Bibliography Tag: environmental impacts

Bibliography Index

Armiliato et al., 2014

Armiliato N, Ammar D, Nezzi L, Straliotto M, Muller YM, Nazari EM, “Changes in ultrastructure and expression of steroidogenic factor-1 in ovaries of zebrafish Danio rerio exposed to glyphosate,” Journal of Toxicology and Environmental Health A, 2014, 77:7, DOI: 10.1080/15287394.2014.880393.

ABSTRACT

Glyphosate is a broad-spectrum organophosphate (OP) herbicide, highly soluble in water, and when applied in terrestrial systems it penetrates into soil, eventually reaching the aquatic community and affecting nontarget organisms. The aim of this study was to evaluate the toxicity of glyphosate on ovaries of zebrafish (Danio rerio). Ovaries (n = 18 per triplicate) were exposed to 65 μg/L of glyphosate [N-(phosphonomethyl) glycine] for 15 d. This concentration was determined according to Resolution 357/2005/CONAMA/Brazil, which establishes the permissible concentration of glyphosate in Brazilian inland waters. Nonexposed ovaries (n = 18 per triplicate) were used as control. Subsequently, morphology and expression of steroidogenic factor-1 (SF-1) of exposed and nonexposed ovaries was determined. No apparent changes were noted in general morphology of exposed and nonexposed ovaries. However, a significant increase in diameter of oocytes was observed after exposure to glyphosate. When ovarian ultrastructure was examined the presence of concentric membranes, appearing as myelin-like structures, associated with the external membranes of mitochondria and with yolk granules was found. After glyphosate exposure, immunohistochemistry and immunoblotting revealed greater expression of SF-1 in the oocytes, which suggests a relationship between oocyte growth and SF-1 expression. These subtle adverse effects of glyphosate on oocytes raised a potential concern for fish reproduction. These results contribute to understanding glyphosate-induced toxicity to nontarget organisms, showing subcellular and molecular impairments that may affect reproduction in +female fish.

Islam et al., 2018

Faisal Islam, Jian Wang, Muhammad A. Farooq, Muhammad S.S. Khan, Ling Xu, Jinwen Zhu, Min Zhao, Stéphane Muños, Qing X. Li, Weijun Zhou, “Potential impact of the herbicide 2,4-dichlorophenoxyacetic acid on human and ecosystems,” Environment International, 2018, 111, DOI: 10.1016/j.envint.2017.10.020.

ABSRACT: The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is applied directly to aquatic and conventional farming systems to control weeds, and is among the most widely distributed pollutants in the environment. Non-target organisms are exposed to 2,4-D via several ways, which could produce toxic effects depending on the dose, frequency of exposure, and the host factors that influence susceptibility and sensitivity. An increasing number of experimental evidences have shown concerns about its presence/detection in the environment, because several investigations have pointed out its potential lethal effects on non-target organisms. In this review, we critically evaluated the environmental fate and behavior of 2,4-D along with its eco-toxicological effects on aquatic, plants and human life to provide concise assessment in the light of recently published reports. The findings demonstrate that 2,4-D is present in a low concentration in surface water of regions where its usage is high. The highest concentrations of 2,4-D were detected in soil, air and surface water surrounded by crop fields, which suggest that mitigation strategies must be implanted locally to prevent the entry of 2,4-D into the environment. A general public may have frequent exposure to 2,4-D due to its wide applications at home lawns and public parks, etc. Various in vivo and in vitro investigations suggest that several species (or their organs) at different trophic levels are extremely sensitive to the 2,4-D exposure, which may explain variation in outcomes of reported investigations. However, implications for the prenatal exposure to 2,4-D remain unknown because 2,4-D-induced toxicity thresholds in organism have only been derived from juveniles or adults. In near future, introduction of 2,4-D resistant crops will increase its use in agriculture, which may cause relatively high and potentially unsafe residue levels in the environment. The recent findings indicate the urgent need to further explore fate, accumulation and its continuous low level exposure impacts on the environment to generate reliable database which is key in drafting new regulation and policies to protect the population from further exposure.

Schütte et al., 2017

Gesine Schütte, Michael Eckerstorfer, Valentina Rastelli, Wolfram Reichenbecher, Sara Restrepo‑Vassalli, Marja Ruohonen‑Lehto, Anne‑Gabrielle Wuest Saucy, and Martha Mertens, “Herbicide resistance and biodiversity: agronomic and environmental aspects of genetically modified herbicide-resistant plants,” Environmental Sciences Europe, 2017, 29:5, DOI: 10.1186/s12302-016-0100-y.

