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

Carcinogenic effects of long-term exposure from prenatal life to glyphosate and glyphosate-based herbicides in Sprague-Dawley rats

BACKGROUND

Glyphosate-based herbicides (GBHs) are the world's most widely used weed control agents. Public health concerns have increased since the International Agency for Research on Cancer (IARC) classified glyphosate as a probable human carcinogen in 2015. To further investigate the health effects of glyphosate and GBHs, the Ramazzini Institute launched the Global Glyphosate Study (GGS), which is designed to test a wide range of toxicological outcomes. Reported here are the results of the carcinogenicity arm of the GGS.

METHODS

Glyphosate and two GBHs, Roundup Bioflow used in the European Union (EU) and RangerPro used in the U.S., were administered to male and female Sprague-Dawley (SD) rats, beginning at gestational day 6 (via maternal exposure) through 104 weeks of age. Glyphosate was administered through drinking water at three doses: the EU acceptable daily intake (ADI) of 0.5 mg/kg body weight/day, 5 mg/kg body weight/day and the EU no-observed adverse effect level (NOAEL) of 50 mg/kg body weight/day. The two GBH formulations were administered at the same glyphosate-equivalent doses.

RESULTS

In all 3 treatment groups, statistically significant dose-related increased trends or increased incidences of benign and malignant tumors at multiple anatomic sites were observed compared to historical and concurrent controls. These tumors arose in haemolymphoreticular tissues (leukemia), skin, liver, thyroid, nervous system, ovary, mammary gland, adrenal glands, kidney, urinary bladder, bone, endocrine pancreas, uterus and spleen (hemangiosarcoma). Increased incidences occurred in both sexes. Most of these involved tumors that are rare in SD rats (background incidence < 1%) with 40% of leukemias deaths in the treated groups occurring before 52 weeks of age and increased early deaths were also observed for other solid tumors.

CONCLUSIONS

Glyphosate and GBHs at exposure levels corresponding to the EU ADI and the EU NOAEL caused dose-related increases in incidence of multiple benign and malignant tumors in SD rats of both sexes. Early-life onset and mortality were observed for multiple tumors. These results provide robust evidence supporting IARC's conclusion that there is "sufficient evidence of carcinogenicity [of glyphosate] in experimental animals". Furthermore, our data are consistent with epidemiological evidence on the carcinogenicity of glyphosate and GBHs.

Glyphosate-based herbicide as a potential risk factor for breast cancer

Breast cancer is the most common neoplasm in women worldwide, with both genetic and environmental factors playing a role in its development. Glyphosate, the active ingredient in widely used agricultural herbicides, is recognized as a potential carcinogen and endocrine disruptor, making it a candidate for inducing epigenetic modifications linked to breast cancer. This study investigates the effects of the glyphosate-based herbicide Roundup® on non-tumorigenic (MCF10A) and tumorigenic (MCF7 and MDA-MB-231) breast cell lines, focusing on the expression of key breast cancer-related genes. Additionally, the study examines the association with epigenetic modifications and the use of epidrugs to reverse potential alterations, aiming to understand the risks and mechanisms of herbicide action. Results indicate that Roundup® affects cells through a non-estrogenic mechanism, impacting both hormone-dependent and -independent cells with varying toxic and proliferative effects depending on dose and exposure time. Moreover, it altered the expression of breast cancer-related genes such as BRCA1 and BRCA2 at low doses. The use of epigenetic modulators was able to reverse some Roundup®-induced changes, suggesting the herbicide's role in epigenetic modifications. Overall, these findings highlight the importance of understanding glyphosate-based herbicide mechanisms in humans, which could enable personalized prevention strategies to mitigate breast cancer risks.

