A comparative ecological risk assessment for herbicides used on spring wheat: the effect of glyphosate when used within a glyphosate-tolerant wheat system

Abstract

Glyphosate-tolerant spring wheat currently is being developed and most likely will be the first major genetically engineered crop to be marketed and grown in several areas of the northern Great Plains of the United States. The public has expressed concerns about environmental risks from glyphosate-tolerant wheat. Replacement of traditional herbicide active ingredients with glyphosate in a glyphosate-tolerant spring wheat system may alter ecological risks associated with weed management. The objective of this study was to use a Tier 1 quantitative risk assessment methodology to compare ecological risks for 16 herbicide active ingredients used in spring wheat. The herbicide active ingredients included 2,4-D, bromoxynil, clodinafop, clopyralid, dicamba, fenoxaprop, flucarbazone, glyphosate, MCPA, metsulfuron, thifensulfuron, tralkoxydim, triallate, triasulfuron, tribenuron, and trifluralin. We compared the relative risks of these herbicides to glyphosate to provide an indication of the effect of glyphosate when it is used in a glyphosate-tolerant spring wheat system. Ecological receptors and effects evaluated were avian (acute dietary risk), wild mammal (acute dietary risk), aquatic vertebrates (acute risk), aquatic invertebrates (acute risk), aquatic plants (acute risk), nontarget terrestrial plants (seedling emergence and vegetative vigor), and groundwater exposure. Ecological risks were assessed by integrating toxicity and exposure, primarily using the risk quotient method. Ecological risks for the 15 herbicides relative to glyphosate were highly variable. For risks to duckweed, green algae, groundwater, and nontarget plant seedling emergence, glyphosate had less relative risk than most other active ingredients. The differences in relative risks were most pronounced when glyphosate was compared with herbicides currently widely used on spring wheat.

Efecto del uso de suelo en las hormigas (Formicidae: Hymenoptera) de Tikinmul, Campeche, México

“…La toxicidad directa de los herbicidas sobre los invertebrados del suelo parece ser baja (Bohan et al 2005, Peterson & Hulting 2004, Römbke & García 2000, por lo que el efecto del glifosato sobre las poblaciones de hormigas puede ser una consecuencia secundaria a la pérdida de vegetación (Guiseppe et al 2006, Guynn et al 2004. Se puede hipotetizar que de la misma forma que los herbicidas afectan de manera indirecta las poblaciones de hormigas al eliminar la vegetación, los fertilizantes podrían beneficiar a la mirmecofauna al favorecer el crecimiento de las plantas.…”

Wood production, wood technology, and biotechnological impacts

“…The herbicide glyphosate is considered less detrimental to the environment than other herbicides since it is non toxic to humans and biodegradable (Williams et al 2000, Peterson & Hulting 2004. On the other hand, herbicide resistant plants and their complementary herbicide are offered by the same company which causes dependency of the forester or farmer on a few companies and reduces the diversity of cultivated plant varieties.…”

Toxic effects of Trebon®, a synthetic pyrethroid based insecticide formulation, on Oreochromis mossambicus (Family: Cichlidae)

“…In spite of this, Trebon ® remains in the environment for a considerable period of time displaying a little mobility and rapidly absorbing into sediment and eventually bio-accumulating in aquatic food chains (Orrick and Pease 2009). This is further aggravated by their improper spray where spraying is done many times above the recommended frequencies and also at higher doses (Peterson and Hulting 2004). Sometimes they are sprayed directly into water.…”