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Trends in glyphosate herbicide use in the United States and globally

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Abstract and Figures

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.
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Benbrook Environ Sci Eur (2016) 28:3
DOI 10.1186/s12302-016-0070-0
Trends inglyphosate herbicide use
inthe United States andglobally
Charles M. Benbrook*
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.
Keywords: Glyphosate, Herbicide use, Genetic engineering, Herbicide-tolerant crops, Roundup, Pesticide use
© 2016 Benbrook. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License
(, which permits unrestricted use, distribution, and reproduction in any medium,
provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license,
and indicate if changes were made.
A Swiss chemist working for a pharmaceutical com-
pany, Dr. Henri Martin, discovered glyphosate
[N-(phosphonomethyl) glycine] in 1950 [1]. Because no
pharmaceutical applications were identified, the mol-
ecule was sold to a series of other companies and samples
were tested for a number of possible end uses. A Mon-
santo chemist, Dr. John Franz, identified the herbicidal
activity of glyphosate in 1970, and a formulated end-use
product called Roundup was first sold commercially by
Monsanto in 1974 [2].
For two decades, the number and diversity of agri-
cultural and non-farm uses grew steadily, but the
volume sold was limited because glyphosate could only
be sprayed where land managers wanted to kill all vegeta-
tion (e.g., between the rows in orchards and viticulture;
industrial yards; and, train, pipeline, and powerline rights
of way). Some applications were, and still are made after
a crop is harvested, to control late-season weeds that
escaped other control measures. In some regions, des-
iccant applications are made late in the growing season
to speed up harvest operations, especially in small grain
In 1996, so-called “Roundup Ready” (RR), genetically
engineered (GE) herbicide-tolerant (HT) soybean, maize,
and cotton varieties were approved for planting in the
U.S. is technological breakthrough made it possible
to utilize glyphosate as a broadcast, post-emergence her-
bicide, thereby dramatically extending the time period
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Benbrook Environ Sci Eur (2016) 28:3
during which glyphosate-based herbicides could be
applied. Alfalfa and sugar beets engineered to tolerate
glyphosate were first approved and commercially mar-
keted in 2005 and 2008, respectively, but federal lawsuits
citing procedural violations of the National Environmen-
tal Policy Act delayed full commercial sales until 2011 for
RR alfalfa and 2012 for RR sugar beets [3, 4].
To quantify the environmental and human health
impacts stemming from pesticide use, it is essential to
know how much pesticide is being applied in a region
on a given crop, collectively across all crops, and in
other places (e.g., forests, rangeland, along rights-of-way,
industrial yards). Ideally, data are available on the land
area and crops treated; the timing and method of appli-
cations; rates and number of application; the formulation
applied and the total volume applied per hectare. Unfor-
tunately, all these data are rarely available.
Rising use heightens risk concerns. Growing reliance on
the broad-spectrum herbicide glyphosate has triggered
the spread of tolerant and resistant weeds in the U.S.
and globally [510]. To combat weeds less sensitive to
glyphosate, farmers typically increase glyphosate appli-
cation rates and spray more often [1113]. In addition,
next-generation herbicide-tolerant crops are, or will soon
be on the market genetically engineered to withstand the
application of additional herbicides (up to over a dozen),
including herbicides posing greater ecological, crop dam-
age, and human health risks (e.g., 2,4-D and dicamba) [6].
is paper presents trends in glyphosate use in order to
help researchers better understand and quantify the risks
and benefits stemming from uses of glyphosate-based
herbicides. Detailed data on trends in glyphosate use in
the U.S., both in and outside the agricultural sector, are
presented, while the data on global glyphosate use are
less complete and more uncertain. Fortunately, sufficient
data are available to track the impact of GE herbicide-
tolerant (HT) crops on global glyphosate-based herbicide
(GBH) use since 2010 [1417].
In order to better understand the many factors driving
the trajectory of glyphosate’s use and impacts, two time-
line graphics are presented in the “Discussion” section,
Use data
roughout this paper, all references to glyphosate or
glyphosate-based herbicides encompass all commercial
end-use formulations. All data on volumes of glyphosate
applied refer to kilograms or pounds of the active ingre-
dient glyphosate, rather than glyphosate plus the adju-
vants and surfactants included in an end-use formulation
to enhance uptake by weeds and facilitate mixing and
spray applications.
Glyphosate is applied in a variety of forms including
isopropylamine salt, ammonium salt, diammonium salt,
dimethylammonium salt, and potassium salt [1]. E.g., in
its corn pesticide use survey in 2014, the National Agri-
cultural Statistics Service (NASS) collected data on four
different forms of glyphosate applied at different rates:
isopropylamine salt, glyphosate, glyphosate ammonium
salt, and glyphosate potassium salt [11]. Total corn hec-
tares treated with glyphosate in the U.S. and kilograms
of active ingredient applied are the sum across the four
forms of glyphosate. “Total glyphosate” rate of appli-
cation is calculated as an average of the four applica-
tion rates reported for the different forms of glyphosate,
weighed by the area treated with each form of glyphosate.
e same process can be used to calculate “total glypho-
sate” average number of applications per hectare.
Four data points are generally collected and/or calcu-
lated when government agencies or private survey com-
panies report pesticide use data on a given crop in a
defined area and time period: (1) the percent of crop hec-
tares treated with a given pesticide; (2) the average rate
of application; (3) the average number of applications per
crop year; and (4) total kilograms of pesticide applied to
the crop. When a data source does not report total kilo-
grams or pounds applied, or one other of the above key
parameters, the missing variable can be calculated based
where Weightp,c is the amount of pesticide p applied to
crop c (kg active ingredient [a.i.]), AreaTreatedp,c is the
area of crop c to which the pesticide p is applied (ha),
TotalAreac is the total area planted with crop c (ha), and
Ratep,c is the “Rate per Crop Year” for pesticide p on crop
c. “Rate per Crop Year” is the product of the average rate
of application multiplied by the number of applications
per crop year, and is a useful metric because certain crops
may be planted in the fall and harvested the next spring
or summer of the following year.
U.S. data sources
e U.S. Department of Agriculture (USDA), through the
National Agricultural Statistics Service (NASS), has col-
lected reasonably comprehensive pesticide use data for
major grain, row crop, fruit, and vegetable crops since
1990 [18]. Periodic USDA surveys are also available to
track pesticide use on major crops back into the 1970s.
Between 1997 and 2007, the U.S. Environmental Pro-
tection Agency (EPA) issued several reports on the vol-
umes of pesticides applied in the agricultural, industrial/
government, and urban/suburban sectors [1923]. EPA
use reports capture a number of lower-volume pesticide
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Benbrook Environ Sci Eur (2016) 28:3
Million Acres
Percent Acres Treated
Soybean Acres
Percent Acres Treated with Glyphosate Total Acres Planted
Number of Herbicides per Acre
Herbicide Use per Acre
Overall Soybean Herbicide Use
Avg Number of Herbicides per Acre Total Herbicide Use per Acre
Percent of Total
Number of Apps and Rate
Reliance on Glyphosate in Soybean Producon
Glyphosate as Percent of Total Herbicide UseGlyphosate Number of Applicaons
Glyphosate Rate per Crop Year
Bushels per Acre
Yield per Seed (lbs)
Soybean Producon
Bushels per Acre Yield per Seed Planted (lbs)
Fig. 1 Trends in U.S. soybean production and glyphosate use
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Page 4 of 15
Benbrook Environ Sci Eur (2016) 28:3
uses not included in USDA surveys and are the only pub-
lic source of data on industrial/government and subur-
ban/urban pesticide use.
Data on glyphosate use on specific crops in the U.S.
are primarily drawn from pesticide use surveys carried
out by the USDA’s NASS. Pesticide applications at the
national and state level have been reported since 1990 by
NASS for most major field crops; fruit crops have been
surveyed in odd years; and vegetables have been covered
in even years [18].
Estimates of overall GBH use by U.S. farmers and
ranchers are available from three sources: the sum
of crop-specific NASS data in any given year; the
EPA periodic reports noted above; and, the pesticide
use data set compiled by the U.S. Geological Survey
(USGS), which in turn draws heavily on private survey
data [2426]. Both the EPA and USGS use data com-
pilations augment NASS data with a variety of other
information sources that cover uses not included in
NASS surveys. In addition, a number of private com-
panies conduct surveys of pesticide use in the U.S. and
around the world, although detailed results are not
publicly accessible.
NASS surveys a limited number of crops in any given
year. In the tables that follow, pesticide use is linearly
interpolated in years lacking survey data but bounded by
reported values. In years before the first, or after the last
NASS survey, annual values are extrapolated (see [27],
Additional file1: Tables for details).
In each year, NASS strives to collect data on states that
collectively account for at least 85% of the area planted
nationally to a given crop. For some crops, 15 or more
states are surveyed to reach this threshold, while in other
crops only two states are required (e.g., lemons in 2011,
two states; corn in 2010, 21 states). Accordingly, when
NASS reports national estimates of total pesticide use on
surveyed acres of a given crop, the data typically under-
estimate total national crop use by~15%, since national
acres planted always exceeds NASS acres surveyed. is
is why in several Additional file1: Tables [27] the pounds
of herbicides applied are reported on both NASS-sur-
veyed acres and total national acre. To estimate use on
all planted hectares/acres, the average rate of application
per crop year on NASS-surveyed acres is applied to the
total planted area [28].
