Ecological risk assessment for aquatic organisms from over-water uses of glyphosate.

TLDR: Risks from the use of glyphosate +MON 0818 (Roundup) were slightly greater than those from glyphosate and surfactants such as LI 700; however, in over-water uses, risks were still considered small; similar small risks were observed for measured concentrations of glyphosate in surface waters resulting from aerial application of Vision to forestry areas in Canada.

Abstract: Although the herbicide glyphosate is most widely used in agriculture, some is used for the control of emergent aquatic weeds in ditches, wetlands, and margins of water bodies, largely as the formulation Rodeo. This article presents an ecological risk assessment (ERA) of glyphosate and some of the recommended surfactants as used in or near aquatic systems. Glyphosate does not bioaccumulate, biomagnify, or persist in a biologically available form in the environment. Its mechanism of action is specific to plants and it is relatively nontoxic to animals. As a commercial product, glyphosate may be formulated with surfactants that increased efficacy but, in some cases, are more toxic to aquatic organisms than the parent material. For this risk assessment, three model exposure scenarios--static or low-flow systems such as ponds, flowing waters such as streams, and systems subjected to tidal flows such as estuaries--were chosen and application rates from 1 to 8 kg glyphosate/ha were modeled. Additional measured e...