Exploring the half-life of glyphosate in human urine samples

Reassuring Quantitative Analysis of Glyphosate and Aminomethylphosphonic Acid Levels in Breast Milk Using Liquid Chromatography Mass Spectrometry

Purpose: The World Health Organization's International Agency on Research for Cancer has determined that glyphosate is "probably carcinogenic to humans." There is a great public interest to investigate whether glyphosate are detected in breast milk. Thus, the goal of this study was to assess the concentration of glyphosate and its main metabolite in breast milk. Materials and Methods: Liquid chromatography was performed at 25°C using a Luna NH2, 50 × 2 mm, 3⎛ m (Phenomenex) analytical column. Electrospray ionization mass spectrometry was collected using negative ionization mode. The calibration curve for glyphosate ranged from 10 to 250 ng/mL. The detection limit was 1 ng/mL. Results: Breast milk samples were collected from 74 women, which included vegans (n = 26), vegetarians (n = 22), and nonvegetarians (n = 26). One of the 74 milk samples contained a detectable concentration of glyphosate and an additional 7 were found to contain aminomethylphosphonic acid. Conclusions: In breast milk samples collected mainly from women residing in urban regions of the United States, glyphosate detection was rare. Consistently, breastfed infants have a low or minimal risk of being exposed to glyphosate through ingestion of mother's milk. It is possible that the presence/absence and/or level of concentration of milk glyphosate depend on a place of residency and time of breastfeeding vis-à-vis time of its agricultural application.

Glyphosate exposure, muscular health and functional limitations in middle-aged and older adults

BACKGROUND

Glyphosate is the most widely used herbicide worldwide, both in domestic and industrial settings. Experimental research in animal models has demonstrated changes in muscle physiology and reduced contractile strength associated with glyphosate exposure, while epidemiological studies have shown associations between glyphosate exposure and adverse health outcomes in critical biological systems affecting muscle function.

METHODS

This study used data from a nationally representative survey of the non-institutionalized U.S. general population (NHANES, n = 2132). Urine glyphosate concentrations were determined by ion chromatography with tandem mass spectrometry. Hand grip strength (HGS) was measured using a Takei Dynamometer, and relative strength estimated as the ratio between HGS in the dominant hand and the appendicular lean mass (ALM) to body mass index (ALMBMI) ratio. Low HGS and low relative HGS were defined as 1 sex-, age- and race-specific SD below the mean. Physical function limitations were identified as significant difficulty or incapacity in various activities.

RESULTS

In fully-adjusted models, the Mean Differences (MD) and 95% confidence intervals [95%CI] per doubling increase in glyphosate concentrations were -0.55 [-1.09, -0.01] kg for HGS in the dominant hand, and -0.90 [-1.58. -0.21] kg for HGS/ALMBMI. The Odds Ratios (OR) [95% CI] for low HGS, low relative HGS and functional limitations by glyphosate concentrations were 1.27 [1.03, 1.57] for low HGS; 1.43 [1.05; 1.94] for low relative HGS; 1.33 [1.08, 1.63] for stooping, crouching or kneeling difficulty; 1.17 [0.91, 1.50] for lifting or carrying items weighting up to 10 pounds difficulty; 1.21 [1.01, 1.40] for standing up from armless chair difficulty; and 1.47 [1.05, 2.29] for ascending ten steps without pause difficulty.

CONCLUSIONS

Glyphosate exposure may be a risk factor for decreased grip strength and increased physical functional limitations. More studies investigating the influence of this and other environmental pollutants on functional aging are needed.

Glyphosate as a Food Contaminant: Main Sources, Detection Levels, and Implications for Human and Public Health

Glyphosate is a broad-spectrum pesticide that has become the most widely used herbicide globally. However, concerns have risen regarding its potential health impacts due to food contamination. Studies have detected glyphosate in human blood and urine samples, indicating human exposure and its persistence in the organism. A growing body of literature has reported the health risks concerning glyphosate exposure, suggesting that the daily intake of contaminated food and water poses a public health concern. Furthermore, countries with high glyphosate usage and lenient regulations regarding food and water contamination may face more severe consequences. In this context, in this review, we examined the literature regarding food contamination by glyphosate, discussed its detection methods, and highlighted its risks to human health.

Biological Monitoring of Glyphosate Exposure among Knapsack Sprayers in Khon Kaen, Thailand

Sprayers' exposure to glyphosate was analyzed through detection of its biomarker in spot urine biological monitoring, and the health risk was assessed using the biomatrix model. Urine samples were collected from 15 sprayers after spraying, and the glyphosate concentration was determined by using the DLLME-HPLC method with a UV detector. The calibration curve for glyphosate was linear in the range of 0.4-100 µg/L, while the limits of detection and quantification were 0.1 µg/L and 0.4 µg/L, respectively. The human health risk was estimated using the hazard quotient (HQ) and the biomatrix of risk assessment. The internal dose ranged from 0.0001 to 0.0021 mg/kg b.w./day. The non-cancer HQ showed no potential health risk concerns (HQ < 1). The biomatrix of health risk assessment, based on urinary glyphosate concentration, exhibited a strong correlation with the health risk matrix model. This correlation was determined by considering the likelihood of exposure, calculated from the quantity of glyphosate used and the usage of personal protective equipment (r = 0.854, p < 0.001). Although low risk was observed in sprayers, proper PPE use and the application of more knowledge are required. The simplified health risk assessment can be used for easy self-assessment of risk in preventive action regarding health risk awareness among sprayers.

Urinary biomonitoring of glyphosate exposure among male farmers and nonfarmers in the Biomarkers of Exposure and Effect in Agriculture (BEEA) study

Glyphosate is the most widely applied herbicide worldwide. Glyphosate biomonitoring data are limited for agricultural settings. We measured urinary glyphosate concentrations and assessed exposure determinants in the Biomarkers of Exposure and Effect in Agriculture (BEEA) study. We selected four groups of BEEA participants based on self-reported pesticide exposure: recently exposed farmers with occupational glyphosate use in the last 7 days (n = 98), farmers with high lifetime glyphosate use (>80th percentile) but no use in the last 7 days (n = 70), farming controls with minimal lifetime use (n = 100), and nonfarming controls with no occupational pesticide exposures and no recent home/garden glyphosate use (n = 100). Glyphosate was quantified in first morning void urine using ion chromatography isotope-dilution tandem mass spectrometry. We estimated associations between urinary glyphosate concentrations and potential determinants using multivariable linear regression. Glyphosate was detected (≥0.2 µg/L) in urine of most farmers with recent (91 %) and high lifetime (93 %) use, as well as farming (88 %) and nonfarming (81 %) controls; geometric mean concentrations were 0.89, 0.59, 0.46, and 0.39 µg/L (0.79, 0.51, 0.42, and 0.37 µg/g creatinine), respectively. Compared with both control groups, urinary glyphosate concentrations were significantly elevated among recently exposed farmers (P < 0.0001), particularly those who used glyphosate in the previous day [vs. nonfarming controls; geometric mean ratio (GMR) = 5.46; 95 % confidence interval (CI): 3.75, 7.93]. Concentrations among high lifetime exposed farmers were also elevated (P < 0.01 vs. nonfarming controls). Among recently exposed farmers, glyphosate concentrations were higher among those not wearing gloves when applying glyphosate (GMR = 1.91; 95 % CI: 1.17, 3.11), not wearing long-sleeved shirts when mixing/loading glyphosate (GMR = 2.00; 95 % CI: 1.04, 3.86), applying glyphosate exclusively using broadcast/boom sprayers (vs. hand sprayer only; GMR = 1.70; 95 % CI: 1.00, 2.92), and applying glyphosate to crops (vs. non-crop; GMR = 1.72; 95 % CI: 1.04, 2.84). Both farmers and nonfarmers are exposed to glyphosate, with recency of occupational glyphosate use being the strongest determinant of urinary glyphosate concentrations. Continued biomonitoring of glyphosate in various settings is warranted.

Factors influencing occupational exposure to pyrethroids and glyphosate: An analysis of urinary biomarkers in Malaysia, Uganda and the United Kingdom

BACKGROUND

Long-term exposure to pesticides is often assessed using semi-quantitative models. To improve these models, a better understanding of how occupational factors determine exposure (e.g., as estimated by biomonitoring) would be valuable.

METHODS

Urine samples were collected from pesticide applicators in Malaysia, Uganda, and the UK during mixing/application days (and also during non-application days in Uganda). Samples were collected pre- and post-activity on the same day and analysed for biomarkers of active ingredients (AIs), including synthetic pyrethroids (via the metabolite 3-phenoxybenzoic acid [3-PBA]) and glyphosate, as well as creatinine. We performed multilevel Tobit regression models for each study to assess the relationship between exposure modifying factors (e.g., mixing/application of AI, duration of activity, personal protective equipment [PPE]) and urinary biomarkers of exposure.

