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Glyphosate (
IUPAC name In chemical nomenclature, a preferred IUPAC name (PIN) is a unique name, assigned to a chemical substance and preferred among the possible names generated by IUPAC nomenclature. The "preferred IUPAC nomenclature" provides a set of rules for choo ...
: ''N''-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide and crop desiccant. It is an
organophosphorus compound Organophosphorus compounds are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective i ...
, specifically a phosphonate, which acts by inhibiting the plant enzyme
5-enolpyruvylshikimate-3-phosphate synthase 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase is an enzyme produced by plants and microorganisms. EPSPS catalyzes the chemical reaction: : phosphoenolpyruvate (PEP) + 3-phospho shikimate (S3P) phosphate + 5-enolpyruvylshikimate-3-phosphat ...
. It is used to kill weeds, especially annual
broadleaf weeds Broadleaf weeds are unwanted tough plants that may grow in lawns, gardens or yards. They can be easy to spot when growing among grasses. They multiply with ease and can be very hard to eradicate. Basic characteristics Broadleaf weeds can emerge ...
and grasses that compete with
crop A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydropon ...
s. Its herbicidal effectiveness was discovered by
Monsanto The Monsanto Company () was an American agrochemical and agricultural biotechnology corporation founded in 1901 and headquartered in Creve Coeur, Missouri. Monsanto's best known product is Roundup, a glyphosate-based herbicide, developed in ...
chemist
John E. Franz John E. Franz (born December 21, 1929) is an organic chemist who discovered the herbicide glyphosate while working at Monsanto Company in 1970. The chemical became the active ingredient in Roundup, a broad-spectrum, post-emergence herbicide. Fra ...
in 1970. Monsanto brought it to market for agricultural use in 1974 under the trade name Roundup. Monsanto's last commercially relevant United States
patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A ...
expired in 2000. Farmers quickly adopted glyphosate for agricultural weed control, especially after Monsanto introduced glyphosate-resistant Roundup Ready crops, enabling farmers to kill weeds without killing their crops. In 2007, glyphosate was the most used herbicide in the United States' agricultural sector and the second-most used (after 2,4-D) in home and garden, government and industry, and commercial applications. From the late 1970s to 2016, there was a 100-fold increase in the frequency and volume of application of glyphosate-based herbicides (GBHs) worldwide, with further increases expected in the future. This was partly in response to the global emergence and spread of glyphosate-resistant weeds, requiring greater application to maintain effectiveness. The development of
glyphosate resistance Glyphosate (IUPAC name: ''N''-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plant enzyme 5-enolpyruvylshiki ...
in weed species is emerging as a costly problem. Glyphosate is absorbed through foliage, and minimally through roots, and transported to growing points. It inhibits a plant
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
involved in the synthesis of three aromatic amino acids:
tyrosine -Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word "tyrosine" is from the G ...
,
tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...
, and
phenylalanine Phenylalanine (symbol Phe or F) is an essential α-amino acid with the formula . It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine. This essential amin ...
. It is therefore effective only on actively growing plants and is not effective as a pre-emergence herbicide. An increasing number of crops have been genetically engineered to be tolerant of glyphosate (e.g.
Roundup Ready soybean A genetically modified soybean is a soybean (''Glycine max'') that has had DNA introduced into it using genetic engineering techniques. In 1996, the first genetically modified soybean was introduced to the U.S. by Monsanto. In 2014, 90.7 millio ...
, the first Roundup Ready crop, also created by Monsanto), which allows farmers to use glyphosate as a post-emergence herbicide against weeds. While glyphosate and formulations such as Roundup have been approved by regulatory bodies worldwide, concerns about their effects on humans and the environment have persisted. A number of regulatory and scholarly reviews have evaluated the relative toxicity of glyphosate as an herbicide. The WHO and FAO Joint committee on pesticide residues issued a report in 2016 stating the use of glyphosate formulations does not necessarily constitute a health risk, and giving an
acceptable daily intake Acceptable daily intake or ADI is a measure of the amount of a specific substance (originally applied for a food additive, later also for a residue of a veterinary drug or pesticide) in food or drinking water that can be ingested (orally) daily ove ...
limit of 1 milligram per kilogram of body weight per day for chronic toxicity. The consensus among national pesticide regulatory agencies and scientific organizations is that labeled uses of glyphosate have demonstrated no evidence of human carcinogenicity. The German Federal Institute for Risk Assessment toxicology review in 2013 found that with regard to positive correlations between exposure to glyphosate formulations and risk of various cancers, including
non-Hodgkin lymphoma Non-Hodgkin lymphoma (NHL), also known as non-Hodgkin's lymphoma, is a group of blood cancers that includes all types of lymphomas except Hodgkin lymphomas. Symptoms include enlarged lymph nodes, fever, night sweats, weight loss, and tiredne ...
, "the available data is contradictory and far from being convincing". A meta-analysis published in 2014 identified an increased risk of NHL in workers exposed to glyphosate formulations. In March 2015, the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...
's
International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...
(IARC) classified glyphosate as "probably carcinogenic in humans" ( category 2A) based on epidemiological studies, animal studies, and ''
in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology a ...
'' studies. In contrast, the
European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002, ...
concluded in November 2015 that "the substance is unlikely to be
genotoxic Genotoxicity is the property of chemical agents that damage the genetic information within a cell causing mutations, which may lead to cancer. While genotoxicity is often confused with mutagenicity, all mutagens are genotoxic, but some genotoxic s ...
(i.e. damaging to DNA) or to pose a
carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...
ic threat to humans", later clarifying that while carcinogenic glyphosate-containing formulations may exist, studies "that look solely at the active substance glyphosate do not show this effect." In 2017, the
European Chemicals Agency The European Chemicals Agency (ECHA; ) is an agency of the European Union which manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, Evaluation, Authorisation and Restricti ...
(ECHA) classified glyphosate as causing serious eye damage and as toxic to aquatic life, but did not find evidence implicating it as a carcinogen, a mutagen, toxic to reproduction, nor toxic to specific organs.


Discovery

Glyphosate was first synthesized in 1950 by Swiss chemist Henry Martin, who worked for the Swiss company Cilag. The work was never published. Stauffer Chemical patented the agent as a chemical chelator in 1964 as it binds and removes minerals such as
calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...
,
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...
,
manganese Manganese is a chemical element with the Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of ...
,
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
, and
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
. Somewhat later, glyphosate was independently discovered in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
at Monsanto in 1970.
Monsanto The Monsanto Company () was an American agrochemical and agricultural biotechnology corporation founded in 1901 and headquartered in Creve Coeur, Missouri. Monsanto's best known product is Roundup, a glyphosate-based herbicide, developed in ...
chemists had synthesized about 100 derivatives of aminomethylphosphonic acid as potential water-softening agents. Two were found to have weak herbicidal activity, and
John E. Franz John E. Franz (born December 21, 1929) is an organic chemist who discovered the herbicide glyphosate while working at Monsanto Company in 1970. The chemical became the active ingredient in Roundup, a broad-spectrum, post-emergence herbicide. Fra ...
, a chemist at Monsanto, was asked to try to make analogs with stronger herbicidal activity. Glyphosate was the third analog he made. Franz received the National Medal of Technology of the United States in 1987 and the Perkin Medal for Applied Chemistry in 1990 for his discoveries. Monsanto developed and patented the use of glyphosate to kill weeds in the early 1970s and first brought it to market in 1974, under the Roundup brandname. While its initial patent expired in 1991, Monsanto retained exclusive rights in the United States until its patent on the isopropylamine salt expired in September 2000. In 2008, United States Department of Agriculture (
USDA The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of comme ...
)
Agricultural Research Service The Agricultural Research Service (ARS) is the principal in-house research agency of the United States Department of Agriculture (USDA). ARS is one of four agencies in USDA's Research, Education and Economics mission area. ARS is charged with ext ...
(ARS) scientist Stephen O. Duke and Stephen B. Powles – an Australian weed expert – described glyphosate as a "virtually ideal" herbicide. In 2010 Powles stated: "glyphosate is a one in a 100-year discovery that is as important for reliable global food production as penicillin is for battling disease." As of April 2017, the Canadian government stated that glyphosate was "the most widely used herbicide in Canada", at which date the product labels were revised to ensure a limit of 20% POEA by weight.
Health Canada Health Canada (HC; french: Santé Canada, SC)Health Canada is the applied title under the Federal Identity Program; the legal title is Department of Health (). is the department of the Government of Canada responsible for national health poli ...
's
Pest Management Regulatory Agency The Pest Management Regulatory Agency (PMRA) is the Canadian government agency responsible for the regulation of pest control products in Canada under the federal authority of the '' Pest Control Products Act'' and Regulations. The agency is a br ...
found no risk to humans or the environment at that 20% limit, and that all products registered in
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
at that time were at or below that limit.


Chemistry

Glyphosate is an aminophosphonic analogue of the natural amino acid
glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...
and, like all amino acids, exists in different ionic states depending on pH. Both the phosphonic acid and
carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxyli ...
moieties can be ionised and the
amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...
group can be protonated and the substance exists as a series of zwitterions. Glyphosate is soluble in water to 12 g/L at room temperature. The original synthetic approach to glyphosate involved the reaction of
phosphorus trichloride Phosphorus trichloride is an inorganic compound with the chemical formula PCl3. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic ...
with
formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
followed by
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysi ...
to yield a phosphonate. Glycine is then reacted with this phosphonate to yield glyphosate, and its name is taken as a contraction of the compounds used in this synthesis step, namely glycine and a phosphonate. :PCl3 + H2CO → Cl2P(=O)−CH2Cl :Cl2P(=O)−CH2Cl + 2 H2O → (HO)2P(=O)−CH2Cl + 2 HCl :(HO)2P(=O)−CH2Cl + H2N−CH2−COOH → (HO)2P(=O)−CH2−NH−CH2−COOH + HCl The main deactivation path for glyphosate is hydrolysis to aminomethylphosphonic acid.


