Meeting Abstract

P3.53  Monday, Jan. 6 15:30  Individual and combined effects of ibuprofen and its photodegradants on southern toad tadpoles BROWN, J.B.*; TURNER, S.E.; RAMIREZ , J.N.; CORY, W.C.; WELCH, A.M.; College of Charleston; College of Charleston; College of Charleston; College of Charleston; College of Charleston jbbrown@g.cofc.edu

Many pharmaceuticals are not completely broken down within the body and may not be adequately removed during wastewater treatment. Once released into the environment, these pharmaceuticals can be converted into related compounds, which may be more toxic than the original molecule. In addition, pharmaceuticals and their degradants are expected to co-occur during the degradation process, yet little to no information exists about the effects of such compounds in combination. Ibuprofen is one of the most commonly used pharmaceuticals and exists in appreciable concentrations in the environment. In the presence of sunlight, ibuprofen degrades into 4-isobutylacetophenone. This photodegradant is less polar than the parent molecule and is therefore predicted to be more toxic. Using tadpoles of the southern toad (Anaxyrus terrestris) as a representative freshwater vertebrate, we tested the relative toxicity of ibuprofen and its photodegradant as well as their toxicity in combination. Tests of acute toxicity (measured as median lethal concentration at 96 hours) showed that the photodegradant was more toxic than ibuprofen, as predicted by their relative polarities. In addition, the mixture of ibuprofen and its photodegradant was more toxic than predicted based on the effects of either compound alone, showing a moderately synergistic effect. Thus, photodegradation of ibuprofen in the environment is predicted to result in increased risk for freshwater organisms. More generally, understanding the biological effects of pharmaceuticals and their degradants, alone and in combination, is important for assessing the environmental impact of pharmaceutical pollution in freshwater ecosystems.