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From Source Water to Tap Water to Spa and Swimming Pool Water: Effects of Disinfectanta and Precursors and Implications for Exposure and Toxicity
Citation:
Daiber, E., S. Richardson, S. Anduri, D. DeMarini, E. Blatchely III, AND M. Afifi. From Source Water to Tap Water to Spa and Swimming Pool Water: Effects of Disinfectanta and Precursors and Implications for Exposure and Toxicity. Presented at ASMS Conference, Minneapolis, MN, June 09 - 13, 2013.
Impact/Purpose:
To be presented at ASMS Conference June 9-15, 2013 im Minneapolis, MN
Description:
Introduction The current study investigated the effect of different disinfection treatments on the disinfection by-products (DBPs) formed in finished drinking water vs. tap water vs. swimming pool water vs. spa waters. To this end, samples across the complete water pathway (untreated source waters>finished drinking water-> tap water-> pool/spa water) were collected in different regions of the United States, including both public and private swimming pools and spas. This enables the study of the formation and fate ofDBPs at different points in this pathway, including the untreated source water (which generally does not contain DBPs), disinfection at the drinking water treatment plant, transport through the distribution system to the tap (where DBPs can either increase or decrease in concentration), followed by additional disinfection in the swimming pool/spa. Methods Raw, finished, tap, spa and swimming pool water samples (52 L) were collected from 6 spa locations in the U.S. where chlorine, bromine, or ozone-chlorine was used for disinfection. DBPs were comprehensively identified using gas chromatography (GC)/mass spectrometry (MS), and several DBPs (the 4 regulated trihalomethanes (THM4), the 9 chloro/bromohaloacetic acids (HAA9), halonitriles, haloketones, chloral hydrate, chloramines, and cyanogens halides) were quantified using GC/electron capture detection, GC/MS, and membrane introduction mass spectrometry (MIMS). In addition, total organic chlorine (TOCl) and total organic bromine (TOBr) were measured using a Total Organic Halogen Analyzer interfaced to an ion chromatograph . In vitro toxicity studies were carried out using the Ames Assay and the Chinese hamster ovary (CHO) assay. Results More than 120 DBPs, including halomethanes, halonitriles, haloketones, haloaldehydes, halonitromethanes, haloacids and halodiacids, were identified in the spas and swimming pools, including several previously unidentified DBPs. High resolution-MS was helpful in the identification of the unknowns. DBPs and mutagenicity progressively increased from source -7 finished water (at plant) -7 tap water -7 spa/swimming pool samples. The mutagenicity followed a trend similar to the HAA9 concentrations in this treatment pathway. Maximum levels ofTHMs and HAAs reached 515 ).lg/L and 5300 ).lg/L, respectively in the private brominated spa and the public chlorinated spa from location 1. The highest mutagenicity was found in the public brominated spa. Following a swimming competition, HAA9levels increased dramatically (from 84 ).lg/L to 5300) .lg/L), but THM4levels decreased slightly, likely due to volatilization (transfer of volatile THMs into the headspace) from swimmer activity. Samples collected from the public brominated spa (3683 rev/L-eq) were more mutagenic than those samples collected from the public chlorinated spa (2058 rev/L-eq), despite a lower concentration ofHAA9. TOCl in the public chlorinated spa was 2x the concentration in the public chlorinated swimming pool. After 3 weeks of continuous use, the public brominated spa contained similar concentrations of TOCl and TOBr to the public brominated swimming pool. Overall, private spas contained lower concentrations of measured DBPs than public spas. However, TOCl and TOBr were highest in the private brominated spa (possibly due to unreacted bromochlorodimethylhydantoin [BCDMH] disinfectant). Comprehensive GC/MS analysis of these samples is leading to a more complete picture of DBP exposure and also to the discovery of new DBPs. Novel Aspects To our knowledge, this is the first time that the formation ofDBPs and accompanying changes in toxicity have been followed over the complete water pathway cycle from untreated source waters to finished drinking water to tap water to pool/spa water.
