Toxic compounds in herbicides without glyphosate

Fluorene-induced stress in the benthic oligochaete Tubifex tubifex: A multi-biomarker assessment of toxicological pathways and mechanisms under acute and subchronic exposures

This study examined the multifaceted impacts of fluorene exposure on Tubifex tubifex, encompassing acute (survival analysis and behavioral responses) and subchronic exposure regimens (antioxidant enzyme response and histopathology), molecular docking studies, and generalized read-across analysis. Survival analysis revealed concentration-dependent increases in toxicity over varying time intervals, with LC50 values decreasing from 30.072 mg/L at 24 h to 12.365 mg/L at 96 h, emphasizing the time-sensitive and concentration-responsive nature of the stressor. Behavioral responses were both concentration- and duration-dependent. While Erratic Movement and Clumping Tendency exhibited earlier responses (within 24 h) at lower concentrations, the wrinkling effect and mucus secretion) exhibited delayed onset, suggesting intricate regulatory mechanisms underlying adaptability to environmental challenges; moreover, the wrinkling effect was consistently induced at higher concentrations, indicating greater sensitivity to the toxic effects of fluorene. With sublethal environmentally relevant concentrations-1.24 mg/l and 2.47 mg/L i.e., 10% and 20% 96 h, respectively-the antioxidant enzyme response (i.e., upregulation of SOD, CAT, and GST) with increasing fluorene concentration, revealing a nonlinear, hormetic response, suggested adaptive protection at lower doses but inhibition at higher concentrations. Histopathological examination indicated that higher fluorene concentrations caused cellular proliferation, inflammation, and severe tissue damage in the digestive tract and body wall. Molecular docking studies demonstrated robust interactions between fluorene and major stress biomarker enzymes, disrupting their functions and inducing oxidative stress. Interactions with cytochrome c oxidase suggested interference with cellular energy production. Generalized Read-Across (GenRA) analysis unveiled shared toxicity mechanisms among fluorene and its analogs, involving the formation of reactive epoxides and the influence of cytochrome P450 enzymes. The diverse functional groups of these analogs, particularly chlorine-containing compounds, were implicated in toxicity through lipid peroxidation and membrane damage. Adverse outcome pathways and broader consequences for aquatic ecosystem health are discussed.

GLYPHOSATE IMPACT on human health and the environment: Sustainable alternatives to replace it in Mexico

Glyphosate is a broad-spectrum, non-selective herbicide used to control weeds and protect agricultural crops, and it is classified as potentially carcinogenic by the International Agency for Research on Cancer. In Mexico, the use of pesticides is a common practice, including glyphosate. However, on December 31st, 2020, the Mexican government decreed the prohibition of this herbicide as of January 2024. In this review, we investigate the association between glyphosate and cancer risk and found that most of the studies focused using animals showing negative effects such as genotoxicity, cytotoxicity and neurotoxicity, some studies used cancer cell lines showing proliferative effects due to glyphosate exposure. To our knowledge, in Mexico, there are no scientific reports on the association of glyphosate with any type of cancer. In addition, we reviewed the toxicological effects of the herbicide glyphosate, and the specific case of the current situation of the use and environmental damage of this herbicide in Mexico. We found that few studies have been published on glyphosate, and that the largest number of publications are from the International Agency for Research on Cancer classification to date. Additionally, we provide data on glyphosate stimulation at low doses as a biostimulant in crops and analytical monitoring techniques for the detection of glyphosates in different matrices. Finally, we have tried to summarize the actions of the Mexican government to seek sustainable alternatives and replace the use of glyphosate, to obtain food free of this herbicide and take care of the health of the population and the environment.

Triazine Herbicide and NPK Fertilizer Exposure: Accumulation of Heavy Metals and Rare Earth Elements, Effects on Cuticle Melanization, and Immunocompetence in the Model Species Tenebrio molitor