RESULTS

From the Malaysia, Uganda, and UK studies, 81, 84, and 106 study participants provided 162, 384 and 212 urine samples, respectively. Pyrethroid use on the sampling day was most common in Malaysia (n = 38; 47%), and glyphosate use was most prevalent in the UK (n = 93; 88%). Median pre- and post-activity 3-PBA concentrations were similar, with higher median concentrations post-compared to pre-activity for glyphosate samples in the UK (1.7 to 0.5 μg/L) and Uganda (7.6 to 0.8 μg/L) (glyphosate was not used in the Malaysia study). There was evidence from individual studies that higher urinary biomarker concentrations were associated with mixing/application of the AI on the day of urine sampling, longer duration of mixing/application, lower PPE protection, and less education/literacy, but no factor was consistently associated with exposure across biomarkers in the three studies.

CONCLUSIONS

Our results suggest a need for AI-specific interpretation of exposure modifying factors as the relevance of exposure routes, levels of detection, and farming systems/practices may be very context and AI-specific.

Surface multi-walled carbon nanotube modified quaternary amine-functionalized polymers for purification and determination of glyphosate and its four metabolites in plasma samples

The present study focused on the pretreatment and detection of GLY and its four metabolites AMPA, N-acetyl AMPA, N-methyl GLY and N-acetyl GLY in plasma samples. Multi-walled carbon nanotube-modified quaternary amine-functionalized polymers (QA-PDNV@MWCNTs) were synthesized in a controlled manner by self-assembly, and its morphology and composition were extensively characterized. The QA-PDNV@MWCNTs microspheres were then used as an SPE adsorbent for the preparation and rapid determination of GLY and its four metabolites in plasma samples combined with ultra-performance liquid chromatography-high resolution mass spectrometry (UPLCHRMS). The SPE conditions based on QA-PDNV@MWCNTs were optimized for GLY and its metabolites to obtain the best purification efficiency. The experimental results show that when the adsorbent contains 8% MWCNTs, it can balance the adsorption of target analytes and the purification performance of the adsorbent for impurities. In addition, this study compared the QA-PDNV@MWCNTs based SPE method with the commercial Waters Oasis MAX SPE cartridge and the results showed that the developed method in this study has better resistance to matrix interference. Under optimal conditions, the recoveries of GLY and its metabolites spiked in plasma were 82.6-99.4 % with relative standard deviations (RSDs) of 1.0-7.8 %. The limits of detection (LODs, S/N ≥ 3) and limits of quantification (LOQs, S/N ≥ 9) of the method were 0.05-0.33 μg/L and 0.15-1.00 μg/L, respectively. Finally, the developed QA-PDNV@MWCNTs based SPE-UPLCHRMS method was used to confirm GLY poisoning not only on the basis of the detection of the GLY prototype, but also on the basis of its four metabolites.

Glyphosate spraying exacerbates nitrogen and phosphorus loss in karst slope farmland

Glyphosate herbicide is an indispensable material in agricultural production. In order to explore the potential environmental effects of glyphosate application in karst slope farmland, this paper used a variable slope steel tank to simulate the surface microtopography and underground pore structure characteristics of karst slope farmland, and combined with artificial rainfall experiments to explore the migration path of glyphosate in karst slope farmland and the impact of spraying glyphosate on soil nitrogen and phosphorus loss. The results showed that under the condition of heavy rain, glyphosate in karst slope farmland was mainly transported and diffused by surface runoff, supplemented by underground runoff; secondly, in different hydrological paths, glyphosate directly affected the content of nitrogen and phosphorus in runoff, and all showed extremely significant positive correlation (p < 0.001). In addition, rainfall conditions such as rainfall intensity, rainfall duration, and runoff affected the content of nitrogen and phosphorus in runoff to varying degrees. In conclusion, the application of glyphosate significantly increased the content of nitrogen and phosphorus in different runoff and accelerated the loss of nitrogen and phosphorus from soil, which not only led to soil degradation, but also threatened the safety of aquatic ecosystem. Therefore, in the prevention and control of agricultural non-point source pollution, the threat of glyphosate to the surrounding aquatic ecosystem cannot be ignored, especially in karst areas with frequent rainstorms and serious water erosion, long-term monitoring and risk assessment of glyphosate are needed.

The Effect of Pesticide Spray Season and Residential Proximity to Agriculture on Glyphosate Exposure among Pregnant People in Southern Idaho, 2021

BACKGROUND

Glyphosate is one of the most heavily used pesticides in the world, but little is known about sources of glyphosate exposure in pregnant people living in agricultural regions.

OBJECTIVE

Our objective was to evaluate glyphosate exposure during pregnancy in relation to residential proximity to agriculture as well as agricultural spray season.

METHODS

We quantified glyphosate concentrations in 453 urine samples collected biweekly from a cohort of 40 pregnant people in southern Idaho from February through December 2021. We estimated each participant's glyphosate exposure as the geometric mean (GM) of glyphosate concentrations measured in all samples (average n = 11 samples/participant), as well as the GM of samples collected during the pesticide "spray season" (defined as those collected 1 May-15 August; average n = 5 samples/participant) and the "nonspray season" (defined as those collected before 1 May or after 15 August; average n = 6 samples/participant). We defined participants who resided < 0.5 km from an actively cultivated agriculture field to live "near fields" and those residing ≥ 0.5 km from an agricultural field to live "far from fields" (n = 22 and 18, respectively).

RESULTS

Among participants living near fields, urinary glyphosate was detected more frequently and at significantly increased GM concentrations during the spray season in comparison with the nonspray season (81% vs. 55%; 0.228 μ g / L vs. 0.150 μ g / L , p < 0.001 ). In contrast, among participants who lived far from fields, neither glyphosate detection frequency nor GMs differed in the spray vs nonspray season (66% vs. 64%; 0.154 μ g / L vs. 0.165 μ g / L , p = 0.45 ). Concentrations did not differ by residential proximity to fields during the nonspray season (0.154 μ g / L vs. 0.165 μ g / L , for near vs. far, p = 0.53 ).

DISCUSSION

Pregnant people living near agriculture fields had significantly increased urinary glyphosate concentrations during the agricultural spray season than during the nonspray season. They also had significantly higher urinary glyphosate concentrations during the spray season than those who lived far from agricultural fields at any time of year, but concentrations did not differ during the nonspray season. These findings suggest that agricultural glyphosate spray is a source of exposure for people living near fields. https://doi.org/10.1289/EHP12768.

Self-reported and urinary biomarker-based measures of exposure to glyphosate and mancozeb and sleep problems among smallholder farmers in Uganda

OBJECTIVE

We aim to showcase the impact of applying eight different self-reported and urinary biomarker-based exposure measures for glyphosate and mancozeb on the association with sleep problems in a study among 253 smallholder farmers in Uganda.

METHODS

The questionnaire-based exposure measures included: (1) the number of application days of any pesticide in the last 7 days (never, 1-2; >2 days) and six glyphosate and mancozeb-specific measures: (2) application status over the last 12 months (yes/no), (3) recent application status (never, last 7 days and last 12 months), (4) the number of application days last 12 months, (5) average exposure-intensity scores (EIS) and (6) EIS-weighted number of application days in last 12 months. Based on 384 repeated urinary biomarker concentrations of ethylene thiourea (ETU) and glyphosate from 84 farmers, we also estimated (7) average biomarker concentrations for all 253 farmers. Also in the 84 farmers the measured pre-work and post-work biomarker concentrations were used (8). Multivariable logistic regression models were used to assess the association between the exposure measures and selected Medical Outcomes Study Sleep Scale (MOS-SS) indices (6-item, sleep inadequacy and snoring).

RESULTS

We observed positive associations between (1) any pesticide application in the last 7 days with all three MOS-SS indices. Glyphosate application in the last 7 days (3) and mancozeb application in the last 12 months (3) were associated with the 6-item sleep problem index. The estimated average urinary glyphosate concentrations showed an exposure-response association with the 6-item sleep problem index and sleep inadequacy in the same direction as based on self-reported glyphosate application in the last 7 days. In the analysis with the subset of 84 farmers, both measured and modelled post-work urinary glyphosate concentration showed an association with snoring.

CONCLUSIONS

Self-reported, estimated average biomarker concentrations and measured urinary biomarker exposure measures of glyphosate and mancozeb showed similar exposure-response associations with sleep outcomes.

Epidemiologic studies of glyphosate and non-Hodgkin's lymphoma: A review with consideration of exposure frequency, systemic dose, and study quality

I reviewed the epidemiologic literature for glyphosate and non-Hodgkin's lymphoma (NHL) in the context of the frequency of exposure in each epidemiologic study, systemic dose from biomonitoring studies of applicators, and aspects of study quality. Nine studies were identified, 7 case control and 2 cohort, by a literature search and a review of reference lists from published studies and recent regulatory evaluations. All but one study involved exposure scenarios that were so infrequent that they are not credible for cancer causation. Most studies failed to address potential confounding from other pesticides. Only one study - the US Agricultural Health Study (AHS) - included individuals with relatively frequent exposure to glyphosate and involved comprehensive statistical analyses to address potential confounding by personal factors and other pesticide exposures. The AHS did not find an association between glyphosate and NHL, even among the most frequently exposed participants (≥ 109 days of use) (RR = 0.80, 95% CI 0.60, 1.06). These findings are consistent with observations that glyphosate systemic doses from agricultural applications are many orders of magnitude less than daily lifetime doses considered by regulatory agencies to impart no excess risk of deleterious health effects, even for sensitive subpopulations.

