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Journal ArticleDOI

Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins.

01 Jan 2012-Pest Management Science (Pest Manag Sci)-Vol. 68, Iss: 1, pp 16-30
TL;DR: 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.
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 10000 Mg in 1992 to more than 80000 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 aminomethylphosphonicacid (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 andflow 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. c � 2011 Society of Chemical Industry

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Citations
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Journal ArticleDOI
TL;DR: Glyphosate will likely remain the most widely applied pesticide worldwide for years to come, and interest will grow in quantifying ecological and human health impacts, according to published global pesticide use data.
Abstract: Accurate pesticide use data are essential when studying the environmental and public health impacts of pesticide use. Since the mid-1990s, significant changes have occurred in when and how glyphosate herbicides are applied, and there has been a dramatic increase in the total volume applied. Data on glyphosate applications were collected from multiple sources and integrated into a dataset spanning agricultural, non-agricultural, and total glyphosate use from 1974–2014 in the United States, and from 1994–2014 globally. Since 1974 in the U.S., over 1.6 billion kilograms of glyphosate active ingredient have been applied, or 19 % of estimated global use of glyphosate (8.6 billion kilograms). Globally, glyphosate use has risen almost 15-fold since so-called “Roundup Ready,” genetically engineered glyphosate-tolerant crops were introduced in 1996. Two-thirds of the total volume of glyphosate applied in the U.S. from 1974 to 2014 has been sprayed in just the last 10 years. The corresponding share globally is 72 %. In 2014, farmers sprayed enough glyphosate to apply ~1.0 kg/ha (0.8 pound/acre) on every hectare of U.S.-cultivated cropland and nearly 0.53 kg/ha (0.47 pounds/acre) on all cropland worldwide. Genetically engineered herbicide-tolerant crops now account for about 56 % of global glyphosate use. In the U.S., no pesticide has come remotely close to such intensive and widespread use. This is likely the case globally, but published global pesticide use data are sparse. Glyphosate will likely remain the most widely applied pesticide worldwide for years to come, and interest will grow in quantifying ecological and human health impacts. Accurate, accessible time-series data on glyphosate use will accelerate research progress.

1,153 citations

Journal ArticleDOI
TL;DR: GBHs are the most heavily applied herbicide in the world and usage continues to rise; Worldwide, GBHs often contaminate drinking water sources, precipitation, and air, especially in agricultural regions and regulatory estimates of tolerable daily intakes for glyphosate in the United States and European Union are based on outdated science.
Abstract: The broad-spectrum herbicide glyphosate (common trade name “Roundup”) was first sold to farmers in 1974. Since the late 1970s, the volume of glyphosate-based herbicides (GBHs) applied has increased approximately 100-fold. Further increases in the volume applied are likely due to more and higher rates of application in response to the widespread emergence of glyphosate-resistant weeds and new, pre-harvest, dessicant use patterns. GBHs were developed to replace or reduce reliance on herbicides causing well-documented problems associated with drift and crop damage, slipping efficacy, and human health risks. Initial industry toxicity testing suggested that GBHs posed relatively low risks to non-target species, including mammals, leading regulatory authorities worldwide to set high acceptable exposure limits. To accommodate changes in GBH use patterns associated with genetically engineered, herbicide-tolerant crops, regulators have dramatically increased tolerance levels in maize, oilseed (soybeans and canola), and alfalfa crops and related livestock feeds. Animal and epidemiology studies published in the last decade, however, point to the need for a fresh look at glyphosate toxicity. Furthermore, the World Health Organization’s International Agency for Research on Cancer recently concluded that glyphosate is “probably carcinogenic to humans.” In response to changing GBH use patterns and advances in scientific understanding of their potential hazards, we have produced a Statement of Concern drawing on emerging science relevant to the safety of GBHs. Our Statement of Concern considers current published literature describing GBH uses, mechanisms of action, toxicity in laboratory animals, and epidemiological studies. It also examines the derivation of current human safety standards. We conclude that: (1) GBHs are the most heavily applied herbicide in the world and usage continues to rise; (2) Worldwide, GBHs often contaminate drinking water sources, precipitation, and air, especially in agricultural regions; (3) The half-life of glyphosate in water and soil is longer than previously recognized; (4) Glyphosate and its metabolites are widely present in the global soybean supply; (5) Human exposures to GBHs are rising; (6) Glyphosate is now authoritatively classified as a probable human carcinogen; (7) Regulatory estimates of tolerable daily intakes for glyphosate in the United States and European Union are based on outdated science. We offer a series of recommendations related to the need for new investments in epidemiological studies, biomonitoring, and toxicology studies that draw on the principles of endocrinology to determine whether the effects of GBHs are due to endocrine disrupting activities. We suggest that common commercial formulations of GBHs should be prioritized for inclusion in government-led toxicology testing programs such as the U.S. National Toxicology Program, as well as for biomonitoring as conducted by the U.S. Centers for Disease Control and Prevention.

