Postnatal exposure to a glyphosate-based herbicide modifies mammary gland growth and development in Wistar male rats

Glyphosate: Hepatotoxicity, Nephrotoxicity, Hemotoxicity, Carcinogenicity, and Clinical Cases of Endocrine, Reproductive, Cardiovascular, and Pulmonary System Intoxication

Glyphosate (GLP) is an active agent of GLP-based herbicides (GBHs), i.e., broad-spectrum and postemergent weedkillers, commercialized by Monsanto as, e.g., Roundup and RangerPro formulants. The GBH crop spraying, dedicated to genetically engineered GLP-resistant crops, has revolutionized modern agriculture by increasing the production yield. However, abusively administered GBHs' ingredients, e.g., GLP, polyoxyethyleneamine, and heavy metals, have polluted environmental and industrial areas far beyond farmlands, causing global contamination and life-threatening risk, which has led to the recent local bans of GBH use. Moreover, preclinical and clinical reports have demonstrated harmful impacts of GLP and other GBH ingredients on the gut microbiome, gastrointestinal tract, liver, kidney, and endocrine, as well as reproductive, and cardiopulmonary systems, whereas carcinogenicity of these herbicides remains controversial. Occupational exposure to GBH dysregulates the hypothalamic-pituitary-adrenal axis, responsible for steroidogenesis and endocrinal secretion, thus affecting hormonal homeostasis, functions of reproductive organs, and fertility. On the other hand, acute intoxication with GBH, characterized by dehydration, oliguria, paralytic ileus, as well as hypovolemic and cardiogenic shock, pulmonary edema, hyperkalemia, and metabolic acidosis, may occur fatally. As no antidote has been developed for GBH poisoning so far, the detoxification is mainly symptomatic and supportive and requires intensive care based on gastric lavage, extracorporeal blood filtering, and intravenous lipid emulsion infusion. The current review comprehensively discusses the molecular and physiological basics of the GLP- and/or GBH-induced diseases of the endocrine and reproductive systems, and cardiopulmonary-, nephro-, and hepatotoxicities, presented in recent preclinical studies and case reports on the accidental or intentional ingestions with the most popular GBHs. Finally, they briefly describe modern and future healthcare methods and tools for GLP detection, determination, and detoxification. Future electronically powered, decision-making, and user-friendly devices targeting major GLP/GBH's modes of actions, i.e., dysbiosis and the inhibition of AChE, shall enable self-handled or point-of-care professional-assisted evaluation of the harm followed with rapid capturing GBH xenobiotics in the body and precise determining the GBH pathology-associated biomarkers levels.

Branching morphogenesis of the mouse mammary gland after exposure to benzophenone-3

Pubertal mammary branching morphogenesis is a hormone-regulated process susceptible to exposure to chemicals with endocrine disruptive capacity, such as the UV-filter benzophenone-3 (BP3). Our aim was to assess whether intrauterine or in vitro exposure to BP3 modified the branching morphogenesis of the female mouse mammary gland. For this, pregnant mice were dermally exposed to BP3 (0.15 or 50 mg/kg/day) from gestation day (GD) 8.5 to GD18.5. Sesame oil treatment served as control. Changes of the mammary glands of the offspring were studied on postnatal day 45. Further, mammary organoids from untreated mice were cultured under branching induction conditions and exposed for 9 days to BP3 (1 × 10-6 M, 1 × 10-9 M, or 1 × 10-12 M with 0.01% ethanol as control) to evaluate the branching progression. Mice that were exposed to BP3 in utero showed decreased mRNA levels of progesterone receptor (PR) and WNT4. However, estradiol and progesterone serum levels, mammary histomorphology, proliferation, and protein expression of estrogen receptor alpha (ESR1) and PR were not significantly altered. Interestingly, direct exposure to BP3 in vitro also decreased the mRNA levels of PR, RANKL, and amphiregulin without affecting the branching progression. Most effects were found after exposure to 50 mg/kg/day or 1 × 10-6 M of BP3, both related to sunscreen application in humans. In conclusion, exposure to BP3 does not impair mammary branching morphogenesis in our models. However, BP3 affects PR transcriptional expression and its downstream mediators, suggesting that exposure to BP3 might affect other developmental stages of the mammary gland.

In vivo estrogenicity of glyphosate, its formulations, and AMPA on transgenic zebrafish (Danio rerio) embryos

In this study, the disrupting effects of glyphosate (GLY), aminomethylphosphonic acid (AMPA), and three glyphosate-based herbicides (GBHs) on vitellogenesis in a non-concentration-dependent manner are reported for the first time in 120 h of acute exposure of zebrafish at environmentally relevant concentrations. GBHs are commonly used worldwide in weed control management. Due to their extensive application, they frequently occur in aquatic ecosystems and may affect various organisms. The active substance GLY and its major by-product, AMPA, are the most thoroughly studied chemicals; however, the adverse effects of the complex formulas of GBHs with diverse and unknown content of co-formulants are still not sufficiently researched. This study focused on the embryotoxicity, sublethal malformations, and estrogenic potency of GLY, AMPA, and four commonly used GBHs on zebrafish embryos using a wild type and an estrogen-sensitive, transgenic zebrafish line (Tg(vtg1:mCherry)). After 120 h of exposition, AMPA did not cause acute toxicity, while the LC50 of GLY was 160 mg/L. The GBHs were more toxic with LC50 values ranging from 31 to 111 GLY active equivalent (a.e.) mg/L. Exposure to 0.35-2.8 mg/L GBHs led to sublethal abnormalities: typical symptoms were structural deformation of the lower jaw and anomalies in the olfactory region. Deformity rates were 10-30% in the treated groups. In vivo, fluorescently expressed vtg1 mCherry protein in embryonic liver was detected by a non-invasive microscopic method indicating estrogenic action through vitellogenin production by GLY, AMPA, and GBHs. To confirm the in vivo findings, RT-qPCR method was performed to determine the levels of the estrogenicity-related vtg1 mRNA. After 120 h of exposure to GLY, AMPA, and three GBHs at a concentration of 0.35 mg/L, the expression of vtg1 gene was significantly up-regulated. Our results highlight the risk that short-term GLY and GBH exposure can cause developmental malformations and disrupt the hormonal balance in zebrafish embryos.