ABSTRACT:

Farmland biodiversity is an important characteristic when assessing sustainability of agricultural practices and is of major international concern. Scientific data indicate that agricultural intensification and pesticide use are among the main drivers of biodiversity loss. The analysed data and experiences do not support statements that herbicide-resistant crops provide consistently better yields than conventional crops or reduce herbicide amounts. They rather show that the adoption of herbicide-resistant crops impacts agronomy, agricultural practice, and weed management and contributes to biodiversity loss in several ways: (i) many studies show that glyphosate-based herbicides, which were commonly regarded as less harmful, are toxic to a range of aquatic organisms and adversely affect the soil and intestinal microflora and plant disease resistance; the increased use of 2,4-D or dicamba, linked to new herbicide-resistant crops, causes special concerns. (ii) The adoption of herbicide-resistant crops has reduced crop rotation and favoured weed management that is solely based on the use of herbicides. (iii) Continuous herbicide resistance cropping and the intensive use of glyphosate over the last 20 years have led to the appearance of at least 34 glyphosate-resistant weed species worldwide. Although recommended for many years, farmers did not counter resistance development in weeds by integrated weed management, but continued to rely on herbicides as sole measure. Despite occurrence of widespread resistance in weeds to other herbicides, industry rather develops transgenic crops with additional herbicide resistance genes. (iv) Agricultural management based on broad-spectrum herbicides as in herbicide-resistant crops further decreases diversity and abundance of wild plants and impacts arthropod fauna and other farmland animals. Taken together, adverse impacts of herbicide-resistant crops on biodiversity, when widely adopted, should be expected and are indeed very hard to avoid. For that reason, and in order to comply with international agreements to protect and enhance biodiversity, agriculture needs to focus on practices that are more environmentally friendly, including an overall reduction in pesticide use. (Pesticides are used for agricultural as well non-agricultural purposes. Most commonly they are used as plant protection products and regarded as a synonym for it and so also in this text.) FULL TEXT

Charles, 2017c

Dan Charles,  “A Wayward Weedkiller Divides Farm Communities, Harms Wildlife,” NPR, October 7, 2017.

SUMMARY:

This NPR radio story focuses on the farmer to farmer conflicts engendered by the dicamba drift crisis.  Some farmers are eager for the new technology to address herbicide-resistant glyphosate, while others are devastated by drift damage.   David Wildly, an Arkansas soybean farmer says “It’s something that is so heartbreaking to me. I see farmers taking sides, and enemies being made.”   Farmers who support dicamba-resistant technology hope everyone will soon be using them so neighbors can’t be harmed.  The story then raises the issue of damage to native vegetation that pollinators rely on.  Richard Coy, a beekeeper with 13,000 hives in some of the most affected states, has seen damage to vegetation impacting blooming.  According to Coy, honey production across the region is down about one-third on average. FULL TEXT

 

Hettinger, 2017

Johnathan Hettinger, “Complaints surge about weed killer dicamba’s damage to oak trees,” October 9, 2017, Midwest Center for Investigative Reporting.

SUMMARY:

Dicamba drift is being blamed for damage to oak trees in Iowa, Illinois, and Tennessee.  More than 1,000 complaints were filed in Iowa, and in Tennessee the oak trees at the state’s largest natural lake were damaged.  Monsanto declined to comment, and a BASK spokesperson encourages growers who see damage to contact them but states that they “don’t believe volatility is a driving factor based on past research and experience.”  The article reports that internal Monsanto emails obtained through a Freedom of Information Act request, show the company is trying to shift the blame for oak tree damage to other pesticides.  FULL TEXT

Coupe et. al, 2012

Richard H Coupe, Stephen J Kalkhoff, Paul D Capelc, and Caroline Gregoired, “Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins,” Pest Management Science, 2012, 68:1, 16-30, DOI: 10.1002/ps.2212.

ABSTRACT:

BACKGROUND: Glyphosate [N-(phosphonomethyl)glycine] is a herbicide used widely throughout the world in the production of many crops and is heavily used on soybeans, corn and cotton. Glyphosate is used in almost all agricultural areas of the United States, and the agricultural use of glyphosate has increased from less than 10 000 Mg in 1992 to more than 80 000 Mg in 2007. The greatest intensity of glyphosate use is in the midwestern United States, where applications are predominantly to genetically modified corn and soybeans. In spite of the increase in usage across the United States, the characterization of the transport of glyphosate and its degradate aminomethylphosphonic acid (AMPA) on a watershed scale is lacking.

RESULTS: Glyphosate and AMPA were frequently detected in the surface waters of four agricultural basins. The frequency and magnitude of detections varied across basins, and the load, as a percentage of use, ranged from 0.009 to 0.86% and could be related to three general characteristics: source strength, rainfall runoff and flow route.

CONCLUSIONS: Glyphosate use in a watershed results in some occurrence in surface water; however, the watersheds most at risk for the offsite transport of glyphosate are those with high application rates, rainfall that results in overland runoff and a flow route that does not include transport through the soil. FULL TEXT

Zobiole et. al, 2010b

Luiz Henrique Saes Zobiole, Rubem Silvério de Oliveira Jr., Robert John Kremer, Jamil Constantin, Carlos Moacir Bonato, Antonio Saraiva Muniz, “Water use efficiency and photosynthesis of glyphosate-resistant soybean as affected by glyphosate,” Biochemistry and Physiology, 2010, 97: 182-193, DOI: 10.1016/j.pestbp.2010.01.004.

