Towards an understanding of pharmaceutical exposure and bioaccumulation in effluent-dependent systems.
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Environmental risks of pharmaceuticals and other contaminants of emerging concern (CECs) are not well understood due to relatively limited information on fate, transport, exposure, bioaccumulation and effects. The objective of this research was to improve understanding of the relationships among CEC accumulation in aquatic organisms through developing robust analytical methods and studying exposure and bioaccumulation. In chapter 2, an isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was successfully developed and applied to identify 15 pharmaceuticals and 2 pharmaceutically-active metabolites in fish tissues. The method was successfully applied to trout samples collected from different river locations in Utah, USA. In chapter 3, occurrence, removal and discharge of selected CECs were compared between municipal and on-site treatment systems receiving a common wastewater influent. Such a unique study design was conducted at the Baylor Wastewater Research Program site at the Waco Municipal Area Sewerage System, Waco, Texas, USA. This novel comparative examination of centralized and decentralized effluent quality also employed a fish plasma model approach to estimate the therapeutic hazards of pharmaceuticals in each effluent discharge. Within investigated treatment systems, the septic system consistently possessed the lowest water quality and therapeutic hazards. Coupling a constructed subsurface wetland may lower ecological risks associated with effluent discharge from septic systems. Occurrence and bioaccumulation of pharmaceuticals and other CECs were then examined in a common snail (Planorbid sp.) grazer and periphyton from the North Bosque River in central Texas, USA, during a historic drought when stream flow was effluent-dependent. Limited observations of pharmaceuticals in periphyton compared to water and snail samples suggested that water exposure represented the primary route of pharmaceutical exposure to Planorbid sp. in the North Bosque River. In chapter 5, a fish plasma model, initially developed from laboratory studies and applied in chapter 3 to assess effluent quality, was tested to examine observed versus predicted internal doses of select pharmaceuticals in the North Bosque River. In addition, characterization of trophic transfer for select pharmaceuticals suggested that uptake of ionizable pharmaceuticals by aquatic organisms in this effluent-dependent wadeable stream more likely resulted from inhalation than dietary exposure.