The increasing use of agrochemicals, including fertilizers and herbicides, has led to worrying metal contamination of soils and waters and raises serious questions about the effects of their transfer to different levels of the trophic web. Accumulation and biomagnification of essential (K, Na, Mg, Zn, Ca), nonessential (Sr, Hg, Rb, Ba, Se, Cd, Cr, Pb, As), and rare earth elements (REEs) were investigated in newly emerged adults of Tenebrio molitor exposed to field-admitted concentrations of a metribuzin-based herbicide and an NPK blend fertilizer. Chemical analyses were performed using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) supported by unsupervised pattern recognition techniques. Physiological parameters such as cuticle melanization, cellular (circulating hemocytes), and humoral (phenoloxidase enzyme activity) immune responses and mass loss were tested as exposure markers in both sexes. The results showed that NPK fertilizer application is the main cause of REE accumulation in beetles over time, besides toxic elements (Sr, Hg, Cr, Rb, Ba, Ni, Al, V, U) also present in the herbicide-treated beetles. The biomagnification of Cu and Zn suggested a high potential for food web transfer in agroecosystems. Gender differences in element concentrations suggested that males and females differ in element uptake and excretion. Differences in phenotypic traits show that exposure affects metabolic pathways involving sequestration and detoxification during the transition phase from immature-to-mature beetles, triggering a redistribution of resources between sexual maturation and immune responses. Our findings highlight the importance of setting limits for metals and REEs in herbicides and fertilizers to avoid adverse effects on species that provide ecosystem services and contribute to soil health in agroecosystems.

Dual-functional lignin-based hydrogels for sustained release of agrochemicals and heavy metal ion complexation

An effective way of improving the efficiency of agrochemicals and improving crop yield and quality is by slow or sustained release, which is conducive to environmental protection. Meanwhile, the excessive amount of heavy metal ions in soil can create toxicity in plants. Here, we prepared lignin-based dual-functional hydrogels containing conjugated agrochemical and heavy metal ligands through free-radical copolymerization. The content of the agrochemicals (including plant growth regulator 3-indoleacetic acid (IAC) and herbicide 2,4-dichlorophenoxyacetic acid (DCP)) in the hydrogels were tuned by changing the hydrogel composition. The conjugated agrochemicals could slowly release through the gradual cleavage of the ester bond. As a result of the release of the DCP herbicide, the growth of lettuce was effectively regulated, thus confirming the feasibility and effectiveness of this system in application. At the same time, due to the presence of metal chelating groups (such as COOH, phenolic OH, and tertiary amine) the hydrogels could act as adsorbents or stabilizers towards heavy metal ions for improving the soil remediation and preventing the adsorption of these toxic metals by plant roots. Specifically, Cu(II) and Pb(II) could be adsorbed >380 and 60 mg/g, respectively.

Petroleum in Pesticides: A Need to Change Regulatory Toxicology

Toxicological investigations of pesticides largely focus on the declared active ingredient, which constitutes only between a few percent to around 50% of the total formulation. The complete formulations are unknown. For each declared active ingredient, there are dozens or hundreds of formulations. We demonstrate that petroleum has always been and is still always in pesticides. Gas chromatography and mass spectrometry (GC-MS) were applied for 24 pesticides. The measured compounds were the 16-priority polycyclic aromatic hydrocarbons (PAHs). The ratio of the PAHs to the threshold of toxicity was from 2.16 to 8288 times. The levels and distribution of PAHs per pesticide were different. Petroleum residues appear to be a waste product. The declared active component is taken alone for toxicity calculations, such as the acceptable daily intake (ADI). The PAHs with 2-3 cycles are more represented in pesticides than those with 4-6 cycles, which underlines that the petroleum residues appear to come mainly from crude unburned material. The ADI should be divided by 1000 if it is considered that petroleum residues amplify the toxicity by 1000. The admixture of PAHs in pesticides can be highly carcinogenic or toxic in the long term, even more than the declared active ingredient itself.

Glyphosate, Roundup and the Failures of Regulatory Assessment

Roundup is the most widely used herbicide in agriculture. It contains glyphosate as the ‘active ingredient’, together with formulants. There are various versions of Roundup, with somewhat different effects depending on the formulants. Most genetically-modified crops are designed to tolerate Roundup, thus allowing spraying against weeds during the growing season of the crop without destroying it. Having been so heavily used, this herbicide is now found in the soil, water, air, and even in humans worldwide. Roundup may also remain as a residue on edible crops. Many studies have found harm to the environment and to health, making it imperative to regulate the use of Roundup and to ensure that its various formulations pose no danger when used in the long-term. Unfortunately, regulators may only assess the ‘active ingredient’, glyphosate, and ignore the toxicity of the formulants, which can be far more toxic than the active ingredient. This omission is in violation of a ruling by the Court of Justice of the European Union. There are close ties between the regulators and the industry they are supposed to regulate. Objectionable practices include ‘revolving doors’ between the regulators and the industry, heavy reliance on unpublished papers produced by the industry while dismissing papers published by independent scientists, and strong covert influence on the regulatory process by industry. Although this paper focuses on the European Union (EU), the situation is much the same in the United States.