Toxicological concerns regarding glyphosate, its formulations, and co-formulants as environmental pollutants: a review of published studies from 2010 to 2025

Over the last decade and worldwide, an enormous investment in research and data collection has been made in the hope of better understanding the possible ecological and toxicological impacts triggered by glyphosate (GLY). This broad-spectrum, systemic herbicide became the most heavily applied pesticide ever in the 2000s. It is sprayed in many different ways in both agricultural and non-agricultural settings, resulting in multiple routes of exposure to organisms up and down the tree of life. Yet, relatively little is known about the environmental fate of GLY-based herbicide (GBH) formulations, and even less on how GBH co-formulants alter the absorption, distribution, metabolism, excretion, and toxicity of GLY. The environmental fate of GLY depends on several abiotic and biotic factors. As a result of heavy annual GBH use over several decades, GLY residues are ubiquitous, and sometimes adversely affect non-target terrestrial and aquatic organisms. GLY has become a frequent contaminant in drinking water and food chains. Human exposures have been associated with numerous adverse health outcomes including carcinogenicity, metabolic syndrome, and reproductive and endocrine-system effects. Nonetheless, the existence and magnitude of GLY-induced effects on human health remain in dispute, especially in the case of heavily exposed applicators. A wide range of biochemical/physiological modes of action have been elucidated. Various GBH co-formulants have long been considered as inert ingredients relative to herbicidal activity but clearly contribute to GLY-induced hazards and risk gradients. In light of already-identified toxicological and ecosystem impacts, the intensive research focuses on GLY and GBHs should continue, coupled in the interim with commonsense, low-cost changes in use patterns and label requirements crafted to slow the spread of GLY-resistant weeds and reduce applicator and general-population exposures.

Ecotoxicological mechanism of glyphosate on Moerella iridescens: Evidence from enzyme, histology and metabolome

This study aimed to elucidate the regulatory mechanisms underlying the toxic effects of glyphosate (GLY) on rainbow clam (M. iridescens), with implications for their culture and conservation. GLY residues in aquatic systems raise significant environmental and public health concerns, yet the underlying mechanisms remain largely elusive. In this study, M. iridescens were acutely exposed to GLY at various concentrations (0, 2.34, 5.45, 12.74, 29.74, and 69.46 mg/L) for 7 days. Gill and hepatopancreas samples were collected to assess oxidative stress status and histopathological examination. Additionally, three concentration groups low concentration (LC) group at 2.34 mg/L, medium concentration (MC) group at 12.74 mg/L, and high concentration (HC) group at 69.46 mg/L were selected for metabolomic analysis. The findings indicated that GLY exposure led to oxidative stress and structural changes in tissues. The metabolomic analysis suggested that GLY exposure exacerbates inflammatory responses and disrupts endocrine function, and sex hormones.

The key characteristics concept

In evaluating whether a chemical can cause cancer or another adverse outcome, three lines of evidence are typically considered: epidemiology, animal bioassays and mechanistic evidence. The key characteristics (KCs) form the basis of a uniform approach for searching, organizing, and evaluating mechanistic evidence to support hazard identification. KCs are the established properties of the toxicants themselves and are generated from our understanding of mechanisms of toxicity. KCs have been published for carcinogens, endocrine disruptors and reproductive, liver immune and cardiovascular toxicants. We noted that several KCs were common to different types of toxicants, whereas others were highly specific. Hence, there may be overlapping umbrella KCs for potentially hazardous bioactive chemicals that could be used in predictive toxicology. There are, however, also clearly unique KCs for chemicals that primarily target a specific organ and these unique KCs could be especially important to predicting target organ toxicity. It is possible that in silico approaches, in vitro tests, and in vivo biomarkers could be developed, which predict the "umbrella" and "unique" KCs of hazardous chemicals. However, given the significance of human evidence, the development of a set of biomarkers that could be used to measure the KCs in molecular epidemiology studies is also important.

IARC Workshop on the Key Characteristics of Carcinogens: Assessment of End Points for Evaluating Mechanistic Evidence of Carcinogenic Hazards

BACKGROUND

The 10 key characteristics (KCs) of carcinogens form the basis of a framework to identify, organize, and evaluate mechanistic evidence relevant to carcinogenic hazard identification. The 10 KCs are related to mechanisms by which carcinogens cause cancer. The International Agency for Research on Cancer (IARC) Monographs programme has successfully applied the KCs framework for the mechanistic evaluation of different types of exposures, including chemicals, metals, and complex exposures, such as environmental, occupational, or dietary exposures. The use of this framework has significantly enhanced the identification and organization of relevant mechanistic data, minimized bias in evaluations, and enriched the knowledge base regarding the mechanisms of known and suspected carcinogens.