Mapping the key characteristics of carcinogens for glyphosate and its formulations: A systematic review

Glyphosate was classified as a probable human carcinogen (Group 2A) by the International Agency for Research on Cancer (IARC) partially due to strong mechanistic evidence in 2015. Since then, numerous studies of glyphosate and its formulations (GBF) have emerged. These studies can be evaluated for cancer hazard identification with the newly described ten key characteristics (KC) of carcinogens approach. Our objective was to assess all in vivo, ex vivo, and in vitro mechanistic studies of human and experimental animals (mammals) that compared exposure to glyphosate/GBF with low/no exposure counterparts for evidence of the ten KCs. A protocol with our methods adhering to PRISMA guidelines was registered a priori (INPLASY202180045). Two blinded reviewers screened all in vivo, ex vivo, and in vitro studies of glyphosate/GBF exposure in humans/mammals reporting any KC-related outcome available in PubMed before August 2021. Studies that met inclusion criteria underwent data extraction conducted in duplicate for each KC outcome reported along with key aspects of internal/external validity, results, and reference information. These data were used to construct a matrix that was subsequently analyzed in the program R to conduct strength of evidence and quality assessments. Of the 2537 articles screened, 175 articles met inclusion criteria, from which we extracted >50,000 data points related to KC outcomes. Data analysis revealed strong evidence for KC2, KC4, KC5, KC6, KC8, limited evidence for KC1 and KC3, and inadequate evidence for KC7, KC9, and KC10. Notably, our in-depth quality analyses of genotoxicity (KC2) and endocrine disruption (KC8) revealed strong and consistent positive findings. For KC2, we found: 1) studies conducted in humans and human cells provided stronger positive evidence than counterpart animal models; 2) GBF elicited a stronger effect in both human and animal systems when compared to glyphosate alone; and 3) the highest quality studies in humans and human cells consistently revealed strong evidence of genotoxicity. Our analysis of KC8 indicated that glyphosate's ability to modulate hormone levels and estrogen receptor activity is sensitive to both exposure concentration and formulation. The modulations observed provide clear evidence that glyphosate interacts with receptors, alters receptor activation, and modulates the levels and effects of endogenous ligands (including hormones). Our findings strengthen the mechanistic evidence that glyphosate is a probable human carcinogen and provide biological plausibility for previously reported cancer associations in humans, such as non-Hodgkin lymphoma. We identified potential molecular interactions and subsequent key events that were used to generate a probable pathway to lymphomagenesis.

Effects of glyphosate-based herbicides and glyphosate exposure on sex hormones and the reproductive system: From epidemiological evidence to mechanistic insights

Glyphosate-based herbicides (GBHs) containing glyphosate as the active component are extensively used worldwide. Concerns have arisen about their potential risk to human, as glyphosate has been detected in human body fluids. Current controversies surround the endocrine-disrupting properties and transgenerational inheritance of diseases and germline epimutations resulting from exposure to GBHs and glyphosate. This review discusses evidence from in vitro, in vivo, and clinical studies on their impact on sex hormone regulation and reproductive system. Evidence suggests that they act as endocrine-disrupting chemicals, which altering sex hormone levels. Mechanistically, they interfere with hormone signaling pathways by disrupting proteins involved in hormone transport and metabolism. Pathological changes have been observed in male and female reproductive systems, potentially leading to reproductive toxicity. Prenatal exposure may lead to transgenerational inheritance of pathologies and sperm epimutations. However, due to the complexity of glyphosate formulations containing adjuvants identifying higher risk components in environmental exposure becomes challenging.

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.

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.

Exposure to glyphosate in the United States: Data from the 2013-2014 National Health and Nutrition Examination Survey

BACKGROUND

Exposure to glyphosate, the most used herbicide in the United States, is not well characterized. We assessed glyphosate exposure in a representative sample of the U.S. population ≥ 6 years from the 2013-2014 National Health and Nutrition Examination Survey.

METHODS

We quantified glyphosate in urine (N = 2,310) by ion chromatography isotope-dilution tandem mass spectrometry. We conducted univariate analysis using log-transformed creatinine-corrected glyphosate concentrations with demographic and lifestyle covariates we hypothesized could affect glyphosate exposure based on published data including race/ethnicity, sex, age group, family income to poverty ratio, fasting time, sample collection season, consumption of food categories (including cereal consumption) and having used weed killer products. We used multiple logistic regression to examine the likelihood of glyphosate concentrations being above the 95th percentile and age-stratified multiple linear regression to evaluate associations between glyphosate concentrations and statistically significant covariates from the univariate analysis: race/ethnicity, sex, age group, fasting time, cereal consumption, soft drink consumption, sample collection season, and urinary creatinine.

RESULTS

Glyphosate weighted detection frequency was 81.2 % (median (interquartile range): 0.392 (0.263-0.656) μg/L; 0.450 (0.266-0.753) μg/g creatinine). Glyphosate concentration decreased from age 6-11 until age 20-59 and increased at 60+ years in univariate analyses. Children/adolescents and adults who fasted > 8 h had significantly lower model-adjusted geometric means (0.43 (0.37-0.51) μg/L and 0.37 (0.33-0.39) μg/L) than those fasting ≤ 8 h (0.51 (0.46-0.56) μg/L and 0.44 (0.41-0.48) μg/L), respectively. The likelihood (odds ratio (95 % CI)) of glyphosate concentrations being > 95th percentile was 1.94 (1.06-3.54) times higher in people who fasted ≤ 8 h than people fasting > 8 h (P = 0.0318).