Total volume ofglyphosate applied
NASS use data were downloaded and integrated into the
“Pesticide Use Data System” (PUDS). Additional file1:
Tables S6–S15 [27] report glyphosate use in the U.S. on
grain crops, fruits, vegetables, nuts, and other crops for
1982, 1992, 1995, 1998, 2001, 2004, and every 2 years
thereafter through 2014. ese tables report average rates
of glyphosate application and rate per crop year weighted
by the acres treated with each of the multiple forms of
glyphosate included in NASS surveys. Total pounds of
all forms of glyphosate applied to all crops surveyed by
NASS are shown in Additional file1: Table S17 [27]. Val-
ues in years when NASS did not survey a given crop are
interpolated or extrapolated (see Additional file1: Table
S17 for details).
Little or no government or published survey data
are accessible on the volume of glyphosate applied on
canola and pima cotton, as well as two more recently
approved and planted GE-HT crops (alfalfa, sugar
beets). Estimates of GBH use on these crops were made
for 2012–2014 in Additional file 1: Table S16, based
on NASS data on acres planted, estimates of adoption
of glyphosate-tolerant varieties issued by commodity
groups, academic weed management specialists, or in
trade press articles.
EPA pesticide use summary reports
Pesticide use reports have been released by the EPA for
1987, 1993, and every two years thereafter through 2007
ese reports encompass more crops and agricultural
uses than the NASS reports, and also quantify use in
three sectors: “U.S. Agriculture,” “Industrial/Commer-
cial/Government,” and “Home and Garden.” EPA pesti-
cide use reports draw on NASS survey results, a number
of proprietary pesticide use datasets, and pesticide pro-
duction and use data submitted by registrants, or col-
lected during the course of a regulatory review of a given
e EPA has not reported pesticide use data since 2007.
However, NASS coverage of the major uses of glyphosate
is somewhat consistent since 2007, and the U.S. Geologi-
cal Survey (USGS) has also issued detailed reports and
a dataset of pesticide use covering 1992-2011 [25, 29].
Results from NASS, EPA, and USGS are integrated in
Additional file1: Table S18 [27] to produce annual data
from 1974 through 2014 in glyphosate use in agriculture,
non-agricultural applications, and total glyphosate use.
Global glyphosate use data sources and estimates. A
special issue of the journal Pest Management Science in
2000 focused on glyphosate uses, issues, and challenges.
Woodburn [29] summarized global glyphosate use from
1994–1997, and provided valuable information on agri-
cultural and non-agricultural uses. Woodburn’s analysis
drew upon proprietary data sources and surveys.
Several sources of industry data on global glyphosate
production are available for 2011–2014 [3033]. Global
use data in Additional file 1: Table S23 between 1997
and 2011 are interpolated and track the annual rates of
growth in the U.S.
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Benbrook Environ Sci Eur (2016) 28:3
Glyphosate use onherbicide‑tolerant hectares
Global soybean production in 2014 was 315.4 million
metric tons (11.6 million bushels), with the U.S. (108
million metric tons), Brazil (94.5 mill. metric tons), and
Argentina (56 mill. metric tons) accounting for 82% of
the global harvest [34]. e International Service for
the Acquisition of Agri-Biotech Applications (ISAAA)
compiles annual, global data by country, continent, and
worldwide on hectares planted to various GE crop vari-
eties ([1417], [27], Additional file 1: Table S20). Data
from these briefs were combined with estimates of aver-
age glyphosate rates of application ([27], Additional
file1: Table S21), yielding estimates of total glyphosate
use from 1996 to 2014 on GE, herbicide-tolerant cotton,
maize, soybeans, and canola, and globally for all crops
([27], Additional file1: Table S23).
Use in Argentina and Brazil. GE-HT soybeans
accounted for 100 and 93% of the soybean hectares
planted in Argentina and Brazil in 2014 [34]. Sistema
Integrado de Información Agropecuaria (Ministerio de
Agricultura Ganadaria y Pesca) reports data on hec-
tares planted to soybeans in Argentina [35], and the
Instituto Brasileiro de Geografia e Estatística (IBGE)
provides the same data for Brazil [36]. For Argen-
tina and Brazil, Soystats [34] provides percent of area
planted to GE-HT soybeans for 2000–2014. Benbrook
[37] and Meyer and Cederberg [38] provide informa-
tion on glyphosate use rates per crop year, which are
substantially higher than those in the U.S. Ferraro and
Ghersa [39] also document applications to soybeans in
Argentina that can range up to seven per year, substan-
tially more than in the U.S.
Glyphosate use inthe U.S
Farmers and ranchers in the U.S. applied an estimated
0.36 million kg of active ingredient (0.8 million pounds)
in 1974 (Table1). e volume applied increased steadily,
but not dramatically, through 1995, to 12.5 million kg (28
million pounds).
e 12.5 million kg applied in 1995, prior to the GE era,
made glyphosate the seventh most heavily applied pes-
ticide in U.S. agriculture that year, according to the EPA
([27], Additional file1: Table S19). e top-six pesticides
applied by U.S. farmers and ranchers in 1995 included
two herbicides mostly used on corn (#1 atrazine, and #2
metolachlor), three soil fumigants primarily applied on
fruit and vegetable crops (#3-5, metam-sodium, methyl-
bromide, dichloropropene), and one broad-leaf herbicide
relied on in multiple cropping systems (#6, 2,4-D).
As GE-HT crops gained market share in 1996–2000,
agricultural applications of glyphosate in the U.S. rose
rapidly, reaching 36 million kg (79 million pounds) by
2000 (Table1). at year, agricultural uses of glyphosate
accounted for 80% of total national use (in 1974, the agri-
cultural share of total glyphosate use was about 60%). A
decade later in 2010, agriculture’s share had risen to 90%.
From 1974–2014, a total of 1.37 billion kg of glyphosate
(3.0 billion pounds) was applied in the U.S. agricultural
sector (Table1).
Glyphosate use in the agricultural sector rose 300-fold
from 1974 to 2014 (0.36–113.4 million kg; 0.8–250 mil-
lion pounds). Non-agricultural uses rose less dramati-
cally, by 43-fold in the same time period, because there
were far fewer new, non-agricultural uses registered.
Glyphosate has been on the market as a herbicide for
42years. In the first 31 of these years (1974–2004), U.S.,
farmers applied only~27% of the total volume (weight)
of glyphosate applied since 1974. Nearly 67 % of total
agricultural glyphosate use in the U.S. since 1974 has
occurred in just the last 10years (Table2).
Use bycrop inthe U.S
Table 3 provides an overview of trends since 1990 in
glyphosate applications on 12 major crops in the U.S.
surveyed by NASS, as well as an estimate of use on all
Table 1 Glyphosate active ingredient use inthe United States: 1974–2014
Data in thousands of kilograms or pounds of glyphosate active ingredient. From the National Agriculture Statistical Service pesticide use data and the Environmental
Protection Agency pesticide industry and use reports (1995, 1997, 1999, 2001, 2007). See Additional le1: Table S18 for details
1974 1982 1990 1995 2000 2005 2010 2012 2014
Glyphosate Use (1000 kg) 635 3538 5761 18,144 44,679 81,506 118,298 118,753 125,384
Agricultural 363 2268 3357 12,474 35,720 71,441 106,963 107,192 113,356
Non-agricultural 272 1270 2404 5670 8958 10,065 11,335 11,562 12,029
Glyphosate use (1000 lb) 1400 7800 12,700 40,000 98,500 179,690 260,804 261,807 276,425
Agricultural 800 5000 7400 27,500 78,750 157,500 235,814 236,318 249,906
Non-agricultural 600 2800 5300 12,500 19,750 22,190 24,989 25,489 26,519
Share agricultural (%) 57.1 64.1 58.3 68.8 79.9 87.7 90.4 90.3 90.4
Share non-agricultural (%) 42.9 35.9 41.7 31.3 20.1 12.3 9.6 9.7 9.6
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Benbrook Environ Sci Eur (2016) 28:3
other crops. Soybeans accounted for about one-third
of total agricultural glyphosate use in 1990, a share
that rises to almost one-half by 2014 (Table 3). e
three major GE-HT crops (soybeans, maize, cotton)
accounted for~200 million pounds of glyphosate use
based on NASS data, or 80% of total farm and ranch
use in 2014 (249.9 million pounds; Table3). USGS data
for 2012 place total GBH use on the three GE-HT crops
at 235 million pounds; the difference between NASS
and USGS data arises from higher USGS estimates of
use on corn and cotton.
Detailed glyphosate use data for NASS-surveyed crops
are provided in Additional file1: Tables S11–21 [27] for
1982, 1992, 1995, 1998, 2001, 2004, and every even year
thereafter through 2014. In each table, the following crop
groups are used: grains, fruits, vegetables, nuts, and other
crops. For each crop and year, the data points include
percent of acres treated, rate of application, number of
applications, rate per crop year, pounds applied to sur-
veyed acres and to total national crop acres. Additional
file1: Table S5 provides glyphosate herbicide data at the
state level for winter wheat in Kansas from 1993–2012.