Synthesis

Two main approaches are used to synthesize glyphosate industrially, both of which proceed via the
Kabachnik–Fields reaction In organophosphorus chemistry, the Kabachnik–Fields reaction is a three-component organic reaction forming α-aminomethylphosphonates from an amine, a carbonyl compound, and a dialkyl phosphonate, (RO)2P(O)H (that are also called dialkylphosphit ...
. The first is to react iminodiacetic acid and
formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
with phosphorous acid (sometimes formed ''in situ'' from
phosphorus trichloride Phosphorus trichloride is an inorganic compound with the chemical formula PCl3. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic ...
using the water generated by the Mannich reaction of the first two reagents).
Decarboxylation Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is ...
of the
hydrophosphonylation In chemistry hydrophosphonylation refers to any reaction where addition across a double bond generates a phosphonate (RP(O)(OR')2) group. Examples include the Kabachnik–Fields reaction, where a dialkylphosphite reacts across an imine to form an am ...
product gives the desired glyphosate product. Iminodiacetic acid is usually prepared on-site by various methods depending on reagent availability. : The second uses
glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...
in place of iminodiacetic acid. This avoids the need for decarboxylation but requires more careful control of
stoichiometry Stoichiometry refers to the relationship between the quantities of reactants and products before, during, and following chemical reactions. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equ ...
, as the primary amine can react with any excess formaldehyde to form bishydroxymethylglycine, which must be hydrolysed during the
work-up In chemistry, work-up refers to the series of manipulations required to isolate and purify the product(s) of a chemical reaction. Typically, these manipulations may include: * quenching a reaction to deactivate any unreacted reagents. * coolin ...
to give the desired product. : This synthetic approach is responsible for a substantial portion of the production of glyphosate in China, with considerable work having gone into recycling the triethylamine and methanol solvents. Progress has also been made in attempting to eliminate the need for triethylamine altogether.


Impurities

Technical grade glyphosate is a white powder which, according to FAO specification, should contain not less than 95% glyphosate.
Formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
, classified as a known human carcinogen, and ''N''-nitrosoglyphosate, have been identified as toxicologically relevant impurities. The FAO specification limits the formaldehyde concentration to a maximum of 1.3 g/kg glyphosate. ''N''-Nitrosoglyphosate, "belonging to a group of impurities of particular concern as they can be activated to genotoxic carcinogens", should not exceed 1 ppm.


Formulations

Glyphosate is marketed in the United States and worldwide by many
agrochemical An agrochemical or agrichemical, a contraction of ''agricultural chemical'', is a chemical product used in industrial agriculture. Agrichemical refers to biocides ( pesticides including insecticides, herbicides, fungicides and nematicides) a ...
companies, in different solution strengths and with various adjuvants, under dozens of tradenames. As of 2010, more than 750 glyphosate products were on the market. In 2012, about half of the total global consumption of glyphosate by volume was for agricultural crops, with
forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. ...
comprising another important market. Asia and the Pacific was the largest and fastest growing regional market. As of 2014, Chinese manufacturers collectively are the world's largest producers of glyphosate and its precursors and account for about 30% of global exports. Key manufacturers include Anhui Huaxing Chemical Industry Company,
BASF BASF SE () is a German multinational chemical company and the largest chemical producer in the world. Its headquarters is located in Ludwigshafen, Germany. The BASF Group comprises subsidiaries and joint ventures in more than 80 countries ...
,
Bayer CropScience Bayer AG (, commonly pronounced ; ) is a German multinational pharmaceutical and biotechnology company and one of the largest pharmaceutical companies in the world. Headquartered in Leverkusen, Bayer's areas of business include pharmaceutica ...
(which also acquired the maker of glyphosate,
Monsanto The Monsanto Company () was an American agrochemical and agricultural biotechnology corporation founded in 1901 and headquartered in Creve Coeur, Missouri. Monsanto's best known product is Roundup, a glyphosate-based herbicide, developed in ...
),
Dow AgroSciences Dow AgroSciences LLC was a wholly owned subsidiary of the Dow Chemical Company specializing in not only agricultural chemicals such as pesticides, but also seeds and biotechnology solutions. The company was based in Indianapolis, Indiana, in ...
,
DuPont DuPont de Nemours, Inc., commonly shortened to DuPont, is an American multinational chemical company first formed in 1802 by French-American chemist and industrialist Éleuthère Irénée du Pont de Nemours. The company played a major role in ...
, Jiangsu Good Harvest-Weien Agrochemical Company, Nantong Jiangshan Agrochemical & Chemicals Co.,
Nufarm Nufarm is an Australian agricultural chemical company headquartered in Melbourne, Australia. Established in 1956, the company was founded by Max Fremder. It holds more than 2,100 product registrations, and markets products in more than 100 countri ...
, SinoHarvest,
Syngenta Syngenta AG is a provider of agricultural science and technology, in particular seeds and pesticides with its management headquarters in Basel, Switzerland. It is owned by ChemChina, a Chinese state-owned enterprise. Syngenta was found ...
, and Zhejiang Xinan Chemical Industrial Group Company. Glyphosate is an acid molecule, so it is formulated as a
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
for packaging and handling. Various salt formulations include isopropylamine, diammonium, monoammonium, or potassium as the
counterion 160px, Polystyrene sulfonate, a cation-exchange resin, is typically supplied with as the counterion.">cation-exchange_resin.html" ;"title="Polystyrene sulfonate, a cation-exchange resin">Polystyrene sulfonate, a cation-exchange resin, is typical ...
. The active ingredient of the Monsanto herbicides is the isopropylamine
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
of glyphosate. Another important ingredient in some formulations is the
surfactant Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsion#Emulsifiers , ...
polyethoxylated tallow amine (POEA). Some brands include more than one salt. Some companies report their product as acid equivalent (ae) of glyphosate acid, or some report it as active ingredient (ai) of glyphosate plus the salt, and others report both. To compare performance of different formulations, knowledge of how the products were formulated is needed. Given that different salts have different weights, the acid equivalent is a more accurate method of expressing and comparing concentrations. Adjuvant loading refers to the amount of adjuvant already added to the glyphosate product. Fully loaded products contain all the necessary adjuvants, including
surfactant Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsion#Emulsifiers , ...
; some contain no adjuvant system, while other products contain only a limited amount of adjuvant (minimal or partial loading) and additional surfactants must be added to the spray tank before application. Products are supplied most commonly in formulations of 120, 240, 360, 480, and 680 g/L of active ingredient. The most common formulation in agriculture is 360 g/L, either alone or with added cationic surfactants.Alberta Agriculture and Rural Development. April 26, 2006
Quick Guide to Glyphosate Products – Frequently Asked Questions
For 360 g/L formulations, European regulations allow applications of up to 12 L/ha for control of perennial weeds such as couch grass. More commonly, rates of 3 L/ha are practiced for control of annual weeds between crops.


Mode of action

Glyphosate interferes with the shikimate pathway, which produces the
aromatic amino acids An aromatic amino acid is an amino acid that includes an aromatic ring. Among the 20 standard amino acids, the following are classically considered aromatic: phenylalanine, tryptophan and tyrosine. Although histidine contains an aromatic ring, ...
phenylalanine Phenylalanine (symbol Phe or F) is an essential α-amino acid with the formula . It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine. This essential amin ...
,
tyrosine -Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word "tyrosine" is from the G ...
and
tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...
in plants and microorganisms – but does not exist in the genome of animals, including humans. It blocks this pathway by inhibiting the enzyme
5-enolpyruvylshikimate-3-phosphate synthase 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase is an enzyme produced by plants and microorganisms. EPSPS catalyzes the chemical reaction: : phosphoenolpyruvate (PEP) + 3-phospho shikimate (S3P) phosphate + 5-enolpyruvylshikimate-3-phosphat ...
(EPSPS), which catalyzes the reaction of
shikimate Shikimic acid, more commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid. It is an important biochemical metabolite in plants and microorganisms. Its name comes from the Japanese flower ''shik ...
-3-phosphate (S3P) and
phosphoenolpyruvate Phosphoenolpyruvate (2-phosphoenolpyruvate, PEP) is the ester derived from the enol of pyruvate and phosphate. It exists as an anion. PEP is an important intermediate in biochemistry. It has the highest-energy phosphate bond found (−61.9 kJ/m ...
to form 5-enolpyruvyl-shikimate-3-phosphate (EPSP). Glyphosate is absorbed through foliage and minimally through roots, meaning that it is only effective on actively growing plants and cannot prevent seeds from germinating. After application, glyphosate is readily transported around the plant to growing roots and leaves and this
systemic Systemic fundamental to a predominant social, economic, or political practice. This refers to: In medicine In medicine, ''systemic'' means affecting the whole body, or at least multiple organ systems. It is in contrast with ''topical'' or ''loc ...
activity is important for its effectiveness. Inhibiting the enzyme causes shikimate to accumulate in plant tissues and diverts energy and resources away from other processes, eventually killing the plant. While growth stops within hours of application, it takes several days for the leaves to begin turning yellow. Glyphosate may chelate Co which contributes to its mode of action. Under normal circumstances, EPSP is dephosphorylated to chorismate, an essential precursor for the amino acids mentioned above. These amino acids are used in protein synthesis and to produce secondary metabolites such as
folate Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing an ...
s, ubiquinones, and naphthoquinone. X-ray crystallographic studies of glyphosate and EPSPS show that glyphosate functions by occupying the binding site of the phosphoenolpyruvate, mimicking an intermediate state of the ternary enzyme–substrate complex. Glyphosate inhibits the EPSPS enzymes of different species of plants and microbes at different rates.