Urinary Glyphosate, 2,4-D and DEET Biomarkers in Relation to Neurobehavioral Performance in Ecuadorian Adolescents in the ESPINA Cohort

BACKGROUND

Herbicides are the most used class of pesticides worldwide, and insect repellents are widely used globally. Yet, there is a dearth of studies characterizing the associations between these chemical groups and human neurobehavior. Experimental studies suggest that glyphosate and 2,4-dichlorophenoxyacetic acid (2,4-D) herbicides can affect neurobehavior and the cholinergic and glutamatergic pathways in the brain. We aim to assess whether herbicides and insect repellents are associated with neurobehavioral performance in adolescents.

METHODS

We assessed 519 participants (11-17 years of age) living in agricultural communities in Ecuador. We quantified urinary concentrations of glyphosate, 2,4-D, and two N,N-diethyl-meta-toluamide (DEET) insect repellent metabolites [3-(diethylcarbamoyl)benzoic acid (DCBA) and 3-(ethylcarbamoyl)benzoic acid (ECBA)] using isotope-dilution mass spectrometry. We assessed neurobehavioral performance using 9 subtests across 5 domains (attention/inhibitory control, memory/learning, language, visuospatial processing, and social perception). We characterized the associations using generalized estimating equations and multiple imputation for metabolites below detection limits. Models were adjusted for demographic and anthropometric characteristics, urinary creatinine, and sexual maturation. Mediation by salivary cortisol, dehydroepiandrosterone, 17 β -estradiol , and testosterone was assessed using structural equation modeling.

RESULTS

The mean of each neurobehavioral domain score was between 7.0 and 8.7 [standard deviation (SD) range: 2.0-2.3]. Glyphosate was detected in 98.3% of participants, 2,4-D in 66.2%, DCBA in 63.3%, and ECBA in 33.4%. 2,4-D was negatively associated with all neurobehavioral domains, but statistically significant associations were observed with attention/inhibition [score difference per 50% higher metabolite concentration ( β ) = - 0.19 95% confidence interval (CI): - 0.31 , - 0.07 ], language [β = - 0.12 (95% CI: - 0.23 , - 0.01 )], and memory/learning [β = - 0.11 (95% CI: - 0.22 , 0.01)]. Glyphosate had a statistically significant negative association only with social perception [β = - 0.08 (95% CI: - 0.14 , - 0.01 )]. DEET metabolites were not associated with neurobehavioral performance. Mediation by gender and adrenal hormones was not observed.

CONCLUSION

This study describes worse neurobehavioral performance associated with herbicide exposures in adolescents, particularly with 2,4-D. Replication of these findings among other pediatric and adult populations is needed. https://doi.org/10.1289/EHP11383.

Biomonitoring Equivalents for glyphosate

One of the most widely used herbicides worldwide, glyphosate is registered for use in many agricultural and non-agricultural settings. Accordingly, regulatory authorities develop toxicology reference values (TRVs) to conduct risk assessments for potential exposures. Exposures to glyphosate are typically biomonitored via measures of glyphosate in urine. However, measured concentrations of glyphosate in urine, with units mg/L urine, cannot be directly interpreted using the available TRVs as they are presented in terms of daily intake levels (e.g. mg/kg-bw per day). In this evaluation, we review available health-based risk assessments and TRVs for glyphosate and derive Biomonitoring Equivalent (BE) values for interpretation of population biomonitoring data. Biomonitoring Equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, human milk, etc.) that is consistent with an existing health-based TRVs such as a reference dose (RfD) or tolerable daily intake (TDI). The BE values derived in this manuscript are screening values that can help public health officials and regulators interpret glyphosate biomonitoring data.

Underestimation of glyphosate intake by the methods currently used by regulatory agencies

The acceptable daily intake (ADI) is an estimate of the amount of a substance in food or beverages that can be consumed daily over a lifetime without presenting an appreciable risk to health. To assess the risk of ingesting glyphosate, regulatory agencies compare glyphosate daily intake to ADI. Based on published data on urine glyphosate levels measured according to known quantities of ingested glyphosate, our objectives were to test the robustness of the mathematical model currently used to calculate glyphosate daily intake, and to propose alternative models based on urinary excretion kinetics. Our results support that the quantity of ingested glyphosate is systematically underestimated by the model currently used by regulatory agencies, whereas the other models evaluated showed better estimations, with differences according to gender. Our results also show a great variability between individuals, leading to some uncertainties notably with regards to the ADI, and further support that glyphosate excretion varies significantly among individuals who follow a similar dosing regimen. In conclusion, our study highlights the lack of reliability of assessment processes carried out by regulatory agencies for glyphosate in particular, and pesticides in general, and questions the relevance of such processes supposed to safeguard human health and the environment.

Occurrence and exposure assessment of glyphosate in the environment and its impact on human beings

Glyphosate is a broad-spectrum and one of the most widely used herbicides in the world, which has led to its high environmental dissemination. In 2015, the International Agency for Research on Cancer stated that glyphosate was a probable human carcinogen. Since then, several studies have provided new data about the environmental exposure of glyphosate and its consequences on human health. Thus, the carcinogenic effects of glyphosate are still under debate. This work aimed to review glyphosate occurrence and exposure since 2015 up to date, considering studies associated with either environmental or occupational exposure and the epidemiological assessment of cancer risk in humans. These articles showed that herbicide residues were detectable in all spheres of the earth and studies on the population showed an increase in the concentration of glyphosate in biofluids, both in the general population and in the occupationally exposed population. However, the epidemiological studies under review provided limited evidence for the carcinogenicity of glyphosate, which was consistent with the International Agency for Research on Cancer classification as a probable carcinogen.

Urinary Glyphosate Concentrations among Pregnant Participants in a Randomized, Crossover Trial of Organic and Conventional Diets

BACKGROUND

Consumption of an organic diet reduces exposure to a range of agricultural pesticides. Only three studies have examined the effect of an organic diet intervention on exposure to the herbicide glyphosate, the most heavily used agricultural chemical in the world. Despite its widespread use, the primary sources of glyphosate exposure in humans are poorly understood.

OBJECTIVE

Our objective was to examine the effect of an organic diet intervention on urinary glyphosate concentrations among pregnant individuals.

METHODS

We conducted a 2-wk randomized crossover trial in which 39 pregnant participants living near (≤ 0.5 km ) and far (> 0.5 km ) from agricultural fields received a 1-wk supply of conventional groceries and 1 wk of organic groceries, randomized to order. We collected daily first morning void urine samples and analyzed composite samples from each week for glyphosate. We examined differences in urinary glyphosate concentrations between the conventional week and the organic week among all participants and stratified by residential proximity to an agricultural field.

RESULTS

Median specific gravity-adjusted glyphosate concentrations were 0.19 μ g / L and 0.16 μ g / L during the conventional and organic weeks, respectively. We observed modest decreases in urinary glyphosate concentrations from the conventional to organic week among far-field participants, but no difference among near-field participants. In secondary analyses excluding participants who did not meet a priori criteria of compliance with the intervention, we observed significant decreases in urinary glyphosate concentrations, particularly among far-field participants (p < 0.01 - 0.02 , depending on exclusion criteria).

DISCUSSION

This trial is the first to examine the effect of an organic diet intervention on glyphosate among people living near and far from agricultural fields. Our results suggest that diet is an important contributor to glyphosate exposure in people living > 0.5 km from agricultural fields; for people living near crops, agriculture may be a dominant exposure source during the pesticide spray season. https://doi.org/10.1289/EHP12155.

Urinary glyphosate and AMPA levels in a cross-sectional study of postmenopausal women: Associations with organic eating behavior and dietary intake

Animal and epidemiologic studies suggest that there may be adverse health effects from exposure to glyphosate, the most highly used pesticide in the world, and its metabolite aminomethylphosphonic acid (AMPA). Meanwhile, consumption of organic foods (presumably grown free of chemical pesticides) has increased in recent years. However, there have been limited biomonitoring studies assessing the levels of human glyphosate and AMPA exposure in the United States. We examined urinary levels of glyphosate and AMPA in the context of organic eating behavior in a cohort of healthy postmenopausal women residing in Southern California and evaluated associations with demographics, dietary intake, and other lifestyle factors. 338 women provided two first-morning urine samples and at least one paired 24-h dietary recall reporting the previous day's dietary intake. Urinary glyphosate and AMPA were measured using LC-MS/MS. Participants reported on demographic and lifestyle factors via questionnaires. Potential associations were examined between these factors and urinary glyphosate and AMPA concentrations. Glyphosate was detected in 89.9% of urine samples and AMPA in 67.2%. 37.9% of study participants reported often or always eating organic food, 30.2% sometimes, and 32.0% seldom or never. Frequency of organic food consumption was associated with several demographic and lifestyle factors. Frequent organic eaters had significantly lower urinary glyphosate and AMPA levels, but not after adjustment for covariates. Grain consumption was significantly associated with higher urinary glyphosate levels, even among women who reported often or always eating organic grains. Soy protein and alcohol consumption as well as high frequency of eating fast food were associated with higher urinary AMPA levels. In conclusion, in the largest study to date examining paired dietary recall data and measurements of first-void urinary glyphosate and AMPA, the vast majority of subjects sampled had detectable levels, and significant dietary sources in the American diet were identified.