cropCSM: designing safe and potent herbicides with graph-based signatures

Herbicides have revolutionised weed management, increased crop yields and improved profitability allowing for an increase in worldwide food security. Their widespread use, however, has also led to a rise in resistance and concerns about their environmental impact. Despite the need for potent and safe herbicidal molecules, no herbicide with a new mode of action has reached the market in 30 years. Although development of computational approaches has proven invaluable to guide rational drug discovery pipelines, leading to higher hit rates and lower attrition due to poor toxicity, little has been done in contrast for herbicide design. To fill this gap, we have developed cropCSM, a computational platform to help identify new, potent, nontoxic and environmentally safe herbicides. By using a knowledge-based approach, we identified physicochemical properties and substructures enriched in safe herbicides. By representing the small molecules as a graph, we leveraged these insights to guide the development of predictive models trained and tested on the largest collected data set of molecules with experimentally characterised herbicidal profiles to date (over 4500 compounds). In addition, we developed six new environmental and human toxicity predictors, spanning five different species to assist in molecule prioritisation. cropCSM was able to correctly identify 97% of herbicides currently available commercially, while predicting toxicity profiles with accuracies of up to 92%. We believe cropCSM will be an essential tool for the enrichment of screening libraries and to guide the development of potent and safe herbicides. We have made the method freely available through a user-friendly webserver at http://biosig.unimelb.edu.au/crop_csm.

Glyphosate vs. Glyphosate-Based Herbicides Exposure: A Review on Their Toxicity

Glyphosate-based herbicide has been the first choice for weed management worldwide since the 1970s, mainly due to its efficacy and reported low toxicity, which contributed to its high acceptance. Many of the recent studies focus solely on the persistence of pesticides in soils, air, water or food products, or even on the degree of exposure of animals, since their potential hazards to human health have raised concerns. Given the unaware exposure of the general population to pesticides, and the absence of a significant number of studies on occupational hazards, new glyphosate-induced toxicity data obtained for both residual and acute doses should be analyzed and systematized. Additionally, recent studies also highlight the persistence and toxicity of both glyphosate metabolites and surfactants present in herbicide formulations. To renew or ban the use of glyphosate, recently published studies must be taken into account, aiming to define new levels of safety for exposure to herbicide, its metabolites, and the toxic excipients of its formulations. This review aims to provide an overview of recent publications (2010–present) on in vitro and in vivo studies aimed at verifying the animal toxicity induced by glyphosate, its metabolite aminomethylphosphonic acid (AMPA) and glyphosate-based formulations, evaluated in various experimental models. Apart from glyphosate-induced toxicity, recent data concerning the role of surfactants in the toxicity of glyphosate-based formulations are discussed.

Excretion of Heavy Metals and Glyphosate in Urine and Hair Before and After Long-Term Fasting in Humans

Background: Dietary exposure to environmental pollutants in humans is an important public health concern. While long-term fasting interrupts the dietary exposure to these substances, fat mobilization as an energy source may also release bioaccumulated substances. This was, to our knowledge, only investigated in obese people decades ago. This study explored the effects of 10-days fasting on the excretion of heavy metals and glyphosate.

Methods: Urinary levels of arsenic, chromium, cobalt, lead, nickel, mercury and glyphosate were measured before and after 10 fasting days in 109 healthy subjects. Additionally, hair analysis was done before and ten weeks after fasting in 22 subjects.

Results: Fasting caused a decrease in body weight, and in urinary arsenic (by 72%) and nickel (by 15%) concentrations. A decrease in lead hair concentrations (by 30%) was documented. Urinary mercury levels were unchanged for chromium, cobalt and glyphosate, which were undetectable in most of the subjects. Additionally, fatigue, sleep disorders, headache and hunger were reduced. Body discomfort symptoms diminished four weeks after food reintroduction.

Conclusions: The results of this study provide the first insights into the changes in heavy metal excretion caused by long-term fasting. Further studies focusing on the kinetics of efflux between different compartments of the body are needed.

Clinical Trial Registration:https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00016657, identifier: DRKS00016657.

