In order to take an effective countermeasure based on measurements of toxicities by bioassays, information about the possible toxicity controlling chemicals is necessary. In this study, a new method of identifying toxicity-controlling chemicals using bioassay database and actual toxicity data is presented, and its feasibility is examined through its application to on 25 waste landfill leachates as models of environmental water. By comparing two important parameters describing dose-response relationship (the EC50 value and the slope) between the landfill leachate samples and 255 kinds of chemicals, whose bioassay database has been recently organized in Japan, in some samples, we successfully listed possible candidates of toxicity-controlling chemicals as targets for chemical analysis, such as biophenol-A and chlorophenols. Subsequently-performed chemical analyses successfully showed the presence of such chemicals, and the concentration of these chemicals partly explained the observed toxicity of these samples. The new presented methodology is specifically effective in listing possible toxicity-controlling chemicals based on two important parameters of a dose-response relationship, and thereby enables targeted and cost-effective chemical analysis.