CONCLUSIONS

These first nationally representative data suggest that over four-fifths of the U.S. general population ≥ 6 years experienced recent exposure to glyphosate. Variation in glyphosate concentration by food consumption habits may reflect diet or lifestyle differences.

Molecular and Histological Effects of Glyphosate on Testicular Tissue of the Lizard Podarcis siculus

The expansion of agriculture produces a steady increase in habitat fragmentation and degradation due to the increased use of pesticides and herbicides. Habitat loss and alteration associated with crop production play an important role in reptile decline, among which lizards are particularly endangered. In this study, we evaluated testicular structure, steroidogenesis, and estrogen receptor expression/localization after three weeks of oral exposure to glyphosate at 0.05 and 0.5 μg/kg body weight every other day in the field lizard Podarcis siculus. Our results show that glyphosate affected testicular morphology, reduced spermatogenesis, altered gap junctions and changed the localization of estrogen receptors in germ cells, increasing their expression; the effects were mostly dose-dependent. The result also demonstrates that glyphosate, at least at these concentrations, did not influence steroidogenesis. Overall, the data indicate that this herbicide can disturb the morphophysiology of the male lizard's reproductive system, with obviously detrimental effects on their reproductive fitness. The effects of glyphosate must be considered biologically relevant and could endanger the reproductive capacity not only of lizards but also of other vertebrates, including humans; a more controlled and less intensive use of glyphosate in areas devoted to crop production would therefore be advisable.

Direct Effects of Glyphosate on In Vitro T Helper Cell Differentiation and Cytokine Production

Glyphosate (G) is the active ingredient of the most used herbicides worldwide. Its use is currently very debated, as several studies indicating its hazard and toxicity are emerging. Among them, there is evidence of adverse effects on the immune system. The aim of this work was to investigate if G could directly affect immune cells. Peripheral blood mononuclear cells (PBMC) obtained from healthy donors were used as experimental model. PBMC were expose to G and stimulated with PMA/ionomycin, T helper (Th) cell differentiation and cytokine production were assessed by flow cytometry and enzyme-linked immunosorbent assay, respectively. A reduction of Th1/Th2 ratio, mainly due to a decrease in Th1 cells, was observed following G exposure. Results show an enhancement of IL-4 and IL-17A production, and a reduction of IFN-γ. Based on literature evidence that suggest G being an endocrine disruptor, we investigated the role of nuclear estrogen receptors (ER). ERα/ERβ inhibition by ICI 182,780 abolished the effects of G on IFN-γ and IL-4 release, suggesting a role of ER in the observed effects. To further characterize the mechanism of action of G, miRNAs, both in exosome and intracellular, were investigated. A statistically significant increase in miR-500a-5p was observed following G treatment. The blockage of miR-500a-5p, using a specific antagomir, prevented G-induced reduction of IFN-γ production. Finally a relationship between miR-500a-5p up-regulation and ER was observed. Overall, these results suggest that G can directly act on T cells, altering T cell differentiation and cytokines production.

Altered uterine angiogenesis in rats treated with a glyphosate-based herbicide

Glyphosate-based herbicides (GBHs) are the agrochemicals most used around the globe. However, they might have adverse effects on human and animal health. Previously, we showed that female rats neonatally exposed to GBHs exhibit altered expression of morphogenetic molecules and biomarkers of uterine development. We also observed a reduction in the size of implantation sites, altered expression of decidualization-related molecules, and increased post-implantation losses. Since decidualization comprises morphogenetic, biochemical and vascular changes, here we investigated the effects of neonatal GBH exposure on uterine angiogenesis in neonatal and pregnant rats. To achieve this, Wistar female rats were exposed to saline solution or GBH (2 mg glyphosate/kg-bw/day) on post-natal days (PND) 1, 3, 5 and 7. On PND8, uterine samples were collected for developmental studies. On PND90, the remaining females were mated and in the morning of gestational day (GD) 9, the implantation sites were collected. Angiogenesis-related molecules and cells involved in this process were identified and/or measured by immunohistochemistry or RT-PCR. On PND8, GBH-treated rats showed increased vascular endothelial growth factor (VEGF) expression and decreased Notch1, inducible nitric oxide synthase (iNOS) and Angiopoietin-2 (Ang2) mRNA levels. Vascular area, vessel diameter, endothelial cell proliferation, VEGF and Nestin protein expression, and VEGF, Notch1, iNOS and cyclooxygenase-2 (Cox-2) genes were downregulated in implantation sites of exposed females, while Ang2, VEGF receptor 1 and interleukin-10 (IL-10) were increased. Mast cells and macrophages were increased on PND8 and GD9 of treated rats. The increased Transforming growth factor-beta expression in the antimesometrial zone and IL-10 mRNA expression suggest that the M2 type is the predominant population of macrophages on implantation sites. In conclusion, neonatal GBH exposure alters the expression of angiogenesis-related molecules at neonatal uterine development and decidual reaction, suggesting altered vascular support. These alterations might contribute to the increased post-implantation losses observed in GBH-treated rats.

