Glyphosate: environmental contamination, toxicity and potential risks to human health via food contamination

Exploring the glyphosate-degrading characteristics of a newly isolated, highly adapted indigenous bacterial strain, Providencia rettgeri GDB 1

This study explored the characteristics of a newly isolated glyphosate (GLYP)-degrading bacterium Providencia rettgeri GDB 1, for GLYP bioremediation. Due to the serial selection pressure of high GLYP concentrations for enriched isolation, this highly tolerant GLYP biodegrader shows very promising capabilities for GLYP removal (approximately 71.4% degradation efficiency) compared to previously reported strains. High performance liquid chromatography analyses showed aminomethylphosphonic acid (AMPA) rather than sarcosine (SAR) to be the sole intermediate of GLYP decomposition via the AMPA formation pathway. Moreover, GLYP biodegradation was biochemically favorable in aerobic cultures due to its strong growth-associated characteristics. To the best of our knowledge, this is the first report to indicate that bacterial strains in the Providencia genus could demonstrate highly promising GLYP-degrading characteristics in environments with high GLYP contents.

Impact of the glyphosate-based commercial herbicide, its components and its metabolite AMPA on non-target aquatic organisms

Glyphosate (GLY) is the active ingredient of several herbicide formulations widely used to control weeds in agricultural and non-agricultural areas. Due to the intensive use of GLY-based herbicides and their direct application on soils, some of their components, including the active ingredient, may reach the aquatic environment through direct run-off and leaching. The present study assessed the acute toxicity and genotoxicity of the GLY-based formulation Atanor 48 (ATN) and its major constituents GLY, surfactant polyethoxylated tallow amine (POEA), as well as the main metabolite of GLY aminomethylphosphonic acid (AMPA) on non-target aquatic organisms. The toxic effects of these chemicals were evaluated in the fish embryo acute toxicity test with zebrafish (Danio rerio), while genotoxic effects were investigated in the comet assays with cells from zebrafish larvae and rainbow trout gonad-2 (RTG-2). GLY and AMPA caused no acute toxic effect, while ATN and POEA induced significant lethal effects in zebrafish (LC50-96 h 76.50 mg/L and 5.49 mg/L, respectively). All compounds were genotoxic in comet experiments with zebrafish larvae (LOEC 1.7 mg/L for GLY, ATN, AMPA and 0.4 mg/L for POEA). Unlike in vivo, only POEA induced DNA damage in RTG-2 cells (LOEC 1.6 mg/L), suggesting that it is a direct acting genotoxic agent. In summary, these data indicate that the lethal effects on zebrafish early-life stages can be ranked in the following order from most to least toxic: surfactant POEA > formulation ATN > active ingredient GLY ≈ metabolite AMPA. Genotoxic effects were observed in both RTG-2 cells (only POEA) and zebrafish (all test compounds) with the lowest tested concentrations. Therefore, it is important to evaluate different toxicological endpoints as well as use different non-target organisms to predict the hazards of GLY-based formulations and their components and breakdown product to aquatic biota.

Insights into the Glyphosate Adsorption Behavior and Mechanism by a MnFe2O4@Cellulose-Activated Carbon Magnetic Hybrid

To enhance the removal of the negatively charged organophosphorus pesticide (OPP) glyphosate (GLY), we prepared a positively charged MnFe₂O₄@cellulose activated carbon (CAC) hybrid by immobilizing MnFe₂O₄ nanoparticles on the CAC surface via a simple one-pot solvothermal method, scanning electron microscopy, BET, transmission electron microscopy, IR, Raman, X-ray diffraction, and X-ray photoelectron spectroscopy analysis which proved the successful synthesis of MnFe₂O₄ with a particle size of 100-300 nm. The particles were distributed on the surface of CAC to form the MnFe₂O₄@CAC hybrid. MnFe₂O₄@CAC exhibited a positive charge at pH below 6 and had good magnetic properties and dispersion stability. The maximum GLY adsorption capacity of MnFe₂O₄@CAC (167.2 mg/g) was much higher than that of CAC (61.44 mg/g) and MnFe₂O₄ nanoparticles (93.48 mg/g). The adsorption process was dominated by chemisorption, and the formation of new chemical bonds between GLY and MnFe₂O₄ was confirmed by simulations. The newly formed chemical bonds were attributed to the conjugation between p electrons of the adsorbent and the d electrons of the adsorbate. Collectively, the results indicate that the as-prepared MnFe₂O₄@CAC is promising for anionic pollutant adsorption and the removal of OPPs, and our mechanistic results are of guiding significance in environmental cleanup.

Assessment of Glyphosate Induced Epigenetic Transgenerational Inheritance of Pathologies and Sperm Epimutations: Generational Toxicology

Ancestral environmental exposures to a variety of factors and toxicants have been shown to promote the epigenetic transgenerational inheritance of adult onset disease. One of the most widely used agricultural pesticides worldwide is the herbicide glyphosate (N-(phosphonomethyl)glycine), commonly known as Roundup. There are an increasing number of conflicting reports regarding the direct exposure toxicity (risk) of glyphosate, but no rigorous investigations on the generational actions. The current study using a transient exposure of gestating F0 generation female rats found negligible impacts of glyphosate on the directly exposed F0 generation, or F1 generation offspring pathology. In contrast, dramatic increases in pathologies in the F2 generation grand-offspring, and F3 transgenerational great-grand-offspring were observed. The transgenerational pathologies observed include prostate disease, obesity, kidney disease, ovarian disease, and parturition (birth) abnormalities. Epigenetic analysis of the F1, F2 and F3 generation sperm identified differential DNA methylation regions (DMRs). A number of DMR associated genes were identified and previously shown to be involved in pathologies. Therefore, we propose glyphosate can induce the transgenerational inheritance of disease and germline (e.g. sperm) epimutations. Observations suggest the generational toxicology of glyphosate needs to be considered in the disease etiology of future generations.

