Characteristics of trihalomethane (THM) production and associated health risk assessment in swimming pool waters treated with different disinfection methods Jin Lee a,b , Kwang-Tae Ha b , Kyung-Duk Zoh a, ⁎ a Institute of Health and Environment, School of Public Health, Seoul National University, Seoul 110-799, South Korea b Seoul Metropolitan Government Research Institute of Public Health and Environment, Gyeonggi Province 427-070, South Korea ARTICLE DATA ABSTRACT Article history: Received 15 March 2008 Received in revised form 10 November 2008 Accepted 13 November 2008 Available online 20 December 2008 Swimming pool water must be treated to prevent infections caused by microbial pathogens. In Korea, the most commonly used disinfection methods include the application of chlorine, ozone/chlorine, and a technique that uses electrochemically generated mixed oxidants (EGMOs). The purpose of this study was to estimate the concentrations of total trihalomethanes (TTHMs) in indoor swimming pools adopting these disinfection methods, and to examine the correlations between the concentrations of THMs and TTHMs and other factors affecting the production of THMs. We also estimated the lifetime cancer risks associated with various exposure pathways by THMs in swimming pools. Water samples were collected from 183 indoor swimming pools in Seoul, Korea, and were analyzed for concentrations of each THM, TOC, and the amount of KMnO 4 consumption. The free chlorine residual and the pH of the pool water samples were also measured. The geometric mean concentrations of TTHMs in the swimming pool waters were 32.9 ± 2.4 μg/L for chlorine, 23.3 ± 2.2 μg/L for ozone/chlorine, and 58.2 ± 1.7 μg/L for EGMO. The concentrations of THMs differed significantly among the three treatment methods, and the correlation between THMs and TTHMs and the other factors influencing THMs varied. The lifetime cancer risk estimation showed that, while risks from oral ingestion and dermal exposure to THMs are mostly less than 10 - 6 , which is the negligible risk level defined by the US EPA, however swimmers can be at the greater risk from inhalation exposure (7.77 × 10 - 4 – 1.36 × 10 - 3 ). © 2008 Elsevier B.V. All rights reserved. Keywords: Chlorine Electrochemically generated mixed oxidants Ozone/chlorine Carcinogenic risk Noncarcinogenic risk TOC 1. Introduction Disinfecting swimming pool water is important to protect swimmers against infection by microbiological pathogens. In many countries, chlorine is the most common disinfectant used for this purpose. When chlorine reacts with organic matter in water, a variety of chlorinated disinfection by- products (DBPs) including trihalomethanes (THMs) such as chloroform, bromodichloromethane (BDCM), dibromochloro- methane (DBCM), and bromoform, as well as haloacetic acids and haloacetonitriles, can be formed (Nieuwenhuijsen et al., 2000; Gunten et al., 2001). Of these DBPs, THMs, the major by- products of chlorination, have been recognized as carcino- genic halogenated substances that are potentially hazardous to human health (Garcia-Villanova et al., 1997; Hsu et al., 2001; Lee et al., 2001). Swimming pool water must be disinfected frequently to prevent outbreak of waterborne diseases because pool water is continuously polluted by swimmers and is recycled with a long replacement time. Consequently, THMs in chlorinated SCIENCE OF THE TOTAL ENVIRONMENT 407 (2009) 1990 – 1997 ⁎ Corresponding author. Tel.: +82 2 740 8891; fax: +82 2 745 9104. E-mail address: zohkd@snu.ac.kr (K.-D. Zoh). 0048-9697/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2008.11.021 available at www.sciencedirect.com www.elsevier.com/locate/scitotenv