Disruption of developmental programming with long-term consequences after exposure to a glyphosate-based herbicide in a rat model

Glyphosate-based herbicides (GBHs) have been associated with endocrine disrupting effects on reproductive organs. We examined whether postnatal exposure to GBH affects developmental programming of the uterus with long-term consequences. Female Wistar pups received vehicle (control) or GBH (2 mg of glyphosate/kg/day) from postnatal day (PND) 1 to PND7, where the developing uterus is highly sensitive to endocrine disruption. Short-, mid- and long-term effects were evaluated on PND8, PND120 and PND600, respectively. GBH induced hyperplasia and epigenetic alterations in the uterus of neonatal females (PND8). DNA hypermethylation, enrichment of H3K9me3 and reductions of H3K27me3 at regulatory regions of the morphoregulatory gene Hoxa10 resulted in gene downregulation. In young adult females (PND120), GBH increased 17β-estradiol (E2) and decreased progesterone (P4) serum levels, altering estrous cyclicity. Aged females (PND600) exposed to GBH developed leiomyoma and pre-neoplastic glandular lesions in the uterus. Vaginal rhabdomyosarcoma and intrahepatic bile duct adenoma were also observed. In conclusion, neonatal exposure to GBH altered the expression and induced hypermethylation of the Hoxa10 gene in uterine tissue at early life, and increased E2/P4 ratio serum level at middle-age. We propose that epigenetic reprogramming of Hoxa10 in association with hormonal imbalance could be among the possible mechanisms underlying the long-term adverse effects detected in GBH-exposed rats.

Effects of low-concentration glyphosate and aminomethyl phosphonic acid on zebrafish embryo development

Glyphosate (GLY) is the most widely used broad-spectrum, non-selective herbicide in the world, whose main degradation product is aminomethyl phosphonic acid (AMPA). Because of long-term and large-scale use, residual GLY and AMPA in the environment pose great environmental and human health threats. The purpose of this study is to evaluate the effects and mechanism of residual low-concentrations of GLY and AMPA in the environment on the development of zebrafish embryos. Zebrafish embryos were exposed to 0, 1, 10, 100, and 700 ng·mL-1 GLY and AMPA for 72 h (from 2 to 74 h post-fertilization). With increasing exposure dose, heart rates of both embryos and larvae showed a rising trend and obvious arrhythmia appeared. Defects in cardiac development and function of zebrafish juveniles may be related to altered transcription levels of cardiac development genes (TBX5, NKX2.5, BMP4) and apoptosis genes (Bcl-2, Bax). In addition, pericardial edema and bone deformation of zebrafish embryos may be caused by inhibition of Na+/K+-ATPase and Ca2+-ATPase after exposure to GLY and AMPA. The present results demonstrated that at typical environmental residual concentrations of GLY and AMPA had similar developmental toxicity in zebrafish embryos.

Effects of Salvia hispanica L. (chia) seed on blood coagulation, endothelial dysfunction and liver fibrosis in an experimental model of Metabolic Syndrome

The aim of this study was to analyze blood coagulation, endothelial dysfunction and liver fibrosis in an experimental model of Metabolic Syndrome (MS) induced by chronic administration of a sucrose-rich diet (SRD) and to evaluate the effects of chia seed as a therapeutic strategy. Male Wistar rats were fed with a reference diet (RD) - 6 months - or a SRD - 3 months. Then, the last group was randomly divided into two subgroups. One subgroup continued receiving the SRD for up to 6 months and the other was fed with a SRD where whole chia seed was incorporated as the source of dietary fat for the next 3 months (SRD + CHIA). Results showed that rats fed a SRD for a long period of time develop dyslipidemia, visceral adiposity, insulin resistance, and a hypercoagulable and hypofibrinolytic basal state. Hepatic VCAM-1 (main adhesion molecules involved in endothelial dysfunction) expression was significantly increased. In addition, the SRD group presented hepatic steatosis, a significant increase in interstitial collagen deposition and hydroxyproline content. Liver TGF-β1 (a key cytokine involved in fibrogenesis) levels increased and a negative correlation with PPARα protein mass levels was found. The administration of chia seed for 3 months reversed dyslipidemia, visceral adiposity and insulin resistance. Platelet count, coagulation parameters and plasma fibrinogen levels were normalized. In the liver tissue, VCAM-1 expression, steatosis, interstitial collagen deposition and the hydroxyproline content decreased. TGF-β1 expression was decreased and this was associated with an increase in the PPARα protein levels. The present study showed new aspects in the progression from liver steatosis to fibrosis in dyslipidemic insulin-resistant rats chronically fed a sucrose-rich diet. Chia seed supplementation could be used as a functional food and a potential dietary strategy to prevent or ameliorate disorders related to atherothrombotic cardiovascular events and NASH.

Earthworms accelerated the degradation of the highly toxic acetochlor S-enantiomer by stimulating soil microbiota in repeatedly treated soils

This study investigated the effects of earthworms on the enantioselective degradation of chloroacetamide herbicide acetochlor with soil microorganisms in repeatedly treated soils. The S-enantiomer degraded more slowly and exerted stronger inhibition on soil microbial functions than the R-enantiomer in single soil system. A synergistic effect was observed between soil microorganisms and earthworms that accelerated the degradation of both the enantiomers, particularly the highly toxic S-enantiomer, which resulted in the preferential degradation of S-enantiomer in soil-earthworm system. Earthworms stimulated five potential indigenous degraders (i.e. Lysobacter, Kaistobacter, Flavobacterium, Arenimonas, and Aquicell), induced two new potential degraders (i.e. Aeromonas and Algoriphagus), and also significantly strengthened the correlations among these seven dominant potential degraders and other microorganisms. Notably, the relative abundances of Flavobacterium and Aeromonas in soil treated with earthworms for S-enantiomer were higher than those for R-enantiomer. Furthermore, earthworms significantly stimulated overall soil microbial activity and improved three microbial metabolic pathways, and xenobiotics biodegradation and metabolism, signal transduction, cell motility, particularly for the S-enantiomer treatment with earthworms, which alleviated the strong inhibition of S-enantiomer on microbial community functions. This study confirmed that earthworms accelerated the degradation of the highly toxic acetochlor S-enantiomer in soil, providing a potential approach in chloroacetamide herbicide-polluted soil remediation.