Glyphosate exposure and preterm birth: A nested case-control pilot study

Preterm birth (PTB) is associated with a high risk of infant mortality and long-term adverse health effects. Glyphosate is a broad-spectrum herbicide applied in agricultural and non-agricultural settings. Studies suggested an association between maternal exposure to glyphosate and PTB among mostly racially homogenous populations, though results were inconsistent. The objective of this pilot study was to inform the design of a larger and more definitive study of glyphosate exposure and adverse birth outcomes in a racially-diverse population. Urine was obtained from 26 women with a PTB as cases and 26 women with a term birth as controls, from participants enrolled in a birth cohort in Charleston, South Carolina. We used binomial logistic regression to estimate associations between urinary glyphosate and the odds of PTB, and multinomial regression to estimate associations between maternal racial identity and urinary glyphosate among controls. Glyphosate was unrelated to PTB (odds ratio (OR) = 1.06, 95% CI: 0.61, 1.86). Women who identified as Black had greater odds (OR = 3.83, 95% CI: 0.13, 111.33) of having categorical "high" glyphosate (> 0.28 ng/mL) and lesser odds (OR = 0.79, 95% CI: 0.05, 12.21) of "low" glyphosate (< 0.03 ng/mL) relative to women who identified as white, suggesting a potential racial disparity, although the effect estimates were imprecise and included the null. Given concerns of potential reproductive toxicity of glyphosate, the results merit confirmation in a larger investigation to determine specific sources of glyphosate exposure, incorporating longitudinal urinary glyphosate measures during pregnancy and a comprehensive measure of diet.

Association of Lifetime Exposure to Glyphosate and Aminomethylphosphonic Acid (AMPA) with Liver Inflammation and Metabolic Syndrome at Young Adulthood: Findings from the CHAMACOS Study

BACKGROUND

The prevalence of liver disorders and metabolic syndrome has increased among youth. Glyphosate, the most widely used herbicide worldwide, could contribute to the development of these conditions.

OBJECTIVE

We aimed to assess whether lifetime exposure to glyphosate and its degradation product, aminomethylphosphonic acid (AMPA), is associated with elevated liver transaminases and metabolic syndrome among young adults.

METHODS

We conducted a prospective cohort study (n = 480 mother-child dyads) and a nested case-control study (n = 60 cases with elevated liver transaminases and 91 controls) using data from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS). We measured glyphosate and AMPA concentrations in urine samples collected during pregnancy and at child ages 5, 14, and 18 y from cases and controls. We calculated glyphosate residue concentrations: [glyphosate  +   ( 1.5 × AMPA ) ]. We estimated the amount of agricultural-use glyphosate applied within a 1 - km radius of every residence from pregnancy to age 5 y for the full cohort using California Pesticide Use Reporting data. We assessed liver transaminases and metabolic syndrome at 18 y of age.

RESULTS

Urinary AMPA at age 5 y was associated with elevated transaminases [relative risk (RR) per 2 - fold increase = 1.27 , 95% confidence interval (CI): 1.06, 1.53] and metabolic syndrome (RR = 2.07 , 95% CI: 1.38, 3.11). Urinary AMPA and glyphosate residues at age 14 y were associated with metabolic syndrome [RR = 1.80 (95% CI: 1.10, 2.93) and RR = 1.88 (95% CI: 1.03, 3.42), respectively]. Overall, a 2-fold increase in urinary AMPA during childhood was associated with a 14% and a 55% increased risk of elevated liver transaminases and metabolic syndrome, respectively. Living near agricultural glyphosate applications during early childhood (birth to 5 y of age) was also associated with metabolic syndrome at age 18 y in the case-control group (RR = 1.53 , 95% CI: 1.16, 2.02).

DISCUSSION

Childhood exposure to glyphosate and AMPA may increase risk of liver and cardiometabolic disorders in early adulthood, which could lead to more serious diseases later in life. https://doi.org/10.1289/EHP11721.

Urinary concentrations and determinants of glyphosate and glufosinate in pregnant Canadian participants in the MIREC study

BACKGROUND

Glyphosate is the most widely applied herbicide in agriculture. Glufosinate is a broad spectrum herbicide used to manage glyphosate-resistant weeds. Despite the widespread use of these herbicides, biomonitoring data - which inform risk assessment and management - are sparse.

OBJECTIVES

To identify determinants of urinary concentrations of these herbicides and their metabolites in pregnancy.

METHODS

We measured urinary concentrations of glyphosate, glufosinate, and their primary metabolites aminomethylphosphonic acid (AMPA) and 3-methylphosphinicopropionic acid (3-MPPA) in a single spot urine specimen collected during the first trimester of pregnancy from the Maternal-Infant Research on Environmental Chemicals (MIREC) study. MIREC recruited about 2000 pregnant women from 10 Canadian cities between 2008 and 2011. We used UItra-Performance Liquid Chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) with sensitive limits of detection to quantify analyte concentrations. We examined urinary concentrations according to maternal sociodemographics, sample collection characteristics, reported pesticide use, and consumption of fruits, vegetables, legumes, and grain products. We used ANOVA models with specific gravity-standardized chemical concentrations as the dependent variable to determine associations with maternal and sample determinants.

RESULTS

Among women with biobanked urine samples (n = 1829-1854), 74% and 72% had detectable concentrations of glyphosate and AMPA, respectively. In contrast, one and six percent of women had detectable concentrations of glufosinate and 3-MPPA, respectively. The specific gravity-standardized geometric mean (95% CI) concentrations of glyphosate and AMPA were 0.112 (0.099-0.127) μg/L and 0.159 (0.147-0.172) μg/L, respectively. We observed a dose-response relationship between consumption of whole grain bread and higher urinary glyphosate concentrations. Season of urine collection and self-reported pesticide use were not associated with increased concentrations of any analyte.

CONCLUSIONS

We detected glyphosate and AMPA in the majority of pregnant women from this predominantly urban Canadian cohort. Diet was a probable route of exposure.

Systematic literature review of the epidemiology of glyphosate and neurological outcomes

PURPOSE

Human health risk assessments of glyphosate have focused on animal toxicology data for determining neurotoxic potential. Human epidemiological studies have not yet been systematically reviewed for glyphosate neurotoxicity hazard identification. The objective of this systematic literature review was to summarize the available epidemiology of glyphosate exposure and neurological outcomes in humans.

METHODS

As of December 2021, 25 eligible epidemiological studies of glyphosate exposure and neurological endpoints were identified and assessed for five quality dimensions using guidance from the U.S. Environmental Protection Agency. Studies that assessed personal use of glyphosate were prioritized, whereas those assessing indirect exposure (other than personal use) were rated as low quality, since biomonitoring data indicate that indirect metrics of glyphosate exposure almost always equate to non-detectable glyphosate doses.

RESULTS

Overall, the scientific evidence on glyphosate and neurotoxicity in humans is sparse and methodologically limited, based on nine included epidemiological studies of neurodegenerative outcomes (two high quality), five studies of neurobehavioral outcomes (two high quality), six studies of neurodevelopmental outcomes (none high quality), and five studies of other and mixed neurological outcomes (one high quality). The five high-quality studies showed no association between glyphosate use and risk of depression, Parkinson disease, or peripheral nerve conduction velocity. Results were mixed among the eight moderate-quality studies, which did not demonstrate consistent associations with any neurological endpoints or categories. Low-quality studies were considered uninformative about possible neurotoxic effects due primarily to questionable assessments of indirect exposure.

CONCLUSIONS

No association has been demonstrated between glyphosate and any neurological outcomes in humans. To move the state of science forward, epidemiological studies should focus on scenarios involving direct and frequent use of glyphosate while collecting information on validated health outcomes, concomitant agricultural exposures, and relevant personal characteristics.

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.

