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Chlorination of Source Water Containing Iodinated X-Ray Contrast Media: Mutagenicity and Identification of New Iodinated Disinfection by-products
Citation:
Postigo, C., D. DeMarini, M. Armstrong, H. Liberatore, K. Lamann, S. Kimura, A. Cuthbertson, S. Warren, S. Richardson, T. Mcdonald, Y. Sey, N. Ackerson, S. Duirk, AND J. Simmons. Chlorination of Source Water Containing Iodinated X-Ray Contrast Media: Mutagenicity and Identification of New Iodinated Disinfection by-products. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 52(22):13047-13056, (2018). https://doi.org/10.1021/acs.est.8b04625
Impact/Purpose:
The Office of Water (OW) of the U.S. EPA has raised concern about the introduction into water of iodinated compounds because chlorination of such compounds during disinfection likely produces iodinated disinfection by-products (I-DBPs), which might be highly toxic and mutagenic. Iodinated X-ray contrast media (ICM) are highly iodinated compounds given routinely to patients for medical imaging of soft tissues by x-ray, and they end up in the water. However, a comprehensive assessment of the formation of I-DBPs and of the mutagenicity of ICM-containing water after chlorination has not been performed. This paper describes such a study and shows that although there is an increase in the formation and concentration of I-DBPs after the chlorination of ICM-containing source water, there is no increase in mutagenicity.
Description:
Iodinated contrast media (ICM) are non-mutagenic agents administered for X-ray imaging of soft tissues. ICM can reach µg/L levels in surface waters because they are administered at high doses, excreted largely un-metabolized, and poorly removed by wastewater treatment. Iodinated disinfection by-products (I-DBPs) are highly genotoxic and have been reported in disinfected waters containing ICM. We assessed the mutagenicity in Salmonella of extracts of chlorinated source water containing one of four ICM (iopamidol, iopromide, iohexol, and diatrizoate). We quantified 21 regulated and non-regulated DBPs, 11 target I-DBPs, and conducted a non-target, comprehensive broad-screen identification of I-DBPs. We detected one new iodo-methane (trichloroiodomethane), three new iodo-acids (dichloroiodoacetic acid, chlorodiiodoacetic acid, bromochloroiodoacetic acid), and two new nitrogenous I-DBPs (iodoacetonitrile and chloroiodoacetonitrile). Their formation depended on the presence of iopamidol as the iodine source; identities were confirmed with authentic standards. This is the first identification in simulated drinking water of iodoacetonitrile, which is highly cytototoxic and genotoxic in mammalian cells. Iopamidol (5 µM) altered the concentrations and relative distribution of several DBP classes, increasing total haloacetonitriles by >10-fold. Chlorination of ICM-containing source water increased I-DBP concentrations but not mutagenicity, indicating that such I-DBPs were either not mutagenic or at concentrations too low to affect mutagenicity.
URLs/Downloads:
DOI: Chlorination of Source Water Containing Iodinated X-Ray Contrast Media: Mutagenicity and Identification of New Iodinated Disinfection by-products