Glyphosate-based herbicides: Evidence of immune-endocrine alteration

Glyphosate (G) is the active ingredient of the most widely used herbicide products. It targets the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), which lacks in humans, suggesting to confer a low mammalian toxicity to G-based herbicides (GBHs). Despite this, the use of G is currently under intense debate. Many studies indicating its hazard and toxicity on non-target organisms are emerging, and associations between GBHs and immune-endocrine disturbances have been described. This review aims to investigate, based on recent epidemiological studies and studies performed in vitro and in vivo in animals, the possible association between GBHs and immune-endocrine alterations. Published data suggest that GBHs have endocrine disrupting potentiality targeting sex and thyroid hormones, although its relevance for humans will require further investigations. Evidence of immunotoxicity are limited compared to those on endocrine effects, but overall highlight possible noxious effects, including lung inflammation and rhinitis. An attractive hypothesis could be the one that connects microbiota dysbiosis with possible immune-endocrine outcomes. Indeed, several intestinal microorganisms express the enzyme EPSPS and, studies are emerging that highlight a possible G-induced dysbiosis. Considering the wide use of GBHs in agriculture, further studies investigating their noxious effects at levels relevant for human exposure should be performed. A critical analysis of emerging evidence of G toxicity is required to better characterize its safety profile. In addition, attention should be paid to the differences between G alone and its formulations, which, containing substances able to increase G absorption, may present a different toxicity profile.

Epigenetic Changes Associated With Exposure to Glyphosate-Based Herbicides in Mammals

Glyphosate is a phosphonomethyl amino acid derivative present in a number of non-selective and systemic herbicides. During the last years the use of glyphosate-based herbicide (GBH) has been increasing exponentially around the world, including Argentina. This fact added to the detection of glyphosate, and its main metabolite, amino methylphosphonic acid (AMPA), in environmental matrices such as soil, sediments, and food, has generated great concern about its risks for humans, animals, and environment. During the last years, there were controversy and intense debate regarding the toxicological effects of these compounds associated with the endocrine system, cancer, reproduction, and development. The mechanisms of action of GBH and their metabolites are still under investigation, although recent findings have shown that they could comprise epigenetic modifications. These are reversible mechanisms linked to tissue-specific silencing of gene expression, genomic imprinting, and tumor growth. Particularly, glyphosate, GBH, and AMPA have been reported to produce changes in global DNA methylation, methylation of specific genes, histone modification, and differential expression of non-coding RNAs in human cells and rodents. Importantly, the epigenome could be heritable and could lead to disease long after the exposure has ended. This mini-review summarizes the epigenetic changes produced by glyphosate, GBHs, and AMPA in humans and rodents and proposes it as a potential mechanism of action through which these chemical compounds could alter body functions.

Glyphosate and the key characteristics of an endocrine disruptor: A review

Glyphosate is a large-spectrum herbicide that was introduced on the market in 1974. Due to its important impact on the crop industry, it has been significantly diversified and expanded being considered the most successful herbicide in history. Currently, its massive use has led to a wide environmental diffusion and its human consumption through food products has made possible to detect it in urine, serum, and breast milk samples. Nevertheless, recent studies have questioned its safety and international agencies have conflicting opinions about its effects on human health, mainly as an endocrine-disrupting chemical (EDC) and its carcinogenic capacity. Here, we conduct a comprehensive review where we describe the most important findings of the glyphosate effects in the endocrine system and asses the mechanistic evidence to classify it as an EDC. We use as guideline the ten key characteristics (KCs) of EDC proposed in the expert consensus statement published in 2020 (La Merrill et al., 2020) and discuss the scopes of some epidemiological studies for the evaluation of glyphosate as possible EDC. We conclude that glyphosate satisfies at least 8 KCs of an EDC, however, prospective cohort studies are still needed to elucidate the real effects in the human endocrine system.

Organic diet intervention significantly reduces urinary glyphosate levels in U.S. children and adults

BACKGROUND

A growing set of studies show that an organic diet is associated with reduced levels of urinary pesticide analytes. However, with the exception of one pilot study of two individuals, diet intervention studies to date have not analyzed glyphosate, the most commonly used herbicide in the United States and globally.

OBJECTIVE

To investigate the impact of an organic diet intervention on levels of glyphosate and its main metabolite, AMPA (aminomethyl phosphonic acid), in urine collected from adults and children.

METHODS

We analyzed urine samples from four racially and geographically diverse families in the United States for five days on a completely non-organic diet and for five days on a completely organic diet (n = 16 participants and a total of 158 urine samples).

RESULTS

Mean urinary glyphosate levels for all subjects decreased 70.93% (95% CI -77.96, -61.65, p<0.010) while mean AMPA levels decreased by 76.71% (95% CI -81.54, -70.62, p < 0.010) within six days on an organic diet. Similar decreases in urinary levels of glyphosate and AMPA were observed when data for adults were examined alone, 71.59% (95% CI -82.87, -52.86, p < 0.01) and 83.53% (95% CI -88.42, -76.56, p < 0.01) and when data for children were examined alone, 70.85% (95% CI -78.52, -60.42, p < 0.01) and 69.85% (95% CI -77.56, -59.48, p < 0.01).

CONCLUSION

An organic diet was associated with significantly reduced urinary levels of glyphosate and AMPA. The reduction in glyphosate and AMPA levels was rapid, dropping to baseline within three days. This study demonstrates that diet is a primary source of glyphosate exposure and that shifting to an organic diet is an effective way to reduce body burden of glyphosate and its main metabolite, AMPA. This research adds to a growing body of literature indicating that an organic diet may reduce exposure to a range of pesticides in children and adults.

