Acute toxicity and ecotoxicological risk assessment of rice pesticides to Lithobates catesbeianus tadpoles

Abstract

The objective of this study was to determine the acute toxicity of some pesticides used in irrigated rice farming to Lithobates catesbeianus tadpoles. The LC_50-96h for commercial formulations containing bentazon, penoxsulam, vegetable oil, permethrin and carbofuran, separately and their mixtures, were determined at the proportions commonly used in the field. The limits of risk concentrations of these products for the studied species were also established. The LC_50-96h for tadpoles was 4,530 mg L⁻¹ for bentazon; 7.52 mg L⁻¹ for penoxsulam + 145.66 mg L⁻¹ of vegetable oil; 81.57 mg L⁻¹ for vegetable oil; 0.10 mg L⁻¹ for permethrin; 29.90 mg L⁻¹ for carbofuran (active ingredients), and 38.79 times the dose used in the field for the mixture of these products. The environmental risk was determined only for permethrin, and care should be taken when using the vegetable oil.

Keywords:

• CL₅₀
• bullfrog
• mixture toxicity
• amphibian
• ecotoxicology
• bentazon
• penoxsulam
• vegetable oil
• permethrin
• carbofuran

Acknowledgments

We are grateful to Andrea G.C. Pimenta and Lúcia Aparecida B.A. Castro for their support with water analysis.

Funding

This study was supported by the CNPq (47/903/2009-4) and CAPES.