Uses

Glyphosate is effective in killing a wide variety of plants, including
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...
es and broadleaf and
woody plant A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposite to herbaceous plants that die back to the ground until sp ...
s. By volume, it is one of the most widely used herbicides. In 2007, glyphosate was the most used herbicide in the United States agricultural sector, with 180 to 185 million pounds () applied, the second-most used in home and garden with 5 to 8 million pounds () and 13 to 15 million pounds () in non-agricultural settings. It is commonly used for
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
,
horticulture Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...
,
viticulture Viticulture (from the Latin word for '' vine'') or winegrowing (wine growing) is the cultivation and harvesting of grapes. It is a branch of the science of horticulture. While the native territory of '' Vitis vinifera'', the common grape vine, r ...
, and
silviculture Silviculture is the practice of controlling the growth, composition/structure, and quality of forests to meet values and needs, specifically timber production. The name comes from the Latin ('forest') and ('growing'). The study of forests and wo ...
purposes, as well as garden maintenance (including home use). It has a relatively small effect on some clover species and morning glory. Glyphosate and related herbicides are often used in
invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...
eradication and habitat restoration, especially to enhance
native plant In biogeography, a native species is indigenous to a given region or ecosystem if its presence in that region is the result of only local natural evolution (though often popularised as "with no human intervention") during history. The term is eq ...
establishment in
prairie Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...
ecosystems. The controlled application is usually combined with a selective herbicide and traditional methods of weed eradication such as mulching to achieve an optimal effect. In many cities, glyphosate is sprayed along the sidewalks and streets, as well as crevices in between pavement where weeds often grow. However, up to 24% of glyphosate applied to hard surfaces can be run off by water. Glyphosate contamination of surface water is attributed to urban and agricultural use. Glyphosate is used to clear
railroad track A railway track (British English and UIC terminology) or railroad track (American English), also known as permanent way or simply track, is the structure on a railway or railroad consisting of the rails, fasteners, railroad ties (sleepers, ...
s and get rid of unwanted aquatic vegetation. Since 1994, glyphosate has been used in aerial spraying in Colombia in coca eradication programs; Colombia announced in May 2015 that by October, it would cease using glyphosate in these programs due to concerns about human toxicity of the chemical.BBC. May 10, 2015
Colombia to ban coca spraying herbicide glyphosate
/ref> Glyphosate is also used for
crop desiccation Pre-harvest crop desiccation refers to the application of an agent to a crop just before harvest to kill the leaves and/or plants so that the crop dries out from environmental conditions ("dry-down") more quickly and evenly. In agriculture, the ter ...
( siccation) to increase harvest yield and uniformity. Glyphosate itself is not a chemical
desiccant A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccants ...
; rather glyphosate application just before harvest kills the crop plants so that the food crop dries from environmental conditions ("dry-down") more quickly and evenly. Because glyphosate is systemic, excess residue levels can persist in plants due to incorrect application and this may render the crop unfit for sale. When applied appropriately, it can promote useful effects. In sugarcane, for example, glyphosate application increases sucrose concentration before harvest. In grain crops (wheat, barley, oats), uniformly dried crops do not have to be
windrow A windrow is a row of cut (mown) hay or small grain crop. It is allowed to dry before being baled, combined, or rolled. For hay, the windrow is often formed by a hay rake, which rakes hay that has been cut by a mowing machine or by scythe into ...
ed (swathed and dried) prior to harvest, but can easily be straight-cut and harvested. This saves the farmer time and money, which is important in northern regions where the growing season is short, and it enhances grain storage when the grain has a lower and more uniform moisture content.


Genetically modified crops

Some micro-organisms have a version of 5-enolpyruvoyl-shikimate-3-phosphate synthetase (EPSPS) resistant to glyphosate inhibition. A version of the enzyme that was both resistant to glyphosate and that was still efficient enough to drive adequate plant growth was identified by Monsanto scientists after much trial and error in an ''
Agrobacterium ''Agrobacterium'' is a genus of Gram-negative bacteria established by H. J. Conn that uses horizontal gene transfer to cause tumors in plants. ''Agrobacterium tumefaciens'' is the most commonly studied species in this genus. ''Agrobacterium ...
'' strain called CP4, which was found surviving in a waste-fed column at a glyphosate production facility. This ''CP4 ''EPSPS gene was
cloned Cloning is the process of producing individual organisms with identical or virtually identical DNA, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction. In the field of biotechnology, ...
and transfected into soybeans. In 1996, genetically modified soybeans were made commercially available. Current glyphosate-resistant crops include soy,
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American English, North American and Australian English), is a cereal grain first domesticated by indigenous peoples of Mexico, indigenous ...
(corn),
canola Close-up of canola blooms Canola flower Rapeseed oil is one of the oldest known vegetable oils. There are both edible and industrial forms produced from rapeseed, the seed of several cultivars of the plant family Brassicaceae. Historically, ...
,
alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as ...
,
sugar beets Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...
, and
cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor pe ...
, with
wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
still under development. In 2015, 89% of corn, 94% of soybeans, and 89% of cotton produced in the United States were from strains that were genetically modified to be herbicide-tolerant - including but not limited to glyphosate.


Environmental fate

Glyphosate has four ionizable sites, with pKa values of 2.0, 2.6, 5.6 and 10.6. Therefore, it is a zwitterion in aqueous solutions and is expected to exist almost entirely in zwitterionic forms in the environment. Zwitterions generally adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts. Glyphosate strongly
sorbs Sorbs ( hsb, Serbja, dsb, Serby, german: Sorben; also known as Lusatians, Lusatian Serbs and Wends) are a indigenous West Slavic ethnic group predominantly inhabiting the parts of Lusatia located in the German states of Saxony and Branden ...
onto
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...
minerals, and, with the exception of
colloid-facilitated transport Colloid-facilitated transport designates a transport process by which colloidal particles serve as transport vector of diverse contaminants in the surface water (sea water, lakes, rivers, fresh water bodies) and in underground water circulating in f ...
, its soluble residues are expected to be poorly mobile in the free porewater of soils. The spatial extent of
ground Ground may refer to: Geology * Land, the surface of the Earth not covered by water * Soil, a mixture of clay, sand and organic matter present on the surface of the Earth Electricity * Ground (electricity), the reference point in an electrical c ...
and
surface water Surface water is water located on top of land forming terrestrial (inland) waterbodies, and may also be referred to as ''blue water'', opposed to the seawater and waterbodies like the ocean. The vast majority of surface water is produced by pre ...
pollution is therefore considered to be relatively limited. Glyphosate is readily degraded by soil microbes to aminomethylphosphonic acid (AMPA, which like glyphosate strongly adsorbs to soil solids and is thus unlikely to leach to groundwater). Though both glyphosate and AMPA are commonly detected in water bodies, a portion of the AMPA detected may actually be the result of degradation of detergents rather than from glyphosate. Glyphosate does have the potential to contaminate surface waters due to its aquatic use patterns and through erosion, as it adsorbs to
colloid A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend ...
al soil particles suspended in
runoff Runoff, run-off or RUNOFF may refer to: * RUNOFF, the first computer text-formatting program * Runoff or run-off, another name for bleed, printing that lies beyond the edges to which a printed sheet is trimmed * Runoff or run-off, a stock marke ...
. Detection in surface waters (particularly downstream from agricultural uses) has been reported as both broad and frequent by the
United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...
(USGS) researchers, although other similar research found equal frequencies of detection in urban-dominated small streams. Rain events can trigger dissolved glyphosate loss in transport-prone soils. The mechanism of glyphosate sorption to soil is similar to that of
phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...
fertilizers, the presence of which can reduce glyphosate sorption. Phosphate fertilizers are subject to release from sediments into water bodies under
anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...
conditions, and similar release can also occur with glyphosate, though significant impact of glyphosate release from sediments has not been established. Limited leaching can occur after high rainfall after application. If glyphosate reaches surface water, it is not broken down readily by water or sunlight. The
half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ...
of glyphosate in soil ranges between 2 and 197 days; a typical field half-life of 47 days has been suggested. Soil and climate conditions affect glyphosate's persistence in soil. The median half-life of glyphosate in water varies from a few to 91 days. At a site in Texas, half-life was as little as three days. A site in Iowa had a half-life of 141.9 days. The glyphosate metabolite AMPA has been found in Swedish forest soils up to two years after a glyphosate application. In this case, the persistence of AMPA was attributed to the soil being frozen for most of the year. Glyphosate adsorption to soil, and later release from soil, varies depending on the kind of soil. Glyphosate is generally less persistent in water than in soil, with 12- to 60-day persistence observed in Canadian ponds, although persistence of over a year has been recorded in the sediments of American ponds. The half-life of glyphosate in water is between 12 days and 10 weeks.


Residues in food products

According to the National Pesticide Information Center fact sheet, glyphosate is not included in compounds tested for by the Food and Drug Administration's Pesticide Residue Monitoring Program, nor in the United States Department of Agriculture's Pesticide Data Program. The U.S. has determined the
acceptable daily intake Acceptable daily intake or ADI is a measure of the amount of a specific substance (originally applied for a food additive, later also for a residue of a veterinary drug or pesticide) in food or drinking water that can be ingested (orally) daily ove ...
of glyphosate at 1.75 milligrams per kilogram of body weight per day (mg/kg/bw/day) while the European Union has set it at 0.5. Pesticide residue controls carried out by EU Member States in 2016 analysed 6,761 samples of food products for glyphosate residues. 3.6% of the samples contained quantifiable glyphosate residue levels with 19 samples (0.28%) exceeding the European maximum residue levels (MRLs), which included six samples of honey and other apicultural products (MRL = 0.05 mg/kg) and eleven samples of buckwheat and other pseudo‐cereals (MRL = 0.1 mg/kg). Glyphosate residues below the European MRLs were most frequently found in dry lentils, linseeds, soya beans, dry peas, tea, buckwheat, barley, wheat and rye. In Canada, a survey of 7,955 samples of food found that 42.3% contained detectable quantities of glyphosate and only 0.6% contained a level higher than the Canadian MRL of 0.1 mg/kg for most foods and 4 mg/kg for beans and chickpeas. Of the products that exceeded MRLs, one third were organic products.
Health Canada Health Canada (HC; french: Santé Canada, SC)Health Canada is the applied title under the Federal Identity Program; the legal title is Department of Health (). is the department of the Government of Canada responsible for national health poli ...
concluded based on the analysis "that there was no long-term health risk to Canadian consumers from exposure to the levels of glyphosate".


