Short-term changes in respiratory biomarkers after swimming in a chlorinated pool

Abstract

Background: Swimming in chlorinated pools involves exposure to disinfection by-products (DBPs) and has been associated with impaired respiratory health.

Objectives: We evaluated short-term changes in several respiratory biomarkers to explore mechanisms of potential lung damage related to swimming pool exposure.

Methods: We measured lung function and biomarkers of airway inflammation [fractional exhaled nitric oxide (FeNO), eight cytokines, and vascular endothelial growth factor (VEGF) in exhaled breath condensate], oxidative stress (8-isoprostane in exhaled breath condensate), and lung permeability [surfactant protein D (SP-D) and the Clara cell secretory protein (CC16) in serum] in 48 healthy nonsmoking adults before and after they swam for 40 min in a chlorinated indoor swimming pool. We measured trihalomethanes in exhaled breath as a marker of individual exposure to DBPs. Energy expenditure during swimming, atopy, and CC16 genotype (rs3741240) were also determined.

Results: Median serum CC16 levels increased from 6.01 to 6.21 microg/L (average increase, 3.3%; paired Wilcoxon test p = 0.03), regardless of atopic status and CC16 genotype. This increase was explained both by energy expenditure and different markers of DBP exposure in multivariate models. FeNO was unchanged overall but tended to decrease among atopics. We found no significant changes in lung function, SP-D, 8-isoprostane, eight cytokines, or VEGF.

Conclusions: We detected a slight increase in serum CC16, a marker of lung epithelium permeability, in healthy adults after they swam in an indoor chlorinated pool. Exercise and DBP exposure explained this association, without involving inflammatory mechanisms. Further research is needed to confirm the results, establish the clinical relevance of short-term serum CC16 changes, and evaluate the long-term health impacts.

Figure 1

Study design and timing of the sample collection and in situ measurements. Urine was also collected for genotoxicity analysis (Kogevinas et al. 2010).

Figure 2

Correlation between the change in serum CC16 concentration and dibromochloromethane (CHClBr₂) in exhaled breath, energy expenditure during swimming, free chlorine in water, and dichloramine (NHCl₂) in water.

Figure 3

Concentration of FeNO and serum CC16 before (B) and after (A) swimming, stratified by atopic status (median and IQR). The Phadiatop test was used to define atopic status. p-Value from a Mann–Whitney test between atopics and nonatopics: 0.022 for FeNO and 0.560 for CC16.