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Bibliography Tag: environmental impacts

Relyea, 2011

Rick A. Relyea, “Amphibians Are Not Ready for Roundup®,” in Wildlife Ecotoxicology: Forensic Approaches, J.E. Elliott et al. (eds.), 2011, DOI 10.1007/978-0-387-89432-4_9.


The herbicide glyphosate, sold under a variety of commercial names including Roundup® and Vision® , has long been viewed as an environmentally friendly  herbicide. In the 1990s, however, after nearly 20 years of use, the first tests were conducted on the herbicide’s effects on amphibians in Australia. The researchers found that the herbicide was moderately toxic to Australian amphibians. The leading manufacturer of glyphosate-based herbicides, Monsanto, declared that the researchers were wrong. Nearly 10 years later, my research group began examining the effects of the herbicides on North American amphibians. Based on an extensive series of experiments, we demonstrated that glyphosate-based herbicides can be highly toxic to larval amphibians. Monsanto declared that we were also wrong. These experiments have formed the basis of a spirited debate between independent, academic researchers, and scientists that either work as consultants for Monsanto or have a vested interest in promoting the application of the herbicide to control undesirable plants in forests and agriculture. The debate also moved into unexpected arenas, including the use of glyphosate-based herbicides in the Colombian drug war in South America where a version of Roundup is being used to kill illegal coca plantations. In 2008, the US EPA completed a risk assessment for the effects of glyphosate-based herbicides on the endangered California red-legged frog (Rana aurora draytonii) and concluded that it could adversely affect the long-termpersistence of the species. More recent data from Colombia have confirmed that the herbicides not only pose a risk to tadpoles in shallow wetlands, but that typical applications rates also can kill up to 30% of adult frogs. As one reflects over the past decade, it becomes clear that our understanding of the possible effects of glyphosatebased herbicides on amphibians has moved from a position of knowing very little and assuming no harm to a position of more precise understanding of which concentrations and conditions pose a serious risk. FULL TEXT

Mahler et. al, 2017

Mahler BJ, Van Metre PC, Burley TE, Loftin KA, Meyer MT, Nowell LH, “Similarities and differences in occurrence and temporal fluctuations in glyphosate and atrazine in small Midwestern streams (USA) during the 2013 growing season,” Science of the Total Environment, 2017 ,579:149-158. DOI: 10.1016/j.scitotenv.2016.10.236.


Glyphosate and atrazine are the most intensively used herbicides in the United States. Although there is abundant spatial and temporal information on atrazine occurrence at regional scales, there are far fewer data for glyphosate, and studies that compare the two herbicides are rare. We investigated temporal patterns in glyphosate and atrazine concentrations measured weekly during the 2013 growing season in 100 small streams in the Midwestern United States. Glyphosate was detected in 44% of samples (method reporting level 0.2μg/L); atrazine was detected above a threshold of 0.2μg/L in 54% of samples. Glyphosate was detected more frequently in 12 urban streams than in 88 agricultural streams, and at concentrations similar to those in streams with high agricultural land use (>40% row crop) in the watershed. In contrast, atrazine was detected more frequently and at higher concentrations in agricultural streams than in urban streams. The maximum concentration of glyphosate measured at most urban sites exceeded the maximum atrazine concentration, whereas at agricultural sites the reverse was true. Measurement at a 2-day interval at 8 sites in northern Missouri revealed that transport of both herbicide compounds appeared to be controlled by spring flush, that peak concentration duration was brief, but that peaks in atrazine concentrations were of longer duration than those of glyphosate. The 2-day sampling also indicated that weekly sampling is unlikely to capture peak concentrations of glyphosate and atrazine.

Bento et. al, 2016

Bento CP, Yang X, Gort G, Xue S, van Dam R, Zomer P, Mol HG, Ritsema CJ, Geissen V, “Persistence of glyphosate and aminomethylphosphonic acid in loess soil under different combinations of temperature, soil moisture and light/darkness,” Science of the Total Environment, 2016, DOI: 10.1016/j.scitotenv.2016.07.215.


The dissipation kinetics of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) were studied in loess soil, under biotic and abiotic conditions, as affected by temperature, soil moisture (SM) and light/darkness. Nonsterile and sterile soil samples were spiked with 16mgkg-1 of glyphosate, subjected to three SM contents (20% WHC, 60% WHC, saturation), and incubated for 30days at 5°C and 30°C, under dark and light regimes. Glyphosate and AMPA dissipation kinetics were fit to single-first-order (SFO) or first-order-multicompartment (FOMC) models, per treatment combination. AMPA kinetic model included both the formation and decline phases. Glyphosate dissipation kinetics followed SFO at 5°C, but FOMC at 30°C. AMPA followed SFO dissipation kinetics for all treatments. Glyphosate and AMPA dissipation occurred mostly by microbial activity. Abiotic processes played a negligible role for both compounds. Under biotic conditions, glyphosate dissipation and AMPA formation/dissipation were primarily affected by temperature, but also by SM. Light regimes didn’t play a significant role. Glyphosate DT50 varied between 1.5 and 53.5days, while its DT90 varied between 8.0 and 280days, depending on the treatment. AMPA persisted longer in soil than glyphosate, with its DT50 at 30°C ranging between 26.4 and 44.5days, and its DT90 between 87.8 and 148days. The shortest DT50/DT90 values for both compounds occurred at 30°C and under optimal/saturated moisture conditions, while the largest occurred at 5°C and reaching drought stress conditions. Based on these results, we conclude that glyphosate and AMPA dissipate rapidly under warm and rainy climate conditions. However, repeated glyphosate applications in fallows or winter crops in countries where cold and dry winters normally occur could lead to on-site soil pollution, with consequent potential risks to the environment and human health. To our knowledge, this study is the first evaluating the combined effect of temperature, soil moisture and light/dark conditions on AMPA formation/dissipation kinetics and behaviour.