OBJECTIVES

We sought to report the main outcomes of an IARC Scientific Workshop convened by the IARC to establish appropriate, transparent, and uniform application of the KCs in future IARC Monographs evaluations.

METHODS

A group of experts from different disciplines reviewed the IARC Monographs experience with the KCs of carcinogens, discussing three main themes: a) the interpretation of end points forming the evidence base for the KCs, b) the incorporation of data from novel assays on the KCs, and c) the integration of the mechanistic evidence as part of cancer hazard identification. The workshop participants assessed the relevance and the informativeness of multiple KCs-associated end points for the evaluation of mechanistic evidence in studies of exposed humans and experimental systems.

DISCUSSION

Consensus was reached on how to enhance the use of in silico, molecular, and cellular high-output and high-throughput data. In addition, approaches to integrate evidence across the KCs and opportunities to improve methodologies of mechanistic evaluation of cancer hazards were explored. The findings described herein and in a forthcoming IARC technical report will support future working groups of experts in reporting and interpreting results under the KCs framework within the IARC Monographs or in other contexts. https://doi.org/10.1289/EHP15389.

Detection of glyphosate, glufosinate, and their metabolites in multi-floral honey for food safety

Beehives can accumulate environmental contaminants as bees gather pollen, propolis, and water from their surroundings, contaminating hive products like honey. Moreover, in multifloral environments, bees can interact with plants treated with different pesticides, often causing higher pesticides concentrations in multi-floral honey than in mono-floral varieties. Glyphosate and glufosinate are both widely used herbicides. Glyphosate accounted for one-third of herbicide sales in Europe in 2017 and continues to raise health concerns, including its potential carcinogenicity. While the European Commission extended glyphosate's authorisation for another 10 years in 2023, concerns remain about its impact on biodiversity and human health. This study aimed to monitor the presence of glyphosate, glufosinate, and their metabolites in 100 samples of multifloral honey representing Italian production by analysis using IC-HRMS. Results indicated that 12% of honey samples contained glyphosate residues ranging from > LOQ to 45 ng g-1, with the highest concentrations detected in the Puglia region. No sample exceeded the maximum residue levels set by EU regulations. Glufosinate and its metabolites were not detected in any samples. These findings underscore the need for continued monitoring of pesticide residues in honey, particularly given the potential 'cocktail effect' of multiple contaminants and their combined toxicity. This study highlights the importance of safeguarding consumer health, especially in vulnerable populations, by addressing gaps in data on pesticide residue levels.

Urinary biomonitoring of exposure to glyphosate and its metabolite amino-methyl phosphonic acid among farmers and non-farmers in Morocco

Glyphosate, a widely used herbicide in global agriculture, poses potential health risks due to environmental and dietary exposure. This study evaluated urinary concentrations of glyphosate and its metabolite, amino-methyl phosphonic acid (AMPA), among farmers and non-farmers in Morocco's Fez-Meknes region, using liquid chromatography-tandem mass spectrometry. Glyphosate was detected in 57.14 % of farmers, 35.41 % of indirectly exposed residents, and 24 % of controls, while AMPA was present in 5.35 % of farmers only. Average glyphosate levels were 0.176 μg/L in farmers, 0.098 μg/L in indirectly exposed individuals, and 0.069 μg/L in controls, with AMPA averaging 0.253 μg/L in farmers. Sociodemographic factors, such as education level, farm residence, and herbicide storage, significantly influenced glyphosate levels, while reusing pesticide containers strongly correlated with elevated glyphosate and AMPA concentrations. Estimated daily intakes (EDIs), hazard quotients (HQs), and a hazard index (HI) were calculated to analyze the obtained data from a health risk perspective. Farmers had higher EDIGM values for AMPA (0.303 µg/d/kg) and Glyphosate (0.140 µg/d/kg) compared to the control group, which had significantly lower values of 0.110 µg/d/kg for AMPA and 0.080 µg/d/kg for Glyphosate. The HQs were calculated considering 0.5 mg/kg BW/day as an acceptable daily intake (ADI), which EFSA has established as a health-based reference value for both analytes. The values obtained were lower than 1, indicating that the health risk from Glyphosate and AMPA exposure was considered acceptable for the studied population.

