prepare the molecularly imprinted material, using glyphosine as the dummy template molecule, to achieve specific adsorption to glyphosate and reduce costs. The optimized polymerization conditions achieved maximum adsorption of 28.6 µg/mg glyphosate by the molecularly imprinted material. The established DMI-SPE-LC/MS/MS method was used to detect glyphosate and its metabolite (aminomethyl)phosphonic acid in tea. The concentration ranges of glyphosate and (aminomethyl)phosphonic acid (from 0.05 to 4 µg/mL) were linear with correlation coefficients of 0.999 and 0.991, respectively. The recoveries of (aminomethyl)phosphonic acid at three spiked levels ranged from 79.95% to 83.74%, with RSDs between 6.40% and 7.45%, while the recoveries of glyphosate ranged from 98.69% to 106.26%, with RSDs between 0.91% and 1.18%. Our results demonstrate that the developed DMI-SPE-LC/MS/MS method achieves high sensitivity and specific detection of glyphosate and its metabolite (aminomethyl)phosphonic acid in tea matrices.

Flow patterns and pathways of legacy and contemporary pesticides in surface waters in tropical volcanic catchments

Severe water pollution issues due to legacy and contemporary pesticides exist in tropical regions and are linked to cash crops requiring intensive plant protection practices. This study aims to improve knowledge about contamination routes and patterns in tropical volcanic settings to identify mitigation measures and analyse risk. To this aim, this paper analyses four years of monitoring data from 2016 to 2019 of flow discharge and weekly pesticide concentrations in the rivers of two catchments grown predominantly with banana and sugar cane in the French West Indies. The banned insecticide chlordecone, applied in banana fields from 1972 to 1993, was still the major source of river contamination, while the currently used herbicide glyphosate, its metabolite aminomethylphosphonic acid (AMPA), and postharvest fungicides also exhibited high contamination levels. A value of 0.5 of the Gustafson Ubiquity Score (GUS) was shown to separate contaminant and noncontaminant pesticides, indicating a high vulnerability to pollution by pesticides in this tropical volcanic context. The patterns and routes of river exposure to pesticides differed markedly between the pesticides in accordance with the hydrological behaviour of volcanic islands and the history and nature of pesticide uses. Concerning chlordecone and its metabolites, observations confirmed previous findings of a main subsurface origin of river contamination by this compound but also showed large erratic short-term variations, suggesting the influence of fast surface transport processes such as erosion for legacy pesticides with large sorption capacity. Concerning herbicides and postharvest fungicides, observations have suggested that surface runoff and fast lateral flow in the vadose zone control river contamination. Accordingly, mitigation options need to be considered differently for each type of pesticide. Finally, this study points out the need for developing specific exposure scenarios for tropical agricultural contexts in the European regulation procedures for pesticide risk assessment.

First hydrological study on the seasonal occurrence of glyphosate, glufosinate, and their metabolites in the Red River system, North Vietnam

We report the spatial and seasonal distribution of organophosphorus herbicides, namely glyphosate (GLYP), glufosinate (GLUF), and their respective metabolites aminomethyl phosphonic acid (AMPA) and 3-(methylphosphinico)-propionic acid (MPPA), in the Red River system (North Vietnam), a major water body in Southeast Asia. The four compounds were measured at 34 sampling stations located from upstream to the estuary during the dry (March) and wet (July) seasons in 2019. Large seasonal variations in herbicide concentrations were measured for the four analytes from upstream to the estuary, with the highest range of variations observed during the wet season. In the surface waters of the Red River, the maximum concentrations of GLUF (234 ng L–1), GLYP (565 ng L–1) and its metabolite AMPA (1329 ng L–1), occurred in the wet season. These values however, are lower than reported in other rivers worldwide. In contrast, the estimated fluxes of these compounds in the Red River water basin were very high during the wet season, i.e., up to 121, 50.2, 284, and 186 kg d–1 for GLYP, GLUF, AMPA, and MPPA, respectively. During both seasons, we observed correlations between the four compounds and ammonium (NH4+), suggesting that both nitrogen containing fertilizers and herbicides were applied in areas close to the river shore. The concentrations and fluxes of the herbicides GLYP, GLUF, and their metabolites determined in the Red River were compared to those recorded in other world river systems, such as the Garonne River (France), thus highlighting the importance of monitoring these compounds in surface waters.

