Analysis of the toxicity of glyphosate and Faena® using the freshwater invertebrates Daphnia magna and Lecane quadridentata

Abstract

With the present contribution an evaluation of the toxicity of the pure herbicide glyphosate and its commercial formulation Faena® is reported using the cladoceran Daphnia magna Strauss and the rotifer Lecane quadridentata Ehrenberg. LC₅₀, EC₅₀, NOEC, and LOEC values for each toxicant and for both test organisms are obtained. Regarding acute toxicity, Faena was 11-fold more toxic to L. quadridentata than pure glyphosate and slightly more toxic to D. magna (1.7-fold). Inhibition of esterase activity in L. quadridentata by glyphosate was the most sensitive end-point; the EC₅₀ was 1500-fold smaller than the LC₅₀. The implications of these results and their comparison with established international and national limit values for glyphosate are discussed.

Keywords:

• Toxicity testing
• glyphosate
• herbicide
• enzyme inhibition

Acknowledgements

We thank the Consejo Estatal de Ciencia y Tecnología de Jalisco (COECYTJAL) for sponsoring this research project. We also thank two anonymous referees for their comments and additions that helped to improve the quality of this article.