Global glyphosate use
Worldwide glyphosate use was modest in the 1970s com-
pared to the most heavily applied herbicides then on the
market (e.g. atrazine, metolachlor). e volume applied
grew relatively slowly until the GE era ([27], Additional
file 1: Table S24). By 1994, global agricultural use had
reached 43 million kg of active ingredient (95 million
pounds). Another 13 million kg were applied outside
agriculture, for a total of 56.3 million kg (124 million
Global agricultural use of glyphosate mushroomed
following adoption of GE-HT crops in 1996. e total
volume applied by farmers rose 14.6-fold, from 51
million kg (113 million pounds) in 1995 to 747 mil-
lion kg (1.65 billion pounds) in 2014 (Table4). In this
same time period, agricultural use of glyphosate in the
U.S. rose 9.1-fold. Global non-agricultural uses have
increased fivefold since the introduction of GE crops,
from 16 million kg in 1995 to 79 million kg (35–175
million pounds; Table4).
Total worldwide glyphosate use (agricultural plus non-
agricultural) rose more than 12-fold from about 67 mil-
lion kg in 1995 to 826 million kg in 2014 (0.15–1.8 billion
pounds; Table4). Over the last decade, 6.1 billion kgs of
glyphosate have been applied, 71.6% of total use world-
wide from 1974–2014 (Table5).
Table 2 Share of total glyphosate active ingredient use
bydecade inthe U.S
Estimated from National Agriculture Statistical Service (NASS), USGS, and EPA
data. See Additional le1: Table S18 for details
Total use
(million kg) Increase
Share of
total use
1974–2014 (%)
1974 0.6 NA 0.0
1975–1984 26 25 1.6
1985–1994 77.1 51 4.8
1995–2004 433 356 26.9
2005–2014 1070 637 66.6
Total 1607
Table 3 Glyphosate active ingredient applied tomajor crop inthe U.S., 1990–2014
Data are pounds of active ingredient applied
National Agriculture Statistical Service. See Additional le1: Table S17 for details
1990 1995 2000 2005 2010 2014
Soybeans 2,663,000 7,628,350 43,870,826 72,043,130 107,697,606 122,473,987
Corn 880,066 2,620,860 4,779,306 25,587,085 69,494,324 68,949,452
Cotton, upland 192,429 1,013,052 10,145,096 16,308,461 17,815,794 17,421,787
Wheat, winter 331,758 239,051 1,702,193 5,045,592 13,922,880 12,353,488
Alfalfa 381,525 402,666 422,334 469,539 479,184 8,853,600
Wheat, spring (excl. durum) 90,659 416,744 1,892,420 2,203,603 4,128,957 4,217,788
Sorghum 236,305 751,913 1,540,931 2,652,943 3,924,301 4,178,573
Sugar beets 36,130 59,012 87,439 118,139 2,226,610 2,763,075
Canola 0 0 552,632 647,368 1,284,317 219,392
Oranges 885,201 1,149,594 1,487,882 1,898,798 1,631,050 1,683,156
Wheat, spring durum 75,308 199,483 450,635 444,785 1,190,234 1,201,807
Barley 13,168 45,563 248,554 658,954 996,626 1,064,160
Other crops 1,897,522 2,733,922 3,736,751 4,249,288 4,648,224 4,526,043
Total crops 7,683,070 17,260,209 70,916,999 132,327,684 229,440,109 249,906,307
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Benbrook Environ Sci Eur (2016) 28:3
Use onGE‑HT crops
For over a decade, the vast majority of hectares planted
to maize, soybeans, canola, and cotton have been geneti-
cally engineered (GE) to be herbicide-tolerant (HT) (see
Fig. 2a; [1517]). In 2012, 265 million kgs of glypho-
sate were applied on GE-HT soybeans, or about 73 %
of all glyphosate applied on GE-HT crops, and 41% of
total, global GBH use (Table6). Between 2010 and 2012,
glyphosate use rose moderately in GE-HT cotton pro-
duction (10%) and soybeans (19%), but more sharply in
GE-HT maize (47%) and canola (36%).
e percent of global agricultural glyphosate use
accounted for by GE-HT crops rose from 51% in 2010 to
56% in 2012 (Table6). is percentage cannot be calcu-
lated accurately for earlier years because comprehensive
ISAAA time series data reporting on hectares planted to
GE-HT crops began in 2010 [14].
Volume applied inthe U.S
e United States has the world’s most complete, pub-
licly accessible data on glyphosate use. e combination
of NASS, EPA, and USGS glyphosate use data provides
a solid foundation to track trends in agricultural, non-
agricultural, and total glyphosate use from commercial
introduction through 2014. A report issued by the
National Center for Food and Agricultural Policy [40]
provides useful, detailed information on glyphosate use
by state and crop for 1995, drawing on NASS, EPA, and
information from land grant university weed manage-
ment specialists.
Annual agricultural glyphosate use volumes in the
nine EPA pesticide use reports issued between 1997 and
2007 exceed NASS annual totals for the same years by
20–70%, largely because EPA had access to multiple data
sources that made it possible to estimate the volume of
glyphosate applied on all crops, as well as non-crop use
patterns (e.g., pasture and range uses). NASS estimates,
on the other hand, were limited in any given year to the
crops surveyed in a particular year, and NASS never or
rarely surveys pesticide use on crops grown on limited
acreage. e differences are largest in the first two dec-
ades of glyphosate use (through 1995), and reflect the
array of glyphosate uses not covered in NASS, crop-by-
crop pesticide use surveys. But as total agricultural use
rises sharply post-1996 in the wake of the introduction
of GE-HT crops, glyphosate use on the major GE crops
(maize, soybeans, cotton) is fully captured in NASS, EPA,
and USGS data. Differences in agricultural use estimates
between the datasets all but disappear by 2007 (NASS,
184.2 million pounds glyphosate use; EPA mid-range,
182.5; USGS, 183.2; [27], Additional file1: Table S18).
Factors driving use upward
Several factors have driven the increase in glyphosate use
since commercial introduction in 1974. In terms of area
treated, the dominant factor has been the commerciali-
zation of GE-HT crops. Not only has glyphosate been
sprayed on more hectares planted to HT crops, it has also
been applied more intensively—i.e., more applications
per hectare in a given crop year, and higher one-time
rates of application [13, 28].
In the U.S. soybean sector, the average number of
glyphosate applications rose from 1.1 per crop year
in 1996 to 1.52 in 2014, while the one-time rate of
Table 4 Global agricultural andnon-agricultural use ofglyphosate: 1994 through2014
Data in thousands of kilograms or pound of glyphosate active ingredient. See Additional le1: Table S24 Table for details
1994 1995 2000 2005 2010 2012 2014
Glyphosate use (1000 kg) 56,296 67,078 193,485 402,350 652,486 718,600 825,804
Agricultural 42,868 51,078 155,367 339,790 578,124 648,638 746,580
Non-agricultural 13,428 16,000 38,118 62,560 74,362 69,962 79,224
Glyphosate use (1000 lb) 124,112 147,882 426,561 887,030 1,438,485 1,584,242 1,820,585
Agricultural 94,508 112,608 342,525 749,108 1,274,546 1,430,002 1,645,927
Non-agricultural 29,604 35,274 84,036 137,922 163,940 154,240 174,658
Share agricultural (%) 76 76 80 84 89 90 90
Share non-agricultural (%) 24 24 20 16 11 10 10
Table 5 Share oftotal global glyphosate active ingredient
use bydecade
Calculated from data in Additional le1: Table S24
Total use
(million kg) Increase from
Share of
total use
1974–2014 (%)
1974 3.2 NA 0.0
1975–1984 130.5 127 1.5
1985–1994 387.3 257 4.5
1995–2004 1909 1522 22.3
2005–2014 6133 4224 71.6
Total 8563
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Page 8 of 15
Benbrook Environ Sci Eur (2016) 28:3
application rose from 0.7 kg/hectare (0.63 pound/acre)
to 1.1kg/hectare (0.98 pound/acre) in the same period
([27], Additional file1: Table S2). Shifts in weed com-
munities favoring species less susceptible to glyphosate,
coupled with the emergence of first, less sensitive, and
eventually glyphosate-resistant weeds drove the incre-
mental rise in the intensity of glyphosate applications on
GE-HT crops [13, 10]. Rising reliance on glyphosate by
soybean producers in the U.S. is graphically portrayed in
Fig.1a, while Fig.1b shows modest change during the GE
era in soybean yield/acre or production per soybean seed
planted. Steady increases in the number of applications
of glyphosate, rate per crop year, and glyphosate’s share
of overall soybean herbicide use are shown in Fig.1c.
Other factors contributed to rising glyphosate use.
ese include steady expansion in the number of crops
Pounds Applied (mil.)
Glyphosate Pounds Applied
Total Agriculture UseCorn UseSoybean UseOther Crops
Price per Pound
Pounds Applied (mil.)
Glyphosate Price per Pound
Pounds Applied in Corn and Soybean Producon Average Price of Glyphosate ($/pound)
Number of Resistant Weeds
Acres (mil.)
Emergence and Spread of Resistant Weeds
Cumulave Number of Glyphosate Resistant Weeds in the U.S.
