Glyphosate - HH-RA.org

Bibliography Tag: glyphosate

Givens et al., 2017

Givens, Wade A., Shaw, David R., Johnson, William G., Weller, Stephen C., Young, Bryan G., Wilson, Robert G., Owen, Micheal D. K., & Jordan, David; “A Grower Survey of Herbicide Use Patterns in Glyphosate-Resistant Cropping Systems;” Weed Technology, 2017, 23(1), 156-161; DOI: 10.1614/wt-08-039.1.

ABSTRACT:

A telephone survey was conducted with growers in Iowa, Illinois, Indiana, Nebraska, Mississippi, and North Carolina to discern the utilization of the glyphosate-resistant (GR) trait in crop rotations, weed pressure, tillage practices, herbicide use, and perception of GR weeds. This paper focuses on survey results regarding herbicide decisions made during the 2005 cropping season. Less than 20% of the respondents made fall herbicide applications. The most frequently used herbicides for fall applications were 2,4-D and glyphosate, and these herbicides were also the most frequently used for preplant burndown weed control in the spring. Atrazine and acetochlor were frequently used in rotations containing GR corn. As expected, crop rotations using a GR crop had a high percentage of respondents that made one to three POST applications of glyphosate per year. GR corn, GR cotton, and non-GR crops had the highest percentage of growers applying nonglyphosate herbicides during the 2005 growing season. A crop rotation containing GR soybean had the greatest negative impact on non-glyphosate use. Overall, glyphosate use has continued to increase, with concomitant decreases in utilization of other herbicides. FULL TEXT

Dean et al., 1995

Dean, E. Riechers, Loyd, M. Wax, Rex, A. Liebl, & Don, G. Bullock; “Surfactant Effects on Glyphosate Efficacy;” Weed Technology, 1995, 9(2), 281-285.

ABSTRACT:

Field and greenhouse studies were performed to examine the influence of various surfactants with glyphosate on whole plant efficacy. Relationships were examined between glyphosate phytotoxicity and surfactant properties, including ionic form, degree of ethoxylation, and hydrophobe composition. Cationic tertiary amine surfactants enhanced glyphosate performance in both field and greenhouse studies. Nonionic allinol and octoxynol surfactants were not effective in combination with glyphosate. In field studies, glyphosate efficacy increased with increasing surfactant ethylene oxide (EO) content. Soybean and velvetleaf responded similarly to glyphosate-surfactant spray applications, as both demonstrated significant linear and quadratic relationships between increasing surfactant ethoxylation and phytotoxicity, while common lambsquarters showed a significant linear relationship only. Cationic surfactants were evaluated in the greenhouse and a significant quadratic regression of glyphosate phytotoxicity to common lambsquarters on increasing surfactant ethoxylation indicated an optimum surfactant EO content of about 10 moles. Both tertiary and quaternary ethoxylated fatty amines were effective with glyphosate in decreasing common lambsquarters’ fresh weight. Fatty amine hydrophobe composition did not correlate with glyphosate phytotoxicity to common lambsquarters. FULL TEXT

Benbrook, 2020

Benbrook, Charles; “Shining a Light on Glyphosate-Based Herbicide Hazard, Exposures and Risk: Role of Non-Hodgkin Lymphoma Litigation in the USA;” European Journal of Risk Regulation, 2020, 11(3), 498-519; DOI: 10.1017/err.2020.16.

ABSTRACT:

Roundup, and other glyphosate-based herbicides, are the most heavily used pesticides in the history of the USA and globally. In March 2015, the International Agency for Research on Cancer (IARC) classified glyphosate as a “probable human carcinogen”. A portion of the 695,000 Americans then living in 2015 with non-Hodgkin lymphoma (NHL) became aware of IARC’s decision. Several thousand Roundup–NHL lawsuits had been filed by the end of 2017, rising to 18,400 by July 2019 and 42,000 by November 2019. Three cases have gone to trial, each won by the plaintiffs. The author has served as an expert witness for the plaintiffs in this litigation and has been compensated for his time spent. The impact of the litigation on the independent assessment of the science useful in determining whether glyphosate and glyphosate-based herbicide exposures are linked to NHL is reviewed, as is why the US Environmental Protection Agency (EPA) and IARC reached such different judgements regarding glyphosate human cancer hazard and risk. Two important “lessons learned” regarding the EPA versus IARC assessment of glyphosate cancer hazard and risk are highlighted. The first arises from differences in the magnitude of applicator risks from mostly dermal exposures to formulated glyphosate-based herbicides compared to just dietary exposures to technical glyphosate. The second relates to missed opportunities to markedly lower applicator exposures and risks with little or no impact on sales via reformulation, added warnings and worker safety provisions, company-driven stewardship programmes and greater determination by the EPA in the 1980s to compel Monsanto to add common-sense worker protection provisions onto Roundup labels (eg “wear gloves when applying this product”). Policy reforms designed to alleviate systemic problems with how pesticide hazards, exposures and risks are analysed, regulated and mitigated are described. FULL TEXT