Widespread occurrence of glyphosate in urine from pet dogs and cats in New York State, USA

Glyphosate is one of the most widely used herbicides in the United States, which has led to its ubiquitous occurrence in food and water and regular detection in human urine at concentrations of 1-10 μg/L. Data pertaining to health risks arising from the ingestion of glyphosate are limited and are the subject of much debate, which demands the need for more exposure information for this herbicide. Very little is known about glyphosate exposure in pets. In this study, we determined concentrations of glyphosate (Glyp) and its derivatives, methyl glyphosate (Me-Glyp) and aminomethylphosphonic acid (AMPA), in urine collected from 30 dogs and 30 cats from New York State, USA. Glyp was the most predominant compound found in pet urine followed by AMPA and Me-Glyp. The mean urinary concentration of ∑Glyp (sum of Glyp + Me-Glyp + AMPA) in cats (mean: 33.8 ± 46.7 ng/mL) was 2-fold higher than that in dogs (mean: 16.8 ± 24.4 ng/mL). Cumulative daily intakes (CDI) of Glyp in dogs and cats estimated from the urinary concentrations were, on average, 0.57 and 1.37 μg/kg bw/d, respectively. The exposure doses were two to four orders of magnitude below the current acceptable daily intake (ADI) suggested by several international health organizations for humans.

Antioxidant and cytoprotective effects of N-acetylcysteine against subchronic oral glyphosate-based herbicide-induced oxidative stress in rats

It is claimed that oxidative stress has a prominent role in the mechanism of toxic effects formed by glyphosate-based herbicide (GBH) in living systems. A strong thiol compound, N-acetylcysteine (NAC), has antioxidative and cytoprotective properties. The objective in this subchronic toxicity study was to identify the prophylactic effect of NAC over histopathological changes and oxidative stress induced by GBH in blood, renal, liver, cardiac, and brain tissues. A sum of 28 male Wistar rats were divided into four equal groups, each containing 7 rats. During the study, group I (control group) was supplied with normal rodent bait and tap water ad libitum. The applied agents were 160 mg/kg NAC to group II, 375 mg/kg as equivalent to 1/10 of lethal dose 50% (LD50) of GBH to group III, and 160 mg/kg of NAC and 375 mg/kg of GBH together once per day as oral gavage to group IV for 8 weeks. While GBH decreased the levels of GSH in blood, liver, kidney, and brain tissues, it considerably increased malondialdehyde levels. On the contrary, these parameters happened to improve in the group supplied with NAC. Besides, it was seen that NAC was observed to improve the histopathologic changes in rat tissues induced by GBH. It was concluded that NAC protects oxidative stress and tissue damage induced by GBH in blood and tissue and this prophylactic effect could be attributed to its antioxidant and free radical sweeper character.

Protective effects of resveratrol on biomarkers of oxidative stress, biochemical and histopathological changes induced by sub-chronic oral glyphosate-based herbicide in rats

The aim of this sub-chronic toxicity study is to determine the protective effects of Resveratrol (Res) on oxidative stress, biochemical and histopathological changes induced by glyphosate-based herbicide (GBH) in the blood, brain, heart, liver and renal tissues. A total of 28 male Wistar rats were equally divided into 4 groups so that each group included 7 rats. In the study, Group I (control group) was given normal rodent feed and tap water ad libitum. Group II (Res group) was given Res 20 mg kg-1, Group III (GBH group) was given GBH of 375 mg kg-1 to achieve 1/10 of Lethal Dose 50% (LD50), and Group IV (Res + GBH) was given Res 20 mg kg-1 and GBH 375 mg kg-1 with oral gavage once a day for 8 weeks. While GBH decreased the glutathione (GSH) levels in the blood, brain, heart, liver and renal tissues, it significantly increased malondialdehyde (MDA) levels. In contrast, the aforementioned parameters were seen to recover in the group to which Res was administered. Moreover, it was observed that Res improved the histopathological changes induced by GBH in rat tissues. In conclusion, Res prevents oxidative stress caused by GBH by preventing lipid peroxidation (LPO) and boosting the antioxidant defense system and decreases the damage in the brain, heart, liver and renal tissues of Wistar rats.

Epigenetic disruption of estrogen receptor alpha is induced by a glyphosate-based herbicide in the preimplantation uterus of rats

Previously, we have shown that perinatal exposure to a glyphosate-based herbicide (GBH) induces implantation failures in rats. Estrogen receptor alpha (ERα) is critical for successful implantation. ERα transcription is under the control of five promoters (E1, OT, O, ON, and OS), which yield different transcripts. Here, we studied whether perinatal exposure to a GBH alters uterine ERα gene expression and prompts epigenetic modifications in its regulatory regions during the preimplantation period. Pregnant rats (F0) were orally treated with 350 mg glyphosate/kg bw/day through food from gestational day (GD) 9 until weaning. F1 females were bred, and uterine samples were collected on GD5 (preimplantation period). ERα mRNA levels and its transcript variants were evaluated by RT-qPCR. Enzyme-specific restriction sites and predicted transcription factors were searched in silico in the ERα promoter regions to assess the methylation status using the methylation-sensitive restriction enzymes-PCR technique. Post-translational modifications of histones were studied by the chromatin immunoprecipitation assay. GBH upregulated the expression of total ERα mRNA by increasing the abundance of the ERα-O transcript variant. In addition, different epigenetic changes were detected in the O promoter. A decrease in DNA methylation was observed in one of the three sites evaluated in the O promoter. Moreover, histone H4 acetylation and histone H3 lysine 9 trimethylation (H3K9me3) were enriched in the O promoter in GBH-exposed rats, whereas H3K27me3 was decreased. All these alterations could account for the increase in ERα gene expression. Our findings show that perinatal exposure to a GBH causes long-term epigenetic disruption of the uterine ERα gene, which could be associated with the GBH-induced implantation failures.