Toxicity

Glyphosate is the active ingredient in herbicide formulations containing it. However, in addition to glyphosate salts, commercial formulations of glyphosate contain additives (known as adjuvants) such as
surfactant Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsion#Emulsifiers , ...
s, which vary in nature and concentration. Surfactants such as
polyethoxylated tallow amine Polyethoxylated tallow amine (also polyoxyethylene tallowamine, POE-tallowamine) refers to a range of non-ionic surfactants derived from animal fats (tallow). They are a class of polyethoxylated amines (POEAs). The abbreviation 'POEA' is often er ...
(POEA) are added to glyphosate to enable it to wet the leaves and penetrate the
cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...
of the plants.


Glyphosate alone


Humans

The acute oral toxicity for mammals is low, but death has been reported after deliberate overdose of concentrated formulations. The surfactants in glyphosate formulations can increase the relative acute toxicity of the formulation. In a 2017 risk assessment, the European Chemicals Agency (ECHA) wrote: "There is very limited information on skin irritation in humans. Where skin irritation has been reported, it is unclear whether it is related to glyphosate or co-formulants in glyphosate-containing herbicide formulations." The ECHA concluded that available human data was insufficient to support classification for skin corrosion or irritation. Inhalation is a minor route of exposure, but spray mist may cause oral or nasal discomfort, an unpleasant taste in the mouth, or tingling and irritation in the throat. Eye exposure may lead to mild conjunctivitis. Superficial corneal injury is possible if irrigation is delayed or inadequate.


Cancer

The consensus among national pesticide regulatory agencies and scientific organizations is that labeled uses of glyphosate have demonstrated no evidence of human carcinogenicity. The Joint FAO/WHO Meeting on Pesticide Residues (JMPR), the
European Commission The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body ...
, the Canadian
Pest Management Regulatory Agency The Pest Management Regulatory Agency (PMRA) is the Canadian government agency responsible for the regulation of pest control products in Canada under the federal authority of the '' Pest Control Products Act'' and Regulations. The agency is a br ...
, the
Australian Pesticides and Veterinary Medicines Authority The Australian Pesticides and Veterinary Medicines Authority (APVMA) is the Australian Government statutory agency responsible for the management and regulation of all agricultural and veterinary chemical products in Australia. History The APVMA ...
and the German Federal Institute for Risk Assessment have concluded that there is no evidence that glyphosate poses a carcinogenic or
genotoxic Genotoxicity is the property of chemical agents that damage the genetic information within a cell causing mutations, which may lead to cancer. While genotoxicity is often confused with mutagenicity, all mutagens are genotoxic, but some genotoxic s ...
risk to humans. The
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...
(EPA) has classified glyphosate as "not likely to be carcinogenic to humans." One international scientific organization, the
International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...
, classified glyphosate in Group 2A, "probably carcinogenic to humans" in 2015. , the evidence for long-term exposure to glyphosate increasing the risk of human cancer remains inconclusive. There is weak evidence human cancer risk might increase as a result of occupational exposure to large amounts of glyphosate, such as in agricultural work, but no good evidence of such a risk from home use, such as in domestic gardening. A meta-analysis published in 2019 looked at whether there was an association between an increased risk of non-Hodgkin lymphoma in humans and high cumulative exposures to glyphosate-based herbicides. The research found a "compelling link" between exposures to glyphosate-based herbicides and increased risk for non-Hodgkin lymphoma. A 2021 meta-analysis of glyphosate exposure and non-Hodgkin lymphoma cautioned that such results can be biased by "assumptions made about both exposure level and latency period."


Other mammals

Amongst mammals, glyphosate is considered to have "low to very low toxicity". The LD50 of glyphosate is 5,000 mg/kg for rats, 10,000 mg/kg in mice and 3,530 mg/kg in goats. The acute dermal LD50 in rabbits is greater than 2,000 mg/kg. Indications of glyphosate toxicity in animals typically appear within 30 to 120 minutes following ingestion of a large enough dose, and include initial excitability and
tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal ( ...
,
ataxia Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of ...
, depression, and
bradycardia Bradycardia (also sinus bradycardia) is a slow resting heart rate, commonly under 60 beats per minute (BPM) as determined by an electrocardiogram. It is considered to be a normal heart rate during sleep, in young and healthy or elderly adults, ...
, although severe toxicity can develop into collapse and convulsions. A review of unpublished short-term rabbit-feeding studies reported severe toxicity effects at 150 mg/kg/day and " no observed adverse effect level" doses ranging from 50 to 200 mg/kg/day. Glyphosate can have carcinogenic effects in nonhuman mammals. These include the induction of positive trends in the incidence of renal tubule carcinoma and
haemangiosarcoma Hemangiosarcoma is a rapidly growing, highly invasive variety of cancer that occurs almost exclusively in dogs, and only rarely in cats, horses, mice, or humans (vinyl chloride toxicity). It is a sarcoma arising from the lining of blood vessels; ...
in male mice, and increased pancreatic islet-cell adenoma in male rats. In reproductive toxicity studies performed in rats and rabbits, no adverse maternal or offspring effects were seen at doses below 175–293 mg/kg/day. Glyphosate-based herbicides may cause life-threatening
arrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adult ...
s in mammals. Evidence also shows that such herbicides cause direct electrophysiological changes in the cardiovascular systems of rats and rabbits.


Aquatic fauna

In many freshwater invertebrates, glyphosate has a 48-hour LC50 ranging from 55 to 780 ppm. The 96-hour LC50 is 281 ppm for grass shrimp (''Palaemonetas vulgaris'') and 934 ppm for
fiddler crabs The fiddler crab or calling crab may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae, well known for their sexually dimorphic claws; the males' major claw is much larger than the minor claw, while ...
(''Uca pagilator''). These values make glyphosate "slightly toxic to practically non-toxic".


Antimicrobial activity

The
antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...
activity of glyphosate has been described in the microbiology literature since its discovery in 1970 and the description of glyphosate's mechanism of action in 1972. Efficacy was described for numerous bacteria and fungi. Glyphosate can control the growth of
apicomplexa The Apicomplexa (also called Apicomplexia) are a large phylum of parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of non-photosynthetic plastid called an apicoplast, and an apical complex structure. Th ...
n parasites, such as '' Toxoplasma gondii'', ''
Plasmodium falciparum ''Plasmodium falciparum'' is a unicellular protozoan parasite of humans, and the deadliest species of ''Plasmodium'' that causes malaria in humans. The parasite is transmitted through the bite of a female '' Anopheles'' mosquito and causes the ...
'' (malaria), and ''
Cryptosporidium parvum ''Cryptosporidium parvum'' is one of several species that cause cryptosporidiosis, a parasitic disease of the mammalian intestinal tract. Primary symptoms of ''C. parvum'' infection are acute, watery, and nonbloody diarrhea. ''C. parvum'' in ...
'', and has been considered an antimicrobial agent in mammals. Inhibition can occur with some
Rhizobium ''Rhizobium'' is a genus of Gram-negative soil bacteria that fix nitrogen. ''Rhizobium'' species form an endosymbiotic nitrogen-fixing association with roots of (primarily) legumes and other flowering plants. The bacteria colonize plant cells ...
species important for soybean nitrogen fixation, especially under moisture stress.


Soil biota

When glyphosate comes into contact with the soil, it can be bound to soil particles, thereby slowing its degradation. Glyphosate and its degradation product, aminomethylphosphonic acid are considered to be much more benign toxicologically and environmentally than most of the herbicides replaced by glyphosate. A 2016 meta-analysis concluded that at typical application rates glyphosate had no effect on soil microbial biomass or respiration. A 2016 review noted that contrasting effects of glyphosate on earthworms have been found in different experiments with some species unaffected, but others losing weight or avoiding treated soil. Further research is required to determine the impact of glyphosate on earthworms in complex ecosystems.


Endocrine disruption

In 2007, the EPA selected glyphosate for further screening through its Endocrine Disruptor Screening Program (EDSP). Selection for this program is based on a compound's prevalence of use and does not imply particular suspicion of
endocrine The endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the circulatory system, regulating distant target organs. In vertebrates, the hypothalamus is the neur ...
activity. On June 29, 2015, the EPA released the Weight of Evidence Conclusions of the EDSP Tier 1 screening for glyphosate, recommending that glyphosate not be considered for Tier 2 testing. The Weight of Evidence conclusion stated "...there was no convincing evidence of potential interaction with the
estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
,
androgen An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...
or
thyroid The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The ...
pathways." A review of the evidence by the European Food Safety Authority published in September 2017 showed conclusions similar to those of the EPA report.


Effect on plant health

Some studies have found causal relationships between glyphosate and increased or decreased disease resistance. Exposure to glyphosate has been shown to change the species composition of endophytic bacteria in plant hosts, which is highly variable.