Abstract 4222: Glyphosate and AMPA exposure: Associations with dietary intake and other factors

Abstract Background: Animal and epidemiologic studies suggest that exposure to the weed killer, glyphosate, and its primary metabolite aminomethylphosphonic acid (AMPA), is associated with increased risk for cancer, including breast cancer and non-Hodgkin's lymphoma. The International Agency for Research on Cancer (IARC) has categorized glyphosate as a “probable carcinogen,” yet glyphosate is the most highly used pesticide in the world. Biomonitoring studies assessing levels of human glyphosate and AMPA exposure in the United States have been limited. Thus, we examined urinary levels of these chemicals in a cohort of postmenopausal women residing in Southern California and evaluated associations with demographics, dietary intake, and other behavioral factors. Methods: 338 postmenopausal women provided two first-morning urine samples and at least one paired 24-hour dietary recall. Participants also reported on demographic and other factors. Urinary glyphosate and AMPA were measured using LC-MS/MS. Results: Glyphosate was detected in nearly 90% of urine samples and AMPA in 67.2%. Urinary glyphosate and AMPA levels were lower in women who reported high levels of organic eating (p=0.04 and p=0.01, respectively). Urinary glyphosate was lower in women who reported higher levels of physical activity (p=0.03). Multivariate analysis showed that grain consumption, particularly refined grains, was significantly associated with higher urinary glyphosate levels (adjusted p=0.004). Alcohol consumption (adjusted p=0.001) and frequency of eating fast-food (adjusted p=0.006) were associated with higher urinary AMPA levels, while fruit (adjusted p=0.03) and corn (adjusted p=0.008) consumption were associated with lower AMPA. Conclusions: In the largest study to date examining paired dietary recall data and measurements of urinary glyphosate and AMPA, the vast majority of women sampled had detectable levels. Consumption of certain foods, including grains and alcoholic beverages, were associated with higher urinary levels of glyphosate and AMPA. Citation Format: Rachel McFarland Lucia, Xiyue Liao, Wei-Lin Huang, Danielle Forman, Alexis Kim, Argyrios Ziogas, Trina M. Norden-Krichmar, Deborah Goodman, Andrea Alvarez, Irene Masunaka, Khyatiben Pathak, Marissa McGilvrey, Victoria David-Dirgo, Apurva Hegde, Patrick Pirrotte, Hannah Lui Park. Glyphosate and AMPA exposure: Associations with dietary intake and other factors. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4222.

Adsorption of glyphosate and metabolite aminomethylphosphonic acid (AMPA) from water by polymer-based spherical activated carbon (PBSAC)

Glyphosate (GLY) is the most commonly used herbicide worldwide, and aminomethylphosphonic acid (AMPA) is its main metabolite. Their occurrence in ground and surface waters causes diseases in humans, while complex physico-chemical properties hinder detection and effective removal. Polymer-based spherical activated carbon (PBSAC) can adsorb many micropollutants efficiently and, hence, overcome the shortfalls of conventional treatment methods. The static adsorption of a mixture of GLY and AMPA by PBSAC was investigated with varying PBSAC properties and relevant solution chemistry. The results show that PBSAC can remove 95% GLY and 57% AMPA from an initial concentration of 1 µg/L at pH 8.2. PBSAC properties (size, activation level, and surface charge) have a strong influence on herbicide removal, where surface area plays a key role. Low to neutral pH favors non-charge interactions and results in good adsorption, while higher temperatures equally enhance GLY/AMPA adsorption by PBSAC. The work demonstrated the effective removal of GLY to meet the European guideline concentration (0.1 µg/L), while AMPA could not be removed to the required level.