Scribner et al., 2007

Elisabeth A. Scribner, William A. Battaglin, Robert J. Gilliom, and Michael T. Meyer, “Concentrations of Glyphosate, Its Degradation Product, Aminomethylphosphonic Acid, and Glufosinate in Ground- and Surface-Water, Rainfall, and Soil Samples Collected in the United States, 2001-06,” August 2007, United States Geological Service.


The U.S. Geological Survey conducted a number of studies from 2001 through 2006 to investigate and document the occurrence, fate, and transport of glyphosate, its degradation product, aminomethylphosphonic acid (AMPA), and glufosinate in 2,135 ground- and surface-water samples, 14 rainfall samples, and 193 soil samples. Analytical methods were developed to detect and measure glyphosate, AMPA, and glufosinate in water, rainfall, and soil. Results show that AMPA was detected more frequently and occurred at similar or higher concentrations than the parent compound, glyphosate, whereas glufosinate was seldom found in the environment. Glyphosate and AMPA were detected more frequently in surface water than in ground water. Trace levels of glyphosate and AMPA may persist in the soil from year to year. The methods and data described in this report are useful to researchers and regulators interested in the occurrence, fate, and transport of glyphosate and AMPA in the environment.  FULL TEXT


de Brito Rodrigues et al., 2017

Laís de Brito Rodrigues, Rhaul de Oliveira , Flávia Renata Abe, Lara Barroso Brito, Diego Sousa Moura, Marize Campos Valadares, Cesar Koppe Grisolia, Danielle Palma de Oliveria, and Gisele Augusto Rodrigues de Oliveira, “Ecotoxicological Assessment of Glyphosate-Based Herbicides,” Environmental Toxicology and Chemistry, 2017, 36:7, DOI: 10.1002/etc.3580.


Glyphosate-based herbicides are the most commonly used worldwide because they are effective and relatively nontoxic to nontarget species. Unlimited and uncontrolled use of such pesticides can have serious consequences for human health and ecological balance. The present study evaluated the acute toxicity and genotoxicity of 2 glyphosate-based formulations, Roundup Original (Roundup) and Glyphosate AKB 480 (AKB), on different organisms: cucumber (Cucumis sativus), lettuce (Lactuca sativa), and tomato (Lycopersicon esculentum) seeds, and microcrustacean Artemia salina and zebrafish (Danio rerio) early life stages. For the germination endpoint, only L. esculentum presented significant sensitivity to AKB and L. sativa to Roundup, whereas both formulations significantly inhibited the root growth of all species tested. Both AKB and Roundup induced significant toxicity to A. salina; both are classified as category 3, which indicates a hazard for the aquatic environment, according to criteria of the Globally Harmonized Classification System. However, Roundup was more toxic than AKB, with 48-h median lethal concentration (LC50) values of 14.19 mg/L and 37.53 mg/L, respectively. For the embryo–larval toxicity test, Roundup proved more toxic than AKB for the mortality endpoint (96-h LC50 values of 10.17 mg/L and 27.13 mg/L, respectively), whereas for the hatching parameter, AKB was more toxic than Roundup. No significant genotoxicity to zebrafish larvae was found. We concluded that AKB and Roundup glyphosate-based formulations are phytotoxic and induce toxic effects in nontarget organisms such as A. salina and zebrafish early life stages.  FULL TEXT

van Bruggen et al., 2018

Ariena H.C. van Bruggen, Max Teplitski, Volker Mai, Kwang Cheol Jeong, Joan D. Flocks, Maria R. Finckh, and J. Glenn Morris, Jr., “Environmental and health effects of the herbicide glyphosate,” 2018,  Science of the Total Environment, 2018, 616-617,  DOI: 10.1016/j.scitotenv.2017.10.309.


BACKGROUND: The WHO reclassified the herbicide glyphosate as probably carcinogenic to humans, and concerns about potential side effects of the large-scale use of glyphosate have increased. We are interested in potential indirect effects of glyphosate on animal, human and plant health due to shifts in microbial community composition and antibiotic resistance in soil, plant surfaces and intestinal tracts.