Glyphosate-based formulations

Glyphosate-based formulations may contain a number of adjuvants, the identities of which may be proprietary. Surfactants are used in herbicide formulations as
wetting Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. This happens in presence of a gaseous phase or another liquid phase not miscible with ...
agents, to maximize coverage and aid penetration of the herbicide(s) through plant leaves. As agricultural spray adjuvants, surfactants may be pre-mixed into commercial formulations or they may be purchased separately and mixed on-site.
Polyethoxylated tallow amine Polyethoxylated tallow amine (also polyoxyethylene tallowamine, POE-tallowamine) refers to a range of non-ionic surfactants derived from animal fats (tallow). They are a class of polyethoxylated amines (POEAs). The abbreviation 'POEA' is often er ...
(POEA) is a surfactant used in the original Roundup formulation and was commonly used in 2015. Different versions of Roundup have included different percentages of POEA. A 1997 US government report said that Roundup is 15% POEA while Roundup Pro is 14.5%. Since POEA is more toxic to fish and amphibians than glyphosate alone, POEA is not allowed in aquatic formulations.Gary L. Diamond and Patrick R. Durkin February 6, 1997, under contract from the United States Department of Agriculture
Effects of Surfactants on the Toxicity of Glyphosate, with Specific Reference to RODEO
/ref> A 2000 review of the ecotoxicological data on Roundup shows at least 58 studies exist on the effects of Roundup on a range of organisms. This review concluded that "...for terrestrial uses of Roundup minimal acute and chronic risk was predicted for potentially exposed non-target organisms".


Human

Acute toxicity and chronic toxicity are dose-related. Skin exposure to ready-to-use concentrated glyphosate formulations can cause irritation, and
photocontact dermatitis Phytophotodermatitis, also known as berloque dermatitis or margarita photodermatitis, is a cutaneous phototoxic inflammatory reaction resulting from contact with a light-sensitizing botanical agent followed by exposure to ultraviolet light (from ...
has been occasionally reported. These effects are probably due to the preservative benzisothiazolin-3-one. Severe skin burns are very rare. Inhalation is a minor route of exposure, but spray mist may cause oral or nasal discomfort, an unpleasant taste in the mouth, or tingling and irritation in the throat. Eye exposure may lead to mild conjunctivitis. Superficial corneal injury is possible if irrigation is delayed or inadequate. Death has been reported after deliberate overdose. Ingestion of Roundup ranging from 85 to 200 ml (of 41% solution) has resulted in death within hours of ingestion, although it has also been ingested in quantities as large as 500 ml with only mild or moderate symptoms. Adult consumption of more than 85 ml of concentrated product can lead to corrosive esophageal burns and kidney or liver damage. More severe cases cause "respiratory distress, impaired consciousness,
pulmonary edema Pulmonary edema, also known as pulmonary congestion, is excessive liquid accumulation in the tissue and air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia and respiratory failure. It is due ...
,
infiltration Infiltration may refer to: Science, medicine, and engineering *Infiltration (hydrology), downward movement of water into soil *Infiltration (HVAC), a heating, ventilation, and air conditioning term for air leakage into buildings *Infiltration (me ...
on chest X-ray, shock, arrhythmias, renal failure requiring haemodialysis, metabolic acidosis, and hyperkalaemia" and death is often preceded by
bradycardia Bradycardia (also sinus bradycardia) is a slow resting heart rate, commonly under 60 beats per minute (BPM) as determined by an electrocardiogram. It is considered to be a normal heart rate during sleep, in young and healthy or elderly adults, ...
and
ventricular arrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adult ...
s. While the surfactants in formulations generally do not increase the toxicity of glyphosate itself, it is likely that they contribute to its acute toxicity. A 2000 review concluded that "under present and expected conditions of new use, there is no potential for Roundup herbicide to pose a health risk to humans". A 2012 meta-analysis of epidemiological studies (seven cohort studies and fourteen case-control studies) of exposure to glyphosate formulations found no correlation with any kind of cancer. The 2013 systematic review by the German Institute for Risk Assessment of epidemiological studies of workers who use pesticides, and were exposed to glyphosate formulations found no significant risk, stating that "the available data are contradictory and far from being convincing". However, a 2014 meta-analysis of the same studies found a correlation between occupational exposure to glyphosate formulations and increased risk of B cell lymphoma, the most common kind of non-Hodgkin lymphoma. Workers exposed to glyphosate were about twice as likely to get B cell lymphoma. A 2016 systematic review and meta-analysis found no causal relationship between glyphosate exposure and risk of any type of lymphohematopoietic cancer including non-Hodgkin lymphoma and multiple myeloma. The same review noted that the positive associations found may be due to bias and confounding. The
Natural Resources Defense Council The Natural Resources Defense Council (NRDC) is a United States-based 501(c)(3) non-profit international environmental advocacy group, with its headquarters in New York City and offices in Washington D.C., San Francisco, Los Angeles, Chicago, Bo ...
has criticized that review, noting that it was funded by Monsanto. A 2015 systematic review of 10 observational studies found that except for an excess of
attention deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by excessive amounts of inattention, hyperactivity, and impulsivity that are pervasive, impairing in multiple contexts, and otherwise age-inap ...
among children born to glyphosate appliers, there was no evidence that glyphosate exposure among pregnant mothers caused adverse developmental outcomes in their children. Noting the limited size and scope of the review articles available, the authors noted that "these negative findings cannot be taken as definitive evidence that GLY, at current levels of occupational and environmental exposures, brings no risk for human development and reproduction."


Aquatic fauna

Glyphosate products for aquatic use generally do not use surfactants, and aquatic formulations do not use POEA due to aquatic organism toxicity. Due to the presence of POEA, such glyphosate formulations only allowed for terrestrial use are more toxic for amphibians and fish than glyphosate alone. The half-life of POEA (21–42 days) is longer than that for glyphosate (7–14 days) in aquatic environments. Aquatic organism exposure risk to terrestrial formulations with POEA is limited to drift or temporary water pockets where concentrations would be much lower than label rates. Some researchers have suggested the toxicity effects of pesticides on amphibians may be different from those of other aquatic fauna because of their lifestyle; amphibians may be more susceptible to the toxic effects of pesticides because they often prefer to breed in shallow, lentic, or ephemeral pools. These habitats do not necessarily constitute formal water-bodies and can contain higher concentrations of pesticide compared to larger water-bodies. Studies in a variety of amphibians have shown the toxicity of GBFs containing POEA to amphibian larvae. These effects include interference with gill morphology and mortality from either the loss of osmotic stability or
asphyxiation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can ...
. At sub-lethal concentrations, exposure to POEA or glyphosate/POEA formulations have been associated with delayed development, accelerated development, reduced size at
metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...
, developmental malformations of the tail, mouth, eye and head, histological indications of intersex and symptoms of oxidative stress. Glyphosate-based formulations can cause
oxidative stress Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal ...
in bullfrog tadpoles. A 2003 study of various formulations of glyphosate found, " herisk assessments based on estimated and measured concentrations of glyphosate that would result from its use for the control of undesirable plants in wetlands and over-water situations showed that the risk to aquatic organisms is negligible or small at application rates less than 4 kg/ha and only slightly greater at application rates of 8 kg/ha." A 2013
meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting m ...
reviewed the available data related to potential impacts of glyphosate-based herbicides on amphibians. According to the authors, the use of glyphosate-based pesticides cannot be considered the major cause of amphibian decline, the bulk of which occurred prior to the widespread use of glyphosate or in pristine tropical areas with minimal glyphosate exposure. The authors recommended further study of per-species and per-development-stage chronic toxicity, of environmental glyphosate levels, and ongoing analysis of data relevant to determining what if any role glyphosate might be playing in worldwide amphibian decline, and suggest including amphibians in standardized test batteries.


Genetic damage

Several studies have not found mutagenic effects, so glyphosate has not been listed in the
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...
or the
International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...
databases. Various other studies suggest glyphosate may be mutagenic. The IARC monograph noted that glyphosate-based formulations can cause DNA strand breaks in various
taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
of animals ''in vitro''.


Government and organization positions


European Food Safety Authority

A 2013 systematic review by the German Institute for Risk Assessment (BfR) examined more than 1000
epidemiological Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evid ...
studies, animal studies, and ''
in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology a ...
'' studies. It found that "no classification and labelling for carcinogenicity is warranted" and did not recommend a carcinogen classification of either 1A or 1B. It provided the review to EFSA in January 2014 which published it in December 2014.Renewal Assessment Report: Glyphosate. Volume 1. Report and Proposed Decision. December 18, 2013. German Institute for Risk Assessment, page 65. Downloaded from http://dar.efsa.europa.eu/dar-web/provision (registration required) In November 2015, EFSA published its conclusion in the Renewal Assessment Report (RAR), stating it was "unlikely to pose a carcinogenic hazard to humans". The EU was largely informed by this report when it made its decision on the use of glyphosate in November 2017. EFSA's decision and the BfR report were criticized in an
open letter An open letter is a letter that is intended to be read by a wide audience, or a letter intended for an individual, but that is nonetheless widely distributed intentionally. Open letters usually take the form of a letter addressed to an indiv ...
published by 96 scientists in November 2015 saying that the BfR report failed to adhere to accepted scientific principles of open and transparent procedures. The BfR report included unpublished data, lacked authorship, omitted references, and did not disclose conflict-of-interest information. In April 2016, Dr. Vytenis Andriukaitis, European Commissioner for Health and Food Safety, wrote an
open letter An open letter is a letter that is intended to be read by a wide audience, or a letter intended for an individual, but that is nonetheless widely distributed intentionally. Open letters usually take the form of a letter addressed to an indiv ...
to the Chair of the Board of the Glyphosate Task Force at
Monsanto The Monsanto Company () was an American agrochemical and agricultural biotechnology corporation founded in 1901 and headquartered in Creve Coeur, Missouri. Monsanto's best known product is Roundup, a glyphosate-based herbicide, developed in ...
Europe asking them to publish the full studies provided to the EFSA.