Exposure to a glyphosate-based herbicide formulation, but not glyphosate alone, has only minor effects on adult rat testis

Glyphosate has been suggested to be an endocrine disrupting chemical capable of disrupting male reproduction. There are conflicting data, however, with studies reporting effects from exposure to either glyphosate alone or to herbicide formulations, making comparisons difficult. We assessed rat testis histopathology and androgen function following two weeks exposure to either glyphosate at 2.5 and 25 mg/kg bw/day (5x and 50x Acceptable Daily Intake, ADI, respectively), or equivalent high dose of glyphosate in a herbicide formulation; Glyfonova. We observed no significant effects on testes or testosterone synthesis in rats exposed to glyphosate. Limited effects were observed in rats exposed to Glyfonova, with a small upregulation of the steroidogenic genes Cyp11a1 and Cyp17a1. We conclude that glyphosate alone has no effect on adult rat testis at exposure levels up to 25 mg/kg bw/day. Glyfonova induced only minor effects on steroidogenic gene expression, likely caused by additives other than glyphosate.

Synthesis, biological activity and molecular modelling studies of shikimic acid derivatives as inhibitors of the shikimate dehydrogenase enzyme of Escherichia coli

Shikimic acid (SA) pathway is the common route used by bacteria, plants, fungi, algae, and certain Apicomplexa parasites for the biosynthesis of aromatic amino acids and other secondary metabolites. As this essential pathway is absent in mammals designing inhibitors against implied enzymes may lead to the development of antimicrobial and herbicidal agents harmless to humans. Shikimate dehydrogenase (SDH) is the fourth enzyme of the SA pathway. In this contribution, a series of SA amide derivatives were synthesised and evaluated for in vitro SDH inhibition and antibacterial activity against Escherichia coli. All tested compounds showed to be mixed type inhibitors; diamide derivatives displayed more inhibitory activity than synthesised monoamides. Among the evaluated compounds, molecules called 4a and 4b were the most active derivatives with IC50 588 and 589 µM, respectively. Molecular modelling studies suggested two different binding modes of monoamide and diamide derivatives to the SDH enzyme of E. coli.

In vitro evaluation of genomic damage induced by glyphosate on human lymphocytes

Glyphosate is an important broad-spectrum herbicide used in agriculture and residential areas for weed and vegetation control, respectively. In our study, we analyzed the in vitro clastogenic and/or aneugenic effects of glyphosate by chromosomal aberrations and micronuclei assays. Human lymphocytes were exposed to five glyphosate concentrations: 0.500, 0.100, 0.050, 0.025, and 0.0125 μg/mL, where 0.500 μg/mL represents the established acceptable daily intake value, and the other concentrations were tested in order to establish the genotoxicity threshold for this compound. We observed that chromosomal aberration (CA) and micronuclei (MNi) frequencies significantly increased at all tested concentrations, with exception of 0.0125 μg/mL. Vice versa, no effect has been observed on the frequencies of nuclear buds and nucleoplasmic bridges, with the only exception of 0.500 μg/mL of glyphosate that was found to increase in a significant manner the frequency of nucleoplasmic bridges. Finally, the cytokinesis-block proliferation index and the mitotic index were not significantly reduced, indicating that glyphosate does not produce effects on the proliferation/mitotic index at the tested concentrations.

Detection of glyphosate residues in companion animal feeds

The widespread adoption of genetically modified, glyphosate-tolerant corn and soybean varieties in US crop production has led to a dramatic increase in glyphosate usage. Though present at or below regulatory limits currently set for human foodstuffs, the concentration of glyphosate in companion animal feed is currently unknown. In the present study, 18 commercial companion animal feeds from eight manufacturers were analyzed for glyphosate residues using ELISA. Every product contained detectable glyphosate residues in the range of 7.83 × 101-2.14 × 103 μg kg-1 dry weight, with the average and medians being 3.57 × 102 and 1.98 × 102 μg kg-1 respectively. Three products were tested for within-bag variation and six were tested for lot to lot variation. Little within-bag variation was found, but the concentration of glyphosate varied by lot in half of the products tested. Glyphosate concentration was significantly correlated with crude fiber content, but not crude fat or crude protein. Average daily intakes by animals consuming feeds containing the median glyphosate concentration are estimated to result in exposures that are 0.68-2.5% of the Allowable Daily Intake (ADI) for humans in the US and EU, which are 1750 and 500 μg kg-1 respectively. Consumption of the most contaminated feed, however, would result in exposure to 7.3% and 25% of the above ADIs, though the relevance of such an exposure to companion animals is currently unknown. Companion animal feeds contained 7.83 × 101-2.14 × 103 μg kg-1 glyphosate which is likely to result in pet exposure that is 4-12 times higher than that of humans on a per Kg basis.