Gillezeau et al., 2020

Gillezeau, C., Lieberman-Cribbin, W., & Taioli, E.; “Update on human exposure to glyphosate, with a complete review of exposure in children;” Environmental Health, 2020, 19(1), 115; DOI: 10.1186/s12940-020-00673-z.

ABSTRACT:

BACKGROUND: Glyphosate, a commonly used pesticide, has been the topic of much debate. The effects of exposure to glyphosate remains a contentious topic. This paper provides an update to the existing literature regarding levels of glyphosate exposure in occupationally exposed individuals and focuses or reviewing all the available published literature regarding glyphosate exposure levels in children.

METHODS: A literature review was conducted and any articles reporting quantifiable exposure levels in humans published since January 2019 (the last published review on glyphosate exposure) were reviewed and data extracted and standardized.

RESULTS: A total of five new studies reporting exposure levels in humans were found including 578 subjects. Two of these studies focused on occupationally exposed individuals while three of them focused on glyphosate exposure levels in children. Given the sparse nature of the new data, previously identified studies on exposure to glyphosate in children were included in our analysis of children’s exposure. The lowest average level of glyphosate exposure reported was 0.28 μg/L and the highest average exposure levels reported was 4.04 μg/L.

CONCLUSION: The literature on glyphosate exposure levels, especially in children, remains limited. Without more data collected in a standardized way, parsing out the potential relationship between glyphosate exposure and disease will not be possible. FULL TEXT

Franke et al., 2020

Franke, A. A., Li, X., & Lai, J. F.; “Analysis of glyphosate, aminomethylphosphonic acid, and glufosinate from human urine by HRAM LC-MS;” Analytical and Bioanalytical Chemistry, 2020; DOI: 10.1007/s00216-020-02966-1.

ABSTRACT:

Aminomethylphosphonic acid (AMPA) is the main metabolite of glyphosate (GLYP) and phosphonic acids in detergents. GLYP is a synthetic herbicide frequently used worldwide alone or together with its analog glufosinate (GLUF). The general public can be exposed to these potentially harmful chemicals; thus, sensitive methods to monitor them in humans are urgently required to evaluate health risks. We attempted to simultaneously detect GLYP, AMPA, and GLUF in human urine by high-resolution accurate-mass liquid chromatography mass spectrometry (HRAM LC-MS) before and after derivatization with 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) or 1-methylimidazole-sulfonyl chloride (ImS-Cl) with several urine pre-treatment and solid phase extraction (SPE) steps. Fmoc-Cl derivatization achieved the best combination of method sensitivity (limit of detection; LOD) and accuracy for all compounds compared to underivatized urine or ImS-Cl-derivatized urine. Before derivatization, the best steps for GLYP involved 0.4 mM ethylenediaminetetraacetic acid (EDTA) pre-treatment followed by SPE pre-cleanup (LOD 37 pg/mL), for AMPA involved no EDTA pre-treatment and no SPE pre-cleanup (LOD 20 pg/mL) or 0.2-0.4 mM EDTA pre-treatment with no SPE pre-cleanup (LOD 19-21 pg/mL), and for GLUF involved 0.4 mM EDTA pre-treatment and no SPE pre-cleanup (LOD 7 pg/mL). However, for these methods, accuracy was sufficient only for AMPA (101-105%), while being modest for GLYP (61%) and GLUF (63%). Different EDTA and SPE treatments prior to Fmoc-Cl derivatization resulted in high sensitivity for all analytes but satisfactory accuracy only for AMPA. Thus, we conclude that our HRAM LC-MS method is suited for urinary AMPA analysis in cross-sectional studies. FULL TEXT

Connolly et al., 2020

Connolly, A., Coggins, M. A., & Koch, H. M.; “Human Biomonitoring of Glyphosate Exposures: State-of-the-Art and Future Research Challenges;” Toxics, 2020, 8(3); DOI: 10.3390/toxics8030060. https://www.ncbi.nlm.nih.gov/pubmed/32824707.

