Blood and breath analyses as biological indicators of exposure to trihalomethanes in indoor swimming pools

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Abstract

In this article, exposure to trihalomethanes (THMs) in indoor swimming pools as a consequence of water chlorination is reported. Environmental and biological monitoring of THMs was performed in order to assess the uptake of these substances after a defined period in five competitive swimmers, regularly attending an indoor swimming pool to train for competition during four sampling sessions. Analyses were performed by gas-chromatography and the following THMs were detected: chloroform (CHCl3), bromodichloromethane (CHBrCl2), dibromochloromethane (CHBr2Cl) and bromoform (CHBr3). CHCl3 appeared the most represented compound both in water and in environmental air before and after swimming. CHBrCl2 and CHBr2Cl were always present, even though at lower levels than CHCl3. CHBr3 was rarely present. In relation to biological monitoring, CHCl3, CHBrCl2 and CHBr2Cl were detected in all alveolar air samples collected inside the swimming pool. Before swimming, after 1 h at rest at the pool edge, the mean values were 29.4±13.3, 2.7±1.2 and 0.8±0.8 μg/m3, respectively, while after spending 1 h swimming, higher levels were detected (76.5±18.6, 6.5±1.3 and 1.4±0.9 μg/m3, respectively). Only CHCl3 was detected in all plasma samples (mean: 1.4±0.5 μg/l) while CHBrCl2 and CHBr2Cl were observed only in few samples at a detection limit of 0.1 μg/l. After 1 h at rest, at an average environmental exposure of approx. 100 μg/m3, the THM uptake was approx. 30 μg/h (26 μg/h for CHCl3, 3 μg/h for CHBrCl2 and 1.5 μg/h for CHBr2Cl). After 1 h swimming, the THM uptake is approx. seven times higher than at rest: a THM mean uptake of 221 μg/h (177 μg/h, 26 μg/h and 18 μg/h for CHCl3, CHBrCl2 and CHBr2Cl, respectively) was evaluated at an environmental concentration of approx. 200 μg/m3.

Introduction

In recent years, some studies have been performed to evaluate the presence of trihalomethanes (THMs), including chloroform (CHCl3), bromodichloromethane (CHBrCl2), dibromochloromethane (CHBr2Cl) and bromoform (CHBr3), in indoor swimming pools. THMs are the main by-products of water chlorination when disinfection is performed with sodium hypochlorite or, more recently, with sodium dichloroisocyanurate. Among THMs, CHCl3 is the most represented one.

It is well known that THMs are volatile substances that can vaporise from water to environmental air depending on many variables, such as vapour pressure, water solubility, the water/air contact area, etc. (Beech et al., 1980; Lahl et al., 1981; Aggazzotti and Predieri, 1986; Aggazzotti et al., 1987, Aggazzotti et al., 1995; Aiking et al., 1994; Levesque et al., 1994; Weisel and Shepard, 1994; Camman and Hübner, 1995).

Studies on environmental monitoring for CHCl3 in indoor swimming pools were performed in Northern Italy where, since 1986, indoor swimming pools were visited in many sampling sessions. CHCl3 concentrations in water ranged from 9 to 179 μg/l and were significantly related to CHCl3 levels in indoor air, to free and combined chlorine residuals and to water pH. The number of swimmers present in the pools was significantly related with the concentration of CHCl3 in environmental air as a consequence of the turbulence induced in the water (Aggazzotti and Predieri, 1986; Aggazzotti et al., 1995).

THMs can enter the body by three different exposure routes: inhalation, dermal absorption and ingestion. Exposure assessment models, pharmacokinetic models and experimental data (obtained in clean-air chambers) were developed in order to estimate the internal dose and the metabolism of these volatile substances (Gordon et al., 1988; Corley et al., 1990; Wester and Maibach, 1994). Some studies were performed for the intake and uptake of CHCl3 or other THMs in subjects exposed to these substances by contaminated tap water (Lindstrom and Pleil, 1996; Weisel and Jo, 1996), while few data exist about biological monitoring in indoor environments, such as indoor swimming pools. Moreover, the presence of THMs was usually evaluated in blood, urine and alveolar air compartments separately (Aggazzotti et al., 1990, Aggazzotti et al., 1993; Camman and Hübner, 1995; Wallace et al., 1996).

The aim of this study was to simultaneously evaluate THM levels in the blood of swimmers and alveolar air, in order to further investigate the relationship among these substances in different matrices at known environmental levels and to evaluate the uptake of these substances in indoor swimming pools.

Section snippets

Materials and methods

The study was performed in Modena, Italy, on five subjects, all competitive swimmers, daily attending an indoor swimming pool to train for competition. They were three males and two females, with a mean age of 18.6 years (range: 17–21 years).

The subjects were following the same training program regarding to the type of swimming, the intensity of the physical activity and the length of the time spent swimming.

Informed consent was obtained from each subject and data were gathered about the

Results

The mean values and ranges of THMs in water and environmental air observed inside the swimming pool during four repeated sampling sessions are reported in Table 1. Two sets of environmental air data are reported, as we asked the subjects to rest for 1 h at the pool-side with nobody inside the pool before swimming for 1 h to train for competition with many other people (approx. 40–50 subjects). As shown, CHCl3, CHBrCl2, CHBr2Cl were always present in water and environmental air, while CHBr3 was

Discussion

In the present study, exposure to THMs in indoor swimming pools and the uptake in swimmers were evaluated. To date no biological monitoring had been performed in swimmers for THMs other than CHCl3, and no data are available on blood and breath analyses performed at the same point in time on the same subjects. This study is an attempt to fill the gap in the knowledge of the exposure to these substances and the uptake in a definite environment, such as an indoor swimming pool.

THM concentrations

Acknowledgements

We are indebted to the Head of Sports-Recreation Department, City of Modena, Italy and to the swimmers who participated to our study. This study was supported by grants from the Italian Ministry of University and Scientific and Technological Research (40% and 60%).

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