Environmental fate and behaviour of glyphosate
The fate of glyphosate in soil and plants has been studied extensively over the past few decades. Glyphosate binds very tightly to most soils and sediments in the environment and therefore glyphosate is generally not available for uptake by roots of nearby plants and poses very little risk of damaging the following crops or other plants in the vicinity of the application zone 4,5.
For the same reason, glyphosate residues are not likely to leach into groundwater and only limited amounts of glyphosate are found in surface water as a result of runoff. Studies examining the fate of glyphosate over several years found that typically, less than 1 per cent of the glyphosate amount applied was lost as runoff from agricultural fields 3.
The favourable safety profile of glyphosate has contributed to the widespread use of glyphosate based plant protection products. Glyphosate binds very tightly to most soils and sediments in the environment and therefore glyphosate is not likely to leach into groundwater. The photo shows a field 30 days after the application of a glyphosate herbicide. (© Monsanto)
Glyphosate that reaches surface water is rapidly adsorbed to sediment and degraded to aminomethylphosphonic acid (AMPA). Subsequently, AMPA is further degraded to naturally-occurring substances such as carbon dioxide and phosphate 5. Consistent with peer-reviewed published literature data recently submitted to EU regulatory agencies show that glyphosate is readily degraded in soil under standard laboratory conditions and in the field. For laboratory studies the median degradation half-life was 5.8 days, with a range from 1 to 60.2 days. Under a wide range of climatic conditions in the field the median dissipation half-life was 16.5 days with a range from 2.3 to 143.3 days. In most conditions, over 90% of the applied amount of glyphosate dissipates within six months. The glyphosate and AMPA levels that have been detected in surface waters are low compared to acute and chronic aquatic toxicity levels. This means that even in the event of glyphosate runoff or spray drift from fields, there is only a negligible risk to aquatic organisms.
- Glyphosate safety profile for human health
- Glyphosate safety profile for non-target wildlife and plants
Last update: 18 July 2013