Sufficient disinfection and minimized disinfection by-products (DBPs) are major issues of pool water treatment to prevent both diseases from microorganisms and health impacts from DBPs. Disinfection is essential since each bather introduces numerous, partly pathogenic microorganisms. Furthermore, the input of 1 to 1.5g of organic carbon (TOC) of each bather from skin, hair, body fluids and cosmetics provide a reservoir of reaction partners for the disinfectant, the so-called precursors of DBP formation. DBPs are, therefore, formed by reaction of the disinfectant with precursor compounds of the bather load and of natural organic carbon already present in the fill-up water [1]. Trihalomethanes (THMs) serve as the major indicator of DBP formation and, therefore, a threshold value is set for THMs in German Norm DIN 19643. However, THMs are only one class of DBPs, beside other like haloacetic acids (HAAs), haloacetonitriles (HAcNs), haloketones or halocarbonyls. Parameters of formation and removal of nonTHMs are not always similar to those of THMs. In addition, toxicity of DBPs can be much diverse from THMs and, therefore, minimization of toxic compounds should be a focus of surveillance and optimization of pool water treatment [2]. For example, the strong bacterial mutagen MX occurs at concentrations 1000 times lower than THMs, but has been recognized as the major cause of mutagenicity in chlorinated waters. Recent studies have shown epidemiological evidence for adverse health effects from swimming in chlorinated pool water, which is suggested to be caused by nitrogen trichloride, a to date not well investigated aspect of DBP formation [3]. This means that surveillance and operation of pool water treatment is between the devil and the deep blue sea of feasible and simply manageable analysis methods and the comprehensive survey of all DBPs of toxic significance. In this dilemma, the successful application of modern analytical methods serves the examination and assessment of pool water very well [4]. Means of DBP prevention include the reduction of the input of DBP precursors and their efficient removal. The bather load can be reduced by the behavior of people before and during pool attendance and by more efficient filtration and oxidation techniques, e.g. membrane filtration and advanced oxidation. It may also be beneficial to increase air circulation in indoor pool settings to reduce the levels of volatile DBPs. In the end, it will be important to maintain microbial disinfection while minimizing potentially harmful DBPs. The goal would be to maintain the positive health effects of swimming through exercise while reducing other potential adverse health risks. References
[2] Glauner T, Waldmann P, Frimmel GH, Zwiener C, Swimming pool water – fractionation and genotoxicological characterization of organic constituents. Water Res. 39 (2005) 4494-4502. [3] Bernard et al., Lung hyperpermeability and asthma prevalence in schoolchildren: unexpected associations with the attendance at indoor chlorinated swimming pools. Occup. Environ. Med. 60 (2003) 385-94. [4] Zwiener C, Richardson SD, Analysis of DBPs in drinking water by liquid chromatography/mass spectrometry and related mass spectrometric techniques. Trends Anal. Chem. 24 (2005) 613-621. In conclusion, the task of pool water treatment will be to maintain microbial disinfection while minimizing potentially harmful DBPs. The final goal would be to maintain the positive health effects of swimming through exercise while reducing other potential adverse health risks. Dr. Christian Zwiener is currently the Head of the Department of Organic Analysis and Water Technology at the Engler-Bunte-Institut, Universitat Karlsruhe in Germany. He teaches the following courses in Oxidation and Disinfection in Water Treatment, General Chemistry and Chemistry in Aqueous Solutions, Inorganic Chemistry and Water Chemistry. Dr. Zwiener received his Ph.D. from the Technical University of Munich, Institute for Hydrochemistry and Environmental Analysis. His main research interests include environmental analysis of organic trace compounds with hyphenated techniques, behavior and fate of organic trace compounds in water treatment, pharmaceutical residues (analysis and behavior in wastewater and drinking water treatment), oxidation and disinfection by-products in drinking and swimming pool water (analysis occurrence and minimization), and contaminated sites (analysis of metabolites and their use as indicators for biodegradation). Dr. Zwiener is a reviewer for Environmental Science and Technology, Analytical Chemistry, Analytical and Bioanalytical Chemistry and Water Research. He is a member of the German Association of Chemists in the subdivision of Water Chemistry, Analytical Chemistry and Environmental Science and Ecotoxicology, as well as a member of the International Water Association (IWA). He is a Specialists Auditor for QMS according to ISO 9000ff and is a member of Standardization Working Groups pesticide analysis, halogenated hydrocarbons, and LC-MS analysis.
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