Glyphosate residue in honey and impacts on Africanized bee hives under field conditions

Honey and other bee products may contain residues of different substances, including pesticides, which is considered a public health problem. In addition, they characterize risks to the health of Apis mellifera, which have been showing an increasing decline in their populations. There are many protocols for identifying pesticides in bee products which, in general, are complex matrices whose results of routine investigations in control laboratories are rarely disclosed. In this sense, the objective of the present study was to determine the presence of residues of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) in honey, as well as its effect on the strength of the hive of A. mellifera. Samples were collected from hives experimentally exposed to food containing a sublethal dose of Roundup® and conducted by hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry (HILIC-MS/MS). The AMPA content was lower than the method’s detection limit in honey samples from hives that received food containing the herbicide. It was possible to quantify glyphosate one week after the last artificial feeding (R1 8.45 ± 1.09 µg g−1; R2 8.15 ± 2.14 µg g−1; R3 23.90 ± 2.95 µg g−1). In a hive sample fed for more than four weeks, glyphosate was present in lower concentrations (3.12 ± 0.89 µg g−1) with no detection of AMPA. From the analysis of the strength of the hives, we observed a decrease in the population of adult individuals and the brood area, the absence of a queen, and no construction of royal cells by the workers in the hives of the Roundup® treatment in comparison to the control group, in which the hives remained with queen size, high adult and brood population, and food stock. Although present, glyphosate did not undergo degradation in honey during the evaluated period. Thus, we could infer that the presence of Roundup® in bee feed may be present in honey, representing a risk to consumers’ health and economic damage to beekeepers. This is the first study that evaluated the effect of glyphosate residues on hive strength, contributing to the understanding of the Roundup® mode of action in different aspects that affect the survival of colonies under field conditions.

Mechanistic modeling indicates rapid glyphosate dissipation and sorption-driven persistence of its metabolite AMPA in soil.

Residual concentrations of glyphosate and its main transformation product aminomethylphosphonic acid (AMPA) are often observed in soils. The factors controlling their biodegradation are currently not well understood. We analyzed sorption-limited biodegradation of glyphosate and AMPA in soil with a set of microcosm experiments. A mechanistic model that accounts for equilibrium and kinetic sorption facilitated interpretation of the experimental results. Both compounds showed a biphasic dissipation with an initial fast (up to Days 7-10) and subsequent slower transformation rate, pointing to sorption-limited degradation. Glyphosate transformation was well described by considering only equilibrium sorption. Model simulations suggested that only 0.02-0.13% of total glyphosate was present in the soil solution and thus bioavailable. Glyphosate transformation was rapid in solution (time required for 50 % dissipation of the total initially added chemical [DT50 ]=3.9min), and, despite strong equilibrium sorption, total glyphosate in soil dissipated quickly (DT50 =2.4d). Aminomethylphosphonic acid dissipation kinetics could only be described when considering both equilibrium and kinetic sorption. In comparison to glyphosate, the model simulations showed that a higher proportion of total AMPA was dissolved and directly bioavailable (0.27-3.32%), but biodegradation of dissolved AMPA was slower (DT50 =1.9h). The model-based data interpretation suggests that kinetic sorption strongly reduces AMPA bioavailability, leading to increased AMPA persistence in soil (DT50 =12d). Thus, strong sorption combined with rapid degradation points to low risks of glyphosate leaching by vertical transport through soil in the absence of preferential flow. Ecotoxicological effects on soil microorganisms might be reduced. In contrast, AMPA persists, rendering these risks more likely.

Glyphosate used as desiccant contaminates plant pollen and nectar of non-target plant species

Pesticide products containing glyphosate as a systemic active ingredient are some of the most extensively used herbicides worldwide. After spraying, residues have been found in nectar and pollen collected by bees foraging on treated plants. This dietary exposure to glyphosate could pose a hazard for flower-visiting animals including bees, and for the delivery of pollination services. Here, we evaluated whether glyphosate contaminates nectar and pollen of targeted crops and non-target wild plants. Oilseed rape was selected as focal crop species, and Rubus fruticosus growing in the hedgerows surrounding the crop was chosen as non-target plant species. Seven fields of oilseed rape, where a glyphosate-based product was applied, were chosen in east and southeast Ireland, and pollen and nectar were extracted from flowers sampled from the field at various intervals following glyphosate application. Pollen loads were taken from honeybees and bumblebees foraging on the crop at the same time. Glyphosate and aminomethylphosphonic acid (AMPA) residues were extracted using acidified methanol and their concentrations in the samples were determined by a validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Glyphosate was detected in R. fruticosus nectar and pollen samples that were taken within a timeframe of two to seven days after the application on the crop as a desiccant. No glyphosate was detected when the application took place before or more than two months prior to our sampling in any of the evaluated matrices. The metabolite AMPA was not detected in any samples. To gain further insight into the potential extent of translocation within both plants and soil when a crop is desiccated using glyphosate before harvesting, and the potential impacts on bees, we recommend a longitudinal study of the presence and fate of glyphosate in non-target flowering plants growing nearby crop fields, over a period of several days after glyphosate application.

