Ecological Toxicity of Substitute Perfluorinated Compound (PFBA, PFBS, PFHXA)

In this study, the ecological toxicity of three substitute perfluoroalkyl substances (PFBA, PFBS, PFHxA) was measured through acute and chronic toxicity tests using Daphnia magna, a representative species of aquatic organisms. The result of this study indicated that the acute toxicity of PFBA and PFBS for D. magna were 25 times and 111 times lower, respectively, than those of PFOA and PFOS. Similarly, the chronic toxicity of PFBA and PFBS for D. magna were 126 times and 397 times lower, respectively, than those of PFOA and PFOS. Therefore, the ecological toxicity of the substitute perfluoroalkyl substances to D. magna seems to be significantly lower than that of PFOA and PFOS. Meanwhile, in this study, the acute toxicity of PFHxA (six carbon substance) was approximately 11 times lower than that of PFOA (eight carbon substance), but about two times higher than that of PFBA (four carbon substance). This finding suggest that the ecological toxicity of perfluoroalkyl substances decreases as the carbon chain length decreases. In addition, the ratio of acute to chronic toxicity (ACR) for PFBA and PFBS (both four carbon substance) showed about a two-fold difference, indicating that, among perfluoroalkyl substances with the same number of carbon atoms, those with a sulfonic acid group (e. g. PFBS) exhibit higher toxicity than those with a carboxylic acid group (e.g PFBA). Although the tested substitute perfluoroalkyl substances showed lower toxicity to D. magna compared to conventional PFOA and PFOS, they are still not easily removed in wastewater treatment processes and do not readily degrade in the natural environment. Therefore, if the usage of these substitute perfluoroalkyl substances increases, their concentration in the environment is expected to rise. Consequently, further research is necessary to assess long-term exposure and its potential impact on ecosystems due to these substitute perfluoroalkyl substances.