How to accurately assay the algal toxicity of pesticides with low water solubility.

A novel method for assaying and calculating the toxicity of water-insoluble pesticides to green algae has been put forward in this work. First, a solvent is selected for use in bioassays; there should be a detailed screening to identify a solvent with inherently low toxicity to the test organism. Second, the EC50 is determined for selected pesticides by measuring the toxicity of various concentrations of each of the selected pesticides in a fixed concentration of selected solvent. Third, concentrations of the selected solvent are varied and the EC50 of each pesticide tested is assayed at a fixed concentration. Fourth, several suitable groups of solvent concentrations are selected and the corresponding EC50 values of tested pesticides are considered to establish the linear regression equation. Letting the solvent concentration be zero, one calculates the corresponding EC50 value, which corresponds to the inherent toxicity of the tested pesticide.