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Potential exposure to human prescription pharmaceutical residues from wastewater
Citation:
KOSTICH, M., A. BATT, AND J. M. LAZORCHAK. Potential exposure to human prescription pharmaceutical residues from wastewater. Presented at Toxicology and Risk Assessment Conference, West Chester, OH, April 15, 2008.
Impact/Purpose:
A great deal of uncertainty exists regarding the extent to which humans and wildlife are exposed to chemical stressors in aquatic resources. Scientific literature is replete with studies of xenobiotics in surface waters, including a recent national USGS survey of endocrine disrupting chemicals; however, biological significance of these chemical data is in question since chemical bioavailability is largely unknown and biological events may be induced by undetected chemicals and varying ecological conditions (i.e., total nitrogen and phosphorus). Whole effluent toxicity data exist, but do not answer specific exposure questions that may support detailed ecological risk assessments. Interpretation of data arising from exposure to complex chemical mixtures is even more problematic. A solution to these problems is development of sensitive and specific cellular indicators of exposure in aquatic organisms. The potential for development is enhanced by emergent resources in molecular biology and associated technologies, most notably DNA microarrays consisting of transcriptionally relevant nucleic acid sequences that can be used to detect altered gene expression in cells, tissues and various life stages of organisms exposed to chemical and natural stressors.
Description:
Pharmaceuticals in the environment (PiE) pose a complicated problem, involving multiple dissimilar compounds, multiple routes of potential exposure, and a range of potentially affected organisms that span the tree of life. Key uncertainties include not knowing which of the thousands of available active pharmaceutical ingredients (APIs) to study, uncertainties about the most significant routes of human or ecological exposure, and (for ecotoxicology) identifying susceptible species. Our research to date has focused on a broad class of pharmaceuticals frequently discussed in the PiE context (human prescription pharmaceuticals) introduced into the environment via a frequently cited PiE source (municipal wastewater effluents). We have used published marketing data and wastewater production rates to predict the maximum likely wastewater concentration (PEC) of each of 400 top-selling APIs potentially entering the environment each year. APIs were prioritized for monitoring based on their PEC's projected potential to affect human biology, inhibit microbial growth, or affect other organisms. Chemical monitoring studies, which are currently underway, will be used to refine the model-based risk estimates, and select APIs for toxicological investigation under environmentally relevant conditions. We have examined the conservation of molecular drug targets across the tree of life in order to nominate taxa which might be affected by low-level API exposure.