A technical announcement from the U.S. Geological Survey (USGS) released August 29 of this year reports that “glyphosate, also known by its tradename Roundup, is commonly found in rain and rivers in agricultural areas in the Mississippi River watershed,” the area of greatest use for the herbicide as a weed-controller on GM corn, soybeans and cotton.

“Though glyphosate is the mostly widely used herbicide in the world, we know very little about its long-term effects to the environment,” says Paul Capel, USGS chemist and author on the study. “This study is one of the first to document the consistent occurrence of this chemical in streams, rain and air throughout the growing season.” According to the announcement, glyphosate use has increased from less than 11,000 tons in 1992 to more than 88,000 tons in 2007.