Academic journal article Environmental Health Perspectives

Childhood Asthma and Environmental Exposures at Swimming Pools: State of the Science and Research Recommendations

Academic journal article Environmental Health Perspectives

Childhood Asthma and Environmental Exposures at Swimming Pools: State of the Science and Research Recommendations

Article excerpt

OBJECTIVES: Recent studies have explored the potential for swimming pool disinfection by-products (DBPs), which are respiratory irritants, to cause asthma in young children. Here we describe the state of the science on methods for understanding children's exposure to DBPs and biologies at swimming pools and associations with new-onset childhood asthma and recommend a research agenda to improve our understanding of this issue.

DATA SOURCES: A workshop was held in Leuven, Belgium, 21-23 August 2007, to evaluate the literature and to develop a research agenda to better understand children's exposures in the swimming pool environment and their potential associations with new-onset asthma. Participants, including clinicians, epidemiologists, exposure scientists, pool operations experts, and chemists, reviewed the literature, prepared background summaries, and held extensive discussions on the relevant published studies, knowledge of asthma characterization and exposures at swimming pools, and epidemiologic study designs.

SYNTHESIS: Childhood swimming and new-onset childhood asthma have clear implications for public health. If attendance at indoor pools increases risk of childhood asthma, then concerns are warranted and action is necessary. If there is no such relationship, these concerns could unnecessarily deter children from indoor swimming and/or compromise water disinfection.

CONCLUSIONS: Current evidence of an association between childhood swimming and new-onset asthma is suggestive but not conclusive. Important data gaps need to be filled, particularly in exposure assessment and characterization of asthma in the very young. Participants recommended that additional evaluations using a multidisciplinary approach are needed to determine whether a clear association exists.

KEY WORDS: aerosols, biologies, childhood asthma, DBPs, disinfection by-products, epidemiology, study design, swimming pools. Environ Health Perspect 117:500-507 (2009). doi: 10.1289/ ehp. 11513 available via [Online 30 September 2008]


This review derives from a workshop held in Leuven, Belgium, in August 2007 to develop a research agenda that would lead to a better understanding of children's exposure to disinfection by-products and biologics in the swimming pool environment and whether such exposures are associated with asthma. Other health end points are of interest to those investigating swimming pool exposures but were outside the scope of the workshop.

Disinfection of swimming pools is essential to prevent outbreaks of infectious illnesses from recreational waters (Centers for Disease Control and Prevention 2007). However, traditional chemical disinfection processes result in the formation of disinfection by-products (DBPs) (Aggazzotti and Predieri 1986; Aggazzotti et al. 1998; Beech et al. 1980; Chu and Nieuwenhuijsen 2002; Fantuzzi et al. 2001; Glauner et al. 2005; Judd and Jeffrey 1995; Kim et al. 2002; Li and Blatchley 2007; Weil et al. 1980; Weisel and Shepard 1994; Zwiener et al. 2007). The specific types and levels of DBPs formed depend on numerous factors, including the type and amount of disinfectant used, characteristics of the swimming pool and pool water, and swimmer hygiene (Zwiener et al. 2007).

Swimming had been recommended as a sport for children with childhood asthma because there is experimental and observational evidence from short-term studies that swimming is less asthmagenic than other types of vigorous exercise and that asthmatics may tolerate swimming better than other types of physical activity. They may do so because of the horizontal position of the body during swimming, which alters the breathing pathway compared with other forms of exercise, or the high humidity present in indoor pools (Bar-Yishay et al. 1982; Bundgaard et al. 1982; Fitch and Morton 1971; Inbar et al. 1980; Matsumoto et al. 1999; Reggiani et al. 1988). …

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