ABSTRACT:

Previous studies comparing cultivars of different maturity groups in different soils demonstrated that early maturity group cultivars were more sensitive to glyphosate injury than those of other maturity groups. In this work, we evaluated the effect of increasing rates of glyphosate on water absorption and photosynthetic parameters in early maturity group cultivar BRS 242 GR soybean. Plants were grown in a complete nutrient solution and subjected to a range of glyphosate rates either as a single or sequential leaf application. Net photosynthesis, transpiration rate, stomatal conductance, sub-stomatal CO2, carboxylation efficiency, fluorescence, maximal fluorescence and chlorophyll content were monitored right before and at different stages after herbicide application; water absorption was measured daily. All photosynthetic parameters were affected by glyphosate. Total water absorbed and biomass production by plants were also decreased as glyphosate rates increased, with the affect being more intense with a single full rate than half the rate applied in two sequential applications. Water use efficiency (WUE) was significantly reduced with increasing rates of glyphosate.  FULL TEXT

Londo et al., 2014

Jason Paul Londo, John McKinney, Matthew Schwartz, Mike Bollman, Cynthia Sagers, and Lidia Watrud, “Sub-lethal glyphosate exposure alters flowering phenology and causes transient male-sterility in Brassica spp,” BMC Plant Biology, 2014, 14:70.

ABSTRACT:

BACKGROUND: Herbicide resistance in weedy plant populations can develop through different mechanisms such as gene flow of herbicide resistance transgenes from crop species into compatible weedy species or by natural evolution of herbicide resistance or tolerance following selection pressure. Results from our previous studies suggest that sub-lethal levels of the herbicide glyphosate can alter the pattern of gene flow between glyphosate resistant Canola®, Brassica napus, and glyphosate sensitive varieties of B. napus and B. rapa. The objectives of this study were to examine the phenological and developmental changes that occur in Brassica crop and weed species following sub-lethal doses of the herbicides glyphosate and glufosinate. We examined several vegetative and reproductive traits of potted plants under greenhouse conditions, treated with sub-lethal herbicide sprays.

RESULTS: Our results indicate that exposure of Brassica spp. to a sub-lethal dose of glyphosate results in altering flowering phenology and reproductive function. Flowering of all sensitive species was significantly delayed and reproductive function, specifically male fertility, was suppressed. Higher dosage levels typically contributed to an increase in the magnitude of phenotypic changes.

CONCLUSIONS: These results demonstrate that Brassica spp. plants that are exposed to sub-lethal doses of glyphosate could be subject to very different pollination patterns and an altered pattern of gene flow that would result from changes in the overlap of flowering phenology between species. Implications include the potential for increased glyphosate resistance evolution and spread in weedy communities exposed to sub-lethal glyphosate.  FULL TEXT

Johnson et. al, 2009

William G. Johnson, Vince M. Davis, Greg R. Kruger, Stephen C. Weller, “Influence of glyphosate-resistant cropping systems on weed species shifts and glyphosate-resistant weed populations,” European Journal of Agonomy, 2009, 31, 162-172, DOI: 10.1016/j.eja.2009.03.008.

ABSTRACT:

Glyphosate-resistant (GR) crops have facilitated increases in conservation tillage production practices and simplified weed control in GR corn, soybean, canola and cotton. Increased reliance on glyphosate, many times as the only active ingredient used, has resulted in weed species shifts and the evolution of weed populations resistant to glyphosate. However, weed shifts and the evolution of herbicide resistance are not new in regard to glyphosate use. Similar effects have been documented to many other historically important weed control advancements for agricultural crop production. GR crop technology was developed to utilize glyphosate for postemergence weed control and industry scientists suggested that there was little fear of weed shifts and resistance evolution due to the broad spectrum of weeds controlled by glyphosate. However, over the last decade, the most problematic weeds in agronomic cropping systems have shifted away from perennial grass and perennial broadleaf weeds to primarily annual broadleaf weeds. The evolution of several GR annual broadleaf weeds in GR cropping systems has been documented, and glyphosate resistance mechanisms in weeds are currently poorly understood.  FULL TEXT

Bonini et al., 2009

E.A. Bonini, M.L.L. Ferrarese, R. Marchiosi, P.C. Zonetti, O. Ferrarese-Filho, “A simple chromatographic assay to discriminate between glyphosate-resistant and susceptible soybean (Glycine max) cultivars,” European Journal of Agronomy, 2009, 31:3, 1730176, DOI: 10.1016/e.eja.2009.03.006.

ABSTRACT:

In glyphosate-susceptible soybean (Glycine max L. Merrill), the herbicide glyphosate [(N-phosphonomethyl)glycine] inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase, causing a massive accumulation of the metabolite shikimate. This phenomenon does not occur in glyphosate-resistant soybean due the presence of a gene encoding glyphosate-insensitive EPSP synthase. This study proposes a simple and reliable assay as an alternative tool for differentiating glyphosate-resistant from susceptible soybean cultivars. The assay is based on a single extraction of leaf or root tissue. Shikimate is quantified by reversed-phase high–performance liquid chromatography at 220 nm and isocratic elution with phosphoric acid. After glyphosate treatment, tissues of glyphosate-susceptible plants were found to massively accumulate shikimate, whereas the tissues of glyphosate-resistant plants did not accumulate the metabolite.  FULL TEXT

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