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The main deactivation path for glyphosate is hydrolysis to aminomethylphosphonic acid. The first is to react iminodiacetic acid with phosphorous acid and hydrochloric acid sometimes formed in situ by addition of phosphorus trichloride via a modified Mannich reaction. Oxidation then leads to the desired glyphosate product.
Iminodiacetic acid is usually prepared on-site by various methods depending on reagent availability. Dimethyl phosphite is then introduced, which leads to a substitution reaction of the hydroxyl of one of the two hydroxymethyl groups.
Work-up with hydrochloric acid and heat cleaves the remaining hydroxymethyl group from the nitrogen atom and hydrolyzes both phosphate ester linkages. Formaldehyde , classified as a known human carcinogen,   and N-nitrosoglyphosate , have been identified as toxicologically relevant impurities. N-Nitrosoglyphosate, "belonging to a group of impurities of particular concern as they can be activated to genotoxic carcinogens",  should not exceed 1 ppm.
Glyphosate is marketed in the United States and worldwide by many agrochemical companies, in different solution strengths and with various adjuvants , under dozens of tradenames. Various salt formulations include isopropylamine, diammonium, monoammonium, or potassium as the counterion. The active ingredient of the Monsanto herbicides is the isopropylamine salt of glyphosate. Another important ingredient in some formulations is the surfactant polyethoxylated tallow amine.
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 ; 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.
While growth stops within hours of application, it takes several days for the leaves to begin turning yellow. 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.
By volume, it is one of the most widely used herbicides. It has a relatively small effect on some clover species and morning glory. 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 sugarcane, for example, glyphosate application increases sucrose concentration before harvest.
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. 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 strain called CP4, which was found surviving in a waste-fed column at a glyphosate production facility.
In , genetically modified soybeans were made commercially available. The spatial extent of ground and surface water pollution is therefore considered to be relatively limited. 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.
Detection in surface waters particularly downstream from agricultural uses has been reported as both broad and frequent by USGS researchers,  although other similar research found equal frequencies of detection in urban-dominated small streams.
If glyphosate reaches surface water, it is not broken down readily by water or sunlight. The median half-life of glyphosate in water varies from a few to 91 days. A site in Iowa had a half-life of In this case, the persistence of AMPA was attributed to the soil being frozen for most of the year.
However, a field test showed that lettuce , carrots , and barley contained glyphosate residues up to one year after the soil was treated with 3. Glyphosate residues below the European MRLs were most frequently found in dry lentils, linseeds, soya beans, dry peas, tea, buckwheat, barley, wheat and rye. However, in addition to glyphosate salts, commercial formulations of glyphosate contain additives known as adjuvants such as surfactants , which vary in nature and concentration.
Surfactants such as polyethoxylated tallow amine POEA are added to glyphosate to enable it to wet the leaves and penetrate the cuticle 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. Where skin irritation has been reported, it is unclear whether it is related to glyphosate or co-formulants in glyphosate-containing herbicide formulations. Eye exposure may lead to mild conjunctivitis.
Superficial corneal injury is possible if irrigation is delayed or inadequate. The EPA has classified glyphosate as "not likely to be carcinogenic to humans.
The analysis used the most recent update of the Agricultural Health Study cohort published in and five case-control studies published in The research found a "compelling link" between exposures to glyphosate-based herbicides and increased risk for non-Hodgkin lymphoma.
Indications of glyphosate toxicity in animals typically appear within 30 to minutes following ingestion of a large enough dose, and include initial excitability and tachycardia , ataxia , depression, and bradycardia , although severe toxicity can develop into collapse and convulsions. These include the induction of positive trends in the incidence of renal tubule carcinoma and haemangiosarcoma in male mice, and increased pancreatic islet-cell adenoma in male rats.
Evidence also shows that such herbicides cause direct electrophysiological changes in the cardiovascular systems of rats and rabbits. The hour LC50 is ppm for grass shrimp Palaemonetas vulgaris and ppm for fiddler crabs Uca pagilator. These values make glyphosate "slightly toxic to practically non-toxic".
Efficacy was described for numerous bacteria and fungi. Further research is required to determine the impact of glyphosate on earthworms in complex ecosystems. The Weight of Evidence conclusion stated " As agricultural spray adjuvants, surfactants may be pre-mixed into commercial formulations or they may be purchased separately and mixed on-site.
Skin exposure to ready-to-use concentrated glyphosate formulations can cause irritation, and.
Carrasco: un estudio más tóxico que el glifosato