Glyphosate, an aminophosphonate
(non-cholinesterase inhib-itor-organophosphate compound), is used as a
herbicide. It has a low order of toxicity in mammals, but the surfactant or
other components contained in many preparations may contribute to toxic
effects. It is an odourless, colourless to white crystalline powder and is
Glyphosate herbicides are commonly
applied in spray form and primarily formulated as either a water-soluble liquid
or concentrate solution, or a solution made with a water-soluble powder and
other ingredients. The following preparations are also available: pressurised
liquids, aerosols, emulsions, pellets/ tablets, granules, powders, and
Glyphosate formulations and their
toxicity differ depending on the type and concentration of the active
ingredient and/or the added surfactants. The polyoxyethylene tallowamines (e.g.
polyoxyethylene amine or POEA) is a class of surfactants most commonly used in
glyphosate formulations. Other glyphosate herbicide additives include sulfuric
and phosphoric acid and a variety of inert materials.
Glyphos, Roundup, Sampoo.
The surfactant present in commercial
solution, polyoxyethylenea-mine, an anionic surfactant, may be responsible for
many of the toxic effects of glyphosate. Surfactants alone may cause circula-tory
failure, respiratory failure, seizures, generalised oedema and gastric erosion.
Glyphosate appears to undergo
minimal metabolism. Results from animal studies indicate that essentially no
toxic metabolites are produced and nearly 100% of the body burden is parent
of > 200 ml is likely to produce severe toxicity.
While instances of glyphosate
poisoning have not been very common in India, cases are beginning to be
Common features include pain in the mouth and throat,
mucosal erosion/ulceration, vomiting, mild hepatotoxicity, and leukocytosis.
Endoscopy in patients with ulceration showed gastritis, oesophagitis, and
mucosal oedema, but no full thickness injury.
Less commonly, the patient may suffer from diarrhoea,
abnormal mental status, oliguria/anuria, metabolic acidosis; hyperthermia,
pulmonary oedema and shock.
Various cardiac arrhythmias, including ventricular
arrhyth-mias, bradycardia, and cardiac arrest have been reported.
Poor prognosis is associated with the combination of
pulmo-nary oedema, acidosis and hyperkalaemia.
Dermatitis resembling sunburn has been seen when the
material has been in contact with skin for more than 30 minutes. No systemic
symptoms have been seen due to absorption via intact or abraded skin.
Serum levels of glyphosate are not clinically useful in
assessing the severity of exposure or poisoning.
Monitor CBC, serum creatinine, BUN, liver function tests,
serum electrolytes, arterial blood gases, urinalysis, and chest radiograph in
symptomatic patients. Monitor cardiovascular function; including blood pressure
frequently. Obtain baseline ECG; repeat as indicated.
Emesis is not recommended. Instead, rinse the mouth and
dilute with milk or water.
Activated charcoal can be administered in the usual manner.
Obtain consultation concerning endoscopy as soon as
possible, and perform endoscopy within the first 24 hours when indicated. If
burns are found, follow 10 to 20 days later with barium swallow or oesophagram.
Scintigraphy: Scans utilising radioisotope labelled
sucral-fate (technetium 99m) may represent an alternative to endoscopy,
particularly in young children, as no sedation is required for this procedure.
The use of corticosteroids for the treatment of caustic
ingestion is controversial.
The use of antibiotics is suggested
if corticosteroids are used, or if perforation or infection is suspected.
Agents that cover anaerobes and oral flora such as penicillin, ampicillin, or
clindamycin are to be preferred.
For acute lung injury, maintain adequate ventilation and
oxygenation with frequent monitoring of arterial blood gases and/or pulse
oximetry. If a high FIO2 is required to maintain adequate
oxygenation, mechanical ventilation and positive-end-expiratory pressure (PEEP)
may be required; ventilation with small tidal volumes (6 ml/kg) is preferred if
For hypotension, infuse 10 to 20 ml/kg of isotonic fluid and
place in Trendelenburg position. If hypotension persists, administer dopamine
Treat severe acidosis (less than pH 7.1) with IV sodium
bicarbonate. Begin with 1 mEq/kg in adults and in children. Repeat doses of no
more than half the original amount may be given, no more often than every 10
minutes if required.
Glyphosate is excreted rapidly in the urine. Maintaining an
adequate urine output is important as the clearance of glyphosate by the kidney
(52.9 ml/min) was as good as by haemodialysis (52.5 ml/min); both of which were
superior to haemoperfusion (6.4 ml/min).