ABSTRACT:

Glyphosate continues to attract controversial debate following the International Agency for Research on Cancer carcinogenicity classification in 2015. Despite its ubiquitous presence in our environment, there remains a dearth of data on human exposure to both glyphosate and its main biodegradation product aminomethylphosphonic (AMPA). Herein, we reviewed and compared results from 21 studies that use human biomonitoring (HBM) to measure urinary glyphosate and AMPA. Elucidation of the level and range of exposure was complicated by differences in sampling strategy, analytical methods, and data presentation. Exposure data is required to enable a more robust regulatory risk assessment, and these studies included higher occupational exposures, environmental exposures, and vulnerable groups such as children. There was also considerable uncertainty regarding the absorption and excretion pattern of glyphosate and AMPA in humans. This information is required to back-calculate exposure doses from urinary levels and thus, compared with health-based guidance values. Back-calculations based on animal-derived excretion rates suggested that there were no health concerns in relation to glyphosate exposure (when compared with EFSA acceptable daily intake (ADI)). However, recent human metabolism data has reported as low as a 1% urinary excretion rate of glyphosate. Human exposures extrapolated from urinary glyphosate concentrations found that upper-bound levels may be much closer to the ADI than previously reported. FULL TEXT

Pierce et al., 2020

Pierce, J. S., Roberts, B., Kougias, D. G., Comerford, C. E., Riordan, A. S., Keeton, K. A., Reamer, H. A., Jacobs, N. F. B., & Lotter, J. T.; “Pilot study evaluating inhalation and dermal glyphosate exposure resulting from simulated heavy residential consumer application of Roundup((R));” Inhalation Toxicology, 2020, 1-11; DOI: 10.1080/08958378.2020.1814457.

ABSTRACT:

OBJECTIVES: The purpose of this study was to evaluate the individual contributions of inhalation and dermal exposures to urinary glyphosate levels following the heavy residential consumer application of a glyphosate-containing herbicide.

METHODS: A pilot study was conducted in which each participant mixed and continuously spray-applied 16.3 gallons of a 0.96% glyphosate-containing solution for 100 min using a backpack sprayer. Twelve participants were divided evenly into two exposure groups, one equipped to assess dermal exposure and the other, inhalation exposure. Personal air samples (n = 12) and dermal patch samples (n = 24) were collected on the inhalation group participants and analyzed for glyphosate using HPLC-UV. Serial urine samples collected 30-min prior to application and 3-, 6-, 12-, 24-hr (inhalation and dermal groups) and 36-hr (dermal group only) post-application were analyzed for glyphosate and glyphosate’s primary metabolite (AMPA) using HPLC-MS/MS.

RESULTS: The mean airborne glyphosate concentration was 0.0047 mg/m(3), and the mean concentrations of glyphosate for each applicator’s four patch samples ranged from 0.04 microg/mm(2) to 0.25 microg/mm(2). In general, urinary glyphosate, AMPA, and total effective glyphosate levels were higher in the dermal exposure group than the inhalation exposure group, peaked within 6-hr following application, and were statistically indistinguishable from background at 24-hr post-application.

CONCLUSIONS: This is the first study to characterize the absorption and biological fate of glyphosate in residential consumer applicators following heavy application. The results of this pilot study are consistent with previous studies that have shown that glyphosate is rapidly eliminated from the body, typically within 24 hr following application. FULL TEXT

Reeves et al., 2019

Reeves, W. R., McGuire, M. K., Stokes, M., & Vicini, J. L.; “Assessing the Safety of Pesticides in Food: How Current Regulations Protect Human Health;” Advances in Nutrition, 2019, 10(1), 80-88; DOI: 10.1093/advances/nmy061.