Cytotoxicity and hormonal activity of glyphosate-based herbicides

Glyphosate-based herbicides (GBHs) are the most widely used pesticides for weed control. In parallel with the renewal of the active ingredient, polyethoxylated POE(15) containing GBHs were banned in the EU in 2016. Since then, co-formulants were changed and numerous GBHs are marketed with different excipients declared as inert substances. In our study, we focused to determine acute and chronic cytotoxicity (by Aliivibrio fischeri assay) and direct hormonal activity (estrogenic and androgenic effects measured by Saccharomyces cerevisiae BLYES/BLYAS strains, respectively) of glyphosate, AMPA, polyethoxylated POE(15) and 13 GBHs from which 11 formulations do not contain polyethoxylated POE(15). Among the pure substances, neither glyphosate nor AMPA had any effects, while polyethoxylated POE(15) exhibited pronounced toxicity and was also estrogenic but not androgenic. Regarding the acute and chronic cytotoxicity and hormonal activity of GBHs, dilution percentages calculated from EC50 values were in the most cases by one or two order of magnitude lower than the minimum recommended dilution for agricultural and household use. Relation could not be observed between the biological effects and type of glyphosate-salts; hence toxicity could be linked to the co-formulants, which are not even declared in 3 GBHs. Toxicological evaluation must focus on these substances and free accessibility of GBHs should be reconsidered.

Neonatal exposure to a glyphosate-based herbicide alters the uterine differentiation of prepubertal ewe lambs

The exposure to endocrine-disrupting compounds (EDCs), such as glyphosate-based herbicides (GBHs), during early life might alter female fertility. The aim of the present study was to evaluate the effects of neonatal exposure to a GBH on sheep uterine development. To achieve this, Friesian ewe lambs were exposed to GBH (2 mg/kg of body weight/day; n = 12) or vehicle (controls; n = 10) through s.c. injections, from postnatal day (PND) 1 to PND14; on PND45, the uteri were obtained to evaluate histomorphological and molecular parameters. Morphological parameters were determined by picrosirius-hematoxylin staining. Protein expression of Ki67 (as a cell proliferation marker), p27, and molecules involved in uterine organogenetic differentiation was measured by immunohistochemistry. We also determined the mRNA expression of the IGF molecular pathway by RT-PCR. Although histomorphology was not modified, the uteri of GBH-exposed ewe lambs showed lower cell proliferation, together with higher p27 protein expression. In addition, the uteri of GBH-exposed ewe lambs showed increased gene expression of insulin-like growth factor binding protein 3 (IGFBP-3), decreased expression of ERα in the luminal (LE) and glandular (GE) epithelia and in the subepithelial stroma (SS), and lower PR expression in the LE but higher in the GE and SS. In addition, GBH treatment decreased the uterine expression of Wnt5a in the GE, of Wnt7a in the SS, of β-catenin in the LE and GE, of Hoxa10 in the SS, and of Foxa2 in the GE as compared with controls. In conclusion, neonatal exposure to GBH decreased cell proliferation and altered the expression of molecules that control proliferation and development in the uterus. All these changes might have adverse consequences on uterine differentiation and functionality, affecting the female reproductive health of sheep. GBH may be responsible for uterine subfertility, acting as an EDC.

Agrochemicals and neurogenesis

Agrochemicals or pesticides are compounds widely used to prevent, destroy or mitigate pests such as insects, rodents, herbs and weeds. However, most of them also act as environmental estrogens, anti-estrogens and/or antiandrogenic chemicals. In addition, both herbicides (such as glyphosate and paraquat) and insecticides (such as pyrethroids, organophosphates, neonicotinoids and rotenone) have been shown to exert significant adverse effects on hippocampal neurogenesis. These effects are particularly important because neurogenesis dysregulation could be associated with cognitive decline and neuropathologies such as Alzheimer's disease. This review focuses on the most commonly used agrochemicals in Argentina and their effects on the hippocampal neurogenesis of mammals. It also discusses the disruption of hormone synthesis and action as a possible mechanism through which these chemical compounds could alter the brain functions. Finally, we propose some lines of research to study the potential endocrine mechanisms involved in the effects of agrochemicals on human health and biodiversity.

Exposure to a Glyphosate-based Herbicide Alters the Expression of Key Regulators of Mammary Gland Development on Pre-pubertal Male Rats

We previously reported that exposure during gestation and lactation to a low dose of glyphosate-based herbicide (GBH) reduced the area and perimeter of male offspring mammary gland at postnatal day 60 (PND60), whereas a higher dose increased the longitudinal growth of the gland. Here, our aim was to assess whether perinatal exposure to GBH exhibits endocrine disruptive action in male mammary gland at an early time point (pre-puberty), which could be related to the changes observed after puberty. We also wanted to explore whether an early evaluation of the male rat mammary gland is appropriate to assess exposure to potential endocrine disrupting chemicals (EDCs). Pregnant rats were orally exposed, through the diet, to vehicle (saline solution), 3.5 or 350 mg/kg/day of GBH from gestational day 9 until weaning. At PND21, the male offspring were euthanized, and mammary gland samples were collected. The histology and proliferation index of the mammary glands were evaluated, and the mRNA expression of estrogen (ESR1) and androgen (AR) receptors, cyclin D1 (Ccnd1), amphiregulin (Areg), insulin-like growth factor 1 (IGF1), epidermal growth factor receptor (EGFR) and IGF1 receptor (IGF1R) were assessed. Moreover, the phosphorylated-Erk1/2 (p-ERK1/2) protein expression was determined. No differences were observed in mammary epithelial structures and AR expression between experimental groups; however, the proliferation index was reduced in GBH3.5-exposed males. This result was associated with decreased ESR1, Ccnd1, Areg, IGF1, EGFR and IGF1R mRNA expressions, as well as reduced p-Erk1/2 protein expression in these animals. ESR1, Ccnd1, IGF1R and EGFR expressions were also reduced in GBH350-exposed males. In conclusion, the mammary gland development of pre-pubertal male rats is affected by perinatal exposure to GBH. Although further studies are still needed to understand the molecular mechanisms involved in GBH350 exposure, the present results may explain the alterations observed in mammary gland growth of post-pubertal males exposed to low doses of GBH. Our results also suggest that early evaluation of the male rat mammary gland is useful in assessing exposure to potential EDCs. However, analysis of EDCs effects at later time points should not be excluded.

