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Progressive Increase in Disinfection Byproducts and Mutagenicity from Sourceto Tap to Swimming Pool and Spa Water: Implications for Public Health
Citation:
Daiber, E., D. DeMarini, S. Ravuri, H. Liberatore, A. Cuthbertson, A. Thompson-Klemish, J. Byer, Judy Schmid, M. Afifi, E. Blatchley, AND S. Richardson. Progressive Increase in Disinfection Byproducts and Mutagenicity from Sourceto Tap to Swimming Pool and Spa Water: Implications for Public Health. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 50(13):6652-6662, (2016).
Impact/Purpose:
The purpose of this study was to examine several specific issues related to disinfected water and public health. (1) What is the relationship between the concentrations of various disinfection byproducts (DPBs) in the water and the mutagenicity of the water. (2) What differences are there in the concentrations of DBPs and the levels of mutagenicity of waters that are disinfected by chlorine, bromine, or ozone? (3) What changes in the concentrations of DBPs and levels of mutagenicity occur in water starting from source water and going on to finished, tap, swimming pool and hot tub (spa) water? (4) what role do human inputs (skin, urine, hair, cosmetics, etc.) play in the concentrations and types of DPBBs and levels of mutagenicity of swimming pools and spas? The data generated by addressing these questions have provided evidence that the concentrations of certain classes of DBPs correlate highly with the mutagenic potency of disinfected water and that human inputs play a significant role in increasing the concentration of DBPs, the types of DBPs, and the mutagenic potencies of pool and spa waters. Finally, this study shows that there is an increase in the concentrations of DBPs and levels of mutagenicity progressing from source, to finished, to tap, to pool and spa waters. These data will be of interest to the Office of Water because the data provide clear evidence that DBPs concentrations are predictive of the mutagenic potency of disinfected waters, and this is of interest to the Office of Water as they proceed to consider modifications of the allowable concentrations of DBPs in finished, disinfected, drinking water.
Description:
Pools and spas are enjoyed throughout the world for exercise and relaxation. However, there are no previous studies on the mutagenicity of disinfected spa (hot tub) waters or comprehensive identification of disinfection byproducts (DBPs) formed in spas. Using 28 water samples from 7 sites, we report the first integrated mutagenicity and comprehensive analytical chemistry of spas treated with chlorine, bromine, or ozone, along with pools treated with these same disinfectants. Gas chromatography with high-resolution mass spectrometry and membrane-introduction mass spectrometry were used to comprehensively identify and quantify DBPs and other contaminants. Mutagenicity was assessed by the Salmonella mutagenicity assay. More than 100 DBPs were identified, including a new class of DBP not reported previously, bromoimidazoles, which may be formed by the reaction of bromine with histidine or pharmaceuticals (introduced to the water via urine) or personal-care products. The brominated pool/spa waters were 1.8X more mutagenic than chlorinated ones, and spa waters were 1.7X more mutagenic than pool waters (P <0.001). The pool and spa samples were 2.4 and 4.1X more mutagenic, respectively, than their corresponding tap waters (P <0.001). The concentration of the sum of 21 DBPs increased from finished to tap to pool to spa, and mutagenic potency increased from finished/tap to pools to spas (P <0.001). The mutagenic potencies of 8 samples from a chlorinated site correlated (r2 = 0.82-0.92) with the concentrations of bromine- and nitrogen-containing DBPs; those from a brominated site correlated best with the concentration of brominated DBPs (r2 = 0.80). Human use increased significantly the concentration of the sum of 21 DBPs and the mutagenic potencies for 3 of 4 comparisons possible between high- and low-human use of 2 pools and 2 spas. These data are the first evidence that human precursors can increase the concentration of DBPs and mutagenic potencies of these types of waters.
