August 9, 2013

A Case of 28 Years old Gentleman with Roundup Poisoning

28 Years old gentleman, no known medical illness but presented multiple times to casualty for self inflicting injury currently presented with history of alleged drinking one glass of "roundup" two hours prior to presentation after fighting with his wife. He denied suicidal attempt or hallucination but claims drinking it to scare his wife. He exhibit only mild gastrointestinal symptoms including epigastric pain, nausea and vomiting. Upon presentation, he was fully conscious and alert, stable vital signs, intact higher mental status function but poor insights. There was also neglected cut wound over his left dorsum of hand. His ECG and cardiac monitoring is normal. He was treated symptomatically with IV maxolon 10 mg, IV Ranitidine 50 mg, IV Hycosine 20 mg and activated charcoal. Ryle’s tube was inserted but gastric lavage was not done. He was then admitted to general medical ward for observation.

Roundup is a trade name for  herbicide that contains Glyphosate and manufactured by Monsanto.

Glyphosate exist as a chemical structure  N-(phosphonomethyl)glycine with carbon and phosphorus moiety. Differs from the organophosphate containing herbicide, it has no anti cholinesterase effects.

This non selective, broad-spectrum systemic herbicide consists of mixture of water, 15% of polyoxyethyleneamine (POEA), and glyphosate (isopropylamine salt). Depending on either it is produced for commercial use of domestic use, it contains 41% to 1% glyphosate formulations.

Glyphosate inhibits enzyme used for synthesis of aromatic amino acids tyrosine, tryptophan and phenylalanine. POEA is a surfactant that assist in penetration of the chemicals into the herbs tissue.

Even though categorized as category III in term of toxicity (Grade I to IV with I is the most toxic), survey by UK National Poisons Information Service 2005 revealed that it is the fourth most common exposure and third most common implicated in self harm cases. (E Beswick & J Millo)

The mechanism of toxicity in glyphosate formulation is complicated. It is difficult to tell whether toxicity arises do to the effect of glyphosate, surfactants or both.

Experimental studies proposed that POEA toxicity is greater than glyphosate alone and commercial formulations alone. However, there is insufficient data to conclude whether POEA containing preparation is more toxic than other surfactant containing preparation.

Proposed mechanisms of Glyphosate toxicity to mammals include uncoupling of oxidative phosphorylation and glyphosate- or POEA-mediated direct cardiotoxicity. (E Beswick & J Millo)

Accidental ingestion of glyphosate usually give mild and transient gastrointestinal irritation.  Ingestion of >85 ml of concentrated formulation is likely to cause significant toxicity in adult (Bradberry SM et al)

Gastrointestinal corrosive effects, with mouth, throat and epigastric pain and dysphagia are common. Renal and hepatic impairment are also frequent and usually reflect reduced organ perfusion. Respiratory distress, impaired consciousness, pulmonary oedema, infiltration on chest x-ray, shock, arrhythmias, renal failure requiring hemodialysis, metabolic acidosis and hyperkalaemia may supervene in severe cases. Bradycardia and ventricular arrhythmias are often present pre-terminally. Dermal exposure to ready-to-use glyphosate formulations can cause irritation and photo-contact dermatitis has been reported occasionally; these effects are probably due to the preservative Proxel (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, tingling and throat irritation. Eye exposure may lead to mild conjunctivitis, and superficial corneal injury is possible if irrigation is delayed or inadequate. (Bradberry SM et al)

Patient with high fatality rate usually exhibit these features; 1)Ingestion of more than 150 mL Glyphosate, 2) Pulmonary oedema, 3)Hypotension refractory to fluid resuscitation, inotropes or vasopressors, 4) Corrosive effects on the gastrointestinal tract, 4) Tachy- and brady arrhythmias, 5) Renal failure, 6) Elevated liver enzymes, 7) Hyperkalaemia, 8) Metabolic acidosis, 9) Older patients (E Beswick & J Millo)

There is no specific antidote for glyphosate poisoning and the treatment is mostly supportive and organ related treatment.


1. Bradberry SM, Proudfoot AT, Vale JA, "Glyphosate poisoning.", Toxicol Rev. 2004;23(3):159-67.

2. E Beswick, J Millo, "Fatal poisoning with glyphosate surfactant herbicide", JICS Volume 12, Number 1, January 2011

3. Pesticide Action Network Asia and the Pacific on Glyphosate, November 2009

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