638 citations


Cites background from "Fate and transport of glyphosate an..."

  • ...GBHs contaminate drinking water via rainwater, surface runoff and leaching into groundwater, thereby adding drinking water, bathing, and washing water as possible routine exposure pathways [48, 54, 55]....

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Journal ArticleDOI
TL;DR: It is hypothesized that the selection pressure for glyphosate-resistance in bacteria could lead to shifts in microbiome composition and increases in antibiotic resistance to clinically important antimicrobial agents, which would have an impact on plant, animal and human health.

571 citations

Journal ArticleDOI
TL;DR: In this paper, a comprehensive assessment of the environmental occurrence of glyphosate and aminomethylphosphonic acid (AMPA) in the United States conducted to date, summarizing the results of 3,732 water and sediment and 1,018 quality assurance samples collected between 2001 and 2010 from 38 states.
Abstract: Glyphosate use in the United States increased from less than 5,000 to more than 80,000 metric tons/yr between 1987 and 2007. Glyphosate is popular due to its ease of use on soybean, cotton, and corn crops that are genetically modified to tolerate it, utility in no-till farming practices, utility in urban areas, and the perception that it has low toxicity and little mobility in the environment. This compilation is the largest and most comprehensive assessment of the environmental occurrence of glyphosate and aminomethylphosphonic acid (AMPA) in the United States conducted to date, summarizing the results of 3,732 water and sediment and 1,018 quality assurance samples collected between 2001 and 2010 from 38 states. Results indicate that glyphosate and AMPA are usually detected together, mobile, and occur widely in the environment. Glyphosate was detected without AMPA in only 2.3% of samples, whereas AMPA was detected without glyphosate in 17.9% of samples. Glyphosate and AMPA were detected frequently in soils and sediment, ditches and drains, precipitation, rivers, and streams; and less frequently in lakes, ponds, and wetlands; soil water; and groundwater. Concentrations of glyphosate were below the levels of concern for humans or wildlife; however, pesticides are often detected in mixtures. Ecosystem effects of chronic low-level exposures to pesticide mixtures are uncertain. The environmental health risk of low-level detections of glyphosate, AMPA, and associated adjuvants and mixtures remain to be determined.

388 citations


Cites background from "Fate and transport of glyphosate an..."

  • ...…by a series of studies (Scribner et al., 2003, 2007; Kolpin et al., 2004, 2006; Battaglin et al., 2005, 2009; Baker et al., 2006; McCarthy et al., 2011; Coupe et al., 2012), most, but not all of which were designed to determine the fate of glyphosate and AMPA or other pesticides in the environment....

    [...]

  • ...Coupe et al. (2012) also suggest that the %AMPA values should increase with increases in drainage area....

    [...]

  • ...Coupe et al. (2012) suggest that the timing of rainfall runoff events relative to glyphosate and the amount of glyphosate and AMPA in the soil reservoir from previous applications controls %AMPA values in surface water....