Glyphosate decreases mycorrhizal colonization and affects plant-soil feedback

Our aim was to study the effects of glyphosate, tilling practice and cultivation history on mycorrhizal colonization and growth of target (weeds) and non-target (crops) plants. Glyphosate, the world's most widely used pesticide, inhibits an enzyme found in plants but also in microbes. We examined the effects of glyphosate treatment applied in the preceding fall on growth of a perennial weed, Elymus repens (target plant) and a forage grass, Festuca pratensis (non-target plant) and their arbuscular mycorrhizal fungal (AMF) root colonization in a field pot experiment. Non-target plants were sown in the following spring. Furthermore, we tested if glyphosate effects depend on tillage or soil properties modulated by long cultivation history of endophyte symbiotic grass (E+ grass). AMF root colonization, plant establishment and growth, glyphosate residues in plants, and soil chemistry were measured. Glyphosate reduced the mycorrhizal colonization and growth of both target and non-target grasses. The magnitude of reduction depended on tillage and soil properties due to cultivation history of E+ grass. We detected glyphosate residues in weeds and crop plants in the growing season following the glyphosate treatment. Residues were higher in plants growing in no-till pots compared to conspecifics in tilled pots. These results demonstrate negative effects of glyphosate on non-target organisms in agricultural environments and grassland ecosystems.

Glyphosate-based herbicide enhances the uterine sensitivity to estradiol in rats

In a previous work, we detected that postnatal exposure to a glyphosate-based herbicide (GBH) alters uterine development in prepubertal rats causing endometrial hyperplasia and increasing cell proliferation. Our goal was to determine whether exposure to low dose of a GBH during postnatal development might enhance the sensitivity of the uterus to an estrogenic treatment. Female Wistar pups were subcutaneously injected with saline solution (control) or GBH using the reference dose (2 mg/kg/day, EPA) on postnatal days (PND) 1, 3, 5 and 7. At weaning (PND21), female rats were bilaterally ovariectomized and treated with silastic capsules containing 17β-estradiol (E2, 1 mg/mL) until they were 2 months of age. On PND60, uterine samples were removed and processed for histology, immunohistochemistry and mRNA extraction to evaluate: (i) uterine morphology, (ii) uterine cell proliferation by the detection of Ki67, (iii) the expression of the estrogen receptors alpha (ESR1) and beta (ESR2) and (iv) the expression of WNT7A and CTNNB1. GBH-exposed animals showed increased luminal epithelial height and stromal nuclei density. The luminal and glandular epithelium were markedly hyperplastic in 43% of GBH-exposed animals. GBH exposure caused an increase in E2-induced cell proliferation in association with an induction of both ESR1 and ESR2. GBH treatment decreased membranous and cytoplasmic expression of CTNNB1 in luminal and glandular epithelial cells and increased WNT7A expression in the luminal epithelium. These results suggest that early postnatal exposure to a GBH enhances the sensitivity of the rat uterus to estradiol and induces histomorphological and molecular changes associated with uterine hyperplasia.

A commercial Roundup® formulation induced male germ cell apoptosis by promoting the expression of XAF1 in adult mice

Roundup® is extensively used for weed control worldwide. Residues of this compound may lead to side effects of the male reproductive system. However, the toxic effects and mechanisms of Roundup® of male germ cells remain unclear. We aimed to investigate the apoptosis-inducing effects of Roundup® on mouse male germ cells and explore the role of a novel tumor suppressor XAF1 (X-linked inhibitor of apoptosis-associated factor 1) involved in this process. We demonstrated that Roundup® can impair spermatogenesis, decrease sperm motility and concentration, and increase the sperm deformity rate in mice. In addition, excessive apoptosis of germ cells accompanied by the overexpression of XAF1 occurred after Roundup® exposure both in vitro and in vivo. Furthermore, the low expression of XIAP (X-linked inhibitor of apoptosis) induced by Roundup® was inversely correlated with XAF1. Moreover, the knockdown of XAF1 attenuated germ cell apoptosis, improved XIAP expression and inhibited the activation of its downstream target proteins, caspase-3 and PARP, after Roundup® exposure. Taken together, our data indicated that XAF1 plays an important role in Roundup®-induced male germ cell apoptosis. The present study suggested that Roundup® exposure has potential negative implications on male reproductive health in mammals.

Phytotoxicity of Essential Oils on Selected Weeds: Potential Hazard on Food Crops

The chemical composition of winter savory, peppermint, and anise essential oils, and in vitro and in vivo phytotoxic activity against weeds (Portulaca oleracea, Lolium multiflorum, and Echinochloa crus-galli) and food crops (maize, rice, and tomato), have been studied. Sixty-four compounds accounting for between 97.67–99.66% of the total essential oils were identified by Gas Chromatography-Mass Spectrometry analysis. Winter savory with carvacrol (43.34%) and thymol (23.20%) as the main compounds produced a total inhibitory effect against the seed germination of tested weed. Menthol (48.23%), menthone (23.33%), and iso-menthone (16.33%) from peppermint only showed total seed germination inhibition on L. multiflorum, whereas no significant effects were observed with trans-anethole (99.46%) from anise at all concentrations (0.125–1 µL/mL). Low doses of peppermint essential oil could be used as a sustainable alternative to synthetic agrochemicals to control L. multiflorum. The results corroborate that in vivo assays with a commercial emulsifiable concentrate need higher doses of the essential oils to reproduce previous in vitro trials. The higher in vivo phytotoxicity of winter savory essential oil constitutes an eco-friendly and less pernicious alternative to weed control. It is possible to achieve a greater in vivo phytotoxicity if less active essential oil like peppermint is included with other active excipients.

