Toxicity assessment of auxiliary substances of pesticides to Saccharomyces cerevisiae by microcalorimetry

Abstract

Toxicity of three groups of pesticide formulation and its active ingredient was assayed by microcalorimetry of the growth of yeast cells（Saccharomyces cerevisiae）. The toxicity of active ingredient of used pesticide formulation was higher than that of its active ingredient. Especialy, Daconil（MIC: 8.3 mg/l, IC₅₀: 2.0 mg/l）was more toxic than TPN（MIC: 275 mg/l, IC₅₀: 12 mg/l）. To discuss the influence of surfactants, sodium dodecylbenzene sulfonate（DBS）was used with active ingredients and calorimetric parameters such as specific growth actives were determined. It was found active ingredient of toxicity potencial was potentiated by auxiliary substances in the case of the mixture model oxine-copper - DBS and captan - DBS. From these results, we should consider sufficiently the importance of auxiliary substances of pesticide such as surfactants in the case of discussing enviromental impact assessment of pesticide. This method could serve as a convinient simulation before design for a new pesticide formulation.