A Glyphosate-Based Formulation but Not Glyphosate Alone Alters Human Placental Integrity

Glyphosate (G)-based herbicidal formulations, such as the most commonly used one, Roundup (R), are major pesticides used worldwide on food and feed. Pregnant women may be frequently exposed to R compounds. These are composed of G, which is declared as the active principle, and other products contained in formulations, named formulants, which have been declared as inerts and diluents by the manufacturers. These formulants have, in fact, been demonstrated to be much more toxic than G, in particular to placental and embryonic human cells. In this work, we thus compared the effect of G and a GT+ formulation named R, using placental perfusion ex vivo. R, but not G alone, was demonstrated to alter the placental permeability of a known small model molecule, antipyrine. Similar results were observed for the fetal venous flow rate. The transfer of G alone increases with time, but is significantly decreased in presence of its formulants. The perfusion of R provokes a destruction of fetal vessels, as demonstrated by immunohistochemistry. Formulants obviously alter the fetal-placental circulation and placental integrity according to time of exposure. Therefore, G does not appear to be the main toxic agent of R. Formulants, although undeclared, include polyoxyethanolamines, PAHs, or heavy metals, and may be responsible for this toxicity. These compounds are also present in other pesticides. The progressive blood flow reduction due to the toxic compounds of formulations may diminish the nutrient supply to the fetus, alter the development, and may enhance the poisoning effects. Although these are preliminary results, they could at least partially explain some adverse pregnancy outcomes in mothers exposed to pesticides or other environmental pollutants. The debate on glyphosate alone is proven insufficient for the understanding of the toxicity.

Endocrine disruptors also function as nervous disruptors and can be renamed endocrine and nervous disruptors (ENDs)

Endocrine disruption (ED) and endocrine disruptors (EDs) emerged as scientific concepts in 1995, after numerous chemical pollutants were found to be responsible for reproductive dysfunction. The World Health Organization established in the United Nations Environment Programme a list of materials, plasticizers, pesticides, and various pollutants synthesized from petrochemistry that impact not only reproduction, but also hormonal functions, directly or indirectly. Cells communicate via either chemical or electrical signals transmitted within the endocrine or nervous systems. To investigate whether hormone disruptors may also interfere directly or indirectly with the development or functioning of the nervous system through either a neuroendocrine or a more general mechanism, we examined the scientific literature to ascertain the effects of EDs on the nervous system, specifically in the categories of neurotoxicity, cognition, and behaviour. To date, we demonstrated that all of the 177 EDs identified internationally by WHO are known to have an impact on the nervous system. Furthermore, the precise mechanisms underlying this neurodisruption have also been established. It was previously believed that EDs primarily function via the thyroid. However, this study presents substantial evidence that approximately 80 % of EDs operate via other mechanisms. It thus outlines a novel concept: EDs are also neurodisruptors (NDs) and can be collectively termed endocrine and nervous disruptors (ENDs). Most of ENDs are derived from petroleum residues, and their various mechanisms of action are similar to those of "spam" in electronic communications technologies. Therefore, ENDs can be considered as an instance of spam in a biological context.

Design and synthesis of acrylate and acrylamide substituted pyrimidinediones as potential PPO herbicides

PPO herbicides emerge to be widely use in the agricultural field and a focus of research to many scientists due to its environmentally-friendly properties. In lieu with this, this study presents acrylate and acrylamide substituted pyrimidinediones as PPO herbicide candidates. Most synthesized compounds exhibits herbicidal activities against both monocot and dicot weeds, especially, compound 5a which showed non-selective superior activity against the commercialized, Saflufenacil. Compound 5a was further tested for residual effect and showed promising results as shorter period is needed to cultivate the next crops. The synthesized acrylate and acrylamide substituted pyrimidinediones, especially, 5a could potentially be utilized in the development of commercial protoporphyrinogen oxidase inhibitors with further tests and studies.

Dataset of compounds in glyphosate-free herbicides

We analysed 14 recently marketed pesticides for consumers, available in France, Germany, and Poland. They were supposed to be glyphosate-free herbicides; glyphosate was banned for sale to the public in 2019. Measurements of 36 metals, 16 polycyclic aromatic hydrocarbons, 6 essential minerals, and glyphosate plus aminomethyl phosphonic acid, were performed in a laboratory accredited for regulatory purposes. The technologies used were respectively inductively coupled plasma mass spectrometry, gas-chromatography coupled with mass spectrometry, and high-performance liquid chromatography. These data can be used by scientists, the public, and regulatory bodies.