Relationship between agrochemical compounds and mammary gland development and breast cancer

The exposure to agrochemical pesticides has been associated with several chronic diseases, including different types of cancer and reproductive disorders. In addition, because agrochemical pesticides may act as endocrine disrupting chemicals (EDCs) during different windows of susceptibility, they can increase the risk of impairing the normal development of the mammary gland and/or of developing mammary lesions. Therefore, the aim of this review is to summarize how exposure to different agrochemical pesticides suspected of being EDCs can interfere with the normal development of the mammary gland and the possible association with breast cancer. It has been shown that the mammary glands of male and female rats and mice are susceptible to exposure to non-organochlorine (vinclozolin, atrazine, glyphosate, chlorpyrifos) and organochlorine (endosulfan, methoxychlor, hexachlorobenzene) pesticides. Some of the effects of these compounds in experimental models include increased or decreased mammary development, impaired cell proliferation and steroid receptor expression and signaling, increased malignant cellular transformation and tumor development and angiogenesis. Contradictory findings have been found as to whether there is a causal link between the exposure or the pesticide body burden and breast cancer in humans. However, an association has been observed between pesticides (especially organochlorine compounds) and specific subtypes of breast cancer. Further studies are needed in both humans and experimental models to understand how agrochemical pesticides can induce or promote changes in the development, differentiation and/or malignant transformation of the mammary gland.

Toxicity of glyphosate in feed for weanling piglets and the mechanism of glyphosate detoxification by the liver nuclear receptor CAR/PXR pathway

Glyphosate (GLP), the most widely used and productive pesticide worldwide, which safety and reliability gradually become a social concern. It is important to explore the toxic of GLP on the limitation level by governments on piglets and the potential role of hepatic CAR/PXR and Keap1-Nrf2 pathways in low levels of glyphosate detoxification. Compared with the control group, the production performance and organ index of GLP group showed no significant change. However, the liver GLP residue of 40 mg/kg group was significantly higher than the control group. We also found that the activity of ALP increased linearly and DBIL content increased quadratically. Furthermore, GLP could significantly increase SOD and GSH-Px and decrease T-AOC and CAT activities and significantly increase MDA and H2O2 contents (P < 0.05); however, the genes expression of Keap1/Nrf2 pathway was not affected. Gene expression of CAR/PXR pathway showed that GLP could significantly stimulate the expression of CAR, but it could not affect the expression of phase Ⅰ (CYP1A1, CYP1A2, CYP2E1, CYP2A19, CYP3A29), phase Ⅱ (UGT1A6, GSTA1, GSTA2) detoxification enzymes and transporters (MDR1, MRP2, P-gp). Our study showed that although 10-40 mg/kg GLP would inevitably cause some liver damage and dysfunction, it can self-alleviating the toxic effect of GLP.

Glyphosate-based herbicide induces hyperplastic ducts in the mammary gland of aging Wistar rats

Glyphosate-based herbicide (GBH) exposure is known to have adverse effects on endocrine-related tissues. Here, we aimed to determine whether early postnatal exposure to a GBH induces long-term effects on the rat mammary gland. Thus, female Wistar pups were injected with saline solution (Control) or GBH (2 mg glyphosate/kg/day) on postnatal days (PND) 1, 3, 5 and 7. At 20 months of age, mammary gland samples were collected to determine histomorphological features, proliferation index and the expression of steroid hormone receptors expression, by immunohistochemistry, and serum samples were collected to assess 17β-estradiol (E2) and progesterone (P4) levels. GBH exposure induced morphological changes evidenced by a higher percentage of hyperplastic ducts and a fibroblastic-like stroma in the mammary gland. GBH-treated rats also showed a high expression of steroid hormone receptors in hyperplastic ducts. The results indicate that early postnatal exposure to GBH induces long-term alterations in the mammary gland morphology of aging female rats.

Acute uterine effects and long-term reproductive alterations in postnatally exposed female rats to a mixture of commercial formulations of endosulfan and glyphosate

Endosulfan and glyphosate are widely used pesticides and have been associated to reproductive disorders. We examine the acute and long-term effects of postnatal exposure to commercial formulations of endosulfan (EF), glyphosate (glyphosate-based herbicide, GBH) and a mixture of both pesticides (MIX). After birth, female pups of Wistar rats received saline solution (CONTROL), EF (600 μg/kg of b.w/day), GBH (2 mg/kg of b.w/day) or a mixture (at the same doses) from postnatal day (PND) 1 to PND7. The uterine histology and expression of Hoxa10, estrogen (ERα) and progesterone (PR) receptors were evaluated on PND8. Reproductive performance was evaluated on gestational day 19. GBH and MIX rats showed an increment of 1) the incidence of luminal epithelial hyperplasia, 2) PR and Hoxa10 expression. EF modified ERα and Hoxa10 expression. During adulthood, MIX and GBH rats showed higher post-implantation losses while EF alone produced an increase of pre-implantation losses. We showed that the co-administration of both pesticides produced acute uterine effects and long-term deleterious reproductive effects that were similar to those induced by GBH alone. We consider important to highlight the necessity to evaluate the commercial pesticide mixture as a more representative model of human exposure to a high number of pesticides.

