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Technical Papers
DISINFECTION BY-PRODUCTS: NOT JUST AN ISSUE FOR DRINKING WATER, BUT ALSO POTENTIALLY FOR SWIMMING POOL WATERS An analysis of three indoor public swimming pools and one heated indoor public spa in Western Australia RAA Carter, KL Linge, A Heitz, DS Liew, S Allard, CA Joll
ABSTRACT This study has provided a better understanding of the chemistry within the complex swimming pool water system, including the presence of disinfection by-products (DBPs), with the ultimate goal of improving understanding of any impact of exposure to pool waters on public health. In an analysis of three indoor public swimming pools and one heated indoor public spa located in Western Australia all disinfected by chlorination, dichoroacetic acid, trichloroacetaldehyde monohydrate (chloral hydrate), dichloroacetonitrile, N-nitrosomorpholine and N-nitrosodibutylamine were detected at concentrations above their respective drinking water guideline values, with dichloroacetic acid and chloral hydrate being detected up to 6.6 and 40 times higher than their respective Australian drinking water guideline limits. Reasonable concentrations of other DBPs, the N-nitrosamines, haloacetic acids and trihalomethanes, were also detected. High concentration chloramination of synthetic urine led to the formation of N-nitrosodimethylamine (NDMA), a known carcinogen, with nitrogen-containing compounds known to be present in urine being probable precursors. Improved swimmer hygiene was recommended for better chemical water quality in pools.
DISINFECTION
INTRODUCTION Swimming pool chemical water quality is currently a topic of interest internationally, with studies occurring in the United States and Europe; however, few studies have been conducted in Australia. Swimming pool chemical water quality is of possible public health concern due to the formation of disinfection by-products (DBPs), an unwanted consequence of reactions of components of the pool water and
WATER SEPTEMBER 2015
the disinfectant during the swimming pool disinfection process. Disinfection, however, is essential to protect against microbial disease risk (Montgomery, 1985), a risk that is much greater than that posed by the DBPs themselves. Elevated DBPs in drinking water have been linked to several health issues, including asthma, bladder cancer, liver and kidney issues (Villanueva et al., 2007; Villanueva and Font-Ribera, 2012). Respiratory issues have been preliminarily correlated with pool attendance, probably due to chlorinated volatile DBPs, such as chloramines (e.g. Bernard et al., 2006). From a chemical perspective, swimming pools are a complex matrix, with continual addition of a wide range of natural and anthropogenic chemicals via filling waters, disinfectant addition, personal care
products and human body excretions (Figure 1). Natural organic matter (NOM), trace amounts of DBPs and chlorine/ bromine or chloramines/bromamines may be introduced by the filling water, which is commonly disinfected distributed drinking water. Further chlorine or bromine is introduced via addition of a pool disinfectant, with common swimming pool disinfectants including those that are chlorine-based: sodium or calcium hypochlorite and chlorine gas; those that are bromine-based: sodium or potassium bromide in combination with an oxidant such as chlorine or ozone; and the chlorineand bromine-based 1-bromo-3-chloro-5,5dimethylhydantoin (BCDMH). Electrolysis may also be used in a saltwater pool in order to produce hypochlorous acid. Human body excretions (sweat, urine and saliva) and personal care products
Filling Waters: Natural Organic Matter (NOM), Disinfection By-products (DBPs), Chlorine/Bromine Chloramines/Bromamines
Human Body Excretions: Urine Sweat Saliva
Disinfectants: Cl2 / Br2
Personal Care Products: Sunscreens, Lotions, Cosmetics, Soaps, Hair Products
Figure 1. Introduction of natural and anthropogenic chemicals to swimming pool waters.