Projected Acres With One or More Resistant Weeds
Fig. 2 Use and impacts of glyphosate in corn and soybean production
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Page 9 of 15
Benbrook Environ Sci Eur (2016) 28:3
registered for use on glyphosate product labels, the
adoption of no-tillage and conservation tillage systems,
the declining price per pound of active ingredient (see
Fig.2b), new application method and timing options, and
new agricultural use patterns (e.g., as a desiccant to accel-
erate the harvest of small grains, edible beans, and other
e one-time average rate of glyphosate application
on Kansas wheat has incrementally risen threefold, from
0.33kg/hectare in 1993 to 0.95kg/hectare in 2012 ([27],
Additional file1: Table S5). e trend toward no-till and
conservation tillage systems has increased wheat farmer
reliance on herbicides, including glyphosate. e average
two applications in recent years on winter wheat could
include a pre- or at-plant spray, an application during a
summer fallow period, and/or a late-season application
intended to speed up harvest operations (a so-called
“harvest aid” or “green burndown” use) [41]. e average
rate per crop year—the single most important indicator
of the intensity of glyphosate use—rose even more dra-
matically, from 0.47kg/hectare in 1993 to 2.08kg/hectare
in 2012 (4.4-fold).
Harvest-aid uses of glyphosate have become increas-
ingly common since the mid-2000s in U.S. northern-tier
states on wheat, barley, edible beans, and a few other
crops, as well as in much of northern Europe [4143].
Because such applications occur within days of harvest,
they result in much higher residues in the harvested
foodstuffs [42]. To cover such residues, Monsanto and
other glyphosate registrants have requested, and gener-
ally been granted, substantial increases in glyphosate
tolerance levels in several crops, as well as in the ani-
mal forages derived from such crops. Table7 provides
an overview of key crops on which regulatory authori-
ties have granted large increases in glyphosate tolerances
to accommodate GE-HT crop uses, as well as harvest
aid, green burndown applications. Note the 2,000-fold
increase in the glyphosate tolerance on dry alfalfa hay and
silage from 1993 to 2014, an increase made necessary by
the approval and planting of GE-HT alfalfa. In response
to the large increase in expected residues from such uses,
some European countries now prohibit harvest-aid appli-
cations on food crops (e.g., Germany, since May 2014).
Global use ofglyphosate
Farmers worldwide applied about 51.3 million kgs (113
million pounds) of glyphosate in 1995 ([27], Additional
file1: Table S23). To place this volume of global glyphosate
use in perspective, in just one country (the U.S.) that year,
farmers applied~60 million kgs (132 million pounds) of
two herbicides (atrazine and metolachlor) on mostly one
crop (maize) ([27], Additional file1: Table S19).
But the scope and intensity of glyphosate use world-
wide rapidly changed as GE-HT crops gained market
share. ere were about 1.4 billion hectares of actively
farmed, arable cropland worldwide in 2014 [44]. Across
Table 6 Glyphosate use on herbicide-tolerant (HT) crops
andall crops
Data are millions of kilograms of glyphosate active ingredient
National Agriculture Statistic Service, International Service for the Acquisition
of Agri-biotech Applications, and Meyer and Cederburg (2010). See Additional
le1: Table S23 for details
2010 2011 2012
Cotton 8.6 11.8 9.5
North America 5.64 6.99 6.32
Rest of world 3.00 4.8 3.1
Maize 47.7 65.6 70.2
North America 26.1 28.5 31.0
Rest of World 21.63 37.1 39.2
Soybeans 223.7 239.1 265.1
North America 41.9 42.0 43.6
Rest of world 181.7 197.1 221.5
Canola 13.7 16.5 18.6
North America 0.4 0.3 0.5
Rest of world 13.3 16.2 18.1
Global use on HT crops 293.7 333.0 363.4
Global use on All crops 578.1 616.8 648.6
Percent use on HT crops (%) 51 54 56
Table 7 Changes inselected U.S. EPA glyphosate tolerance
levels (ppm)
2012 and 2015 tolerances—40 CFR Part 180.364, “Glyphosate; tolerances for
residues.” 1993 tolerances—”Glyphosate Reregistration Eligibility Document
(RED),” (7508W), Oce of Pesticide Programs, U.S. EPA, September 1993. 1999
tolerances—EPA Tolerance Reassessment document for Reassessed Group 3
tolerances, August 4, 1999
1993 1999 2012 2015
Grain 20 20 20 40
Hay 15 200 200 100
Forage 15 100 100 100
Corn grain 0.1 0.1 5 5
Corn stover NT NT 6 100
Sweetcorn 0.2 0.2 3.5 3.5
Grain 0.1 0.1 0.1 30
Grain 0.1 5 5 30
Straw 0.1 85 85 100
Edible beans 0.2 0.2 5 5
Dry hay 0.2 200 200 400
Silage 0.2 75 75 400
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Page 10 of 15
Benbrook Environ Sci Eur (2016) 28:3
this landmass, there were an estimated 747 million kg of
agricultural applications of glyphosate. Accordingly, if
this volume of glyphosate had been applied evenly, about
0.53kg of glyphosate could have been sprayed on every
hectare of cropland on the planet (0.47 lbs/acre).
Glyphosate was, of course, not applied evenly on every
hectare of cropland. e average rate of glyphosate appli-
cations per hectare per crop year during 2014 fell in the
range of 1.5–2.0kg/hectare [27]. At these rates of appli-
cation, the total volume of glyphosate applied in 2014
was sufficient to treat between 22 and 30 % of globally
cultivated cropland. No pesticide in history has been
sprayed so widely.
Since losing global patent protection around 2000, doz-
ens of companies began manufacturing technical glypho-
sate, and/or formulating glyphosate products. Some
two-dozen Chinese firms now supply 40% of the glypho-
sate used worldwide, and export most of their annual
production [45].
e loss of patent protection and increased generic
manufacturing of glyphosate has placed downward pres-
sure on prices since 2000 [30, 45, 46]. e major manu-
facturer, Monsanto, has typically not competed directly
or solely on price, and instead has been successful in
holding or expanding market share by bundling purchase
of higher-price, Monsanto brand, Roundup herbicides
with the purchase of Monsanto herbicide-tolerant seeds
[4547]. Especially in the U.S., this bundling strategy has
been augmented by various volume incentives and dis-
counts, special financing, rebates for purchase of other
herbicides working through a mode of action other than
glyphosate’s (to delay the spread of resistant weeds), and
other non-price benefits tailored to appeal to large vol-
ume customers [4648].
e diversity of global uses in agriculture and other
sectors has grown over the past 40 years [9], making it
more difficult to compile accurate global data across all
glyphosate uses, especially by sector and specific use. As
a result, global glyphosate use projections can only be
based on industry-wide glyphosate production figures,
as done from 1997–2014 in Table4 and Additional file1:
Table S24 [27].
Impact ofGE‑HT technology
e development and marketing of GE, Roundup Ready
crops fundamentally changed how crop farmers could
apply glyphosate. Before RR technology, farmers could
spray glyphosate prior to crop emergence, for early-sea-
son weed control, or after harvest to clean up late-sea-
son weeds. But with RR crops, glyphosate could also be
sprayed 1–3 times or more after the crop had emerged,
leaving the crop unharmed but controlling all actively
growing weeds. is historically significant technological
advance set the stage for unprecedented and rapid
growth in the area planted to RR crops and sprayed with
glyphosate (from usually less than 10% of cotton, maize,
and soybean acres pre-1996, to 90% or more today) [47,
49, 50].
e interplay of various factors leading to increased
glyphosate use is apparent in Fig. 2a, which shows the
trend in overall glyphosate use on the key GE-HT crops
in the U.S., the correlation between reductions in average
price per pound and use (Fig.2b), and rising use and the
emergence of resistant weeds (Fig.2c).
Use of glyphosate on some GE-HT crops may have
declined, or may soon begin declining in some regions
because (a) adoption of GE-HT soybeans, cotton, and
canola has peaked in most of the countries that have
embraced GE technology [9], and (b) farmer willingness
to pay for repeat applications of glyphosate, or further
increase application rates, typically declines as glypho-
sate-resistant weeds become well established, as they
have in much of the U.S. [13] and in Brazil and Argentina
[10]. On the other hand, GE-HT crops may move into
some regions not previously planting them (e.g., China),
and reductions in the price of generic glyphosate herbi-
cides could lead to more intensive use in some countries.
In the countries that have planted the largest shares of
GE-HT crops (the U.S., Argentina, and Brazil), glypho-
sate use rates per hectare per crop year have risen sharply
since around 2000 [20, Additional file1: Tables S2, S3,
S22]. Worldwide on GE soybean and cotton, average
total herbicide use per crop year per hectare has approxi-
mately doubled from 1996 to 2014, with the increase
in glyphosate volumes applied per hectare accounting
for nearly all of the per hectare increase. Maize herbi-
cide use per hectare has risen modestly, if at all, in large
part because adoption of GE-HT maize hybrids allowed
farmers to reduce reliance on a half-dozen other widely
used maize herbicides applied at relatively high rates
(e.g.,~1kg/hectare per crop year) [11].
