Abstract
OBJECTIVE: The aim of this study was to evaluate the association between exposure to volatile chlorination by-products from swimming during early childhood and the subsequent development of asthma. DATA SOURCE: This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) under CRD42021291850. Searches were carried out in the following electronic databases: PubMed, Cochrane Library, Google Scholar, and ScienceDirect, using the terms "children in early childhood," "swimming in a chlorinated pool," "exposed and unexposed," and "asthma risk," covering studies published between 2003 and 2020. The review included cohort and cross-sectional studies of individuals who swam in chlorinated pools during early childhood. The methodological quality of the studies was evaluated for risk of bias. DATA SYNTHESIS: Out of 6865 studies screened, six met the inclusion criteria, involving 4058 subjects and 310 asthma events (2365 in the exposure group and 1693 in the control group). The combined effect, expressed as an odds ratio for asthma risk in all included studies, was 1.09 (95%CI 0.67-1.77; p=0.740). CONCLUSIONS: This is the first systematic review to comprehensively evaluate the association between swimming in chlorinated pools and the risk of developing asthma. No association was found between childhood swimming in chlorinated pools and the risk of asthma development.