Temperature-based rapid toxicity test using Ceriodaphnia dubia

Toxicants, which may cause the inhibition to the biological process in sewage/wastewater treatment plant, need to be monitored within short time to prevent from serious damage. A new method, Temperature-based rapid toxicity test (TempTox test) using Ceriodaphnia dubia, was developed and compared with the standard 48 hr acute bioassay (Std. 48-hr test). Inorganic toxicants of cadmium, zinc, copper, cyanide, chromium (III), chromium (VI) and organic toxicants of phenol, PCP and pesticides of BPMC, Diazinon, Fenitrothion were tested for TempTox test and Std. 48-hr test. Because the TempTox test is based on just temperature control, C. dubia neonates were exposed to toxicants under high temperature (35.5 °C) condition without any complicated pretreatment. After given exposure time of 1, 1.25, 1.5 hours, the number of the live (no toxic effect) or the dead (toxic effect) was counted with eye without the aid of any microscope and median effective concentrations (EC₅₀ values) were determined. From the results for all toxicants, the TempTox test was proved to be as sensitive as the Std. 48-hr test with shorter-time of just 1.25–1.5 hours. Moreover, the TempTox test was further much more sensitive than alternative bioassays such as the 1-hour I.Q. test and 30-minute Microtox. The TempTox test showed a high applicability of toxicity bioassay for real sewage/wastewater treatment plant by its easiness, rapidity and sensitivity. Finally, the prototype for short-term TempTox test was introduced.