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Effect of iodinated X-ray contrast media in the formation of disinfection byproduts during chlorination and chloramination of water
Citation:
Simmons, J., M. Armstrong, T. Mcdonald, Y. Sey, C. Postigo, H. Liberatore, K. Lamann, S. Kimura, A. Cuthbertson, S. Richardson, AND S. Duirk. Effect of iodinated X-ray contrast media in the formation of disinfection byproduts during chlorination and chloramination of water. SETAC 28Th Annual European Meeting, Rome, ROME, ITALY, May 13 - 17, 2018.
Impact/Purpose:
The impact of anthropogenic chemicals in source water on disinfection byproduct formation is poorly understood and under-studied. This abstract present data on disinfection byproduct formation in waters containing one of four iodinated X-ray contrast media. Both chlorination and chloramination, the most common surface water disinfection scenarios in the US were examined. This chemical analysis data set is the most comprehensive generated and reported to date.
Description:
Iodinated X-ray contrast media (ICMs), used in medical imaging, are poorly metabolized by humans and enter wastewater. As they are incompletely removed during wastewater treatment, ICMs are released to the aquatic environment and have been detected in drinking water sources. ICMs have been identified as iodine sources that may enhance the formation of iodine-containing disinfection byproducts (I-DBPs) during drinking water disinfection. This work investigated the effect of different ICMs, iopamidol (IPAM), iopromide (IPR), diatrizoate (DTZ) and iohexol (IHX), in the formation of different classes of DBPs during source water disinfection by either free chlorination or chloramination. To do this, we performed large-volume (~120 L each), laboratory-controlled, headspace-free disinfection reactions with 5 µM ICM and 100 µM as Cl2 disinfectant concentrations. The resulting DBP mixtures were chemically characterized for 21 targeted non-I-DBPs, 11 targeted I-DBPs, and non-targeted I-DBPs by means of gas chromatography coupled to low- and high-resolution mass spectrometry. The presence of ICMs in source water had no apparent effect on either the concentration or speciation of the four regulated trihalomethanes (chloroform, bromodichloromethane, chlorodibromomethane, bromoform). IPAM, but not other ICMs, enhanced formation of dichloroacetic acid, bromoacetic acid and dibromoacetonitorile during chlorination. I-DBPs formation was slightly enhanced in the presence of ICMs, particularly in chlorinated water containing IPAM, where the highest levels of I-DBPs were formed, and in chloraminated water containing IPR or IHX. The presence of DTZ did not appear to affect I-DBP formation. Non-targeted analysis of the DBP mixtures revealed the formation of novel I-DBPs in chlorinated IPAM-containing water including iodoacetonitrile, chloroiodoaceontirile, trichloroiodomethane and several iodo-acids. Our results indicate that ICMs enhance the formation of both I-DBPs and non-iodinated DBPs when present during chlorination and that IPAM, in particular, is a relevant iodine source in water undergoing chlorination or chloramination. Acknowledgments: CP acknowledges support provided by EU FP7 (No. 274379, Marie Curie IOF) and the Government of Catalonia and the COFUND programme (Marie Curie Actions, EU FP7) (2014 BP_B00064). This abstract does not represent EPA policy.