Exposure to glyphosate-based herbicides and risk for non-Hodgkin lymphoma: A meta-analysis and supporting evidence

Glyphosate is the most widely used broad-spectrum systemic herbicide in the world. Recent evaluations of the carcinogenic potential of glyphosate-based herbicides (GBHs) by various regional, national, and international agencies have engendered controversy. We investigated whether there was an association between high cumulative exposures to GBHs and increased risk of non-Hodgkin lymphoma (NHL) in humans. We conducted a new meta-analysis that includes the most recent update of the Agricultural Health Study (AHS) cohort published in 2018 along with five case-control studies. Using the highest exposure groups when available in each study, we report the overall meta-relative risk (meta-RR) of NHL in GBH-exposed individuals was increased by 41% (meta-RR = 1.41, 95% confidence interval, CI: 1.13-1.75). For comparison, we also performed a secondary meta-analysis using high-exposure groups with the earlier AHS (2005), and we calculated a meta-RR for NHL of 1.45 (95% CI: 1.11-1.91), which was higher than the meta-RRs reported previously. Multiple sensitivity tests conducted to assess the validity of our findings did not reveal meaningful differences from our primary estimated meta-RR. To contextualize our findings of an increased NHL risk in individuals with high GBH exposure, we reviewed publicly available animal and mechanistic studies related to lymphoma. We documented further support from studies of malignant lymphoma incidence in mice treated with pure glyphosate, as well as potential links between glyphosate / GBH exposure and immunosuppression, endocrine disruption, and genetic alterations that are commonly associated with NHL or lymphomagenesis. Overall, in accordance with findings from experimental animal and mechanistic studies, our current meta-analysis of human epidemiological studies suggests a compelling link between exposures to GBHs and increased risk for NHL.

The Ramazzini Institute 13-week pilot study glyphosate-based herbicides administered at human-equivalent dose to Sprague Dawley rats: effects on development and endocrine system

BACKGROUND

Glyphosate-based herbicides (GBHs) are broad-spectrum herbicides that act on the shikimate pathway in bacteria, fungi, and plants. The possible effects of GBHs on human health are the subject of an intense public debate for both its potential carcinogenic and non-carcinogenic effects, including potential effects on the endocrine system The present pilot study examine whether exposure to GBHs at the dose of glyphosate considered to be "safe" (the US Acceptable Daily Intake - ADI - of 1.75 mg/kg bw/day), starting from in utero life, affect the development and endocrine system across different life stages in Sprague Dawley (SD) rats.

METHODS

Glyphosate alone and Roundup Bioflow, a commercial brand of GBHs, were administered in drinking water at 1.75 mg/kg bw/day to F0 dams starting from the gestational day (GD) 6 (in utero) up to postnatal day (PND) 120. After weaning, offspring were randomly distributed in two cohorts: 8 M + 8F/group animals belonging to the 6-week cohort were sacrificed after puberty at PND 73 ± 2; 10 M + 10F/group animals belonging to the 13-week cohort were sacrificed at adulthood at PND 125 ± 2. Effects of glyphosate or Roundup exposure were assessed on developmental landmarks and sexual characteristics of pups.

RESULTS

In pups, anogenital distance (AGD) at PND 4 was statistically significantly increased both in Roundup-treated males and females and in glyphosate-treated males. Age at first estrous (FE) was significantly delayed in the Roundup-exposed group and serum testosterone concentration significantly increased in Roundup-treated female offspring from the 13-week cohort compared to control animals. A statistically significant increase in plasma TSH concentration was observed in glyphosate-treated males compared with control animals as well as a statistically significant decrease in DHT and increase in BDNF in Roundup-treated males. Hormonal status imbalances were more pronounced in Roundup-treated rats after prolonged exposure.

CONCLUSIONS

The present pilot study demonstrate that GBHs exposure, from prenatal period to adulthood, induced endocrine effects and altered reproductive developmental parameters in male and female SD rats. In particular, it was associated with androgen-like effects, including a statistically significant increase of AGDs in both males and females, delay of FE and increased testosterone in female.

Male mammary gland development and methylation status of estrogen receptor alpha in Wistar rats are modified by the developmental exposure to a glyphosate-based herbicide

Postnatal treatment with glyphosate-based herbicides (GBHs) induces endocrine-disrupting effects on the male rat mammary gland. In this study, the effects of developmental exposure to GBH on mammary gland growth and development, and the possible molecular mechanisms involved, were evaluated in pre- and post-pubertal male rats. To this end, pregnant rats were orally exposed through the food to 0, 3.5 or 350 mg GBH/kg bw/day from gestational day 9 until weaning. Mammary gland development and estradiol (E2) and testosterone (T) serum levels of male offspring were evaluated on postnatal day (PND)21 and PND60. Besides, prolactin (PRL) serum levels, proliferation index, androgen (AR) and estrogen receptor alpha (ESR1) expression, ESR1 alternative transcript mRNA levels, and DNA methylation status of ESR1 promoters were assessed on PND60. No differences between groups were observed in mammary gland development at PND21 or in E2 and T levels on both PNDs studied. On PND60, GBH3.5-exposed animals presented similar mammary gland histology but higher AR protein expression than controls, whereas GBH350-exposed males presented a less developed mammary gland, accompanied by a lower proliferation index, similar AR levels, and slightly increased PRL serum levels than controls. In both exposed groups, ESR1 expression was lower than in control rats, being lower in GBH350-exposed rats. GBH also altered the abundance of ESR1 transcript variants by hypermethylation of ESR1 promoters. GHB3.5 decreased only ESR1-OS expression, whereas GBH350 affected ESR1-O, OT and E1 expression. Our results show that developmental exposure to GBH induces epigenetic changes in ESR1, which could be responsible for the altered male mammary gland development observed in GBH350-exposed animals.

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.