OBJECTIVES: We review the scientific literature on glyphosate use, its toxicity to macro- and microorganisms, effects on microbial compositions, and potential indirect effects on plant, animal and human health. We hypothesize that glyphosate use has increased antibiotic resistance and propose study designs for testing this hypothesis.

DISCUSSION: Although the acute toxic effects of glyphosate on mammals are low, the chronic effects on human and animal health could be considerable due to accumulation in the environment. Intensive glyphosate use has led to the selection of glyphosate-resistant weeds and microorganisms. Shifts in microbial compositions due to selective pressure by glyphosate may have contributed to the proliferation of pathogens. Research on a link between glyphosate and antibiotic resistance is scarce. We hypothesize that the selection pressure for glyphosate resistance in bacteria could lead to shifts in microbiome composition and increases in antibiotic resistance.

CONCLUSION: We recommend interdisciplinary research on the associations between glyphosate use, distortions in microbial communities, expansion of antibiotic resistance and the emergence of animal, human and plant diseases. Independent research is needed to revisit the tolerance thresholds for glyphosate residues in food and animal feed taking all possible health risks into account.  FULL TEXT

Casabe et al., 2007

Norma Casabé, Lucas Piola, Julio Fuchs, María Luisa Oneto, Laura Pamparato, Silvana Basack, Rosana Giménez, Rubén Massaro, Juan C. Papa and Eva Kesten, “Ecotoxicological Assessment of the Effects of Glyphosate and Chlorpyrifos in an Argentine Soya Field,” Journal of Soils and Sediment, 2007, DOI: 10.1065/JSS2007.04.224.


BACKGROUND, AIM, AND SCOPE: Continuous application of pesticides may pollute soils and affect non-target organisms. Soil is a complex ecosystem; its components can modulate the effects of pesticides. Therefore, it is recommended to evaluate the potential environmental risk of these compounds in local conditions. We performed an integrated field-laboratory study on an Argentine soya field sprayed with glyphosate and chlorpyrifos under controlled conditions. Our aim was to compare the sensitivity of a series of endpoints for the assessment of adverse effects of the extensive use of these agrochemicals.

MATERIALS AND METHODS: A RR soya field in a traditional farming area of Argentina was sprayed with glyphosate (GLY) or chlorpyrifos (CPF) formulations at the commercially recommended rates, according to a randomized complete block design with 3 replicates. In laboratory assays, Eisenia fetida andrei were exposed to soil samples (0–10 cm depth) collected between the rows of soya. Endpoints linked to behavior and biological activity (reproduction, avoidance behavior and bait-lamina tests) and cellular/subcellular assays (Neutral Red Retention Time –NRRT; DNA damage – Comet assay) were tested. Field assays included litterbag and bait-lamina tests. Physico/chemical analyses were performed on soil samples.

RESULTS: GLY reduced cocoon viability, decreasing the number of juveniles. Moreover, earthworms avoided soils treated with GLY. No effects on either reproduction or on avoidance were observed at the very low CPF concentration measured in the soils sampled 10 days after treatment. Both pesticides caused a reduction in the feeding activity under laboratory and field conditions. NRRT was responsive to formulations of CPF and GLY. Comet assay showed significantly increased DNA damage in earthworms exposed to CPF treated soils. No significant differences in DNA migration were observed with GLY treated soils. Litterbag field assay showed no differences between treated and control plots.     DISCUSSION: The ecotoxicological effects of pesticides can be assessed by monitoring the status of communities in real ecosystems or through the use of laboratory toxicity tests. Litterbag field test showed no influence of the treatments on the organic matter breakdown, suggesting a scarce contribution of soil macrofauna. The bait-lamina test, however, seemed to be useful for detecting the effects of GLY and CPF treatments on the activity of the soil fauna. CPF failed to give significant differences with the controls in the reproduction test and the results were not conclusive in the avoidance test. Although the field population density of earthworms could be affected by multiple factors, the effects observed on the reproduction and avoidance tests caused by GLY could contribute to its decrease, with the subsequent loss of their beneficial functions. Biomarkers measuring effects on suborganism level could be useful to predict adverse effects on soil organisms and populations. Among them, NRRT, a lysosomal destabilization biomarker, resulted in demonstrating more sensitivity than the reproduction and avoidance tests. The Comet assay was responsive only to CPF. Since DNA damage can have severe consequences on populations, it could be regarded as an important indicator to be used in the assessment of soil health.

CONCLUSIONS: Reproduction and avoidance tests were sensitive indicators of GLY exposure, with the former being more labor intensive. Bait-lamina test was sensitive to both CPF and GLY. NRRT and Comet assays revealed alterations at a subcellular level, and could be considered complementary to the biological activity tests. Because of their simplicity, some of these bioassays seemed to be appropriate pre-screening tests, prior to more extensive and invasive testing.

RECOMMENDATIONS AND PERSPECTIVES: This study showed deleterious effects of GLY and CPF formulations when applied at the nominal concentrations recommended for soya crops. Further validation is needed before these endpoints could be used as field monitoring tools in Argentine soya soils (ecotoxicological risk assessment – ERA tools).  FULL TEXT

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