Because GE-HT soybeans account for two-thirds of the
total hectares planted to GE-HT crops worldwide, the
doubling of average herbicide use per hectare of HT soy-
beans drives the sizable increase in overall herbicide on
all GE crop hectares. ere is, as well, a clear connection
throughout South America in the adoption of GE-HT
technology and no-tillage systems [17, 38]. No-till farm-
ing in South America lowers machinery and labor costs,
and reduces soil erosion, but at the expense of height-
ened reliance on herbicides for weed control, and other
pesticides to control insects and fungal pathogens.
Despite gaps in publicly accessible data, the dramati-
cally upward trajectories in glyphosate use in the U.S. and
globally are unmistakable. In the pre-GE era (1974–1995)
in the U.S., non-agricultural glyphosate uses accounted
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Page 11 of 15
Benbrook Environ Sci Eur (2016) 28:3
for~34 to 42% of total use. e share of total glypho-
sate use accounted for by the agricultural sector shifted
markedly upward post-1996, starting at 66% in 1996 and
reaching 81% 5years later (2001) and 92% by 2014 ([27],
Additional file1: Table S18).
e total volume of use and the split between agricul-
tural and non-agricultural uses in the pre-GE era period
are subject to greater uncertainty than in the 1996–2014
period. However, pre-1995 glyphosate use is minor com-
pared to the post-GE period, when both data quantity
and quality improved, especially covering applications in
the U.S. and on global GE-HT hectares planted.
Figure3 arrays milestones in the history of glyphosate dis-
covery, commercialization, and regulation, while Fig.4 dis-
plays key events in the history of glyphosate use and impacts.
Rising use triggers new concerns
Driven by the growing diversity of uses and dramatic
increases in volumes applied, levels of glyphosate and
its primary metabolite aminomethylphosphonic acid
(AMPA) have been detected in the air [51], soil [52],
and water [49, 53]. With few exceptions though, con-
temporary levels of glyphosate in the air, water, and food
result in typical human exposure estimates that remain
well below the “levels of concern” or “Acceptable Daily
Intakes” established by regulatory bodies around the
Still, a growing body of literature points to possible,
adverse environmental, ecological, and human health
consequences following exposure to glyphosate and/or
AMPA, both alone [54] and in combination with inges-
tion of GE proteins (e.g., EPSPS, Bt endotoxins) [55].
Environmental studies encompass possible glyphosate
impacts on soil microbial communities and earthworms
[5658], monarch butterflies [59], crustaceans [60], and
honeybees [61].
Studies assessing possible risks to vertebrates and
humans include evidence of rising residue levels in
soybeans [62, 63], cancer risk [64], and risk of a vari-
ety of other potential adverse impacts on develop-
ment, the liver or kidney, or metabolic processes [54,
55, 6580].
Relative toxicity andimpacts
For years, glyphosate has been regarded as among the
least chronically toxic herbicides for mammals, and
indeed only three EPA-registered synthetic pesticides
in current agricultural use have a higher chronic Refer-
ence Dose (the imidazolinone herbicides imazamox,
imazethapyr, and imazapyr).
For human exposures, the U.S. EPA has set glyphosate’s
daily chronic Reference Dose (cRfD) at 1.75 milligrams
per kilogram of bodyweight (mg/kg bodyweight/day).
e EU-set cRfD for glyphosate was recently raised from
0.3 to 0.5mg/kg/day, 3.5-fold lower than EPA’s. A team of
scientists has compiled evidence supporting the need for
a fivefold reduction in the EU cRfD to 0.1mg/kg/day [81],
a level 17-times lower than EPA’s.
Glyphosate is a moderate dose herbicide with relatively
low acute and chronic mammalian toxicity, to the extent
mammalian risk is accurately reflected in required EPA
toxicology studies. After an exhaustive review, however,
glyphosate was classified in 2015 as a “probable human
carcinogen” by the International Agency for Research on
Cancer [64], based on increased prevalence of rare liver
and kidney tumors in chronic animal feeding studies,
epidemiological studies reporting positive associations
with non-Hodgkin lymphoma, and strong mechanistic
evidence of genotoxicity and ability to trigger oxidative
stress [64].
e body of toxicological studies supporting glypho-
sate’s current EPA and EU cRfD, and hence all contempo-
rary uses of this herbicide, dates back to the early 1970s
through mid-1980s [82]. Recent studies suggest that
glyphosate in its pure form, and some formulated glypho-
sate end-use products, may be triggering epigenetic
1970 2014
1970 19751980 1985 19901995200020052010
First glyphosate patent issued
EPA establishes first glyphosate
tolerance in soybeans -- 2 ppm
First commercial sales of RR maize,
soybeans, and coon in U.S.
publishes soybean
report reporng
Monsanto chemist J. Franz
recognizes herbicidal acvity
of glyphosate
First commercial glyphosate
registraons in the U.S.
Glyphosate agricultural use
reaches 2.8 million kilograms,
less than 1/10th the annual
volume applied of atrazine or
EPA increases
glyphosate wheat
tolerance from
0.1 ppm to 5 ppm
EPA increases glyphosate soybean
tolerance from 6 ppm to 20 ppm to
accommodate residues in RR soybeans
U.S. EPA increases
glyphosate oilseed
crop group
tolerance from 20
ppm to 40 ppm
2006 -2011
Center for Food Safety ligaon
slows deregulaon of new RR crops
(alfalfa and sugarbeets)
Fig. 3 Milestones in the history of glyphosate discovery, commercialization, and regulation
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
Page 12 of 15
Benbrook Environ Sci Eur (2016) 28:3
changes through endocrine-mediated mechanisms [54,
73, 75, 76, 79, 81, 83].
Evidence from multiple studies suggests that the kid-
ney, and secondarily the liver, is at risk of glyphosate-
triggered, or glyphosate-enhanced chronic degeneration
[55, 71, 72, 84, 85]. Industry metabolism studies in farm
animals, rats and mice, and rabbits were conducted in the
1970s and 1980s, and show that in animal feeding stud-
ies, glyphosate levels in the kidney usually exceed those
in the liver by three- to tenfold, and those in the liver
exceed levels in other tissues by a wide margin [86].
e apparent tendency of glyphosate to concentrate in
the kidneys, coupled with glyphosate’s action as a chelat-
ing agent, has led some scientists to hypothesize that
glyphosate can bind to metals in hard drinking water,
creating metallic-glyphosate complexes that may not
pass normally through kidneys [71, 72]. For this, or other
as yet unrecognized reasons, the risk of chronic kidney
disease may be heightened in human and animal popula-
tions with heavy glyphosate exposure.
e IARC classification and emerging evidence rela-
tive to kidney damage and endocrine effects height-
ens the need for, and will complicate ongoing and
future glyphosate worker and dietary-risk assessments.
Annual residue tests are carried out by the U.K. Food
Standards Agency (FSA). Residues of glyphosate were
found in 10–30% of grain-based samples from 2007–
2013, at generally rising levels [87]. Glyphosate and
AMPA residues are present at relatively high, and rising
levels (over 1ppm) in a high percentage of the soybeans
grown in the U.S., Canada, Brazil, Argentina, Paraguay,
countries which account for 86.6% of the 11.6 billion
bushels of soybeans produced globally in 2014, and
nearly all global trade in soybeans and soybean-based
animal feeds [34, 62].
A high level of confidence can be placed in the trends in
glyphosate use in the U.S. because of consistency across
three independently compiled datasets (USDA-NASS,
EPA, and USGS).
A published paper by a pesticide industry consultant
provides solid data on global glyphosate use in 1994–
1997, both in the agricultural and non-agricultural sec-
tors [29]. Lack of publicly accessible data on global
glyphosate use since the mid-1990s increases the uncer-
tainty in the global estimates reported herein. However,
since the majority of the increase in global glyphosate
use since the late-1990s was driven by the adoption of
GE-HT crops, accessible data from ISAAA and the litera-
ture on GE-HT crops provide a solid basis to project total
glyphosate use on GE-HT cropsover the last ~15 years.
By any measure, glyphosate-tolerant crop technology
has been an enormous commercial success, and at least
initially, simplified weed management in maize, soybean,
and cotton crops both in the U.S. and worldwide [2, 9,
88]. For a few years post-1996, one, or at most two appli-
cations of glyphosate proved highly effective and eco-
nomical on nearly all cropland planted to GE-HT seeds.
As a result, the land area treated with glyphosate rose
rapidly. Over time this triggered the emergence of weed
phenotypes less sensitive or resistant to glyphosate. In
response, farmers increased both the rate of glyphosate
application as well as the number of applications [5, 6,
9, 88, 13]. Many farmers also integrated additional her-
bicides into spray programs [57, 89]. As a direct result,
1996 1998 2000 2002 2004 2006 2008 2010 2012 2014
Confirmed glyphosate resistance in 3 weeds
EPSPS gene amplificaon proposed as
glyphosate resistance mechanism (Gaines
et al. 2009)
Palmer amaranth in
Georgia glyphosate
resistant to 3 herbicide
modes of acon,
including glyphosate
~33 million acres
infested with
RR technology in the U.S. increased
herbicide use by 527 million pounds,
1996-2012 (Benbrook 2012)
One or more
weed on
over 100
million acres
in U.S.