US Environmental Protection Agency

In a 1993 review, the
EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
, considered glyphosate to be noncarcinogenic and relatively low in dermal and oral acute toxicity. The EPA considered a "worst case" dietary risk model of an individual eating a lifetime of food derived entirely from glyphosate-sprayed fields with residues at their maximum levels. This model indicated that no adverse health effects would be expected under such conditions. In 2015, the EPA initiated a review of glyphosate's toxicity and in 2016 reported that glyphosate is likely not carcinogenic. In August 2019, the
EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
announced that it no longer allowed labels claiming glyphosate is a carcinogen, as those claims would "not meet the labeling requirements of the Federal Insecticide, Fungicide, and Rodenticide Act" and misinform the public. In 2017, evidence collected in a lawsuit brought against Monsanto by cancer patients revealed company emails which appeared to show a friendly relationship with a senior EPA official.


International Agency for Research on Cancer

In March 2015, the
International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...
(IARC), an intergovernmental agency forming part of the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...
of the
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoni ...
, published a summary of their forthcoming monograph on glyphosate, and classified glyphosate as "probably carcinogenic in humans" (category 2A) based on epidemiological studies, animal studies, and ''in vitro'' studies. It noted that there was "limited evidence" of carcinogenicity in humans for
non-Hodgkin lymphoma Non-Hodgkin lymphoma (NHL), also known as non-Hodgkin's lymphoma, is a group of blood cancers that includes all types of lymphomas except Hodgkin lymphomas. Symptoms include enlarged lymph nodes, fever, night sweats, weight loss, and tiredne ...
. The IARC classifies substances for their carcinogenic potential, and "a few positive findings can be enough to declare a hazard, even if there are negative studies, as well." Unlike the BfR, it does not conduct a risk assessment, weighing benefits against risk. The BfR responded that IARC reviewed only a selection of what they had reviewed earlier, and argued that other studies, including a cohort study called ''Agricultural Health Study'', do not support the classification. The IARC report did not include unpublished studies, including one completed by the IARC panel leader. The agency's international protocol dictates that only published studies be used in classifications of carcinogenicity, since national regulatory agencies including the EPA have allowed agrochemical corporations to conduct their own unpublished research, which may be biased in support of their profit motives.


= Monsanto response and campaign

= Monsanto called the IARC report biased and said it wanted the report to be retracted. In 2017, internal documents from Monsanto were made public by lawyers pursuing litigation against the company, who used the term "Monsanto papers" to describe the documents. This term was later used also by Leemon McHenry and others. The documents indicated Monsanto had planned a public relations effort to discredit the IARC report, and had engaged
Henry Miller Henry Valentine Miller (December 26, 1891 – June 7, 1980) was an American novelist. He broke with existing literary forms and developed a new type of semi- autobiographical novel that blended character study, social criticism, philosophical re ...
to write a 2015 opinion piece in ''
Forbes Magazine ''Forbes'' () is an American business magazine owned by Integrated Whale Media Investments and the Forbes family. Published eight times a year, it features articles on finance, industry, investing, and marketing topics. ''Forbes'' also rep ...
'' challenging the report. Miller did not reveal the connection to Forbes, and according to the ''
New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
'', when Monsanto asked him if he was interested in writing such an article, he replied "I would be if I could start from a high-quality draft" provided by the company. Once this became public, Forbes removed his blog from their site. Two journalists from ''
Le Monde ''Le Monde'' (; ) is a French daily afternoon newspaper. It is the main publication of Le Monde Group and reported an average circulation of 323,039 copies per issue in 2009, about 40,000 of which were sold abroad. It has had its own website si ...
'' won the 2018 European Press Prize for a series of articles on the documents, also titled ''Monsanto Papers''. Their reporting described, among other things, Monsanto's lawyers' letters demanding that IARC scientists turn over documents relating to ''Monograph 112'', which contained the IARC finding that glyphosate was a "probable carcinogen"; several of the scientists condemned these letters as intimidating.


= Reviews of the EFSA and IARC reports

= A 2017 review done by personnel from EFSA and BfR argued that the differences between the IARC's and EFSA's conclusions regarding glyphosate and cancer were due to differences in their evaluation of the available evidence. The review concluded that "Two complementary exposure assessments ... suggests that actual exposure levels are below" the reference values identified by the EFSA "and do not represent a public concern." In contrast, a 2016 analysis concluded that in the EFSA's ''Renewal Assessment Report'', "almost no weight is given to studies from the published literature and there is an over-reliance on non-publicly available industry-provided studies using a limited set of assays that define the minimum data necessary for the marketing of a pesticide", arguing that the IARC's evaluation of ''probably carcinogenic to humans'' "accurately reflects the results of published scientific literature on glyphosate". In October 2017, an article in ''The Times'' revealed that Christopher Portier, a scientist advising the IARC in the assessment of glyphosate and advocate for its classification as possibly carcinogenic, had received consulting contracts with two law firm associations representing alleged glyphosate cancer victims that included a payment of US$160,000 to Portier. The IARC final report was also found to have changed compared to an interim report, through the removal of text saying certain studies had found glyphosate was not carcinogenic in that study's context, and through strengthening a conclusion of "limited evidence of animal carcinogenicity," to "sufficient evidence of animal carcinogenicity".


California Office of Environmental Health Hazard Assessment

In March 2015, the
California Office of Environmental Health Hazard Assessment The Office of Environmental Health Hazard Assessment, commonly referred to as OEHHA (pronounced oh-EEE-ha), is a specialized department within the cabinet-level California Environmental Protection Agency ( CalEPA) with responsibility for evaluatin ...
(OEHHA) announced plans to have glyphosate listed as a known carcinogen based on the IARC assessment. In 2016, Monsanto started a case against OEHHA and its acting director, Lauren Zeise, but lost the suit in March 2017. Glyphosate was listed as "known to the State of California to cause cancer" in 2017, requiring warning labels under Proposition 65. In February 2018, as part of an ongoing case, an injunction was issued prohibiting California from enforcing carcinogenicity labeling requirements for glyphosate until the case was resolved. The injunction stated that arguments by a US District Court Judge for the Eastern District of California " onot change the fact that the overwhelming majority of agencies that that have examined glyphosate have determined it is not a cancer risk." In August 2019, the
EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
also said it no longer allowed labels claiming glyphosate is a carcinogen, as those claims would "not meet the labeling requirements of the Federal Insecticide, Fungicide, and Rodenticide Act" and misinform the public.


European Chemicals Agency

On March 15, 2017 the
European Chemicals Agency The European Chemicals Agency (ECHA; ) is an agency of the European Union which manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, Evaluation, Authorisation and Restricti ...
(ECHA) announced recommendations proceeding from a risk assessment of glyphosate performed by ECHA's Committee for Risk Assessment (RAC). Their recommendations maintained the current classification of glyphosate as a substance causing serious eye damage and as a substance toxic to aquatic life. However, the RAC did not find evidence implicating glyphosate to be a carcinogen, a mutagen, toxic to reproduction, nor toxic to specific organs.


Effects of use


Emergence of resistant weeds

In the 1990s, no glyphosate-resistant weeds were known to exist. By 2014, glyphosate-resistant weeds dominated herbicide-resistance research. At that time, 23 glyphosate-resistant species were found in 18 countries. "Resistance evolves after a weed population has been subjected to intense selection pressure in the form of repeated use of a single herbicide." According to Ian Heap, a weed specialist, who completed his PhD on resistance to multiple herbicides in annual ryegrass (''
Lolium rigidum ''Lolium rigidum'' is a species of annual grass. Common names by which it is known include annual ryegrass, a name also given to Italian ryegrass (''Lolium multiflorum''), rigid ryegrass, stiff darnel, Swiss ryegrass and Wimmera ryegrass. It is ...
'') in 1988 – the first case of an herbicide-resistant weed in Australia – by 2014 ''Lolium rigidum'' was the "world’s worst herbicide-resistant weed" with instances in "12 countries, 11 sites of action, 9 cropping regimens" and affecting "over 2 million hectares." Annual ryegrass has been known to be resistant to herbicides since 1982. The first documented case of glyphosate-resistant ''L. rigidum'' was reported in Australia in 1996 near
Orange, New South Wales Orange is a city in the Central Tablelands region of New South Wales, Australia. It is west of the state capital, Sydney on a great circle at an altitude of . Orange had an estimated urban population of 40,493 Estimated resident population, ...
.Glyphosate Resistance in Crops and Weeds: History, Development, and Management. Editor, Vijay K. Nandula. John Wiley & Sons, 2010 In 2006, farmers associations were reporting 107 biotypes of weeds within 63 weed species with herbicide resistance. In 2009, Canada identified its first resistant weed,
giant ragweed ''Ambrosia trifida'', the giant ragweed, is a species of flowering plant in the family Asteraceae. It is native to North America, where it is widespread in Canada, the United States, and northern Mexico. Distribution It is present in Europ ...
, and at that time 15 weed species had been confirmed as resistant to glyphosate. As of 2010, in the United States of soil were afflicted by herbicide-resistant weeds, or about 5% of the 170 million acres planted with corn, soybeans, and cotton, the crops most affected, in 22 states. In 2012, Charles Benbrook reported that the
Weed Science Society of America The Weed Science Society of America (WSSA) is a nonprofit, learned society focused on weed science. It was founded in 1956. The organization promotes research, education, and extension outreach, provides science-based information to the public an ...
listed 22 herbicide-resistant species in the U.S., with over infested by GR weeds and that
Dow AgroSciences Dow AgroSciences LLC was a wholly owned subsidiary of the Dow Chemical Company specializing in not only agricultural chemicals such as pesticides, but also seeds and biotechnology solutions. The company was based in Indianapolis, Indiana, in ...
had carried out a survey and reported a figure of around . The International Survey of Herbicide Resistant Weeds database lists species that are resistant to glyphosate. In response to resistant weeds, farmers are hand-weeding, using tractors to turn over soil between crops, and using other herbicides in addition to glyphosate. Monsanto scientists have found that some resistant weeds have as many as 160 extra copies of a gene called '' EPSPS,'' the enzyme glyphosate disrupts.


