Etiology

• Glyphosate is commonly used before sowing and also just before harvesting crops.
• It is an organophosphate herbicide with no anticholinesterane activity.

Predisposing factors

General

• Risk of spray drift if used in windy conditions.
• Inadequate storage conditions in mixed enterprises where livestock may have accidental access to pesticides.

Pathophysiology

• Although exposure in livestock has been reported, glyphosate itself is generally considered of low acute toxicity and some of the effects from glyphosate product exposure are due to the presence of a surfactant, usually polyoxyethylene amine (POEA), present in many liquid preparations which aids adsorption of the herbicide onto plants.
• POEA is irritant.
• Ingestion of plant material treated with glyphosate is only likely to cause mild signs.
• Eye and skin irritation are also possible from spray drift, contact with wet plant material or spills of a glyphosate-containing product.

Timecourse

• Limited information.
• Irritant effects are likely to occur soon after exposure.

Epidemiology

• Glyphosate exposure can occur wherever the herbicide is used.
• Cattle do not avoid eating vegetation sprayed with glyphosate.
• The long-term safety of glyphosate exposure, particularly relating to the risk of cancer in humans, has been the subject of much debate with differing conclusions drawn by various national (eg the US Environment Protection Agency (EPA)) and international organizations (eg the European Food Safety Agency (EFSA) and the International Agency for Research on Cancer (IARC)). As a result, domestic and/or commercial use of glyphosate has been banned or is being phased out in some countries.