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Journal ArticleDOI
TL;DR: It was demonstrated that glyphosate and AMPA are present in soils under agricultural activity, and it was found that in stream samples the presence of glyphosate and aminomethylphosphonic acid is relatively more frequent in suspended particulate matter and sediment than in water.

383 citations


Cites background from "Fate and transport of glyphosate an..."

  • ...…transport of glyphosate and AMPA in streams located in United States show that glyphosate and AMPA have been frequently detected in surface waters of agricultural basins where it is used and their concentrations are influenced by source, hydrology and water movement pathways (Coupe et al., 2012)....

    [...]

  • ...Recently, studies about the transport of glyphosate and AMPA in streams located in United States show that glyphosate and AMPA have been frequently detected in surface waters of agricultural basins where it is used and their concentrations are influenced by source, hydrology and water movement pathways (Coupe et al., 2012)....

    [...]

References
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Journal ArticleDOI
TL;DR: Glyphosate (N-[phosphonomethyl]glycine)³ formulated as Round-Up® herbicide,´ was applied on 0.3-to 3.1-ha watersheds at rates of 1.10-, 3.36-, and $.96-kg/ha as a preseeding herbicide in the no-tillage establishment of rescue (Festuca arundinacea L.) and corn (Zea mays L.). Runoff from natural rainfall following early springtime treatments was measured and analyzed to define concentration
Abstract: Glyphosate (N-[phosphonomethyl]glycine)³ formulated as Round-up® herbicide,⁴ was applied on 0.3- to 3.1-ha watersheds at rates of 1.10-, 3.36-, and $.96-kg/ha as a preseeding herbicide in the no-tillage establishment of rescue (Festuca arundinacea L.) and corn (Zea mays L.). Runoff from natural rainfall following early springtime treatments was measured and analyzed to define concentration and transport of glyphosate under these conditions. The highest concentration of glyphosate (5.2 mg/liter) was found in runoff occurring 1 day after treatment at the highest rate. Glyphosate (2 µg/liter) was detected in runoff from this watershed up to 4 months after treatment. For the lower application rates, maximum concentration of the herbicide in runoff was < 100 µg/liter for events occurring 9–10 days after application and decreased to <2 µg/liter within 2 months of treatment. The maximum amount of glyphosate transport by runoff was 1.85% of the amount applied, most of which occurred during a single storm on the day after application. In each of the three study years, herbicide transport in the first runoff event following treatment accounted for 99% of the total runoff transport on one watershed. Glyphosate residues in the upper 2.5 cm of treated soil decreased logarithmically with the logarithm of time; they persisted several weeks longer than in the runoff water.

128 citations

Journal ArticleDOI
TL;DR: These studies suggest that the changes in the dissipation or distribution of glyphosate following repeated applications of glyphosate may be related to shifts in the soil microbial community composition.
Abstract: Background: Repeated applications may have a greater impact on the soil microbial community than a single application of glyphosate. Experiments were conducted to study the effect of one, two, three, four or five applications of glyphosate on soil microbial community composition and glyphosate mineralization and distribution of 14C residues in soil. RESULTS: Fatty acid methyl esters (FAMEs) common to gram-negative bacteria were present in higher concentrations following five applications relative to one, two, three or four applications both 7 and 14 days after application (DAA). Additionally, sequencing of 16S rRNA bacterial genes indicated that the abundance of the gram-negative Burkholderia spp. was increased following the application of glyphosate. The cumulative percentage 14C mineralized 14 DAA was reduced when glyphosate was applied 4 or 5 times relative to the amount of 14C mineralized following one, two or three applications. Incorporation of 14C residues into soil microbial biomass was greater following five glyphosate applications than following the first application 3 and 7 DAA. CONCLUSION: These studies suggest that the changes in the dissipation or distribution of glyphosate following repeated applications of glyphosate may be related to shifts in the soil microbial community composition. Copyright © 2009 Society of Chemical Industry

