Disinfection is a necessary process to inactivate pathogens and prevent outbreaks of infectious diseases
in swimming pool water. Unfortunately, disinfectants can react with many components (e.g., natural
organic matter, bromide, and iodide), thereby resulting in the formation of disinfection byproducts (DBPs)
(Chowdhury et al., 2014; Ersan et al., 2019; Hang et al., 2016; Yang et al., 2016). Toxicological studies have
revealed that many DBPs are carcinogenic and teratogenic, and epidemiological studies have shown that
several health issues are associated with exposure to DBPs, such as reproductive health effects, asthma,
and bladder cancer (Carter and Joll, 2017; Chen et al., 2011; Font-Ribera et al., 2016; Lee et al., 2009). In
a recent study, Font-Ribera et al. (2019) reported moderate associations with micronuclei in reticulocytes
and DBP exposure while swimming in a chlorinated pool. Therefore, the study of DBPs in swimming pool
water is valuable for public health.
The occurrence and speciation of DBPs in swimming pools have been investigated by scholars worldwide
(Carter et al., 2019a; Hang et al., 2016; Righi et al., 2014; Tardif et al., 2016; Xiao et al., 2012; Yang et al.,
2018a). Xiao et al. (2012) investigated swimming pool water that originated from local tap water and was
further treated with a liquid bleach containing 12.5% (by weight) sodium hypochlorite, and detected
numerous new halogenated DBPs. Tardif et al. (2016) assessed the profiles of DBPs in 41 public indoor
swimming pools where chlorine (liquid or solid) was used for water disinfection, and the results indicated
that haloacetic acids (HAAs) (294.8 ± 157.6 μg/L) was the most dominant category followed by
trihalomethanes (THMs) (64.7 ± 26.7 μg/L), haloacetonitriles (HANs) (21.4 ± 17.6 μg/L), 1,1,1-trichloro-2propanone (TCP) (1.9 ± 1.3 μg/L), trichloronitromethane (TCNM) (0.35 ± 0.6 μg/L), and NNitrosodimethylamine (NDMA) (43.1 ± 40.0 ng/L). Carter et al. (2019a) observed the occurrence of 39
DBPs in two outdoor swimming pools over 15 months; one pool was disinfected by chorine gas and
equipped with ultraviolet (UV) treatment, and the other pool was disinfected using chlorine gas and
employed cyanuric acid (20–50 mg/L) as a https://doi.org/10.1016/j.envint.2020.105726 Received 30 July
2019; Received in revised form 17 March 2020; Accepted 6 April 2020 ⁎Corresponding authors at: Center
for Environment and Water Resources, College of Chemistry and Chemical Engineering, Central South
University, Changsha 410083, PR China. E-mail addresses: lihaipu@csu.edu.cn (H. Li), zgyang@csu.edu.cn
(Z. Yang). Environment International 139 (2020) 105726 Available online 13 April 2020 0160-4120/ © 2020
Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/BY-NC-ND/4.0/). T chlorine stabilizer; this study provided the
highest reported concentrations of monochloroacetic acid (MCAA) (6092 μg/L), dichloroacetic acid
(DCAA) (25,977 μg/L), and trichloroacetic acid (TCAA) (11,283 μg/L). In general, among the detected DBPs
in swimming pool water, THMs and HAAs are the predominant components (Carter et al., 2019b; Chen et
al., 2011). THMs, which were the first DBPs to be discovered in 1980, have been widely investigated
(Beech et al., 1980; Chen et al., 2011; Yang et al., 2018a). HAAs, which were first reported in 1999
(Martınez et al., 1999 ́ ), are generally found in higher concentrations than THMs in pools owing to their
low volatility (Chowdhury et al., 2014; Manasfi et al., 2017). In recent years, some other DBPs that are
more cytotoxic and genotoxic than THMs and HAAs have become emerging concerns, including HANs,
haloketones (HKs), TCNM, and nitrosamines (NAs) (Deng et al., 2018; Font-Ribera et al., 2016; Muellner
et al., 2007; Zhang et al., 2018). Although the focus on DBPs in pools has increased, only a few countries
have established swimming pool water quality standards for DBPs (Chowdhury et al., 2014; Yang et al.,
2018b). Thus, more information about DBPs in swimming pools needs to be provided. THMs are the only
organic DBP category known to be regulated (Carter and Joll, 2017; Saleem et al., 2019). However, the
concentrations of HAAs are usually higher than those of THMs, and some other emerging DBPs, such as
nitrogenous DBPs (N-DBPs), have significantly higher toxicity than THMs. Thus, it is necessary to discuss
whether THMs are reliable as the sole indicator of organic DBPs.
Thus far, various categories of DBPs in pools have been identified (Hang et al., 2016). Over 100 DBPs in
chlorinated and brominated swimming pools were identified by Richardson et al. (2010). More than 100
DBPs were identified by Daiber et al. (2016) in pools/spas disinfected using different disinfectants. There
are certain limitations to the detection of DBPs. Because new DBPs are continuously identified and the
analysis methods strongly depend on the properties of the DBPs, it is difficult to identify all DBPs
(Richardson and Ternes, 2018). Moreover, the detection process of organic DBPs is usually conducted in
a laboratory, and the detection result is not timely (Richardson and Ternes, 2018; Walse and Mitch, 2008).
Easily detectable water quality parameters as indicators of DBPs would be beneficial to the monitoring of
DBPs. Previous studies showed that some water quality parameters are significantly correlated with DBPs
in pool water. Lee et al. (2010) found that total organic carbon (TOC) and nitrate (NO3 – ) are positively
correlated with the concentration of total DBPs (the sum of THMs, HAAs, HANs, and chloral hydrate),
while pH is negatively correlated with the concentration of HANs. Yang et al. (2018a) also found that pH
shows negative correlations with both HANs and TCNM, while free residual chlorine (FRC) has positive
correlations with THMs, HANs, and TCNM. These results suggest the possibility of using water quality
parameters as predictors of DBPs in swimming pools.
In this study, a total of 41 typical public swimming pools (16 indoor pools and 25 outdoor pools) were
selected. Twenty-nine DBPs (Table 1), including NAs that were seldom detected, were investigated to
provide basic data for the improvement of a standard. The total lifetime cancer risks posed by dermal
absorption and ingestion of four THMs, two HAAs (DCAA and TCAA), and seven NAs were assessed. The
exposure risks posed by four THMs through inhalation were also assessed. This is the first report of a risk
assessment of NAs in swimming pool water. Furthermore, Spearman correlation analysis was conducted,
and multivariate regression models were developed to predict the DBP concentration in swimming pool
water as a function of water quality parameters.