In silico attempt to reveal the link between cancer development and combined exposure to the maize herbicides: Glyphosate, nicosulfuron, S-metolachlor and terbuthylazine

Pesticides are crucial for crop protection and have seen a 50 % increase in use in the last decade. Besides preventing significant crop losses their use has raised health concerns due to consumer exposure through residues in food and water. The toxicity data from individual components is often used to assess overall mixture toxicity, but uncertainty persists in understanding the behaviors of individual chemicals within these mixtures. Assessing the risk of pesticide mixture exposure remains challenging, potentially leading to overestimation or underestimation of toxicity. This study aims to establish a possible link between exposure to a herbicide mixture and genotoxic effects, focusing on cancer development. Our analysis was focused on four herbicides glyphosate, nicosulfuron, S-metolachlor and terbuthylazine. To determine the link between genes associated with cancer development due to exposure to herbicide mixture, a CTD database tools were used. Through the ToppFun tool molecular function and biological process associated with genes common to the disease of interest and selected herbicides were evaluated. And finally, GeneMANIA was used in order to analyze the function and interaction between common genes of herbicide mixture. Among the 7 common genes for herbicide mixture and cancer development coexpression characteristics were dominant at 65.41 %, 22.14 % of annotated genes shared the same pathway and 7.88 % showed co-localization. Among six target genes involved in genetic disease development co-expression was dominant at 87.34 %, colocalization at 8.03 % and shared protein domains at 4.52 %. Comprehensive molecular analyses, encompassing genomics, proteomics, and pathway analysis, are essential to unravel the specific mechanisms involved in the context of the studied mixture and its potential carcinogenic effects.

Assessment of cytotoxic and genotoxic effects of glyphosate-based herbicide on glioblastoma cell lines: Role of p53 in cellular response and network analysis

Glyphosate, the world's most widely used herbicide, has a low toxicity rating despite substantial evidence of adverse health effects. Furthermore, glyphosate-based formulations (GBFs) contain several other chemicals, some of which are known to be harmful. Additionally, chronic, and acute exposure to GBFs among rural workers may lead to health impairments, such as neurodegenerative diseases and cancer. P53 is known as a tumor suppressor protein, acting as a key regulator of the cellular response to stress and DNA damage. Therefore, mutations in the TP53 gene, which encodes p53, are common genetic alterations found in various types of cancer. Therefore, this study aimed to evaluate the cytotoxicity and genotoxicity of GBF in two glioblastoma cell lines: U87MG (TP53-proficient) and U251MG (TP53-mutant). Additionally, the study aimed to identify the main proteins involved in the response to GBF exposure using Systems Biology in a network containing p53 and another network without p53. The MTT assay was used to study the toxicity of GBF in the cell lines, the clonogenic assay was used to investigate cell survival, and the Comet Assay was used for genotoxicity evaluation. For data analysis, bioinformatics tools such as String 12.0 and Stitch 5.0 were applied, serving as a basis for designing binary networks in the Cytoscape 3.10.1 program. From the in vitro test analyses, it was observed a decrease in cell viability at doses starting from 10 ppm. Comet Assay at concentrations of 10 ppm and 30 ppm for the U251MG and U87MG cell lines, respectively observed DNA damage. The network generated with systems biology showed that the presence of p53 is important for the regulation of biological processes involved in genetic stability and neurotoxicity, processes that did not appear in the TP53-mutant network.