ABSTRACT:

Understanding the magnitude and impact of dietary pesticide exposures is a concern for some consumers. However, the ability of consumers to obtain and understand state-of-the-science information about how pesticides are regulated and how dietary exposure limits are set can be limited by the complicated nature of the regulations coupled with an abundance of sources seeking to cast doubt on the reliability of those regulations. Indeed, these regulations are sometimes not well understood within health care professions. As such, the objective of this review is to provide a historical perspective as to how modern pesticides were developed, current trends in pesticide use and regulation, and measures taken to reduce the risk of pesticide use to the consumer. Throughout the review, we provide specific examples for some of the concepts as they apply to glyphosate-a pesticide commonly used by both farmers and consumers. In addition, we describe current efforts to monitor pesticide use. We are confident that this succinct, yet thorough, review of this topic will be of interest to myriad researchers, public health experts, and health practitioners as they help communicate information about making healthful and sustainable food choices to the public. FULL TEXT

Stephenson and Harris, 2016

Stephenson, C. L., & Harris, C. A.; “An assessment of dietary exposure to glyphosate using refined deterministic and probabilistic methods;” Food and Chemical Toxicology, 2016, 95, 28-41; DOI: 10.1016/j.fct.2016.06.026.

ABSTRACT:

Glyphosate is a herbicide used to control broad-leaved weeds. Some uses of glyphosate in crop production can lead to residues of the active substance and related metabolites in food. This paper uses data on residue levels, processing information and consumption patterns, to assess theoretical lifetime dietary exposure to glyphosate. Initial estimates were made assuming exposure to the highest permitted residue levels in foods. These intakes were then refined using median residue levels from trials, processing information, and monitoring data to achieve a more realistic estimate of exposure. Estimates were made using deterministic and probabilistic methods. Exposures were compared to the acceptable daily intake (ADI)-the amount of a substance that can be consumed daily without an appreciable health risk. Refined deterministic intakes for all consumers were at or below 2.1% of the ADI. Variations were due to cultural differences in consumption patterns and the level of aggregation of the dietary information in calculation models, which allows refinements for processing. Probabilistic exposure estimates ranged from 0.03% to 0.90% of the ADI, depending on whether optimistic or pessimistic assumptions were made in the calculations. Additional refinements would be possible if further data on processing and from residues monitoring programmes were available. FULL TEXT

Mesnage and Antoniou, 2020

Mesnage, Robin, & Antoniou, Michael N.; “Computational modelling provides insight into the effects of glyphosate on the shikimate pathway in the human gut microbiome;” Current Research in Toxicology, 2020, 1, 25-33; DOI: 10.1016/j.crtox.2020.04.001.

ABSTRACT:

The herbicide active ingredient glyphosate can affect the growth of microorganisms, which rely on the shikimate pathway for aromatic amino acid biosynthesis. However, it is uncertain whether glyphosate exposure could lead to perturbations in the population of human gut microbiota. We have addressed this knowledge gap by analysing publicly available datasets to provide new insights into possible effects of glyphosate on the human gut microbiome. Comparison of the abundance of the shikimate pathway in 734 paired metagenomes and metatranscriptomes indicated that most gut bacteria do not possess a complete shikimate pathway, and that this pathway is mostly transcriptionally inactive in the human gut microbiome. This suggests that gut bacteria are mostly aromatic amino acid auxotrophs and thus relatively resistant to a potential growth inhibition by glyphosate. As glyphosate blocking of the shikimate pathway is via inhibition of EPSPS, we classified E. coli EPSPS enzyme homologues as class I (sensitive to glyphosate) and class II (resistant to glyphosate). Among 44 subspecies reference genomes, accounting for 72% of the total assigned microbial abundance in 2144 human faecal metagenomes, 9 subspecies have class II EPSPS. The study of publicly available gut metagenomes also indicated that glyphosate might be degraded by some Proteobacteria in the human gut microbiome using the carbon–phosphorus lyase pathway. Overall, there is limited experimental evidence available for the effects of glyphosate on the human gut microbiome. Further investigations using more advanced molecular profiling techniques are needed to ascertain whether glyphosate and glyphosate-based herbicides can alter the function of the gut microbiome with consequent health implications. FULL TEXT

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