Uptake and reaction to roundup ultra 360 SL in soybean seedlings

Due to the widespread and frequent use of Roundup Ultra 360 SL in crops production, the active substance glyphosate is often present (in the soil or in post-harvest remnants) and may be toxic to plants, including the non-target species. The aim of the current study was to determine the sensitivity of young soybean seedlings to glyphosate in concentrations ranging from 0 to 10 μM. It was demonstrated that the seedlings take small quantities of soil glyphosate up. More of the active substance was found in the shoots than in the roots. From the doses applied, the plant absorbs up to 4% of soil glyphosate, while over 96% remains in the soil. This suggests that only 4% of glyphosate taken up from the soil affects plant seedling development and water management. It modifies the contents of the biogenic amines cadaverine and putrescine as well as the activity of enzymes involved in their biosynthesis, i.e. ornithine decarboxylase and lysine decarboxylase. The free radical content of the roots increased with increasing herbicide doses and time of exposure. The main enzyme involved in the rapid removal of free radicals was superoxide peroxidase, activated by the herbicide treatment, while catalase was not significantly stimulated.

Perinatal exposure to a glyphosate-based herbicide impairs female reproductive outcomes and induces second-generation adverse effects in Wistar rats

Glyphosate-based herbicides (GBHs) are the most globally used herbicides raising the risk of environmental exposition. Here, we investigated whether perinatal exposure to low doses of a GBH alters the female reproductive performance, and/or induced second-generation effects related to congenital anomalies or growth alterations. Pregnant rats (F0) received a GBH through food, in a dose of 2 mg (GBH-LD: GBH-low dose group) or 200 mg (GBH-HD: GBH-high dose group) of glyphosate/kg bw/day from gestational day (GD) 9 until weaning. Body weight gain and vaginal canal-opening of F1 females were recorded. Sexually mature F1 females were mated to evaluate their reproductive performance by assessing the pregnancy rate, and on GD19, the number of corpora lutea, the implantation sites (IS) and resorption sites. To analyze second-generation effects on F2 offspring, we analyzed the fetal morphology on GD19, and assessed the fetal length and weight, and the placental weight. GBH exposure neither altered the body weight gain of F1 females, nor vaginal opening onset. Although all GBH-exposed F1 rats became pregnant, a lower number of IS was detected. F2 offspring from both GBH groups showed delayed growth, evidenced by lower fetal weight and length, associated with a higher incidence of small for gestational age fetuses. In addition, higher placental weight and placental index were found in F2 offspring from GBH-HD dams. Surprisingly, structural congenital anomalies (conjoined fetuses and abnormally developed limbs) were detected in the F2 offspring from GBH-HD group. In conclusion, perinatal exposure to low doses of a GBH impaired female reproductive performance and induced fetal growth retardation and structural congenital anomalies in F2 offspring.

Kinetic study on biodegradation of glyphosate with unacclimated activated sludge

This article is concerned with the study of biodegradation of an organophosphorus herbicide (glyphosate) using unacclimated activated sludge. Glyphosate at different concentrations (0.1, 0.5, 1, 2 and 5 g/L) was tested for cellular growth. On the other hand, the effect of glyphosate on its own biodegradation was studied by evaluating the fittings of different kinetic models (Andrews, Aiba et al., Han and Levenspiel, Luong, Tessier, Webb, Tseng and Wayman, Yano and Koga). According to the obtained results, the activated sludge was able to use glyphosate as the sole carbon source; however, 2 and 5 g/L glyphosate seemed to inhibit cellular growth. Moreover, glyphosate at initial concentrations of 0.1, 0.5 and 1 g/L was completely degraded within 4, 13 and 18 h of incubation, respectively. Yano and Koga model was the best-fit model (R2 = 0.999, F = 173,106 and P = 0.000006).

Molecular assessment of glyphosate-degradation pathway via sarcosine intermediate in Lysinibacillus sphaericus

The widespread use of glyphosate has permeated not only small- and large-scale agriculture, but also the fight against drug trafficking and illicit crops. Health, alimentary security, and the rights of peasant and indigenous communities have been compromised in countries with intensive use of glyphosate-based herbicides. In 2015, the International Agency for Research on Cancer classified this substance as probably carcinogenic to humans, leading to the suspension of aerial glyphosate spraying the same year in countries like Colombia, where glyphosate has been extensively used in illicit crop eradication. Notwithstanding, according to a study of the U.S. Geological Survey, traces of glyphosate and its main degradation product, AMPA, remain in soil year after year. This underscores the urgency and importance of assessing new technologies to degrade glyphosate present in soils and waterbodies without leaving persistent byproducts. The aim of this study was to evaluate Lysinibacillus sphaericus' glyphosate uptake as a carbon and phosphorous source by a sarcosine-mediated metabolic pathway that releases glycine as final degradation product. To accomplish this, molecular and analytic evidence were collected in vitro from sarcosine oxidase activity, a key enzyme of a degradation pathway which releases byproducts that are easy to incorporate into natural biosynthesis routes.

Glyphosate induces growth of estrogen receptor alpha positive cholangiocarcinoma cells via non-genomic estrogen receptor/ERK1/2 signaling pathway

Previous studies showed that glyphosate stimulates breast cancer cell growth via estrogen receptors. The present study investigated the effect of glyphosate on the estrogen signaling pathway involved in the induction of cholangiocarcinoma (CCA) cell growth. HuCCA-1, RMCCA-1 and MMNK-1 were chosen for comparison. The effects of glyphosate on cell growth, cell cycle and molecular signaling pathways were measured. The results showed that HuCCA-1 cells expressed estrogen receptor alpha (ERα), while ERα was not detected in RMCCA-1 and MMNK-1 cells. ERα was mostly expressed in cytoplasmic compartment of HuCCA-1 cells. Estradiol (E2) (10-11-10-5 M) induced cell proliferation in HuCCA-1 but not in RMCCA-1 and MMNK-1 cells. Glyphosate at the same concentration range also induced HuCCA-1 cell proliferation. The S phase of the cell cycle, and protein levels of the cyclin family were significantly increased after treatment of glyphosate or E2. Both compounds also induced the expression of proliferative signaling-related proteins including ERα, VEGFR2, pERK, PI3K(p85), and PCNA. These effects of glyphosate and E2 were abolished by the ER antagonist, 4-hydroxytamoxifen and U0126, a MEK inhibitor. The data from this study indicate that glyphosate can induce cell growth in ERα positive CCA cells through non-genomic estrogen receptor/ERK1/2 signaling pathway.

