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Environmental hormones are harmful synthetic chemicals that can steer human body from functioning properly by mimicking as hormones. Therefore, their gradual accumulation of environmental hormones can initiate many catastrophic effects to our ecological systems inconspicuously hidden from us. It should be important to understand the effect of many environmental hormones on Daphnia’s heartbeat. Daphnia is an aquatic organism as a first consumer that lives in lakes and rivers, feeding on algae and bacteria. Thus, understanding the effects of environmental hormones on Daphnia’s cardiac function should be essential in ecotoxicological aspect.
In this study, eight type of environmental hormones, mostly being commercially available for herbicides and insecticides were chosen. And, Daphnia’s heartbeat changes were measured before and after the 30 minutes incubation in the serially diluted solutions of those environmental hormones. The heartbeat changes by the chemicals presented on the bases of dilution facter as a logatrithmic relative concentration. The initial slope of regression line, maximal heartbeat differences, AUC from each environmental hormones were compared with log Kow. In conclusion, the AUC from heartbeat difference profiles were moderately related to log Kow with regression coefficient 0.560. The study suggested that there could exist a functional relationship of Daphnia’s heartbeat change to chemical properties such as log Kow and it should be prudent to extrapolate the result of Daphnia’s heartbeat data for toxicity for mammols. More study will be done for clarification of the relationship among species.