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.
ABSTRACT:
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.
ABSTRACT:
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
Winchester Herald Chronicle, 2017
“Tennessee Dept. of Agriculture issues new measures for Dicamba,” July 12, 2017, Winchester Herald Chronicle.
SUMMARY:
The Tennessee Department of Agriculture responded to increased farmer-to-farmer complaints of damage from dicamba drift by enacting new rules on dicamba use in the state. The rules include requiring special licensing and record keeping for applicators, banning the use of older formulations for the rest of the season, and limiting the timing that it can be applied, and will be effective through October 1, 2017. FULL TEXT
Gullickson, 2017
Gil Gullickson, “Why Dicamba-Tolerant Soybean Technology is in Trouble,” July 11, 2017, Successful Farming,
SUMMARY:
This article reports on dicamba drift in Missouri, where damage to date is tallied at 203,045 acres on soybeans, as well as over 6,500 acres of other crops and gardens, including certified organic vegetable farms. The damage appears to be caused both by known problems with how and when dicamba is sprayed, and also by greater than expected damage from legal and correct dicamba spraying of the newest varieties that are supposed to be low volatility: BASF’s Engenia, Dupont FeXapan Plus Vapor Grip Technology, and Monsanto’s Xtendimax with Vapor Grip Technology. In response the Missouri Department of Agriculture voted on July 7, 2017 to temporarily suspend all sales and applications of dicamba. FULL TEXT
Begemann and Skiles, 2017
Sonja Begemann and Susan Skiles Luke, July 10, 2017, “Arkansas, Missouri Ban Dicamba,” AgWeb.
SUMMARY:
Effective just after midnight on July 11, Arkansas finalizes a 120-day emergency ban on dicamba sales and use. Missouri also banned dicamba the week before, with the intent of re-opening sales once the investigation into complaints of damage from dicamba drift is complete. The Missouri Soybean Association is quoted as saying that more than 200,000 acres of soybeans are affected in the state. In a statement, Monsanto stressed the importance of “following label and local requirements” for their Roundup Ready Xtend Crop System of dicamba-resistant soybeans. The article lists the number of complaints of dicamba damage in Arkansas as “nearly 600,” up from the 500 reported on July 6, 2017. FULL TEXT
Begemann, 2017
Sonja Begemann, “Dicamba Damage Watch,” July 6, 2017, AgPro.
SUMMARY:
Describes the symptoms of dicamba damage – cupped and wrinkled soybean leaves – and other culprits that could be the cause such as other herbicide damage, pests such as aphids and various plant diseases. It can take 7 to 21 days for dicamba damage to appear, and it will only be evident on new leaves, not those present when the drift occurs. Percentages as low as 0.06 to 1.9% can cause damage resulting in yield loss. FULL TEXT
Charles, 2017b
Dan Charles, “Damage From Wayward Weedkiller Keeps Growing,” July 6, 2017, NPR.
SUMMARY:
NPR Morning Edition radio piece reports that dicamba-related complaints in Arkansas are up from 250 at the end of June to 550 by July 6th. Estimates of potential damaged soybeans are up to 2 million acres. The new Monsanto dicamba resistant cotton and soybean is being blamed for this damage from an herbicide that has been in use for over 50 years. As one farmer quoted in the story puts it, “This technology cannot be allowed to exist. It cannot co-exist with other crops.” On the other side of the debate, farmers using the GE crops claim that dicamba is working great against the herbicide-resistant Palmer amaranth that is plaguing their fields, and Monsanto’s head of crop protection sees all this as “just part of the learning curve.” FULL TEXT
Hickey, 2017
Chris Hickey, “Legislative Panel Delays Decision On Arkansas Dicamba Ban,” July 6, 2017, NPR.
SUMMARY:
Reports that the subcommittee of the Arkansas Legislative Council deferred a decision on whether to ban use and sale of dicamba. Governor Asa Hutchinson referred the decision to the committee following hi approval of a 120-day emergency ban proposed by the Arkansas Plant Board. The subcommittee did approve an emergency rule to increase fines up to $25,000 for misuse of dicamba. All this follows the approval in December of BASF’s Engenia dicamba-based herbicide. The board will re-convene to continue the debate the following week. FULL TEXT
Associated Press, 2017b
Associated Press, “Farm chemical linked to oak damage,” July 2, 2017, Quad-City Times,
SUMMARY:
Reports that almost 1,000 residents of Iowa have contacted the state Department of Natural Resources about damaged leaves on oak trees (photo, right) that looked like insect damage. Research from the University of Illinois in 2004 showed that herbicide drift was likely linked to the condition, known as leaf tatters, due to exposure to chloroacetanilide herbicides like dicamba. Exposure occurs from direct drift but also through atmospheric volubility in areas not close to where the herbicide was applied. White oaks are particularly susceptible, and trees can die if damage to the leaves occurs over multiple years. FULL TEXT
Steed, 2017
Stephen Steed, “Governor approves dicamba prohibition in Arkansas,” Northwest Arkansas Democrat Gazette,
SUMMARY:
Reports that on June 31, Arkansas Governor Asa Hutchinson submitted a letter that approved the Arkansas Plant Board’s proposed 120-emergency ban on dicamba sale and use in the state. He wrote that ” the volume of complaints do justify emergency action;” 507 complaints had been received as of June 31st. The proposed ban next goes to a subcommittee of the Arkansas Legislative Council for review, although their approval is not required for the ban to take effect. The article reports that complaints in neighboring states are also up, with 100 in Missouri and 48 in Mississippi as of the end of June 2017. FULL TEXT