Acute and chronic toxicity of Tetrabromobisphenol A and Tribromophenol to Daphnia magna

To confirm the ecological hazard of two brominated flame retardants-Tetrabromobisphenol A (TBBA) and Tribromophenol(TBP) on Daphnia magna, the acute toxicity (48 h-LC₅₀) and the chronic toxicity (21 d-EC₅ or NOEC for reproduction, intrinsic rate of increase and net reproductive rate) were tested and compared. Depending on the test results, we applied assessment factors to extrapolate the predicted no effect concentration (PNEC) for both chemicals. Results of toxicity tests showed that for both TBBA and TBP, 21 d-EC₅ values for intrinsic rate of increase and net reproductive rate were one or two orders of magnitude lower than 48 h-LC₅₀, which were also lower than the 21 d-NOEC value for reproduction. Hazard assessment of TBBA and TBP indicated that the chronic toxicity-based PNEC value was lower than the acute toxicity-based PNEC. The indicator of EC₅ for reproduction, intrinsic rate of increase and net reproductive rate might be more sensitive in the toxicity characterization of TBBA and TBP on Daphnia magna than that of NOEC. More emphasis should be placed on the chronic toxicity of TBBA and TBP than the acute toxicity, the PNEC derived from chronic toxicity data can adequately protect the population of daphnia magna.