A Human Biomonitoring Study Assessing Glyphosate and Aminomethylphosphonic Acid (AMPA) Exposures among Farm and Non-Farm Families

Glyphosate-based pesticides are the highest-volume used herbicides worldwide. International concerns regarding the potential human adverse effects of glyphosate exposures have heightened since IARC classified glyphosate as probably carcinogenic to humans. Human biomonitoring (HBM) studies have identified ubiquitous exposure to glyphosate and its main breakdown product, aminomethylphosphonic acid (AMPA), from environmental exposures. The IMAGE research project aimed to investigate farm and non-farm families' exposure to glyphosate while aligning with the Human Biomonitoring for Europe (HBM4EU) initiative. The study recruited non-farm and farm families (who use glyphosate on their farms). Each family member provided a urine sample that was analysed using gas chromatography coupled with tandem mass spectrometry, with a limit of quantification of 0.05 µg/L for glyphosate and AMPA. In addition to general information on background exposures in farm and non-farm families, we investigated relationships in exposure between families and family members. We recruited 68 families, including 54 non-farm and 14 farm families (180 vs. 45 individuals). Some pesticide users (n = 14, all male farmers) had slightly elevated AMPA levels compared to other adult participants but, overall, we observed no significant differences between farm and non-farm families. The main metabolite, AMPA, was quantifiable in twice as many samples as glyphosate (61% vs. 32%), with a maximum concentration of 7.24 µg/L vs. 3.21 µg/L. Compared to previous studies, exposure levels were relatively low and far below current health-based guidance values (3% or less for glyphosate and AMPA). Study results suggest potential exposures from residential co-exposures or living with a pesticide user. This is the first study internationally to investigate glyphosate and AMPA across family members (farm and non-farm). We found comparably low glyphosate and AMPA exposures among these families. These results enhance our understanding of glyphosate exposures for different demographic groups and contribute to the scientific knowledge on exposures required for regulatory risk assessments and the re-evaluation of glyphosate in 2022 by the European Commission.

Glyphosate and AMPA in Human Urine of HBM4EU-Aligned Studies: Part B Adults

Within HBM4EU, human biomonitoring (HBM) studies measuring glyphosate (Gly) and aminomethylphosphonic acid (AMPA) in urine samples from the general adult population were aligned and quality-controlled/assured. Data from four studies (ESB Germany (2015-2020); Swiss HBM4EU study (2020); DIET-HBM Iceland (2019-2020); ESTEBAN France (2014-2016)) were included representing Northern and Western Europe. Overall, median values were below the reported quantification limits (LOQs) (0.05-0.1 µg/L). The 95th percentiles (P95) ranged between 0.24 and 0.37 µg/L urine for Gly and between 0.21 and 0.38 µg/L for AMPA. Lower values were observed in adults compared to children. Indications exist for autonomous sources of AMPA in the environment. As for children, reversed dosimetry calculations based on HBM data in adults did not lead to exceedances of the ADI (proposed acceptable daily intake of EFSA for Gly 0.1 mg/kg bw/day based on histopathological findings in the salivary gland of rats) indicating no human health risks in the studied populations at the moment. However, the controversy on carcinogenicity, potential endocrine effects and the absence of a group ADI for Gly and AMPA induce uncertainty to the risk assessment. Exposure determinant analysis showed few significant associations. More data on specific subgroups, such as those occupationally exposed or living close to agricultural fields or with certain consumption patterns (vegetarian, vegan, organic food, high cereal consumer), are needed to evaluate major exposure sources.

Urinary glyphosate kinetics after occupational exposure

Glyphosate-surfactant herbicides are the most used and imported herbicide in Thailand. Urinary biomonitoring is a very important tool for evaluating glyphosate exposures and its adverse health effects. However, the data for glyphosate toxicokinetics, especially in Asian populations, is relatively limited. The majority of farmers in Thailand have long term experience with glyphosate use, but they generally follow poor safety practices, including insufficient or incorrect use of personal protective equipment during pesticide handling activities. Therefore, this study aimed to determine the toxicokinetics of glyphosate and its metabolite in urine among maize farmers from the northern region of Thailand. The effects of personal protective equipment usage, as well as farmer behavior during work, on urinary glyphosate levels were also studied. Full-voided spot urine samples were collected over the exposure assessment period (0-72 h). Urinary glyphosate levels were determined by liquid chromatography tandem mass spectrometry. The maximum concentration in urine (uC_max), the time of peak glyphosate levels in urine (uT_max), and the urinary elimination half-life (ut_1/2) were analyzed using the PKSolver program. The median of uC_max were 27.9, 29.2 and 17.1 μg/g creatinine in a one-time spray group, a two-time spray group Day 1 and a two-time spray group Day 2, respectively. The uT_max was 11.0 h in both study groups. The median of elimination ut_1/2 in the one-time and the two-time spray group were 7.0 and 18.1 h, respectively. Although these estimated urinary elimination half-lives may have been impacted by the variation in exposure doses among the participants, it provides the first urinary toxicokinetic data of glyphosate among the Asian population. The toxicokinetic information could be used to increase knowledge and awareness amongst farmers, particularly to minimize the risk of exposure to glyphosate and reduce possible adverse health effects from using pesticide.

Glyphosate and AMPA in Human Urine of HBM4EU Aligned Studies: Part A Children

Few data are available on the exposure of children to glyphosate (Gly) in Europe. Within HBM4EU, new HBM exposure data were collected from aligned studies at five sampling sites distributed over Europe (studies: SLO CRP (SI); ORGANIKO (CY); GerES V-sub (DE); 3XG (BE); ESTEBAN (FR)). Median Gly concentrations in urine were below or around the detection limit (0.1 µg/L). The 95th percentiles ranged between 0.18 and 1.03 µg Gly/L. The ratio of AMPA (aminomethylphosphonic acid; main metabolite of Gly) to Gly at molar basis was on average 2.2 and the ratio decreased with higher Gly concentrations, suggesting that other sources of AMPA, independent of metabolism of Gly to AMPA in the monitored participants, may concurrently operate. Using reverse dosimetry and HBM exposure data from five European countries (east, west and south Europe) combined with the proposed ADI (acceptable daily intake) of EFSA for Gly of 0.1 mg/kg bw/day (based on histopathological findings in the salivary gland of rats) indicated no human health risks for Gly in the studied populations at the moment. However, the absence of a group ADI for Gly+AMPA and ongoing discussions on e.g., endocrine disrupting effects cast some uncertainty in relation to the current single substance ADI for Gly. The carcinogenic effects of Gly are still debated in the scientific community. These outcomes would influence the risk conclusions presented here. Finally, regression analyses did not find clear associations between urinary exposure biomarkers and analyzed potential exposure determinants. More information from questionnaires targeting exposure-related behavior just before the sampling is needed.

Effects of exposure to glyphosate on oxidative stress, inflammation, and lung function in maize farmers, Northern Thailand

BACKGROUND

Glyphosate is a herbicide which is commonly used in agricultural areas. However, previous studies on glyphosate exposure in farmers and their health are still scarce.

METHODS

A longitudinal pre-post study was performed among maize farmers. Information from questionnaires, urine and blood samples, and lung function were collected a day before and a day after glyphosate application in the morning. The urine samples were analyzed using liquid chromatography-tandem mass spectrometry to detect glyphosate levels. Serum samples were analyzed to detect malondialdehyde (MDA), glutathione (GHS), and C-reactive protein (CRP) levels using thiobarbituric acid, dithiobisnitrobenzoic acid, and nephelometry, respectively. Lung function performances were measured using a spirometer.

RESULTS

A total of 180 maize farmers met the study inclusion criteria. After glyphosate application, it was found that increased urinary glyphosate levels contributed to increased serum MDA (β = 0.024, 95% CI = 0.000, 0.0047) and decreased serum GHS (β = -0.022, 95% CI = -0.037, -0.007), FEV1 (β = -0.134, 95% CI = -0.168, -0.100), FEV1/FVC (β = -0.062, 95% CI = -0.082, -0.042) and PEF (β = -0.952, 95% CI = -1.169, -0.735).

CONCLUSIONS

Exposure to glyphosate during glyphosate application had significant effects on oxidative stress and lung function in maize farmers.

Widespread pesticide contamination of drinking water and impact on cancer risk in Brazil

Pesticides, which are associated with endocrine dysfunction, immunological dysregulation, and cancer, are widespread sources of drinking water contamination. The state of Paraná has a population of 11 million, is the second largest grain producer in Brazil and is a leading consumer of pesticides. In this study, we analyzed the extent of drinking water contamination from 11 proven, probable, or potentially carcinogenic pesticides (alachlor, aldrin-dieldrin, atrazine, chlordane, DDT-DDD-DDE, diuron, glyphosate-AMPA, lindane-γ-HCH, mancozeb-ETU, molinate, and trifluralin) in 127 grain-producing municipalities in the state of Paraná. Extensive contamination of drinking water was found, including legacy pesticides such as aldrin-dieldrin (mean 0.047 ppb), DDT-DDD-DDE (mean: 0.07), chlordane (mean: 0.181), and lindane-HCH (mean: 2.17). Most of the municipalities were significantly above the maximum limits for each one of the currently allowed pesticides (67% for alachlor, 9.44% for atrazine, 96.85% for diuron, 100% for glyphosate-AMPA, 80.31% for mancozeb-ETU, 91.33% for molinate, and 12.6% for trifluralin). Ninety-seven percent of municipalities presented a sum of all pesticides at levels significantly above (189.84 ppb) the European Union preconized limits (<0.5 ppb). Using the mean pesticide concentration in water (ppb), the exposed population for each municipality, and the benchmark cancer risk for pesticides, we estimated the minimum number of cancer cases attributable to pesticide-contaminated drinking water during the period (total of 542 cases). More than 80% were attributed to mancozeb-ETU and diuron. Glyphosate-AMPA and diuron-attributable cases strongly correlated with the total cancer cases in the same period (R = 0.8117 and 0.8138, respectively) as well as with breast cancer cases (R = 0.7695 and 0.7551, respectively). Water contamination was significantly correlated with the sum of the estimated cancer cases for all 11 pesticides detected in each city (R = 0.58 and p < 0.0001). These findings reveal extensive contamination of drinking water in the state of Paraná and suggest that contamination may increase the risk of cancer in this region.