Two swords combination: Smartphone-assisted ratiometric fluorescent and paper sensors for dual-mode detection of glyphosate in edible malt

The long-term and excessive use of glyphosate (GLY) in diverse matrices has caused serious hazard to the human and environment. However, the ultrasensitive detection of GLY still remains challenging. In this study, the smartphone-assisted dual-signal mode ratiometric fluorescent and paper sensors based on the red-emissive gold nanoclusters (R-AuNCs) and blue-emissive carbon dots (B-CDs) were ingeniously designed accurate and sensitive detection of GLY. Upon the presence of GLY, it would quench the fluorescence of B-CDs through dynamic quenching effect, and strengthen the fluorescence response of R-AuNCs due to aggregation-induced enhancement effect. Through calculating the GLY-induced fluorescence intensity ratio of B-CDs to R-AuNCs by using a fluorescence spectrophotometer, low to 0.218 μg/mL of GLY could be detected in lab in a wide concentration range of 0.3-12 μg/mL with high recovery of 94.7-103.1% in the spiked malt samples. The smartphone-assisted ratiometric fluorescent sensor achieved in the 96-well plate could monitor 0-11 μg/mL of GLY with satisfactory recovery of 94.1-107.0% in real edible malt matrices for high-throughput analysis. In addition, a portable smartphone-assisted ratiometric paper sensor established through directly depositing the combined B-CDs/R-AuNCs probes on the test strip could realize on-site measurement of 2-8 μg/mL of GLY with good linear relationship. This study provides new insights into developing the dual-signal ratiometric sensing platforms for the in-lab sensitive detection, high-throughput analysis, and on-site portable measurement of more trace contaminants in foods, clinical and environmental samples.

Dual-recognition "turn-off-on" fluorescent Biosensor triphenylamine-based continuous detection of copper ion and glyphosate applicated in environment and living system

Heavy metal Cu2+ emitted in industry and residues of glyphosate pesticides are pervasive in ecosystems, accumulated in water bodies and organisms' overtime, constituting hazard to human and ecological balance. The development of rapid, highly selective, reversibility and sensitive biosensor in vivo detection for Cu2+ and glyphosate was imminent. A novel dual-recognition fluorescence biosensor MPH was successfully synthesized based on triphenylamine, which demonstrated remarkable ratiometric fluorescence quenching toward Cu2+, while MPH-Cu2+ (1:1) ensemble exhibited ratiometric fluorescence restoration for glyphosate, both with observable color changes in daylight and UV lamp. The biosensor exhibited rapid, outstanding selectivity, anti-interference, and multiple cycles reversibility through "turn-off-on" fluorescence towards Cu2+ and glyphosate, respectively. Surprisingly, the clearly binding mechanisms of MPH to Cu2+ and MPH-Cu2+ ensemble to glyphosate were determined, respectively, based on the Job's plot, FT-IR, ESI-HRMS, 1H NMR titration and theoretical calculations of dynamics and thermodynamics. In addition, biosensor MPH demonstrated successful detection of Cu2+ and glyphosate across diverse environmental samples including tap water, extraction solutions of traditional Chinese medicine honeysuckle and soil samples. In the meantime, fluorescence imaging of Cu2+ and glyphosate at both micro and macro scales in various living organisms, such as rice roots, MCF-7 cells, zebrafish, and mice, were successfully achieved. Overall, this work was expected to become a promising and versatile fluorescence biosensor for rapid and reversible detection of Cu2+ and glyphosate both in vitro and vivo.

Quantum Simulations and Experimental Insights into Glyphosate Adsorption Using Graphene-Based Nanomaterials

The increasing global demand for food and agrarian development brings to light a dual issue concerning the use of substances that are crucial for increasing productivity yet can be harmful to human health and the environment when misused. Herein, we combine insights from high-level quantum simulations and experimental findings to elucidate the fundamental physicochemical mechanisms behind developing graphene-based nanomaterials for the adsorption of emerging contaminants, with a specific focus on pesticide glyphosate (GLY). We conducted a comprehensive theoretical and experimental investigation of graphene-based supports as promising candidates for detecting, sensing, capturing, and removing GLY applications. By combining ab initio molecular dynamics and density functional theory calculations, we explored several chemical environments encountered by GLY during its interaction with graphene-based substrates, including pristine and punctual defect regions. Our results unveiled distinct interaction behaviors: physisorption in pristine and doped graphene regions, chemisorption leading to molecular dissociation in vacancy-type defect regions, and complex transformations involving the capture of N and O atoms from impurity-adsorbed graphene, resulting in the formation of new GLY-derived compounds. The theoretical findings were substantiated by FTIR and Raman spectroscopy, which proposed a mechanism explaining GLY adsorption in graphene-based nanomaterials. The comprehensive evaluation of adsorption energies and associated properties provides valuable insights into the intricate nature of these interactions, shedding light on potential applications and guiding future experimental investigations of graphene-based nanofilters for water decontamination.

