Glyphosate Poisoning

Abstract

Glyphosate is used extensively as a non-selective herbicide by both professional applicators and consumers and its use is likely to increase further as it is one of the first herbicides against which crops have been genetically modified to increase their tolerance. Commercial glyphosate-based formulations most commonly range from concentrates containing 41% or more glyphosate to 1% glyphosate formulations marketed for domestic use. They generally consist of an aqueous mixture of the isopropylamine (IPA) salt of glyphosate, a surfactant, and various minor components including anti-foaming and colour agents, biocides and inorganic ions to produce pH adjustment. The mechanisms of toxicity of glyphosate formulations are complicated. Not only is glyphosate used as five different salts but commercial formulations of it contain surfactants, which vary in nature and concentration. As a result, human poisoning with this herbicide is not with the active ingredient alone but with complex and variable mixtures. Therefore, It is difficult to separate the toxicity of glyphosate from that of the formulation as a whole or to determine the contribution of surfactants to overall toxicity. Experimental studies suggest that the toxicity of the surfactant, polyoxyethyleneamine (POEA), is greater than the toxicity of glyphosate alone and commercial formulations alone. There is insufficient evidence to conclude that glyphosate preparations containing POEA are more toxic than those containing alternative surfactants. Although surfactants probably contribute to the acute toxicity of glyphosate formulations, the weight of evidence is against surfactants potentiating the toxicity of glyphosate. Accidental ingestion of glyphosate formulations is generally associated with only mild, transient, gastrointestinal features. Most reported cases have followed the deliberate ingestion of the concentrated formulation of Roundup (The use of trade names is for product identification purposes only and does not imply endorsement.) (41% glyphosate as the IPA salt and 15% POEA). There is a reasonable correlation between the amount ingested and the likelihood of serious systemic sequelae or death. Advancing age is also associated with a less favourable prognosis. Ingestion of >85 mL of the concentrated formulation is likely to cause significant toxicity in adults. 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, arrythmias, renal failure requiring haemodialysis, 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...

Kidney biomarkers in MCPA-induced acute kidney injury in rats: Reduced clearance enhances early biomarker performance

“…GPSHs cause diarrhoea and gastrointestinal symptoms which can lead to dehydration and hypotension (Adam et al, 1997;Bradberry et al, 2004;Lee et al, 2008;Roberts et al, 2010). Even though normalised concentration slightly improved the statistical difference between poisoned rats and the time-matched controls, absolute concentration generally predicted AKI best, and the other two methods did not increase the ROC diagnostic performance.…”

“…Glyphosate [N-(phosphonomethyl) glycine, CAS # 1017-83-6] is the active ingredient in glyphosate-surfactant herbicides (GPSHs) which are used extensively as non-selective herbicides (Bradberry et al, 2004;Lee et al, 2009). GPSHs usually consist of glyphosate salts (e.g.…”

“…GPSHs usually consist of glyphosate salts (e.g. isopropylamine/IPA, potassium, and di-ammonium salt), surfactant, anti-foaming agents, colour agents, biocides and inorganic ions for pH adjustment (Bradberry et al, 2004;Lee et al, 2009). Commercial products contain approximately 1 to 40%, or sometimes more, glyphosate (Bradberry et al, 2004;Roberts et al, 2010).…”

“…Human intoxication with this herbicide results not only from the active ingredient but also from its complex and variable mixture. Thus polyoxyethyleneamine (POEA) is one of the surfactants extensively used and it has a toxic effect in its own right (Bradberry et al, 2004;Roberts et al, 2010). Glyphosate is one of the most commonly used herbicides in the world, especially in South East Asia (Cobb and Reade, 2010).…”

Hypotension in severe dimethoate self-poisoning

“…These compounds include emulsifiers or surfactants, and organic solvents such as cyclohexanone and xylene. The cardiotoxic effect of the surfactants used in glyphosate herbicide is the best recognized example of co-formulant toxicity (23,24). However, the situation with organophosphorus EC insecticides is less clear with a sparse literature on their co-formulants.…”