New research from McGill University reveals an overlooked impact that the widely used herbicide glyphosate may be having on the environment.

First commercialized by Monsanto under the name Roundup, glyphosate has come under scrutiny in the past, mostly in relation to its potential toxicity. This new research, published recently in the Ecological Society of America’s Frontiers in Ecology and the Environment, focuses not on direct health risks associated with the herbicide, but on its contribution to environmental phosphorus levels, an issue that has yet to receive much attention.

“No one has thus far investigated the impact of glyphosate use on phosphorus loads in agricultural areas, most likely because pesticides have always been considered a negligible source of nutrients,” says Marie-Pier Hébert, lead author of the study and a doctoral student in the Department of Biology at McGill University.

In many agricultural areas, decades of phosphorus-based fertilizer use have led to a saturation of the soil’s capacity to hold the nutrient.