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Predicting variability of aquatic concentrations of human pharmaceuticals
Citation:
KOSTICH, M., A. BATT, S. GLASSMEYER, AND J. M. LAZORCHAK. Predicting variability of aquatic concentrations of human pharmaceuticals. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier Science Ltd, New York, NY, 408(20):4504-4510, (2010).
Impact/Purpose:
Proposed research will provide environmental science and risk assessment communities with advanced molecular biological indicator methods, complete with validation studies and guidance for their application. Early success has been achieved in the transfer of molecular indicator technologies to USEPA Region 9 and State of California.
Description:
Potential exposure to active pharmaceutical ingredients (APIs) in the aquatic environment is a subject of ongoing concern. We recently estimated maximum likely potency-normalized exposure rates at the national level for several hundred commonly used human prescription pharmaceuticals in the U.S., based on marketing data, wastewater production rates, and therapeutic potency. The accuracy of these estimates is unclear, and it is unclear how to use the national-level estimates to predict local exposure rates. In this study we compare our previous predicted environmental concentrations (PECs), which were based on marketing data, with PECs based on regulatory data. We then use local dispensing rates for 12 APIs along with local wastewater production rates to estimate the distribution of local PECs relative to national averages, in order to identifiy an "application factor" suitable for converting national-level PECs into reliable bounds for local concentrations. We compare the national-level PECs and the proposed application factor with measured environmental concentrations (MECs) published in 52 recent peer-reviewed publications. Regulatory data-based national average PECs are uniformly lower than marketing data-based national average PECs, corroborating the intended conservative nature of the marketing data-based PECs. Variability in local API usage and wastewater production rates suggest local PECs may occasionally exceed national averages by about 10-fold. Multiplying national average PECs by an "application factor" of 10 and comparing the resulting predicted maximum local PECs to published MEC data for 83 APIs corroborates the usefulness of 10-fold adjusted national PECs as a reasonable ceiling for measured environmental concentrations.