RP10 Aquatic Ecotoxicology
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(CAR-1117-830971) Amphibian risk assessment and glyphosate herbicides: Key considerations for laboratory and field studies.

Carr, K¹, Levine, S¹, Farmer, D¹, Honegger, J¹, ¹ Monsanto Company, Saint Louis, MO, USA

ABSTRACT- In recent years, a number of published studies have examined the potential for adverse effects of glyphosate herbicide formulations on amphibian growth, development, behavior and survival. These studies have included laboratory, simulated field, and field exposure studies to a variety of amphibian species. Due to the lack of established test guidelines for amphibian studies, the study protocols vary considerably among researchers, which can make comparison of results among multiple studies difficult. Herbicide formulations and exposure concentrations studied vary significantly, and some exposure concentrations are much higher than the levels that have been shown to be present in the environment following herbicide application. Moreover, processes of dissipation from the water column, biodegradation, and bioavailability are often not addressed in the study design. Therefore, the results from studies in which test animals are continuously exposed in artificial systems at unrealistically high concentrations must be evaluated with caution. This presentation examines several recently published studies that have evaluated the potential for effects of glyphosate herbicide formulations to amphibians. This analysis compares the exposure regimes used in these studies with environmentally realistic exposure scenarios, in order to put the results of these studies into the proper context for evaluating ecological risk.

Key words: glyphosate, amphibians, ecological risk assessment