Thyroid Function Disruptors: from nature to chemicals

The modern concept of thyroid disruptors includes man-made chemicals and bioactive compounds from food that interfere with any aspect of the hypothalamus-pituitary-thyroid axis, thyroid hormone biosynthesis and secretion, blood and transmembrane transport, metabolism and local action of thyroid hormones. This review highlights relevant disruptors that effect populations through their diet: directly from food itself (fish oil and polyunsaturated fatty acids, pepper, coffee, cinnamon and resveratrol/grapes), through vegetable cultivation (pesticides) and from containers for food storage and cooking (bisphenol A, phthalates and polybrominated diphenyl ethers). Due to the vital role of thyroid hormones during every stage of life, we review effects from the gestational period through to adulthood, including evidence from in vitro studies, rodent models, human trials and epidemiological studies.

Adsorption performance and mechanism of magnetic reduced graphene oxide in glyphosate contaminated water

In this study, the magnetic reduced graphene oxide (RGO/Fe3O4), with easy separation and high adsorption performance, was prepared and used to treat glyphosate (GLY) contaminated water. GLY adsorption performance of RGO/Fe3O4 was investigated, and influences of pH, adsorption time, temperature, contaminant concentration, and competing anions were analyzed. Moreover, the adsorption mechanism was discussed in the light of several characterization methods, including scanning electron microscopy (SEM), energy dispersive spectrum (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the RGO/Fe3O4 presented a significant GLY adsorption capacity and acid condition was beneficial for this adsorption. The pseudo-second-order kinetic model and the Langmuir model correlated satisfactorily to the experimental data, indicating that this process was controlled by chemical adsorption and monolayer adsorption. Thermodynamic studies revealed that the adsorption of glyphosate onto RGO/Fe3O4 was spontaneous, endothermic, and feasible process. High temperatures were beneficial to GLY adsorption. The GLY adsorption mechanism of RGO/Fe3O4 was mainly attributed to hydrogen-bond interaction, electrostatic interaction, and coordination. Therefore, the RGO/Fe3O4 investigated in this research may offer an attractive adsorbent candidate for treatment of glyphosate contaminated water and warrant further study as a mechanism for glyphosate efficient removal.

Recent advances in glyphosate biodegradation

Glyphosate has emerged as the most widespread herbicide to control annual and perennial weeds. Massive use of glyphosate for decades has resulted in its ubiquitous presence in the environment, and poses a threat to humans and ecosystem. Different approaches such as adsorption, photocatalytic degradation, and microbial degradation have been studied to break down glyphosate in the environment. Among these, microbial degradation is the most effective and eco-friendly method. During its degradation, various microorganisms can use glyphosate as a sole source of phosphorus, carbon, and nitrogen. Major glyphosate degradation pathways and its metabolites have been frequently investigated, but the related enzymes and genes have been rarely studied. There are many reviews about the toxicity and fate of glyphosate and its major metabolite, aminomethylphosphonic acid. However, there is lack of reviews on biodegradation and bioremediation of glyphosate. The aims of this review are to summarize the microbial degradation of glyphosate and discuss the potential of glyphosate-degrading microorganisms to bioremediate glyphosate-contaminated environments. This review will provide an instructive direction to apply glyphosate-degrading microorganisms in the environment for bioremediation.

Oxidative stress, cholinesterase activity, and DNA damage in the liver, whole blood, and plasma of Wistar rats following a 28-day exposure to glyphosate

In this 28 day-study, we evaluated the effects of herbicide glyphosate administered by gavage to Wistar rats at daily doses equivalent to 0.1 of the acceptable operator exposure level (AOEL), 0.5 of the consumer acceptable daily intake (ADI), 1.75 (corresponding to the chronic population-adjusted dose, cPAD), and 10 mg kg-1 body weight (bw) (corresponding to 100 times the AOEL). At the end of each treatment, the body and liver weights were measured and compared with their baseline values. DNA damage in leukocytes and liver tissue was estimated with the alkaline comet assay. Oxidative stress was evaluated using a battery of endpoints to establish lipid peroxidation via thiobarbituric reactive substances (TBARS) level, level of reactive oxygen species (ROS), glutathione (GSH) level, and the activity of glutathione peroxidase (GSH-Px). Total cholinesterase activity and the activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were also measured. The exposed animals gained less weight than control. Treatment resulted in significantly higher primary DNA damage in the liver cells and leukocytes. Glyphosate exposure significantly lowered TBARS in the liver of the AOEL, ADI, and cPAD groups, and in plasma in the AOEL and cPAD group. AChE was inhibited with all treatments, but the AOEL and ADI groups significantly differed from control. Total ChE and plasma/liver ROS/GSH levels did not significantly differ from control, except for the 35 % decrease in ChE in the AOEL and ADI groups and a significant drop in liver GSH in the cPAD and 100xAOEL groups. AOEL and ADI blood GSH-Px activity dropped significantly, but in the liver it significantly increased in the ADI, cPAD, and 100xAOEL groups vs. control. All these findings show that even exposure to low glyphosate levels can have serious adverse effects and points to a need to change the approach to risk assessment of low-level chronic/sub-chronic glyphosate exposure, where oxidative stress is not necessarily related to the genetic damage and AChE inhibition.