Temporal trend and cross-sectional characterization of urinary concentrations of glyphosate in Japanese children from 2006 to 2015

BACKGROUND

Over the past two decades, domestic shipments of glyphosate (Gly), in the form of an ionic salt, have been increasing steadily in Japan. This increase has raising concerns about the effects of chemical exposure on children. The International Agency for Research on Cancer classified Gly as a "probably carcinogenic to humans (Group 2A)" in 2015. The purpose of the current study was to analyze Gly in urine samples of Japanese children to determine temporal changes, seasonal changes, and gender differences.

METHOD

First-morning urine samples were obtained from 50 Japanese children (4-6-year-old) in October of 2006, 2011, and 2015 (total = 150) to investigate the temporal trends in urinary Gly concentrations. Additionally, first-morning urine samples were collected from 3-year-old children in August-September of 2012 (summer; n = 42) and in February of 2013 (winter; n = 42) to investigate the seasonal and gender differences, and the correlations between urinary Gly concentrations and insecticide exposure biomarkers. Urine samples were analyzed to measure for Gly using a liquid chromatography with tandem mass spectrometry (LC-MS/MS).

RESULTS

Detectable Gly concentrations were found in 41% of the 234 children. The 75th percentile and maximum concentrations of urinary Gly were 0.20 and 1.33 μg/L, respectively. The urinary Gly concentration in 2015 was significantly higher than in 2006, suggesting that the Gly exposure levels have been increasing. No seasonal or gender-specific differences in urinary Gly concentrations were observed, and no correlation with insecticide exposure biomarkers was found.

CONCLUSION

This study revealed that Gly exposure trends show an increase between 2006 and 2015, and that season and gender were not the exposure-determining factors. Overall, urinary concentrations of Gly were comparable with studies from other countries.

A Method for the Analysis of Glyphosate, Aminomethylphosphonic Acid, and Glufosinate in Human Urine Using Liquid Chromatography-Tandem Mass Spectrometry

The extensive use of herbicides, such as glyphosate and glufosinate, in crop production during recent decades has raised concerns about human exposure. Nevertheless, analysis of trace levels of these herbicides in human biospecimens has been challenging. Here, we describe a method for the determination of urinary glyphosate, its degradation product aminomethylphosphonic acid (AMPA), and glufosinate using liquid chromatography-tandem mass spectrometry (LC−MS/MS). The method was optimized using isotopically labelled internal standards (13C2, 15N-glyphosate, 13C, 15N, D2-AMPA, and D3-glufosinate) and solid-phase extraction (SPE) with cation-exchange and anion-exchange cartridges. The method provides excellent chromatographic retention, resolution and peak shape of target analytes without the need for strong acidic mobile phases and derivatization steps. The instrument linearity was in the range of 0.1−100 ng/mL, with R > 0.99 in the matrix for all analytes. The method detection limits (MDLs) and the method quantification limits (MQLs) were in the ranges of 0.12 (AMPA and glufosinate)−0.14 (glyphosate) ng/mL and 0.40 (AMPA)−0.48 (glyphosate) ng/mL, respectively. The recoveries of analytes spiked into urine matrix ranged from 79.1% to 119%, with coefficients of variation (CVs) of 4−10%. Repeated analysis of samples for over 2 weeks showed intra-day and inter-day analytical variations of 3.13−10.8% and 5.93−12.9%, respectively. The matrix effects for glyphosate, AMPA, and glufosinate spiked into urine matrix averaged −14.4%, 13.2%, and 22.2%, respectively. The method was further validated through the analysis of external quality assurance proficiency test (PT) urine samples. The method offers optimal sensitivity, accuracy, and precision for the urine-based assessment of human exposure to glyphosate, AMPA, and glufosinate.

Association of Glyphosate Exposure with Blood DNA Methylation in a Cross-Sectional Study of Postmenopausal Women

BACKGROUND

Glyphosate is the most commonly used herbicide in the world and is purported to have a variety of health effects, including endocrine disruption and an elevated risk of several types of cancer. Blood DNA methylation has been shown to be associated with many other environmental exposures, but to our knowledge, no studies to date have examined the association between blood DNA methylation and glyphosate exposure.

OBJECTIVE

We conducted an epigenome-wide association study to identify DNA methylation loci associated with urinary glyphosate and its metabolite aminomethylphosphonic acid (AMPA) levels. Secondary goals were to determine the association of epigenetic age acceleration with glyphosate and AMPA and develop blood DNA methylation indices to predict urinary glyphosate and AMPA levels.

METHODS

For 392 postmenopausal women, white blood cell DNA methylation was measured using the Illumina Infinium MethylationEPIC BeadChip array. Glyphosate and AMPA were measured in two urine samples per participant using liquid chromatography-tandem mass spectrometry. Methylation differences at the probe and regional level associated with glyphosate and AMPA levels were assessed using a resampling-based approach. Probes and regions that had an false discovery rate q < 0.1 in ≥ 90 % of 1,000 subsamples of the study population were considered differentially methylated. Differentially methylated sites from the probe-specific analysis were combined into a methylation index. Epigenetic age acceleration from three epigenetic clocks and an epigenetic measure of pace of aging were examined for associations with glyphosate and AMPA.

RESULTS

We identified 24 CpG sites whose methylation level was associated with urinary glyphosate concentration and two associated with AMPA. Four regions, within the promoters of the MSH4, KCNA6, ABAT, and NDUFAF2/ERCC8 genes, were associated with glyphosate levels, along with an association between ESR1 promoter hypomethylation and AMPA. The methylation index accurately predicted glyphosate levels in an internal validation cohort. AMPA, but not glyphosate, was associated with greater epigenetic age acceleration.

DISCUSSION

Glyphosate and AMPA exposure were associated with DNA methylation differences that could promote the development of cancer and other diseases. Further studies are warranted to replicate our results, determine the functional impact of glyphosate- and AMPA-associated differential DNA methylation, and further explore whether DNA methylation could serve as a biomarker of glyphosate exposure. https://doi.org/10.1289/EHP10174.

The association between urinary glyphosate and aminomethyl phosphonic acid with biomarkers of oxidative stress among pregnant women in the PROTECT birth cohort study

BACKGROUND

Glyphosate is a widely used herbicide in global agriculture. Glyphosate and its primary environmental degradate, aminomethyl phosphonic acid (AMPA), have been shown to disrupt endocrine function and induce oxidative stress in in vitro and animal studies. To our knowledge, these relationships have not been previously characterized in epidemiological settings. Elevated urinary levels of glyphosate and AMPA may be indicative of health effects caused by previous exposure via multiple mechanisms including oxidative stress.

METHODS

Glyphosate and AMPA were measured in 347 urine samples collected between 16 and 20 weeks gestation and 24-28 weeks gestation from pregnant women in the PROTECT birth cohort. Urinary biomarkers of oxidative stress, comprising 8-isoprostane-prostaglandin-F2α (8-iso-PGF2α), its metabolite 2,3-dinor-5,6-dihydro-15-F2 t-isoprostane (8-isoprostane metabolite) and prostaglandin-F2α (PGF2α), were also measured. Linear mixed effect models assessed the association between exposures and oxidative stress adjusting for maternal age, smoking status, alcohol consumption, household income and specific gravity. Potential nonlinear trends were also assessed using tertiles of glyphosate and AMPA exposure levels.

RESULTS

No significant differences in exposure or oxidative stress biomarker concentrations were observed between study visits. An interquartile range (IQR) increase in AMPA was associated with 9.5% (95% CI: 0.5-19.3%) higher 8-iso-PGF2α metabolite concentrations. Significant linear trends were also identified when examining tertiles of exposure variables. Compared to the lowest exposure group, the second and third tertiles of AMPA were significantly associated with 12.8% (0.6-26.5%) and 15.2% (1.8-30.3%) higher 8-isoprostane metabolite, respectively. An IQR increase in glyphosate was suggestively associated with 4.7% (-0.9 to 10.7%) higher 8-iso-PGF2α.

CONCLUSIONS

Urinary concentrations of the main environmental degradate of glyphosate, AMPA, were associated with higher levels of certain oxidative stress biomarkers. Associations with glyphosate reflected similar trends, although findings were not as strong. Additional research is required to better characterize the association between glyphosate exposure and biomarkers of oxidative stress, as well as potential downstream health consequences.

