TY - GEN TI - Understanding the impacts of pH on the toxicity mixtures of antidepressants to Daphnia magna Y1 - 2019/06/24/ A1 - Seo, Jegak A1 - Boxall, Alistair UR - https://www.york.ac.uk/yesi/events/2019/ipieconference/ N2 - Mixtures of antidepressants are detected widely in the aquatic environment and there are concerns that these molecules adversely affect aquatic organisms such as fish and invertebrates. As these molecules are generally basic in nature, effects are likely to be influenced by the pH of the system. In this study, the acute effects of five antidepressants (citalopram, fluoxetine, sertraline, duloxetine and dosulepin) were investigated at six values (5.5, 6.0, 7.0, 7.5, 8.0, and 9.0). EC50 values ranged from 4.45-1.34 mg/L (pH 5.5-9.0) for citalopram (pKa = 9.78), 1.07-0.26 mg/L (pH 6.0-9.0) for fluoxetine (pKa = 9.80), 0.87-0.16 mg/L (pH 7.0-9.0) for sertraline (pKa = 9.85), 4.22-1.47 mg/L (pH 7.0-9.0) for duloxetine (pKa = 9.34), and 1.10-0.27 mg/L (pH 5.5-9.0) for dosulepin (pKa = 9.76). A strong negative correlation was observed between the EC50 of all molecules and the degree of dissociation of each molecule at the study pH values. Chronic and mixture studies are ongoing but, when available, results will be used to parameterize and test a combined pH/mixture toxicity model. AV - public ID - discovery10163164 ER -