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Bibliography Tag: herbicide use

Kleter et al., 2011

Kleter, Gijs A, Unsworth, B, & Harris, Caroline A; “The impact of altered herbicide residues in transgenic herbicide-resistant crops on standard setting for herbicide residues;” Pest Management Science, 2011, 67, 1193-1210; DOI: 10.1002/ps.2128.


The global area covered with transgenic (genetically modified) crops has rapidly increased since their introduction in the mid-1990s.Most of these crops have been rendered herbicide resistant, for which it can be envisaged that the modification has an impact on the profile and level of herbicide residues within these crops. In this article, the four main categories of herbicide resistance, including resistance to acetolactate-synthase inhibitors, bromoxynil, glufosinate and glyphosate, are reviewed. The topics considered are the molecular mechanism underlying the herbicide resistance, the nature and levels of the residues formed and their impact on the residue definition and maximum residue limits (MRLs) defined by the Codex Alimentarius Commission and national authorities. No general conclusions can be drawn concerning the nature and level of residues, which has to be done on a case-by-case basis. International residue definitions and MRLs are still lacking for some herbicide–crop combinations, and harmonisation is therefore recommended. FULL TEXT

Martin et al., 2018

Martin, F. L., Martinez, E. Z., Stopper, H., Garcia, S. B., Uyemura, S. A., & Kannen, V., “Increased exposure to pesticides and colon cancer: Early evidence in Brazil,” Chemosphere, 2018, 209, 623-631. DOI: 10.1016/j.chemosphere.2018.06.118.


Environmental factors may increase colon cancer (CC) risk. It has been suggested that pesticides could play a significant role in the etiology of this malignancy. As agriculture is one of the mainstays of the Brazilian economy, this country has become the largest pesticides consumer worldwide. The CC burden is also increasing in Brazil. Herein, we examined data from the Brazilian Federal Government to determine whether CC mortality and pesticide consumption may be associated. Database of the Ministry of Health provided CC mortality data in Brazil, while pesticide usage was accessed at the website of Brazilian Institute of Environment and Renewable Natural Resources. The CC mortality in the Brazilian states was calculated as standard mortality rates (SMR). All Bayesian analysis was performed using a Markov chain Monte Carlo method in WinBUGS software. We observed that CC mortality has exhibited a steady increase for more than a decade, which correlated with the amount of sold pesticides in the country. Both observations are concentrated in the Southern and the Southeast regions of Brazil. Although ecological studies like ours have methodological limitations, the current dataset suggests the possibility that pesticide exposure may be a risk factor for CC. It warrants further investigation.

Kniss, 2016

Kniss, A. R., “Long-term trends in the intensity and relative toxicity of herbicide use,” Nature Communications, 2017, 8, 14865. DOI: 10.1038/ncomms14865.


Herbicide use is among the most criticized aspects of modern farming, especially as it relates to genetically engineered (GE) crops. Many previous analyses have used flawed metrics to evaluate herbicide intensity and toxicity trends. Here, I show that herbicide use intensity increased over the last 25 years in maize, cotton, rice and wheat. Although GE crops have been previously implicated in increasing herbicide use, herbicide increases were more rapid in non-GE crops. Even as herbicide use increased, chronic toxicity associated with herbicide use decreased in two out of six crops, while acute toxicity decreased in four out of six crops. In the final year for which data were available (2014 or 2015), glyphosate accounted for 26% of maize, 43% of soybean and 45% of cotton herbicide applications. However, due to relatively low chronic toxicity, glyphosate contributed only 0.1, 0.3 and 3.5% of the chronic toxicity hazard in those crops, respectively. FULL TEXT

Hicks et al., 2018

Hicks, Helen L., Comont, David, Coutts, Shaun R., Crook, Laura, Hull, Richard, Norris, Ken, Neve, Paul, Childs, Dylan Z., & Freckleton, Robert P., “The factors driving evolved herbicide resistance at a national scale,” Nature Ecology & Evolution, 2018, 2(3), 529-536. DOI: 10.1038/s41559-018-0470-1.


Repeated use of xenobiotic chemicals has selected for the rapid evolution of resistance, threatening health and food security at a global scale. Strategies for preventing the evolution of resistance include cycling and mixtures of chemicals and diversification of management. We currently lack large-scale studies that evaluate the efficacy of these different strategies for minimizing the evolution of resistance. Here we use a national-scale data set of occurrence of the weed Alopecurus myosuroides (black-grass) in the United Kingdom to address this. Weed densities are correlated with assays of evolved resistance, supporting the hypothesis that resistance is driving weed abundance at a national scale. Resistance was correlated with the frequency of historical herbicide applications, suggesting that evolution of resistance is primarily driven by intensity of exposure to herbicides, but was unrelated directly to other cultural techniques. We find that populations resistant to one herbicide are likely to show resistance to multiple herbicide classes. Finally, we show that the economic costs of evolved resistance are considerable: loss of control through resistance can double the economic costs of weeds. This research highlights the importance of managing threats to food production and healthcare systems using an evolutionarily informed approach in a proactive not reactive manner.