Genotoxicity of Glyphosate on Cultured Human Lymphocytes

Glyphosate-based herbicides are the most used herbicides in the world. Despite being widely used, a dispute exists whether glyphosate-based herbicides have a negative effect on human health, particularly genotoxic effects. Therefore, the aim of this study was to investigate glyphosate genotoxicity on cultured human lymphocytes. Cultured human lymphocytes were treated with different concentrations of glyphosate (20, 40, and 200 µmol/L). Four toxicity measures were examined: frequency of chromosomal aberrations (CAs), frequency of sister-chromatid exchange (SCE), production of 8-OHdG, and cell kinetics analysis. The results show that glyphosate induced significant (P < 0.05) increases in the levels of SCE at the highest used concentration (200 μmol/L). However, no significant elevation in SCE levels was observed at the lower examined concentrations (20 and 40 μmol/L). No significant changes in CA were detected at all examined concentrations (P = 0.86). Also, glyphosate did not induce changes to the normal level of 8-OHdG at all examined concentrations (P = 0.98). Last, no significant changes in either mitotic index or proliferative index were observed at any examined concentrations (P > 0.05). The results collectively indicate a lack of genotoxicity and cytotoxicity of glyphosate in cultured human lymphocytes when dealing with environmentally relevant concentrations (20 and 40 μmol/L). However, being exposed to higher concentrations (200 μmol/L) led to slightly higher level of SCE. Therefore, we recommend cautionary measures when dealing with glyphosate-based herbicides for individuals, such as farmers, who may be extensively exposed to high concentrations of these herbicides.

Glyphosate and AMPA exposure in relation to markers of biological aging in an adult population-based study

BACKGROUND/AIM

Glyphosate, a broad-spectrum herbicide, and its main metabolite aminomethylphosphonic acid (AMPA) are persistent in the environment. Studies showed associations between glyphosate or AMPA exposure and several adverse cellular processes, including metabolic alterations and oxidative stress.

OBJECTIVE

To determine the association between glyphosate and AMPA exposure and biomarkers of biological aging.

METHODS

We examined glyphosate and AMPA exposure, mtDNA content and leukocyte telomere length in 181 adults, included in the third cycle of the Flemish Environment and Health Study (FLEHSIII). DNA was isolated from leukocytes and the relative mtDNA content and telomere length were determined using qPCR. Urinary glyphosate and AMPA concentrations were measured by Gas Chromatography-Tandem Mass Spectrometry (GC-MS-MS). We used multiple linear regression models to associate mtDNA content and leukocyte telomere length with glyphosate or AMPA exposure while adjusting for confounding variables.

RESULTS

A doubling in urinary AMPA concentration was associated with 5.19% (95% CI: 0.49 to 10.11; p = 0.03) longer leukocyte telomere length, while no association was observed with urinary glyphosate concentration. No association between mtDNA content and urinary glyphosate nor AMPA levels was observed.

CONCLUSIONS

This study showed that AMPA exposure may be associated with telomere biology in adults.

Identification of pesticides exposure biomarkers for residents living close to vineyards in France

Biomonitoring can be relevant for assessing pesticides exposure of residents living close to vineyards (LCTV). However, because xenobiotics are generally present at low levels in human biological matrices and the sources of pesticide exposure are multiple, several challenges need to be overcome to reliably assess exposure in residents LCTV. This includes particularly identifying the most appropriate exposure biomarkers, the biological matrices in which they should be measured, and analytical methods that are sufficiently sensitive and specific to quantify them. The aim of the present study was to develop a tiered approach to identify relevant biomarkers and matrices for assessing pesticide exposure in residents LCTV. We used samples from a biobank for 121 adults and children included in a national prevalence study conducted between 2014 and 2016 who lived near or far from vineyards. We analyzed five priority pesticides (folpet, mancozeb, tebuconazole, glyphosate, and copper) and their metabolites in urine and hair samples. We identified relevant biomarkers according to three criteria related to: i) the detection frequency of those pesticides and metabolites in urine and hair, ii) the difference in concentrations depending on residence proximity to vineyards and, iii) the influence of other environmental and occupational exposure sources on pesticide levels. This tiered approach helped us to identify three relevant metabolites (two metabolites of folpet and one of tebuconazole) that were quantified in urine, tended to be higher in residents LCTV than in controls, and were not significantly influenced by occupational, dietary, or household sources of pesticide exposure. Our approach also helped us to identify the most appropriate measurement strategies (biological matrices, analytical methods) to assess pesticide exposure in residents LCTV. The approach developed here was a prerequisite step for guiding a large-scale epidemiological study aimed at comprehensively measuring pesticides exposures in French residents LCTV with a view to developing appropriate prevention strategies.

Target and Suspect Screening of Urinary Biomarkers for Current-use Pesticides: Application of a Simple Extraction Method

Pesticide residues pose a great threat to human health. Biomonitoring with urine samples has often been used to assess pesticide exposure to humans, and identifying appropriate biomarkers is a premise of success. Current-use pesticides (CUPs) including neonicotinoids tend to be transformed in an organism, and thus the biomonitoring studies focusing on parent compounds alone may underestimate their risk. It is imperative to develop effective methods to analyze CUPs and their metabolites simultaneously and to identify viable metabolites as urinary biomarkers. For analyzing xenobiotics in urine, we optimized CH₃ COCH₃ -MgSO₄ extraction coupled with a high-performance liquid chromatography-tandem mass spectrometry detection method. The method had sensitive method detection limits (0.11-1.39 ng/ml), low matrix effects, and satisfactory recovery and precision (49.4% ± 7.2%-99.8% ± 17.8%) for neonicotinoids and their metabolites. Application of the method for real samples showed that children living in rural areas in South China were ubiquitously exposed to CUPs, including neonicotinoids, fipronil, and chlorpyrifos, and urinary residues were mainly in the form of metabolites. Suitable biomarkers were identified for individual neonicotinoids, including imidacloprid-olefin and imidacloprid-guanidine for imidacloprid, acetamiprid-N-desmethyl for acetamiprid, thiacloprid-amide for thiacloprid, and N-desmethyl-thiamethoxam and thiamethoxam for thiamethoxam. Three metabolites were mainly reported in urine samples, including imidacloprid-urea, thiacloprid-amide, and N-desmethyl-thiamethoxam. In addition, the method was also applied for suspect screening, and an additional metabolite (clothianidin-desmethyl-nitrosoguanidine) was identified, showing its potential application in suspect analysis. Environ Toxicol Chem 2022;41:73-80. © 2021 SETAC.

Urinary glyphosate concentration in pregnant women in relation to length of gestation

Human exposure to glyphosate-based herbicides (GBH) is increasing rapidly worldwide. Most existing studies on health effects of glyphosate have focused on occupational settings and cancer outcomes and few have examined this common exposure in relation to the health of pregnant women and newborns in the general population. We investigated associations between prenatal glyphosate exposure and length of gestation in The Infant Development and the Environment Study (TIDES), a multi-center US pregnancy cohort. Glyphosate and its primary degradation product [aminomethylphosphonic acid (AMPA)] were measured in urine samples collected during the second trimester from 163 pregnant women: 69 preterm births (<37 weeks) and 94 term births, the latter randomly selected as a subset of TIDES term births. We examined the relationship between exposure and length of gestation using multivariable logistic regression models (dichotomous outcome; term versus preterm) and with weighted time-to-event Cox proportional hazards models (gestational age in days). We conducted these analyses in the overall sample and secondarily, restricted to women with spontaneous deliveries (n = 90). Glyphosate and AMPA were detected in most urine samples (>94 %). A shortened gestational length was associated with maternal glyphosate (hazard ratio (HR): 1.31, 95 % confidence interval (CI) 1.00-1.71) and AMPA (HR: 1.32, 95%CI: 1.00-1.73) only among spontaneous deliveries using adjusted Cox proportional hazards models. In binary analysis, glyphosate and AMPA were not associated with preterm birth risk (<37 weeks). Our results indicate widespread exposure to glyphosate in the general population which may impact reproductive health by shortening length of gestation. Given the increasing exposure to GBHs and the public health burden of preterm delivery, larger confirmatory studies are needed, especially in vulnerable populations such as pregnant women and newborns.

Biomonitoring of glyphosate and AMPA in the urine of Spanish lactating mothers

The objectives of this study were to evaluate the urinary levels of Glyphosate (Gly) and its metabolite aminomethylphosphonic acid (AMPA) in Spanish breastfeeding mothers (n = 97), to identify the main predictors of exposure and to perform a risk assessment. Urine samples were analyzed using a method based on solid phase extraction and liquid chromatography tandem mass spectrometry (LC-MS/MS) determination. The developed method showed limits of quantification of 0.1 μg/L for both analytes. The detection frequencies (DFs) were 54% for Gly and 60% for AMPA, with geometric means (GMs) of 0.12 μg/L and 0.14 μg/L, respectively. In the statistical analysis, no relationship was found between the urinary levels of Gly and AMPA. Multiple regression analysis showed a significant relationship between the intake of eggs and fruits and Gly levels in urine. Estimated daily intakes (EDIs), hazard quotients (HQs), and a hazard index (HI) were calculated to analyze the obtained data from a health risk perspective. The GMs of the EDIs were 0.31 and 0.37 μg/kg of body weight (BW)/day for Gly and AMPA, respectively. The HQs were calculated considering 0.5 mg/kg BW/day as an acceptable daily intake (ADI), which EFSA has established as a health-based reference value for both analytes. The values obtained were lower than 1, and thus, low health risk due to Gly and AMPA exposure was expected for the population under study.