Glyphosate application increased catabolic activity of gram-negative bacteria but impaired soil fungal community

Glyphosate is a non-selective organophosphate herbicide that is widely used in agriculture, but its effects on soil microbial communities are highly variable and often contradictory, especially for high dose applications. We applied glyphosate at two rates: the recommended rate of 50 mg active ingredient kg-1 soil and 10-fold this rate to simulate multiple glyphosate applications during a growing season. After 6 months, we investigated the effects on the composition of soil microbial community, the catabolic activity and the genetic diversity of the bacterial community using phospholipid fatty acids (PLFAs), community level catabolic profiles (CLCPs), and 16S rRNA denaturing gradient gel electrophoresis (DGGE). Microbial biomass carbon (Cmic) was reduced by 45%, and the numbers of the cultivable bacteria and fungi were decreased by 84 and 63%, respectively, under the higher glyphosate application rate. According to the PLFA analysis, the fungal biomass was reduced by 29% under both application rates. However, the CLCPs showed that the catabolic activity of the gram-negative (G-) bacterial community was significantly increased under the high glyphosate application rate. Furthermore, the DGGE analysis indicated that the bacterial community in the soil that had received the high glyphosate application rate was dominated by G- bacteria. Real-time PCR results suggested that copies of the glyphosate tolerance gene (EPSPS) increased significantly in the treatment with the high glyphosate application rate. Our results indicated that fungi were impaired through glyphosate while G- bacteria played an important role in the tolerance of microbiota to glyphosate applications.

Protective effect of Uncaria tomentosa extract against oxidative stress and genotoxicity induced by glyphosate-Roundup® using zebrafish (Danio rerio) as a model

Oxidative stress and DNA damage are involved in the glyphosate-based herbicide toxicity. Uncaria tomentosa (UT; Rubiaceae) is a plant species from South America containing bioactive compounds with known beneficial properties. The objective of this work was to evaluate the antioxidant and antigenotoxic potential of UT extract in a model of acute exposure to glyphosate-Roundup® (GR) in zebrafish (Danio rerio). We showed that UT (1.0 mg/mL) prevented the decrease of brain total thiols, the increase of lipid peroxidation in both brain and liver, and the decrease of liver GPx activity caused after 96 h of GR (5.0 mg/L) exposure. In addition, UT partially protected against the increase of micronucleus frequency induced by GR exposure in fish brain. Overall, our results indicate that UT protects against damage induced by a glyphosate-based herbicide by providing antioxidant and antigenotoxic effects, which may be related to the phenolic compounds identified in the extract.

Critical Review of the Effects of Glyphosate Exposure to the Environment and Humans through the Food Supply Chain

Glyphosate is a synthesis product and chemical substance that entered in the global market during the 70s. In the beginning, the molecule was used as an active principle in a wide range of herbicides, with great success. This was mainly due to its systemic and non-selective action against vegetable organisms and also to the spread of Genetically Modified Organism (GMO) crops, which over the years were specifically created with a resistance to glyphosate. To date, the product is, for these reasons, the most sprayed and most used herbicide in the world. Because of its widespread diffusion into the environment, it was not long before glyphosate found itself at the center of an important scientific debate about its adverse effects on health and environment. In fact, in 2015 the IARC (International Agency for Research on Cancer, Lyon, France), an organization referred to as the specialized cancer agency of the World Health Organization (WHO, Geneva, Switzerland), classified the substance as “likely carcinogenic” to humans. This triggered an immediate and negative reaction from the producer, who accused the Agency and claimed that they had failed to carry out their studies properly and that these conclusions were largely contradictory to published research. Additionally, in 2015, just a few months after the IARC monography published on glyphosate, the EFSA (European Food Safety Authority, Parma, Italy), another WHO related organization, declared that it was “unlikely” that the molecule could be carcinogenic to humans or that it could cause any type of risk to human health. The conflict between the two organizations of the World Health Organization triggered many doubts, and for this reason, a series of independent studies were launched to better understand what glyphosate’s danger to humans and the environment really was. The results have brought to light how massive use of the herbicide has created over time a real global contamination that has not only affected the soil, surface and groundwater as well as the atmosphere, but even food and commonly used objects, such as diapers, medical gauze, and absorbent for female intimate hygiene. How human health is compromised as a result of glyphosate exposure is a topic that is still very debatable and still unclear and unambiguous. This paper is a review of the results of the main independent recent scientific studies.

Effects of glyphosate on early life stages: comparison between Cyprinus carpio and Danio rerio

Glyphosate (N-(phosphonomethyl)glycine) is an active substance of many herbicides. According to literature studies, glyphosate residues and their metabolites have been commonly detected in surface waters and toxicological reports confirmed negative effects on living organisms. In this study, the acute embryo toxicity of glyphosate into two different fish species-common carp (Cyprinus carpio) and zebrafish (Danio rerio)-was investigated. Lethal endpoints, development disorder, and, in addition, other sublethal endpoints such as hatching rate, formation of somites, and development of eyes, spontaneous movement, heartbeat/blood circulation, pigmentation, and edema were recorded to indicate the mode of action of the toxic compound. Hatching retardation (p < 0.05) was observed in experimental groups of common carp exposed to glyphosate with significant statistical difference especially at the highest concentration after 72, 96, and 120 hpf. The significantly highest cumulative mortality at concentration of 50 mg/l was observed. In contrast, hatching stimulation was observed in embryos of zebrafish exposed to the highest concentration of glyphosate. The significantly highest cumulative mortality for zebrafish was observed only at concentration of 50 mg/l. Based on our results, early life stages of common carp are more sensitive in comparison to zebrafish to the toxic action of glyphosate.

