Iodinated X-ray contrast media (ICM) are a class of pharmaceuticals used to display soft tissue during x-ray imaging. ICM are administrated in doses up to 200g and worldwide consumption of ICM is approximately 3.5x106kg/year. ICM are highly soluble and are excreted through urination/feces within 24 hours. ICM occurrence has been surveyed in German municipal STP effluents, rivers, and groundwater. In STP effluents, concentrations range from non-detect to 15 �g/L. ICM a account for approximately 25% of the extractable organic iodide. Due to the ICM present in STP effluents, respective receiving rivers and creeks had median ICM concentrations up to 0.49 �g/L for iopamidol and 0.23 �g/L for diatrizoate. In the United States, ICM have been detected in source waters at drinking water plant intakes from non-detect to 2 �g/L for iopamidol. ICM have recently been found to serve as precursors in the formation of iodinated disinfection byproducts (iodo-DBPs). Inorganic iodide is known to act as a precursor significantly affecting the rate of DBP formation as well as concentration of total organic halogen (TOX). However, the role and importance of ICM in the formation of TOX and distribution of iodo-DBPs has yet to be fully understood. In this study, three source waters varying in concentrations of aromatic to nitrogenous components were used to examine halogen incorporation pathways into natural organic matter (NOM) as a function of halogen precursor type (i.e., multiple different ICM) and pH. TOX as a function of total organic chloride (TOCl), total organic bromide (TOBr), and total organic iodide (TOI) were quantified as a function of halogenated precursor and chlorinated oxidant (i.e., chlorination, chloramination, and chlorine dioxide). ICM degradation mechanisms will be presented in conjunction with total iodide mass balances determining the reactive iodinated oxidants, which incorporate iodide into the NOM resulting in DBP formation.

Iodinated pharmaceuticals transformation and total organic halogenated (TOX) formation in the presence of NOM and chlorinated oxidants

248th National Meeting (2014)

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