Palmer amaranth

In 2004, a glyphosate-resistant variation of
Palmer amaranth ''Amaranthus palmeri'' is a species of edible flowering plant in the amaranth genus. It has several common names, including carelessweed, dioecious amaranth, Palmer's amaranth, Palmer amaranth, and Palmer's pigweed. It is native to most of the ...
was found in the U.S. state of Georgia and confirmed by a 2005 study. In 2005, resistance was also found in North Carolina. The species can quickly become resistant to multiple herbicides and has developed multiple mechanisms for glyphosate resistance due to selection pressure. The glyphosate-resistant weed variant is now widespread in the southeastern United States. Cases have also been reported in Texas and Virginia.


''Conyza'' species

'' Conyza bonariensis'' (also known as hairy fleabane and buva) and ''
Conyza canadensis ''Erigeron canadensis'' ( synonym ''Conyza canadensis'') is an annual plant native throughout most of North America and Central America. It is also widely naturalized in Eurasia and Australia. Common names include horseweed, Canadian horsewee ...
'' (known as horseweed or marestail) are other weed species that have lately developed glyphosate resistance. A 2008 study on the current situation of glyphosate resistance in South America concluded "resistance evolution followed intense glyphosate use" and the use of glyphosate-resistant soybean crops is a factor encouraging increases in glyphosate use. In the 2015 growing season, glyphosate-resistant marestail proved to be especially problematic to control in Nebraska production fields.


Ryegrass

Glyphosate-resistant ryegrass (''Lolium'') has occurred in most of the Australian agricultural areas and other areas of the world. All cases of evolution of resistance to glyphosate in Australia were characterized by intensive use of the herbicide while no other effective weed control practices were used. Studies indicate resistant ryegrass does not compete well against nonresistant plants and their numbers decrease when not grown under conditions of glyphosate application.


Johnson grass

Glyphosate-resistant Johnson grass (''Sorghum halepense'') has been found in Argentina as well as Arkansas, Louisiana, and Mississippi.


Monarch butterfly populations

Use of 2-4 D and other herbicides like glyphosate to clear
milkweed ''Asclepias'' is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic to hum ...
along roads and fields may have contributed to a decline in
monarch butterfly The monarch butterfly or simply monarch (''Danaus plexippus'') is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. ...
populations in the Midwestern United States. Along with deforestation and adverse weather conditions, the decrease in milkweed contributed to an 81% decline in monarchs. The
Natural Resources Defense Council The Natural Resources Defense Council (NRDC) is a United States-based 501(c)(3) non-profit international environmental advocacy group, with its headquarters in New York City and offices in Washington D.C., San Francisco, Los Angeles, Chicago, Bo ...
(NRDC) filed a suit against the
EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
in 2015, in which it argued that the agency ignored warnings about the potentially dangerous impacts of glyphosate usage on monarchs.


Legal status

Glyphosate was first approved for use in the 1970s, and as of 2010 was labelled for use in 130 countries. In 2017 Vandenberg ''et al.'' cited a 100-fold increase in the use of glyphosate-based herbicides from 1974 to 2014, the possibility that herbicide mixtures likely have effects that are not predicted by studying glyphosate alone, and reliance of current safety assessments on studies done over 30 years ago. They recommended that current safety standards be updated, writing that the current standards "may fail to protect public health or the environment."


European Union

In April 2014, the legislature of the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
passed legislation prohibiting sale of glyphosate to individuals for use at home; commercial sales were not affected. In June 2015, the French Ecology Minister asked nurseries and garden centers to halt over-the-counter sales of glyphosate in the form of Monsanto's Roundup. This was a nonbinding request and all sales of glyphosate remain legal in France until 2022, when it was planned to ban the substance for home gardening. However, more recently the French parliament decided to not to impose a definitive date for such a ban. In January 2019, "the sale, distribution, and use of Roundup 360 a banned" in France. Exemptions for many farmers were later implemented, and a curb of its use by 80% for 2021 is projected. A vote on the relicensing of glyphosate in the EU stalled in March 2016. Member states France, Sweden, and the Netherlands objected to the renewal. A vote to reauthorize on a temporary basis failed in June 2016 but at the last minute the license was extended for 18 months until the end of 2017. On 27 November 2017, in the EU Council a majority of eighteen member states voted in favor of permitting the use of glyphosate for five more years. A
qualified majority A supermajority, supra-majority, qualified majority, or special majority is a requirement for a proposal to gain a specified level of support which is greater than the threshold of more than one-half used for a simple majority. Supermajority ru ...
of sixteen states representing 65% of EU citizens was required to pass the law. The German Minister of Agriculture, Christian Schmidt, unexpectedly voted in favor while the German coalition government was internally divided on the issue which usually results in Germany abstaining. In December 2018, attempts were made to reopen the decision to license the weed-killer. These were condemned by Conservative MEPs, who said the proposal was politically motivated and flew in the face of scientific evidence. In March 2019, the
European Court of Justice The European Court of Justice (ECJ, french: Cour de Justice européenne), formally just the Court of Justice, is the supreme court of the European Union in matters of European Union law. As a part of the Court of Justice of the European U ...
(ECJ) ordered the
European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002, ...
(EFSA) to release all carcinogenicity and toxicity pesticide industry studies on glyphosate to the general public. In March 2019, the
Austrian state Austria is a federal republic made up of nine states (German: ''Länder''). Since ''Land'' is also the German word for "country", the term ''Bundesländer'' (literally ''federal states'') is often used instead to avoid ambiguity. The Constitution ...
of
Carinthia Carinthia (german: Kärnten ; sl, Koroška ) is the southernmost Austrian state, in the Eastern Alps, and is noted for its mountains and lakes. The main language is German. Its regional dialects belong to the Southern Bavarian group. Carin ...
outlawed the private use of glyphosate in residential areas while the commercial application of the herbicide is still permitted for farmers. The use of glyphosate by public authorities and road maintenance crews was already halted a number of years prior to the current ban by local authorities. In June 2019,
Deutsche Bahn The (; abbreviated as DB or DB AG) is the national railway company of Germany. Headquartered in the Bahntower in Berlin, it is a joint-stock company ( AG). The Federal Republic of Germany is its single shareholder. describes itself as the ...
and
Swiss Federal Railways Swiss Federal Railways (german: link=no, Schweizerische Bundesbahnen, ''SBB''; french: link=no, Chemins de fer fédéraux suisses, ''CFF''; it, Ferrovie federali svizzere, ''FFS'') is the national railway company of Switzerland. It is usuall ...
announced that glyphosate and other commonly used herbicides for weed eradication along railway tracks will be phased out by 2025, while more environmentally sound methods for vegetation control are implemented. In July 2019, the
Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
n parliament voted to ban glyphosate in Austria.Nationalrat stimmt für Glyphosatverbot
Austrian parliament votes to forbid Glyphosphat & water is a public good necessary for the existence of a human, orf.at, 2019-07-02
In September 2019, the German Environment Ministry announced that the use of glyphosate will be banned from the end of 2023. The use of glyphosate-based herbicides will be reduced starting from 2020. The assessment process for an approval of glyphosate in the European Union will begin in December 2019. France, Hungary, the Netherlands and Sweden will jointly assess the application dossiers of the producers. The draft report of the assessment group will then be peer-reviewed by the EFSA before the current approval expires in December 2022. The date has since been pushed back, partially due to very high interest and input in the participation process, with the
European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002, ...
(EFSA) even calling it an “unprecedented number”. Because the EFSA has to review all these 2400 comments and almost 400 responses, the process is expected to take longer. The created document is under extra review by the specially formed Glyphosate Renewal Group (GRG) and the Assessment Group on Glyphosate (AGG), the panel consisting of the four mentioned member states. With their responses now being scheduled for September 2022, the consultations with member states are supposed to be held by the very end of 2022. This would allow to finish the final assessment by mid-2023 and pass it on to further legislature to decide.