Adverse impacts on
iron and manganese
uptake (Eker et al
Lolium rigidum --first glyphosate-resistant
weed confirmed in Australia
Glyphosate-resistant Palmer
amaranth confirmed in
Georgia; 10th glyphosate-
resistant weed confirmed
USGS sciensts detect glyphosate
in 60% -100% samples of air and
rain in 3 states (Chang et al 2011)
Glyphosate shown to reduce
water use efficiency in RR
soybean systems (Zobiole et al
Widespread glyphosate use contributes to
58% decline in milkweed and 81% decline in
Monarch buerflies in the Midwest, 1999-
2010 (Pleasants and Oberhauser 2012)
~61 million
infested with
Adverse impacts on
earthworms, honeybees,
aquac organisms
IARC classifies
glyphosate a
Fig. 4 Milestones in glyphosate use and impacts
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Page 13 of 15
Benbrook Environ Sci Eur (2016) 28:3
average herbicide use per hectare on land planted to
GE-HT varieties has, on average, escalated steadily since
the mid-1990s [8, 11, 88, 13].
e upward trend in glyphosate use has, and will likely
continue to contribute to incremental increases in envi-
ronmental loadings and human exposures to glypho-
sate, its major metabolite aminomethylphosphonic acid
(AMPA), and various surfactants and adjuvants used in
formulating end-use glyphosate-based herbicides.
Given that glyphosate is moderately persistent and
mobile, levels in surface and groundwater will likely rise
in step with use, and this will increase the diversity of
potential routes of animal and human exposure.
Human exposures from around the home and urban
uses of glyphosate also warrant closer attention. Most
end-use, glyphosate products sold for home and urban
use in developed countries contain relatively low con-
centrations of glyphosate, so the risk of experiencing
an acutely toxic exposure is minimal. But in develop-
ing countries, risks stemming from applications of more
concentrated glyphosate products and/or applications of
“home-mixed” products should not be ignored.
e frequency and levels of glyphosate and residues in
a variety of foods are increasing, and more refined die-
tary-risk assessments should be carried out. Reasonably
accurate estimates of glyphosate residues and dietary
exposures in areas lacking residue data can be made
drawing on insights gained from risk assessments con-
ducted in areas with accurate glyphosate use and residue
AMPA: aminomethylphosphonic acid; Bt: Bacillus thuringiensis; EPA: Environ-
mental Protection Agency; GBH: glyphosate-based herbicide; GE: genetically
engineered; GE-HT: genetically engineered herbicide-tolerant [crop]; GMO:
genetically engineered organism; HT: herbicide tolerant; Kg: kilogram; NASS:
National Agricultural Statistics Service (a USDA agency); RR: Roundup Ready;
USDA: United States Department of Agriculture; USGS: United States Geologi-
cal Service.
Authors’ information
The author (CMB) conducted the research and wrote the paper while serv-
ing as a Research Professor at Washington State University (position ended
5/15/15). CMB ran the “Measure to Manage” program within the Center for
Sustaining Agriculture and Natural Resources, and has worked for years com-
piling data on pesticide use in the U.S. and globally.
The author thanks his colleagues at Washington State University’s Measure to
Manage Program for assistance in developing the datasets and carrying out
the analysis. Karie Knoke compiled the glyphosate use dataset and produced
the figures. Nicholas Potter helped develop the tables and refine the analysis.
Reviewers provided helpful suggestions for improvement. Also, thanks to the
U.S. Department of Agriculture’s National Agricultural Statistics Service (NASS)
Additional le
Additional le 1. List of supplemental tables.
for compiling and making available information on pesticide use in the U.S.,
and to the EPA for its helpful periodic reports on pesticide use.
Competing interests
The author is a member of the U.S. Department of Agriculture’s AC21 Agri-
cultural Biotechnology Advisory Committee. From June 2012–May 2015, he
served as a Research Professor at Washington State University. Dr. Benbrook’s
program at WSU received funding from foundations, organic food companies,
and coops. He currently serves as an expert witness in litigation focused on
the labeling of foods containing genetically engineered ingredients.
Received: 11 October 2015 Accepted: 11 January 2016
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... of glyphosate-tolerant crops [2]. Today, over 113 million kilograms of glyphosate are utilized agriculturally each year across the United States [2]. ...
... of glyphosate-tolerant crops [2]. Today, over 113 million kilograms of glyphosate are utilized agriculturally each year across the United States [2]. Glyphosate kills weeds and unwanted plants by inhibiting a key enzyme in the shikimate pathway, enolpyruvylshikimate-3-phosphate synthase (EPSPS), preventing aromatic amino acid biosynthesis vital to plants [3]. ...
Full-text available
Background Herbicides are environmental contaminants that have gained much attention due to the potential hazards they pose to human health. Glyphosate, the active ingredient in many commercial herbicides, is the most heavily applied herbicide worldwide. The recent rise in glyphosate application to corn and soy crops correlates positively with increased death rates due to Alzheimer’s disease and other neurodegenerative disorders. Glyphosate has been shown to cross the blood–brain barrier in in vitro models, but has yet to be verified in vivo. Additionally, reports have shown that glyphosate exposure increases pro-inflammatory cytokines in blood plasma, particularly TNFα. Methods Here, we examined whether glyphosate infiltrates the brain and elevates TNFα levels in 4-month-old C57BL/6J mice. Mice received either 125, 250, or 500 mg/kg/day of glyphosate, or a vehicle via oral gavage for 14 days. Urine, plasma, and brain samples were collected on the final day of dosing for analysis via UPLC–MS and ELISAs. Primary cortical neurons were derived from amyloidogenic APP/PS1 pups to evaluate in vitro changes in Aβ 40-42 burden and cytotoxicity. RNA sequencing was performed on C57BL/6J brain samples to determine changes in the transcriptome. Results Our analysis revealed that glyphosate infiltrated the brain in a dose-dependent manner and upregulated TNFα in both plasma and brain tissue post-exposure. Notably, glyphosate measures correlated positively with TNFα levels. Glyphosate exposure in APP/PS1 primary cortical neurons increases levels of soluble Aβ 40-42 and cytotoxicity. RNAseq revealed over 200 differentially expressed genes in a dose-dependent manner and cell-type-specific deconvolution analysis showed enrichment of key biological processes in oligodendrocytes including myelination, axon ensheathment, glial cell development, and oligodendrocyte development. Conclusions Collectively, these results show for the first time that glyphosate infiltrates the brain, elevates both the expression of TNFα and soluble Aβ, and disrupts the transcriptome in a dose-dependent manner, suggesting that exposure to this herbicide may have detrimental outcomes regarding the health of the general population.
... Among the different pesticides used, the herbicide Glyphosate (GLYP), N-(phosphonomethyl) glycine, has been applied extensively over the last 40 years, assuming minimal side effects. However, concerns about the direct and indirect potential health effects of large-scale GLYP usage have recently increased worldwide [5][6][7][8]. ...
Full-text available
Due to its chemical properties, glyphosate [N-(phosphonomethyl)glycine] is one of the most commonly used agricultural herbicides globally. Due to risks associated with human exposure to glyphosate and its potential harmfulness, the need to develop specific, accurate, online, and sensitive methods is imperative. In accordance with this, the present review is focused on recent advances in developing nanomaterial-based sensors for glyphosate detection. Reported data from the literature concerning glyphosate detection in the different matrices using analytical methods (mostly chromatographic techniques) are presented; however, they are expensive and time-consuming. In this sense, nanosensors’ potential applications are explained to establish their advantages over traditional glyphosate detection methods. Zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three- dimensional (3D) materials are reviewed, from biomolecules to metallic compounds. Bionanomaterials have generated research interest due to their selectivity with respect to using enzymes, DNA, or antibodies. On the other hand, Quantum Dots also are becoming relevant for their vast surface area and good limit of detection values (in the range of pM). This review presents all the characteristics and potential applications of different nanomaterials for sensor development, bearing in mind the necessity of a glyphosate detection method with high sensitivity, selectivity, and portability.
... AMPA toxicity is equal to or greater than glyphosate itself (23). Since glyphosate-AMPA is mobile in the environment, its presence in surface and groundwater is likely to increase animal and human exposure (24). The presence of glyphosate in food, although in low concentrations, suggests that glyphosate persists in the food chain "beyond the farm gate" throughout the commercial market, at all stages of storage, transportation and processing, preparation, and finally consumption (25). ...
Full-text available
The aim of this study was to verify the presence of glyphosate in breast milk and to characterize maternal environmental exposure. Sixty-seven milk samples were collected from lactating women in the city of Francisco Beltrão, Paraná, living in urban (n=26) and rural (n=41) areas, at the peak of glyphosate application in corn and soy crops in the region (April and May 2018). To characterize the study population, socio-epidemiological data of the women were collected. To determine glyphosate levels, a commercial enzyme immunosorbent assay kit was used. Glyphosate was detected in all breast milk samples analyzed with a mean value of 1.45 µg/L. Despite some descriptive differences, there were no statistically significant differences (P<0.05) between the categories of the variables tested. Also, glyphosate was detected in drinking water samples from the urban area and in artesian well water from the rural area of the region where the studied population lived. The estimation of the total amount of glyphosate ingested by breastfeeding babies in a period of 6 months was significant. These results suggest that the studied lactating population was contaminated with glyphosate, possibly through continued environmental exposure.
