The environmental fate of a chemical is the processes by which it moves through and undergoes chemical degradation or transformation in the environment. A key environmental property of glyphosate is that it binds tightly to soil. This characteristic reduces its availability for uptake by plants after use, allowing it to be used safely at planting, or adjacent to existing crops, without damaging the crops. The tight binding limits movement through the soil, meaning it won’t affect off-site non-target plants, and also minimizes any exposure to groundwater.
Glyphosate is biologically degraded by soil microorganisms into naturally occurring products, including carbon dioxide and phosphate. The rate of degradation depends on the soil type, microbial content and environmental conditions, with an average half-life across many locations of about a month.
Studies in animals show that there is minimal retention of glyphosate in tissues, and that if exposure does occur, the glyphosate would be rapidly eliminated.
The effects of glyphosate on soil microorganisms have been extensively evaluated. Some bacteria and fungi are sensitive to glyphosate, but observed effects in ecosystems have been minor and reversible. Studies conducted with annual applications for up to 19 years have demonstrated that glyphosate showed no effects on soil biomass or microbial respiration.