Glyphosate and aminomethylphosphonic acid (AMPA) in urine of children and adolescents in Germany - Human biomonitoring results of the German Environmental Survey 2014-2017 (GerES V)

Since the 1970s, glyphosate has become the most used herbicide of the world. The general population is ubiquitously exposed to glyphosate. Its long-term toxicity, carcinogenic potential and other health effects are controversially discussed. Even though the possible health impacts of glyphosate are of global concern, no population-wide monitoring of glyphosate was done yet. This study presents the worldwide first population-representative data on glyphosate and its metabolite aminomethylphosphonic acid (AMPA) for children and adolescents. 2144 first-morning void urine samples of 3-17-year-old children and adolescents living in Germany were analysed for concentrations of glyphosate and AMPA in the German Environmental Survey for Children and Adolescents 2014-2017 (GerESV). In 52 % of the samples (46 % for AMPA) the urinary glyphosate concentrations were above the limit of quantification of 0.1 µg/L. The geometric mean concentrations were 0.107 µg/L (0.090 µg/gcreatinine) for glyphosate and 0.100 µg/L (0.085 µg/gcreatinine) for AMPA. No clear association between exposure to glyphosate or AMPA and vegetarian diet or consumption of cereals, pulses, or vegetables could be identified. The low quantification rate and the 95th percentiles for glyphosate and AMPA of around 0.5 µg/L demonstrate an overall low exposure of the young population in Germany.

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.

Glyphosate Herbicide: Reproductive Outcomes and Multigenerational Effects

Glyphosate base herbicides (GBHs) are the most widely applied pesticides in the world and are mainly used in association with GBH-tolerant crop varieties. Indiscriminate and negligent use of GBHs has promoted the emergence of glyphosate resistant weeds, and consequently the rise in the use of these herbicides. Glyphosate, the active ingredient of all GBHs, is combined with other chemicals known as co-formulants that enhance the herbicide action. Nowadays, the safety of glyphosate and its formulations remain to be a controversial issue, as evidence is not conclusive whether the adverse effects are caused by GBH or glyphosate, and little is known about the contribution of co-formulants to the toxicity of herbicides. Currently, alarmingly increased levels of glyphosate have been detected in different environmental matrixes and in foodstuff, becoming an issue of social concern. Some in vitro and in vivo studies have shown that glyphosate and its formulations exhibit estrogen-like properties, and growing evidence has indicated they may disrupt normal endocrine function, with adverse consequences for reproductive health. Moreover, multigenerational effects have been reported and epigenetic mechanisms have been proved to be involved in the alterations induced by the herbicide. In this review, we provide an overview of: i) the routes and levels of human exposure to GBHs, ii) the potential estrogenic effects of glyphosate and GBHs in cell culture and animal models, iii) their long-term effects on female fertility and mechanisms of action, and iv) the consequences on health of successive generations.

Optimization and validation of a liquid chromatography-tandem mass spectrometry method for the determination of glyphosate in human urine after pre-column derivatization with 9-fluorenylmethoxycarbonyl chloride

In 2015, glyphosate was classified as "Group 2A - probably carcinogenic to humans" by the International Agency for Research on Cancer (IARC). Therefore, public concerns about the environmental and health risks of this substance have rapidly increased. Considering its toxicokinetic characteristics, urinary levels of glyphosate could be a powerful tool for human biomonitoring. Nevertheless, the physicochemical properties of this molecule and the complexity of the matrix make this purpose particularly challenging. In order to solve this problem, the presented study describes a simple LC-MS/MS method for the quantification of glyphosate in human urine after pre-column derivatization with FMOC-Cl. Method development was focused on the optimization of the derivatization reaction in human urine, adjusting critical variables such as pH of borate buffer, FMOC-Cl concentration and derivatization time. Besides, chromatographic separation and spectrometric parameters were also established. The analytical method was fully validated according international guidelines for selectivity, carry over, linearity, accuracy, precision, lower limit of quantitation, matrix effect and stability under different conditions. All performance parameters were within the acceptance criteria. In addition, the method was successfully applied to 52 urine samples obtained from exposed subjects from northern Argentina, laying the foundation for future epidemiological studies.

Prenatal Exposure to Glyphosate and Its Environmental Degradate, Aminomethylphosphonic Acid (AMPA), and Preterm Birth: A Nested Case-Control Study in the PROTECT Cohort (Puerto Rico)

BACKGROUND

Glyphosate (GLY) is the most heavily used herbicide in the world. Despite nearly ubiquitous exposure, few studies have examined prenatal GLY exposure and potentially adverse pregnancy outcomes. Preterm birth (PTB) is a risk factor for neonatal mortality and adverse health effects in childhood.

OBJECTIVES

We examined prenatal exposure to GLY and a highly persistent environmental degradate of GLY, aminomethylphosphonic acid (AMPA), and odds of PTB in a nested case-control study within the ongoing Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) pregnancy cohort in northern Puerto Rico.

METHODS

GLY and AMPA in urine samples collected at 18 ± 2 (Visit 1) and 26 ± 2 (Visit 3) wk gestation (53 cases/194 randomly selected controls) were measured using gas chromatography tandem mass spectrometry. Multivariable logistic regression was used to estimate associations with PTB (delivery < 37 wk completed gestation).

RESULTS

Detection rates in controls were 77.4% and 77.5% for GLY and 52.8% and 47.7% for AMPA, and geometric means (geometric standard deviations) were 0.44 (2.50) and 0.41 ( 2.56 )   μ g / L for GLY and 0.25 (3.06) and 0.20 ( 2.87 )   μ g / L for AMPA, for Visits 1 and 3, respectively. PTB was significantly associated with specific gravity-corrected urinary GLY and AMPA at Visit 3, whereas associations with levels at Visit 1 and the Visits 1-3 average were largely null or inconsistent. Adjusted odds ratios (ORs) for an interquartile range increase in exposure at Visit 3 were 1.35 (95% CI: 0.99, 1.83) and 1.67 (95% CI: 1.26, 2.20) for GLY and AMPA, respectively. ORs for Visit 1 and the visit average were closer to the null.

DISCUSSION

Urine GLY and AMPA levels in samples collected near the 26th week of pregnancy were associated with increased odds of PTB in this modestly sized nested case-control study. Given the widespread use of GLY, multiple potential sources of AMPA, and AMPA's persistence in the environment, as well as the potential for long-term adverse health effects in preterm infants, further investigation in other populations is warranted. https://doi.org/10.1289/EHP7295.

Determination of glyphosate, glufosinate and their major metabolites in urine by the UPLC-MS/MS method applicable to biomonitoring and epidemiological studies

The preoccupation concerning glyphosate (GLYP) has rapidly grown over recent years, and the availability of genetically modified crops that are resistant to GLYP or glufosinate (GLUF) has increased the use of these herbicides. The debate surrounding the carcinogenicity of GLYP has raised interest and the desire to gain information on the level of exposure of the population. GLYP and aminomethylphosphonic acid (AMPA) are commonly simultaneously analysed. GLUF is sometimes also monitored, but its major metabolite, 3-[hydroxy(methyl)phosphinoyl]propionic acid (3MPPA), is rarely present in the method. Using a pentafluorobenzyl derivative to extract the analytes from human urine, we present a method that contains four important analytes to monitor human exposure to GLYP and GLUF. The use of the flash freeze technique speeds up the extraction process and requires less organic solvent than conventional liquid-liquid extraction. The limits of detection in the low μg/L range enable the use of this method for epidemiological studies. The results obtained for 35 volunteers from the Quebec City area are presented with the results from multiple interlaboratory comparisons (G-EQUAS, HBM4EU and OSEQAS). This methodology is currently being used in the Maternal-Infant Research on Environmental Chemicals (MIREC-ENDO) study and in the Canadian Health Measures Survey (CHMS).

Acute Changes in Thyroid Hormone Levels among Thai Pesticide Sprayers

The objective of this study was to investigate the relationship of acute pesticide exposures and acute changes in thyroid hormones among Thai farmers. We recruited 78 farmers, who were scheduled to spray insecticides (chlorpyrifos and/or cypermethrin) or herbicides (paraquat and/or glyphosate). On the day before spraying, farmers collected their first morning void urine and went for blood collection. On the spray day, urine samples were collected at end of the spraying event and they were interviewed with questionnaires. The next morning, the first morning void urine and blood samples were collected. Blood samples were analyzed for thyroid hormones. Urine samples were analyzed for the metabolites of the pesticide sprayed. The results showed that the thyroid hormones, free triiodothyronine (FT3) and total triiodothyronine (T3) were significantly reduced as urinary chlorpyrifos metabolite increased the day after spraying. Total thyroxine (T4) significantly increased as cypermethrin metabolites increased the day after spraying. T4 significantly increased as urinary glyphosate levels increased; however, FT3 and T3 decreased significantly as urinary paraquat levels increased the day after spraying. These findings suggest that acute exposures to the pesticides chlorpyrifos, cypermethrin, paraquat and glyphosate can produce acute effects on the hypothalamic-pituitary-thyroid (HPT) axis, acutely altering thyroid hormone levels.