128 citations

Journal ArticleDOI
TL;DR: Positive relations between glyphosate [N-(phosphonomethyl)glycine] concentrations and preferential flow for the two storms suggest that preferential flow is an important transport pathway to the tile drain.
Abstract: Agricultural subsurface drains, commonly referred to as tile drains, are potentially significant pathways for the movement of fertilizers and pesticides to streams and ditches in much of the Midwest. Preferential flow in the unsaturated zone provides a route for water and solutes to bypass the soil matrix and reach tile drains faster than predicted by traditional displacement theory. This paper uses chloride concentrations to estimate preferential flow contributions to a tile drain during two storms in May 2004. Chloride, a conservative anion, was selected as the tracer because of differences in chloride concentrations between the two sources of water to the tile drain, preferential and matrix flow. A strong correlation between specific conductance and chloride concentration provided a mechanism to estimate chloride concentrations in the tile drain throughout the storm hydrographs. A simple mixing analysis was used to identify the preferential flow component of the storm hydrograph. During two storms, preferential flow contributed 11 and 51% of total storm tile drain flow; the peak contributions, 40 and 81%, coincided with the peak tile drain flow. Positive relations between glyphosate [N-(phosphonomethyl)glycine] concentrations and preferential flow for the two storms suggest that preferential flow is an important transport pathway to the tile drain.

125 citations

Journal ArticleDOI
TL;DR: Comparisons of the agricultural application and the seasonal concentration and load pattern in the main creek from March to November revealed that the occurrence of glyphosate cannot be explained by agricultural use only and more than half of the load during selected rain events originates from urban areas.

116 citations

Journal ArticleDOI
TL;DR: The success of transgenic soybeans for farmers has led to a higher use of glyphosate as a replacement for other herbicides, which has in turn lead to a decline in its effectiveness, and the issue here is not only genetic engineering in itself, but rather the management and governance of this innovation.
Abstract: Transgenic crops are the subject of lively debate and controversy. Despite such controversy, transgenic soybean has undergone a rapid expansion. Among various types of transgenic crops, herbicide-tolerant crops appear to many to be of limited interest, especially in Europe. Nonetheless, herbicide-tolerant crops are the most widely spread in the world. Indeed, glyphosate-tolerant soybean was notably the most cultivated transgenic plant in the world in 2006. In the USA 91% of soybean was transgenic in 2007. How can this particularly significant diffusion in the USA be explained, and what are its impacts? Such issues are addressed in this article, using surveys, studies of numerous statistical data and literature analysis. A first section underlines the importance of soybean in the current development of transgenic crops in the world, and the favourable context for their expansion in the USA. Then follows an analysis of the advantages and drawbacks of transgenic soybean for American farmers. Factors explaining the rapid diffusion of transgenic soybean are also analysed. A comparison of transgenic versus conventional soybean reveals that transgenic glyphosate-tolerant soybean allows both the simplification of weed control and greater work flexibility. Cropping transgenic soybean also fits well with conservation tillage. Transgenic soybean has an economic margin similar to conventional soybean, despite a higher seed cost. The next section describes the evolution of the use of herbicides with transgenic soybean, and some issues linked to the rapid increase in the use of glyphosate. At the beginning a smaller amount of herbicides was used, but this amount increased from 2002, though not steadily. Nonetheless, the environmental and toxicological impacts of pesticides do not only depend on the amounts applied. They also depend on the conditions of use and the levels of toxicity and ecotoxicity. The levels of ecotoxicity seem to have somewhat decreased. The success of transgenic soybeans for farmers has led to a higher use of glyphosate as a replacement for other herbicides, which has in turn led to a decline in its effectiveness. However, the issue here is not only genetic engineering in itself, but rather the management and governance of this innovation. Finally, the prospects of transgenic soybean are addressed. Transgenic soybean with new traits should be placed on the market. The conclusion describes economic context of the development of the first transgenic crops.

114 citations