Other countries

In September 2013, the
Legislative Assembly of El Salvador The Legislative Assembly ( es, Asamblea Legislativa) is the legislative branch of the government of El Salvador. Structure The Salvadoran legislature is a unicameral body. It is made up of 84 deputies, all of whom are elected by direct po ...
approved legislation to ban 53 agrochemicals, including glyphosate; the ban on glyphosate was set to begin in 2015. In the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
, the state of
Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...
preempts local laws that attempt to ban glyphosate. In 2015 there was an attempt to pass legislation at the state level that would repeal that preemption. In May 2015, the
President of Sri Lanka The President of Sri Lanka ( si, ශ්‍රී ලංකා ජනාධිපති ''Śrī Laṃkā Janādhipathi''; ta, இலங்கை சனாதிபதி ''Ilankai janātipati'') is the head of state and head of government of t ...
banned the use and import of glyphosate, effective immediately. However, in May 2018 the Sri Lankan government decided to re-authorize its use in the plantation sector. In May 2015,
Bermuda ) , anthem = "God Save the King" , song_type = National song , song = "Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , es ...
blocked importation on all new orders of glyphosate-based herbicides for a temporary suspension awaiting outcomes of research. In May 2015,
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the ...
announced that it would stop using glyphosate by October 2015 in the destruction of illegal plantations of
coca Coca is any of the four cultivated plants in the family Erythroxylaceae, native to western South America. Coca is known worldwide for its psychoactive alkaloid, cocaine. The plant is grown as a cash crop in the Argentine Northwest, Bolivia, ...
, the raw ingredient for
cocaine Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Am ...
. Farmers have complained that the aerial fumigation has destroyed entire fields of
coffee Coffee is a drink prepared from roasted coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content. It is the most popular hot drink in the world. Seeds of ...
and other legal produce. In April 2019,
Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making ...
's Ministry of Agriculture and Rural Development banned the use of glyphosate throughout the country. In August 2020,
Mexican Mexican may refer to: Mexico and its culture *Being related to, from, or connected to the country of Mexico, in North America ** People *** Mexicans, inhabitants of the country Mexico and their descendants *** Mexica, ancient indigenous people ...
President
Andrés Manuel López Obrador Andrés Manuel López Obrador (; born 13 November 1953), also known by his initials AMLO, is a Mexican politician who has been serving as the 65th president of Mexico since 1 December 2018. He previously served as Head of Government of Mex ...
announced that glyphosate will be gradually phased out of use in Mexico by late 2024. Thailand's National Hazardous Substances Committee decided to ban the use of glyphosate in October 2019 but reversed the decision in November 2019. After a court-ruling in 2018, glyphosate was temporarily banned in
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
. This decision was later overturned, causing major criticism by the federal agency of health (
Anvisa Brazilian Health Regulatory Agency ( pt, Agência Nacional de Vigilância Sanitária, links=no, italics=yes, ''Anvisa'', literally National Health Surveillance Agency) is a regulatory body of the Brazilian government, created in 1999 during Presi ...
). This comes, as the latest evaluations declared glyphosate as noncarcinogenic. Since all carcinogenic agrichemicals are automatically banned in the country, this allowed the continuous use. In New Zealand, glyphosate is an approved herbicide for killing weeds, with the most popular brand being Roundup. Genetically modified crops designed to resist glyphosate are absent in New Zealand. Crops applied with glyphosate must be regulated under the HSNO Act 1996 and ACVM Act 1997.https://www.epa.govt.nz/assets/Uploads/Documents/Hazardous-Substances/Glyphosate-call-for-information/Glyphosate-call-for-information-summary-report-may22.pdf Legal status for glyphosate use in New Zealand is approved for commercial and personal use. Exports of New Zealand honey have been found in 2021 to contain traces of glyphosate, citing Japan to decline imports of affected New Zealand honey. New Zealand has low regulations for glyphosate, despite other countries imposing restrictions or bans on glyphosate.


Legal cases


Lawsuits claiming liability for cancer

In June 2018, in the court case Johnson v. Monsanto Co., Dewayne Johnson, a 46-year-old former California school
groundskeeper Groundskeeping is the activity of tending an area of land for aesthetic or functional purposes, typically in an institutional setting. It includes mowing grass, trimming hedges, pulling weeds, planting flowers, etc. The U.S. Department of Labor e ...
who is dying of
non-Hodgkin lymphoma Non-Hodgkin lymphoma (NHL), also known as non-Hodgkin's lymphoma, is a group of blood cancers that includes all types of lymphomas except Hodgkin lymphomas. Symptoms include enlarged lymph nodes, fever, night sweats, weight loss, and tiredne ...
, took Monsanto (which had been acquired by
Bayer Bayer AG (, commonly pronounced ; ) is a German multinational pharmaceutical and biotechnology company and one of the largest pharmaceutical companies in the world. Headquartered in Leverkusen, Bayer's areas of business include pharmaceutic ...
earlier that month) to trial in San Francisco County superior court, alleging that it has spent decades hiding the cancer-causing dangers of its Roundup herbicides. The judge ordered that jurors be allowed to consider both scientific evidence related to the cause of Johnson's cancer and allegations that Monsanto suppressed evidence of the risks, with possible punitive damages. In August 2018, the jury awarded Johnson US$289 million in damages. Monsanto said they would appeal, saying they were confident that glyphosate does not cause cancer when used appropriately. On appeal, the award was reduced to $78.5 million in November 2018, and subsequently further reduced to $21.5 million in July 2020. In August 2018, the potential for additional cases was estimated at up to 4,000. Bayer announced in April 2019 that over 13,000 lawsuits related to Roundup had been launched in the US. In March 2019, a man was awarded $80 million in a lawsuit claiming Roundup was a substantial factor in his cancer, resulting in
Costco Costco Wholesale Corporation ( doing business as Costco Wholesale and also known simply as Costco) is an American multinational corporation which operates a chain of membership-only big-box retail stores (warehouse club). As of 2022, Costc ...
stores discontinuing sales. In July 2019, U.S. District Judge Vince Chhabria reduced the judgment to $26 million. Chhabria stated that a punitive award was appropriate because the evidence "easily supported a conclusion that Monsanto was more concerned with tamping down safety inquiries and manipulating public opinion than it was with ensuring its product is safe." Chhabria stated that there is evidence on both sides concerning whether glyphosate causes cancer and that the behavior of Monsanto showed "a lack of concern about the risk that its product might be carcinogenic." On 13 May 2019 a jury in California ordered Bayer to pay a couple $2 billion in damages after finding that the company had failed to adequately inform consumers of the possible carcinogenicity of Roundup. On July 26, 2019, an Alameda County judge cut the judgment to $86.7 million, stating that the judgement by the jury exceeded legal precedent. Using litigation discovery emails it was later revealed that in 2015 when Monsanto was discussing papers they wanted to see published to counter the expected IARC glyphosate results they wrote in an email, "An option would be to add Greim and Kier or Kirkland to have their names on the publication, but we would be keeping the cost down by us doing the writing and they would just edit & sign their names so to speak. Recall that is how we handled Williams Kroes & Munro, 2000." In June 2020 Bayer, which acquired Monsanto in 2018, agreed to a $10 billion settlement as a result of a number of class-action lawsuits alleging that Roundup had caused cancer.


Advertising controversies

''The New York Times'' reported that in 1996: :Dennis C. Vacco, the Attorney General of New York, ordered the company Monsanto to pull ads that said Roundup was "safer than table salt" and "practically nontoxic" to mammals, birds and fish. The company withdrew the spots, but also said that the phrase in question was permissible under E.P.A. guidelines. In 2001, French environmental and consumer rights campaigners brought a case against Monsanto for misleading the public about the
environmental impact Environmental issues are effects of human activity on the biophysical environment, most often of which are harmful effects that cause environmental degradation. Environmental protection is the practice of protecting the natural environment on t ...
of its herbicide Roundup, on the basis that glyphosate, Roundup's main component, is classed as "dangerous for the environment" and "toxic for aquatic organisms" by the
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...
. Monsanto's advertising for Roundup had presented it as biodegradable and as leaving the soil clean after use. In 2007, Monsanto was convicted of false advertising and was fined 15,000 euros. Monsanto's French distributor Scotts France was also fined 15,000 euros. Both defendants were ordered to pay damages of 5,000 euros to the Brittany Water and Rivers Association and 3,000 euros to the ''Consommation Logement Cadre de vie'', one of the two main general consumer associations in France. Monsanto appealed and the court upheld the verdict; Monsanto appealed again to the French Supreme Court, and in 2009 it also upheld the verdict. In 2016, a lawsuit was filed against
Quaker Oats The Quaker Oats Company, known as Quaker, is an American food conglomerate based in Chicago. It has been owned by PepsiCo since 2001. History Precursor miller companies In the 1850s, Ferdinand Schumacher and Robert Stuart founded oat mills. ...
in the Federal district courts of both
New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...
and
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
after trace amounts of glyphosate were found in
oatmeal Oatmeal is a preparation of oats that have been de-husked, steamed, and flattened, or a coarse flour of hulled oat grains (groats) that have either been milled (ground) or steel-cut. Ground oats are also called white oats. Steel-cut oats a ...
. The lawsuit alleged that the claim of "100% natural" was
false advertising False advertising is defined as the act of publishing, transmitting, or otherwise publicly circulating an advertisement containing a false claim, or statement, made intentionally (or recklessly) to promote the sale of property, goods, or servic ...
. That same year
General Mills General Mills, Inc., is an American multinational manufacturer and marketer of branded processed consumer foods sold through retail stores. Founded on the banks of the Mississippi River at Saint Anthony Falls in Minneapolis, the company or ...
dropped the label "Made with 100% Natural Whole Grain Oats" from their
Nature Valley Nature Valley is an American brand of bars, snacks and granola owned by General Mills General Mills, Inc., is an American multinational manufacturer and marketer of branded processed consumer foods sold through retail stores. Founded on th ...
granola bars after a lawsuit was filed that claimed the oats contained trace amounts of glyphosate.


Trade dumping allegations

United States companies have cited trade issues with glyphosate being dumped into the western world market areas by Chinese companies and a formal dispute was filed in 2010.


See also

* 2,4-Dichlorophenoxyacetic acid * Ammonium sulfamate *
Atrazine Atrazine is a chlorinated herbicide of the triazine class. It is used to prevent pre-emergence broadleaf weeds in crops such as maize (corn), soybean and sugarcane and on turf, such as golf courses and residential lawns. Atrazine's primary m ...
*
Environmental impact of pesticides The environmental effects of pesticides describe the broad series of consequences of using pesticides. The unintended consequences of pesticides is one of the main drivers of the negative impact of modern industrial agriculture on the environme ...
* Health effects of pesticides *
Integrated pest management Integrated pest management (IPM), also known as integrated pest control (IPC) is a broad-based approach that integrates both chemical and non-chemical practices for economic control of pests. IPM aims to suppress pest populations below the eco ...
*
Monsanto legal cases Monsanto was involved in several high-profile lawsuits, as both plaintiff and defendant. It had been defendant in a number of lawsuits over health and environmental issues related to its products. Monsanto also made frequent use of the courts to de ...
* Pesticide regulation in the United States * Regulation of pesticides in the European Union * Séralini affair


References


Further reading

*


External links

* * * * {{Authority control Herbicides Acetic acids Amines Phosphonic acids Monsanto IARC Group 2A carcinogens Chelating agents Secondary amino acids ja:ラウンドアップ