Gillezeau et al., 2019

Gillezeau, Christina, van Gerwen, Maaike, Shaffer, Rachel M, Rana, Iemaan, Zhang, Luoping, Sheppard, Lianne, & Taioli, Emanuela, “The evidence of human exposure to glyphosate: a review,” Environmental Health, 2019, 18(1), 2. DOI: 10.1186/s12940-018-0435-5.


BACKGROUND: Despite the growing and widespread use of glyphosate, a broad-spectrum herbicide and desiccant, very few studies have evaluated the extent and amount of human exposure.

OBJECTIVE: We review documented levels of human exposure among workers in occupational settings and the general population.

METHODS: We conducted a review of scientific publications on glyphosate levels in humans; 19 studies were identified, of which five investigated occupational exposure to glyphosate, 11 documented the exposure in general populations, and three reported on both.

RESULTS: Eight studies reported urinary levels in 423 occupationally and para-occupationally exposed subjects; 14 studies reported glyphosate levels in various biofluids on 3298 subjects from the general population. Average urinary levels in occupationally exposed subjects varied from 0.26 to 73.5 mug/L; environmental exposure urinary levels ranged from 0.16 to 7.6 mug/L. Only two studies measured temporal trends in exposure, both of which show increasing proportions of individuals with detectable levels of glyphosate in their urine over time.

CONCLUSIONS: The current review highlights the paucity of data on glyphosate levels among individuals exposed occupationally, para-occupationally, or environmentally to the herbicide. As such, it is challenging to fully understand the extent of exposure overall and in vulnerable populations such as children. We recommend further work to evaluate exposure across populations and geographic regions, apportion the exposure sources (e.g., occupational, household use, food residues), and understand temporal trends. FULL TEXT

Benbrook, 2018

Benbrook, Charles, “Why Regulators Lost Track and Control of Pesticide Risks: Lessons From the Case of Glyphosate-Based Herbicides and Genetically Engineered-Crop Technology,” Current Environmental Health Reports, 5:3, 387-395, 2018, DOI:10.1007/s40572-018-0207-y.


PURPOSE OF REVIEW: The approval of genetically engineered (GE) crops in the late 1990s triggered dramatic changes in corn, soybean, and cotton pest management systems, as well as complex, novel regulatory challenges. Lessons learned are reviewed and solutions described.

RECENT FINDINGS: Government-imposed resistance management provisions can work and adapt to changing circumstances, but within the private sector, pressures to gain and hold market share have thus far trumped the widely recognized need for resistance management. Risks arising from the use of formulated pesticides often exceed by a wide margin those in regulatory risk assessments based on data derived from studies on nearly 100% pure active ingredients.

SUMMARY: Innovative policy changes are needed in four problem areas: excessive faith in the accuracy of pre-market risk assessments and regulatory thresholds; post-approval monitoring of actual impacts; risk arising from formulated pesticides, rather than just pure active ingredient; challenges inherent in assessing and mitigating the combined impacts of all GE traits and associated pesticides on agroecosystems, as opposed to each trait or pesticide alone; and, tools to deal with failing pest management systems. 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.


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

Purdue Extension, 2013

Purdue Extension, “Corn and Soybean Herbicide Chart,” 2013.


This chart groups herbicides by their modes of action to assist you in selecting herbicides 1) to maintain greater diversity in herbicide use and 2) to rotate among herbicides with different sites of action to delay the development of herbicide resistance.  FULL TEXT

Benbrook, 2016a

Charles M. Benbrook, “Trends in glyphosate herbicide use in the United States and globally,”  Environmental Sciences Europe, 2016, 28:3, DOI 10.1186/s12302-016-0070-0.


BACKGROUND: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.  FULL TEXT

Harker et al., 2012

K. Neil Harker, John T. O’Donovan, Robert E. Blackshaw, Hugh J. Beckie, C. Mallory-Smith, and Bruce D. Maxwell, “Our View,” Weed Science, 2012, 60, DOI: 10.1614/WS-D-11-00177.1.

Perhaps the incidence and impact of glyphosate-resistant weed species are now great enough that real solutions to glyphosate resistance can be discussed without much backlash. It is clear to most weed scientists who are involved in herbicide research, and even those who are not, that the best way to reduce selection pressure for herbicide resistance is to minimize herbicide use. However, the ‘‘solutions’’ that have emerged in most recent meetings on herbicide resistance have usually involved more herbicide use—herbicide rotation, tank-mixtures, PRE- followed by POST-herbicides, ‘‘right-rates,’’ etc. To an unbiased observer, it would appear that many weed emperors are wearing no clothes. Are we as a weed science discipline choosing to ignore true integrated solutions to the herbicide resistance problem? FULL TEXT

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