Surface Plasmon Resonance Imaging Sensor for Detection of Photolytically and Photocatalytically Degraded Glyphosate

Glyphosate is one of the most widely used pesticides, which, together with its primary metabolite aminomethylphosphonic acid, remains present in the environment. Many technologies have been developed to reduce glyphosate amounts in water. Among them, heterogeneous photocatalysis with titanium dioxide as a commonly used photocatalyst achieves high removal efficiency. Nevertheless, glyphosate is often converted to organic intermediates during its degradation. The detection of degraded glyphosate and emerging products is, therefore, an important element of research in terms of disposal methods. Attention is being paid to new sensors enabling the fast detection of glyphosate and its degradation products, which would allow the monitoring of its removal process in real time. The surface plasmon resonance imaging (SPRi) method is a promising technique for sensing emerging pollutants in water. The aim of this work was to design, create, and test an SPRi biosensor suitable for the detection of glyphosate during photolytic and photocatalytic experiments focused on its degradation. Cytochrome P450 and TiO2 were selected as the detection molecules. We developed a sensor for the detection of the target molecules with a low molecular weight for monitoring the process of glyphosate degradation, which could be applied in a flow-through arrangement and thus detect changes taking place in real-time. We believe that SPRi sensing could be widely used in the study of xenobiotic removal from surface water or wastewater.

Exposure of children to glyphosate in Morocco: Urinary levels and predictors of exposure

Glyphosate is one of the most frequently used organophosphorus plant protection products worldwide, and has recently been classified as probably carcinogenic to humans by the International Agency for Research and Cancer (IARC). We aimed to evaluate the urinary levels of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) in Moroccan children, to identify the main predictors and to perform a risk assessment. Data was collected during a cross sectional study of 48 children from an intensive agricultural area. Measurements included a questionnaire on life-style, socio-demographic and herbicide exposures. Urinary glyphosate and AMPA were extracted using solid phase extraction (SPE) and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Overall, glyphosate and AMPA were detected in 73% and 75% of urine samples, respectively. The mean concentrations were 0.97 μg L−1 (2.06 μg/gcreatinine) for glyphosate and 0.79 μg L−1 (1.52 μg/gcreatinine) for AMPA. Children younger than 5 years had a higher AMPA and glyphosate urine concentration (mean = 2.24 μg L−1; estimation coefficient (EC) = 1.39; 95% CI: 0.54–2.24) (mean = 4.05 μg L−1; EC = 2.92; 95% CI: 1.68–4.15), respectively, than children aged 6–12. Children living near the pesticide spraying fields (<50 m) had 14.91 μg L−1 and 2.35 μg L−1 more glyphosate and AMPA, respectively, than children living in urban counties (95% CI: 8.14–20.91 for glyphosate and 95% CI: 0.55–4.14 for AMPA). AMPA concentration varied significantly with the source of drinking water, AMPA was higher among children that used water from open water sources (mean = 1.49 μg L−1; EC = 2.98; 95% CI/0.67–5.78) compared to those using water from closed water sources. There were also non-significant associations found, such as total household net income, current parental job description, and dietary intake. With the regard to the health risk assessment, estimated daily intake (EDIs), hazard quotient (HQs), and a hazard index (HI) were calculated. The GMs of EDI were 4.38 and 2.26 μg/kg of body weight BW/day for glyphosate and AMPA, respectively. The HQs were calculated considering 0.5 mg/kg BW/day as an acceptable daily intake (ADI), which EFSA has established as a health-based reference value for both analytes. The value obtained were lower than 1, and therefore, low health risk due to glyphosate and AMPA was expected for the target population under the study. This study provides further evidence on factors associated with glyphosate exposure, especially in developing countries.