Environmental and health effects of the herbicide glyphosate

The herbicide glyphosate, N-(phosphonomethyl) glycine, has been used extensively in the past 40years, under the assumption that side effects were minimal. However, in recent years, concerns have increased worldwide about the potential wide ranging direct and indirect health effects of the large scale use of glyphosate. In 2015, the World Health Organization reclassified glyphosate as probably carcinogenic to humans. A detailed overview is given of the scientific literature on the movement and residues of glyphosate and its breakdown product aminomethyl phosphonic acid (AMPA) in soil and water, their toxicity to macro- and microorganisms, their effects on microbial compositions and potential indirect effects on plant, animal and human health. Although the acute toxic effects of glyphosate and AMPA on mammals are low, there are animal data raising the possibility of health effects associated with chronic, ultra-low doses related to accumulation of these compounds in the environment. Intensive glyphosate use has led to the selection of glyphosate-resistant weeds and microorganisms. Shifts in microbial compositions due to selective pressure by glyphosate may have contributed to the proliferation of plant and animal pathogens. Research on a link between glyphosate and antibiotic resistance is still scarce but we hypothesize that the selection pressure for glyphosate-resistance in bacteria could lead to shifts in microbiome composition and increases in antibiotic resistance to clinically important antimicrobial agents. We recommend interdisciplinary research on the associations between low level chronic glyphosate exposure, distortions in microbial communities, expansion of antibiotic resistance and the emergence of animal, human and plant diseases. Independent research is needed to revisit the tolerance thresholds for glyphosate residues in water, food and animal feed taking all possible health risks into account.

Glyphosate, a chelating agent-relevant for ecological risk assessment?

Glyphosate-based herbicides (GBHs), consisting of glyphosate and formulants, are the most frequently applied herbicides worldwide. The declared active ingredient glyphosate does not only inhibit the EPSPS but is also a chelating agent that binds macro- and micronutrients, essential for many plant processes and pathogen resistance. GBH treatment may thus impede uptake and availability of macro- and micronutrients in plants. The present study investigated whether this characteristic of glyphosate could contribute to adverse effects of GBH application in the environment and to human health. According to the results, it has not been fully elucidated whether the chelating activity of glyphosate contributes to the toxic effects on plants and potentially on plant-microorganism interactions, e.g., nitrogen fixation of leguminous plants. It is also still open whether the chelating property of glyphosate is involved in the toxic effects on organisms other than plants, described in many papers. By changing the availability of essential as well as toxic metals that are bound to soil particles, the herbicide might also impact soil life, although the occurrence of natural chelators with considerably higher chelating potentials makes an additional impact of glyphosate for most metals less likely. Further research should elucidate the role of glyphosate (and GBH) as a chelator, in particular, as this is a non-specific property potentially affecting many organisms and processes. In the process of reevaluation of glyphosate its chelating activity has hardly been discussed.

Effects of glyphosate-based herbicides on survival, development and growth of invasive snail (Pomacea canaliculata)

This study tests the hypotheses that whether environmental relevance of glyphosate would help control spread of the invasive snail Pomacea canaliculata, or benefit its population growth worldwide. Our results showed that glyphosate induced acute toxicity to the snail only at high concentrations (96h LC50 at 175mg/L) unlikely to occur in the environment. Long-term exposures to glyphosate at sublethal levels (20 and 120mg/L) caused inhibition of food intake, limitation of growth performance and alterations in metabolic profiles of the snail. It is worth noting that glyphosate at 2mg/L benefited growth performance in P. canaliculata. Chronic exposures of glyphosate significantly enhanced overall metabolic rate and altered catabolism from protein to carbohydrate/lipid mode. Cellular responses in enzyme activities showed that the exposed snails could increase tolerance by their defense system against glyphosate-induced oxidative stress, and adjustment of metabolism to mitigate energy crisis. Our study displayed that sublethal concentrations of glyphosate might be helpful in control of the invasive species by food intake, growth performance and metabolic interruption; whether environmental relevance of glyphosate (≤2mg/L) benefits population growth of P. canaliculata is still inconclusive, which requires further field study.

The impact of pesticides on oxidative stress level in human organism and their activity as an endocrine disruptor

Pesticides cause serious environmental and health problems both to humans and animals. The aim of this review is to discuss selected herbicides and fungicides regarding their mode of action and their influence on basic oxidative stress parameters and endocrine disruption properties tested in selected cell cultures in vitro. Because of numerous difficulties which animal studies are subject to, cell cultures are an excellent experimental model reflecting human exposure to different pesticides through all relevant routes. This experimental model can be used to monitor aggregate and cumulative pesticide exposures.

Organophosphonates utilization by soil strains of Ochrobactrum anthropi and Achromobacter sp

Four bacterial strains from glyphosate- or alkylphosphonates-contaminated soils were tested for ability to utilize different organophosphonates. All studied strains readily utilized methylphosphonic acid and a number of other phosphonates, but differed in their ability to degrade glyphosate. Only strains Ochrobactrum anthropi GPK 3 and Achromobacter sp. Kg 16 utilized this compound after isolation from enrichment cultures with glyphosate. Achromobacter sp. MPK 7 from the same enrichment culture, similar to Achromobacter sp. MPS 12 from methylphosphonate-polluted source, required adaptation to growth on GP. Studied strains varied significantly in their growth parameters, efficiency of phosphonates degradation and characteristic products of this process, as well as in their energy metabolism. These differences give grounds to propose a possible model of interaction between these strains in microbial consortium in phosphonate-contaminated soils.