... Glyphosate is the main active ingredient in the commercial mixture Roundup ® herbicide that has been used worldwide for over 40 years [14,15]. Over 20 years (1994Over 20 years ( -2014, glyphosate-based herbicide (GBH) use increased from 56 million to more than 826 million kg globally, associated with agricultural and non-agricultural practices [16]. This rise is also associated with the introduction of glyphosate-tolerant crops, which possess either the tolerant EPSPS synthase gene, a glyphosate metabolism gene or both genes [17]. ...
Full-text available
The use of glyphosate-based herbicides (GBH) worldwide has increased exponentially over the last two decades increasing the environmental risk to marine and coastal habitats. The present study investigated the effects of a GBH at environmentally relevant concentrations (0, 10, 50, 100, 250, and 500 μg L−1), on the physiology and biochemistry (photosynthesis, pigment, and lipid composition, antioxidative systems and energy balance) of Ulva lactuca, a cosmopolitan marine macroalgae species. Although GBH caused deleterious effects such as the inhibition of photosynthetic activity, particularly at 250 μg L−1, due to impairment of the electron transport in the chloroplasts, these changes are almost completely reverted at the highest concentration (500 μg L−1). This could be related to the induction of tolerance mechanisms at a certain threshold or tipping point. While no changes occurred in the energy balance, an increase in the pigment antheraxanthin is observed jointly with an increase in ascorbate peroxidase activity. These mechanisms might have contributed to protecting thylakoids against excess radiation and the increase in reactive oxygen species, associated with stress conditions, as no increase in lipid peroxidation products was observed. Furthermore, changes in fatty acids profile, usually attributed to the induction of plant stress response mechanisms, demonstrated the high resilience of this macroalgae. Notably, the application of bio-optical tools in ecotoxicology, such as pulse amplitude modulated (PAM) fluorometry and laser-induced fluorescence (LIF), allowed separating the control samples and those treated by GBH in different concentrations with a high degree of accuracy, with PAM more accurate in identifying the different treatments.
... The application of synthetic herbicides is an effective approach to control weeds but causes great waste of resources, and serious problems of environmental pollution and food safety (Vandenberg et al., 2017;Panthi et al., 2019). GM varieties transformed by herbicide-resistant genes give the feasibility to combat weeds and thus help in the safety of the crops without major yield losses (Benbrook, 2016;Ramachandra et al., 2016). Glyphosate [N-(phosphonomethyl) glycine] is a widely used broad-spectrum herbicide that controls weeds by inhibiting the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme and interfering with the shikimate biosynthesis pathway (Funke et al., 2006). ...
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Heterologous expression of exogenous genes, overexpression of endogenous genes, and suppressed expression of undesirable genes are the three strategies of transgenic manipulation for crop improvement. Up to 2020, most (227) of the singular transgenic events (265) of crops approved for commercial release worldwide have been developed by the first strategy. Thirty-eight of them have been transformed by synthetic sequences transcribing antisense or double-stranded RNAs and three by mutated copies for suppressed expression of undesirable genes (the third strategy). By the first and the third strategies, hundreds of transgenic events and thousands of varieties with significant improvement of resistance to herbicides and pesticides, as well as nutritional quality, have been developed and approved for commercial release. Their application has significantly decreased the use of synthetic pesticides and the cost of crop production and increased the yield of crops and the benefits to farmers. However, almost all the events overexpressing endogenous genes remain at the testing stage, except one for fertility restoration and another for pyramiding herbicide tolerance. The novel functions conferred by the heterologously expressing exogenous genes under the control of constitutive promoters are usually absent in the recipient crops themselves or perform in different pathways. However, the endogenous proteins encoded by the overexpressing endogenous genes are regulated in complex networks with functionally redundant and replaceable pathways and are difficult to confer the desirable phenotypes significantly. It is concluded that heterologous expression of exogenous genes and suppressed expression by RNA interference and clustered regularly interspaced short palindromic repeats-cas (CRISPR/Cas) of undesirable genes are superior to the overexpression of endogenous genes for transgenic improvement of crops.
... Actualmente en la agricultura comercial, los campos de turísticos, bordes de carreteras y alrededor de casas y jardines, se utilizan 2 compuestos principales para el control de las plagas causados por las malezas y los insectos: 1) El glifosato (GLY), N-(fosfonometil) glicina, el cual es considerado un herbicida pre-emergente y post-emergente de amplio espectro que se aplica para el control de malezas en zonas agrícolas y urbanas, representando el 71.6% de los ingredientes activos comercializados (Benbrook, 2016;Krimsky, 2021). 2) El imidacloprid (IMID), es un insecticida neonicotinoide de amplio uso que ha sustituido a los insecticidas sistémicos tradicionales como los organofosforados y piretroides, debido a su baja toxicidad para vertebrados y la capacidad de ser translocados por plantas (Alkassab y Kirchner, 2016). ...
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La manzana es una de las frutas más consumidas en el mundo, siendo México uno de los principales productores y el estado de Puebla el tercero del país. El sistema MIAF es una propuesta para la producción de milpa y árboles frutales basada en los sistemas de cultivo tradicional de los valles de Puebla. El objetivo fue evaluar componentes de la calidad de fruto de manzano cv “agua nueva dos”, una mutante derivada de la Golden de Chihuahua, entre manzanos de un sistema MIAF y manzano en monocultivo, en el año 2018 y 2019, en la localidad de San Mateo Capultitlán municipio de Huejotzingo, Puebla, México. Se obtuvieron valores de los componentes de calidad de fruto de manzano similares o superiores bajo sistema MIAF respecto al monocultivo de manzano, resaltando el contenido de ácido málico (MIAF: 0.2084; monocultivo: 0.1998 gr/ 100 gr de pulpa) y el peso de fruto (MIAF: 130.49; monocultivo: 115.26 gr), así como el contenido de sólidos solubles (MIAF: 16.16 °Bx; monocultivo: 16.81 °Bx). La variedad de manzana “agua nueva dos” producida en milpa intercalada con árboles de manzano cuenta con valores adecuados de calidad de fruto para su venta y consumo.
Glyphosate is a globally applied herbicide yet it has been relatively undetectable in‐field samples outside of gold‐standard techniques. Its presumed nontoxicity toward humans has been contested by the International Agency for Research on Cancer, while it has been detected in farmers’ urine, surface waters and crop residues. Rapid, on‐site detection of glyphosate is hindered by lack of field‐deployable and easy‐to‐use sensors that circumvent sample transportation to limited laboratories that possess the equipment needed for detection. Herein, the flavoenzyme, glycine oxidase, immobilized on platinum‐decorated laser‐induced graphene (LIG) is used for selective detection of glyphosate as it is a substrate for GlyOx. The LIG platform provides a scaffold for enzyme attachment while maintaining the electronic and surface properties of graphene. The sensor exhibits a linear range of 10–260 µm, detection limit of 3.03 µm, and sensitivity of 0.991 nA µm−1. The sensor shows minimal interference from the commonly used herbicides and insecticides: atrazine, 2,4‐dichlorophenoxyacetic acid, dicamba, parathion‐methyl, paraoxon‐methyl, malathion, chlorpyrifos, thiamethoxam, clothianidin, and imidacloprid. Sensor function is further tested in complex river water and crop residue fluids, which validate this platform as a scalable, direct‐write, and selective method of glyphosate detection for herbicide mapping and food analysis. A platinum‐decorated, glycine oxidase (GlyOx) functionalized, laser‐induced graphene (LIG) sensor selectively detects the broad range herbicide glyphosate against common herbicides and insecticides. The sensor displays a linear sensing range of 10–260 µm, limit of detection (LOD) of 3.03 µm, and response time of 150 s. Furthermore, the sensor detects glyphosate in complex fluids.
A variety of agricultural conservation trends have gained and lost favour throughout the years, with farm bills in the United States often influencing which conservation practices are implemented. This paper explores the consequences of a set of conservation techniques loosely defined as “no‐till agriculture,” focusing on their implementation and adoption since 1985, at which point such approaches began to be explicitly encouraged under US Farm Bill soil conservation mandates. We begin by noting a core contradiction that has characterized these approaches in the Fifteenmile Watershed of Wasco County, Oregon, where despite high rates of farmer enrollment in no‐till programs, both no‐till agriculture and sustained tillage have led to the increased use of herbicides and sustained sediment runoff. Using a critical physical geography framework that integrates intensive physical field data collection, spatial analysis, social surveys, and interviews, we address the biophysical and social factors collectively driving changes in herbicide use and variable erosion estimates. We draw particular attention to how farm bill support for no‐till has enrolled farmers in a vaguely defined and underregulated conservation practice that may ultimately undermine environmental quality. La popularité des pratiques de conservation agricole évolue au fil des ans aux États‐Unis, au gré des dispositions des législations en la matière. Ce texte se penche sur les conséquences d'une série de techniques de conservation identifiées comme une «agriculture sans labours». Nous analysons leur mise en œuvre depuis 1985, soit à partir du moment où ces techniques ont commencé à être encouragées en vertu des mandats de conservation des sols du US Farm Bill. Nous commençons par noter une contradiction fondamentale caractérisant ces pratiques dans le bassin versant Fifteenmile dans le comté de Wasco, en Oregon, où malgré un taux élevé de participation des agriculteurs à l'agriculture sans labours, cette activité a entraîné une augmentation de l'utilisation des herbicides et un ruissellement soutenu des sédiments. Par la suite, nous étudions les facteurs biophysiques et sociaux qui influencent les changements dans l'utilisation des herbicides et les estimations de l'érosion à l'aide d'un cadre méthodologique associé à la géographie physique critique. Ce cadre intègre une collecte de données sur le terrain, des analyses spatiales, des entrevues et des enquêtes sociales. Nos résultats s'attardent notamment sur la manière dont l'appui à la loi sur l'agriculture sans labours a permis l'utilisation d'une pratique de conservation mal définie et peu réglementée qui peut miner la qualité de l'environnement. No‐till has been broadly used to describe many conservation tillage practices, which has led to inaccurate erosion estimates. Variations in no‐till practices have coincided with unprecedented increases of herbicide. Processes of neoliberalization have influenced the sustainability of no‐till. No‐till has been broadly used to describe many conservation tillage practices, which has led to inaccurate erosion estimates. Variations in no‐till practices have coincided with unprecedented increases of herbicide. Processes of neoliberalization have influenced the sustainability of no‐till.