Urinary glyphosate levels and association with mortality in the 2013-16 National Health and Nutrition Examination Survey

OBJECTIVES

Glyphosate is the most commonly used herbicide in the USA; however, its safety is still under debate. We assessed glyphosate levels and their association with overall mortality in a representative sample of the US adult population from the 2013 to 2016 National Health and Nutrition Examination Survey.

METHODS

We extracted data on urinary glyphosate (N = 2910) measured by ion chromatography isotope-dilution tandem mass spectrometry. Associations between glyphosate concentrations and demographic, lifestyle and other exposures were analyzed. Data were linked to public-use Mortality Files for 2019.

RESULTS

The mean (STD) glyphosate level was 0.53 (0.59) ng/ml, with 25.7% of the subjects having glyphosate levels at or below the detection limit. At multivariate analysis, age and creatinine were associated with glyphosate urinary levels (both P < 0.0001). There was a borderline association between glyphosate levels and mortality (HRadj 1.33; 95% CI 0.99-1.77 P = 0.06). When 3,5,6-trichloropyridinol was excluded from the Cox model, glyphosate exhibits a significant association with mortality (HRadj 1.33; 95% CI 1.00-1.77; P = 0.0532).

CONCLUSIONS

These nationally representative data suggest that recent exposure to glyphosate could be associated with increased mortality. More studies are necessary to understand population-level risk associated with the product, given its widespread use in agriculture.

Glyphosate Use and Mosaic Loss of Chromosome Y among Male Farmers in the Agricultural Health Study

BACKGROUND

Glyphosate is the most commonly used herbicide worldwide and has been implicated in the development of certain hematologic cancers. Although mechanistic studies in human cells and animals support the genotoxic effects of glyphosate, evidence in human populations is scarce.

OBJECTIVES

We evaluated the association between lifetime occupational glyphosate use and mosaic loss of chromosome Y (mLOY) as a marker of genotoxicity among male farmers.

METHODS

We analyzed blood-derived DNA from 1,606 farmers ≥ 50 years of age in the Biomarkers of Exposure and Effect in Agriculture study, a subcohort of the Agricultural Health Study. mLOY was detected using genotyping array intensity data in the pseudoautosomal region of the sex chromosomes. Cumulative lifetime glyphosate use was assessed using self-reported pesticide exposure histories. Using multivariable logistic regression, we estimated odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between glyphosate use and any detectable mLOY (overall mLOY) or mLOY affecting ≥ 10 % of cells (expanded mLOY).

RESULTS

Overall, mLOY was detected in 21.4% of farmers, and 9.8% of all farmers had expanded mLOY. Increasing total lifetime days of glyphosate use was associated with expanded mLOY [highest vs. lowest quartile; OR = 1.75 (95% CI: 1.00, 3.07), p trend = 0.03 ] but not with overall mLOY; the associations with expanded mLOY were most apparent among older (≥ 70 years of age) men [OR = 2.30 (95% CI: 1.13, 4.67), p trend = 0.01 ], never smokers [OR = 2.32 (95% CI: 1.04, 5.21), p trend = 0.04 ], and nonobese men [OR = 2.04 (95% CI: 0.99, 4.19), p trend = 0.03 ]. Similar patterns of associations were observed for intensity-weighted lifetime days of glyphosate use.

DISCUSSION

High lifetime glyphosate use could be associated with mLOY affecting a larger fraction of cells, suggesting glyphosate could confer genotoxic or selective effects relevant for clonal expansion. As the first study to investigate this association, our findings contribute novel evidence regarding the carcinogenic potential of glyphosate and require replication in future studies. https://doi.org/10.1289/EHP12834.