Glyphosate is the most used herbicide globally, but our understanding of human exposure and how different uses affect exposure is not well understood. The aim of this study was to obtain the first data on glyphosate and its primary degradation product aminomethylphosphonic acid (AMPA) concentrations in pooled and individual urine from the Australia and New Zealand region using a sensitive direct injection method and compare results with studies from elsewhere. Pooled urine samples from the Australian general population (n = 125 pools representing >1875 individuals) and individual urine samples (n = 27) from occupationally exposed New Zealand farmers were analysed by LC-MS/MS. Glyphosate was detected above the LOD (0.20–1.25 μg/L) in 8 % of the Australian population pooled urine samples with most detections in the 45–60 years age group. Furthermore, glyphosate (0.85 to 153 μg/L) and AMPA (0.50 to 3.35 μg/L) were detected in 96 % and 33 % of farmers, respectively. The maximum glyphosate urine concentration was 1.7 times above the recommended acceptable daily intake (ADI), when assuming a urinary excretion rate of 1 %. The pooled sampling and analysis approach proved effective for rapid large-scale screening of populations and could be used to determine where targeted and more specific individual sampling may be required.
A confirmatory method was developed and validated for determination of glyphosate (Gly), glufosinate (Glu) and aminomethylphosphonic acid (AMPA) in honey using reversed-phase high performance liquid chromatography (RP-HPLC) coupled with tandem mass-spectrometry (MS/MS). The sample preparation approach consists of extraction by acidified solutions followed by SPE on Oasis HLB, derivatization by FMOC-Cl, concentration and another SPE stage on Oasis WCX. The limit of quantification (LOQ) of 0.05 ppm was reached for Gly, AMPA and Glu. All accuracy values ranged from 85% to 110% for all analytes using both primary and secondary quantitative ion transitions (RSD ≤ 10%). Correlation coefficients were higher than 0.99. The method was applied in 2018-19 for monitoring of honey samples, which revealed agricultural territories with intensive use of glyphosate.
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Glyphosate (GLY) is a herbicide that is widely used in agriculture for weed control. Although reports about the impact of GLY in snails, crustaceans and amphibians exist, few studies have investigated its sublethal effects in non-target organisms such as the honeybee Apis mellifera, the main pollen vector in commercial crops. Here, we tested whether exposure to three sublethal concentrations of GLY (2.5, 5 and 10 mg l-1: corresponding to 0.125, 0.250 and 0.500 μg per animal) affects the homeward flight path of honeybees in an open field. We performed an experiment in which forager honeybees were trained to an artificial feeder, and then captured, fed with sugar solution containing traces of GLYand released from a novel site either once or twice. Their homeward trajectories were tracked using harmonic radar technology. We found that honeybees that had been fed with solution containing 10 mg l-1 GLY spent more time performing homeward flights than control bees or bees treated with lower concentrations. They also performed more indirect homing flights. Moreover, the proportion of direct homeward flights performed after a second release from the same site increased in control bees but not in treated bees. These results suggest that, in honeybees, exposure to levels of GLY commonly found in agricultural settings impairs the cognitive capacities needed to retrieve and integrate spatial information for a successful return to the hive. Therefore, honeybee navigation is affected by ingesting traces of the most widely used herbicide worldwide, with potential long-term negative consequences for colony foraging success.
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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.
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Background: Genetically modified glyphosate-tolerant cultivar varieties have been a commercial success widely known as Roundup Ready plants. As new glyphosate-tolerant varieties are introduced to satisfy agriculture demand, it is relevant to review the scientific evidence that documents the quality and safety of such biotechnology. Assess- ments of genetically modified glyphosate-tolerant plants are partly based on the reports from laboratory compari- sons with non-modified plants (near-isogenic relatives). Such comparative testing is typically performed as analysis of plant material composition and in animal feeding studies. The material for testing is typically produced in test-fields set up as model environments. Most of this research is planned, performed and reported by researchers employed by biotech industry companies. Perspective: The present paper aims to: (1) review 15 reports on compositional analyses of glyphosate-tolerant cultivars and 15 reports from animal feeding studies, (2) discuss recent data indicating glyphosate residue in Roundup Ready soybean, (3) outline recent developments of cultivars with increased tolerance to glyphosate. Findings: The reviewed industry studies show methodological flaws: glyphosate-tolerant GM crops are designed for use with glyphosate herbicide. However, glyphosate herbicides are often not applied in test-study cultivation. In the studies where glyphosate herbicides were applied to growing plants, the produced plant material was not ana- lyzed for glyphosate residues. This review has failed to identify industry studies that mention glyphosate residues in glyphosate-tolerant plants. This indicates that questions and evidence of importance for regulatory assessment have been systematically ignored. Independent research has investigated this issue and found that glyphosate-tolerant plants accumulate glyphosate residues at unexpected high levels. Glyphosate residues are found to have potential to affect plant material composition. Furthermore, these residues are passed on to consumers. Conclusions: Industry studies are not sufficient for regulation. Despite decades of risk assessments and research in this field, specific unanswered questions relating to safety and quality aspects of food and feed from GM crops need to be addressed by regulators. Independent research gives important supplementary insight
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Glyphosate (GLY) is a herbicide that is widely used in agriculture for weed control. Although reports about the impact of GLY in snails, crustaceans and amphibians exist, few studies have investigated its sub-lethal effects in non-target organisms such as the honeybee Apis mellifera, the main pollen vector in commercial crops. Here, we tested whether exposure to three sub-lethal concentrations of GLY (2.5, 5 and 10 mg/L corresponding to 0.125, 0.250 and 0.500 µg/animal) affects the homeward flight path of honeybees in an open field. We performed an experiment in which forager honeybees were trained to an artificial feeder, and then captured, fed with sugar solution containing GLY traces and released from a novel site (the release site, RS) either once or twice. Their homeward trajectories were tracked using harmonic radar technology. We found that honeybees that had been fed with solution containing 10 mg/L GLY spent more time performing homeward flights than control bees or bees treated with lower GLY concentrations. They also performed more indirect homing flights. Moreover, the proportion of direct homeward flights performed after a second release at the RS increased in control bees but not in treated bees. These results suggest that, in honeybees, exposure to GLY doses commonly found in agricultural settings impairs the cognitive capacities needed to retrieve and integrate spatial information for a successful return to the hive. Therefore, honeybee navigation is affected by ingesting traces of the most widely used herbicide worldwide, with potential long-term negative consequences for colony foraging success. © 2015. Published by The Company of Biologists Ltd.
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Herbicide use is increasing worldwide both in agriculture and private gardens. However, our knowledge of potential side-effects on non-target soil organisms, even on such eminent ones as earthworms, is still very scarce. In a greenhouse experiment, we assessed the impact of the most widely used glyphosate-based herbicide Roundup on two earthworm species with different feeding strategies. We demonstrate, that the surface casting activity of vertically burrowing earthworms (Lumbricus terrestris) almost ceased three weeks after herbicide application, while the activity of soil dwelling earthworms (Aporrectodea caliginosa) was not affected. Reproduction of the soil dwellers was reduced by 56% within three months after herbicide application. Herbicide application led to increased soil concentrations of nitrate by 1592% and phosphate by 127%, pointing to potential risks for nutrient leaching into streams, lakes, or groundwater aquifers. These sizeable herbicide-induced impacts on agroecosystems are particularly worrisome because these herbicides have been globally used for decades.
Glyphosate herbicide is the largest-selling single crop-protection chemical product in the market today. This non-selective weedkiller was initially targeted at the non-crop areas in agriculture and for industrial applications but, with the continuing development of minimum- and no-tillage agricultural practices, glyphosate also found usage in a number of crop outlets. Most recently, glyphosate has found direct crop usage on plant varieties that have been genetically modified to be tolerant of glyphosate applications. Such has been the continuing success of the product that its annual volume consumption growth has averaged in excess of 20% in recent years in agricultural use. (C) 2000 Society of Chemical Industry.