Health risks of early swimming pool attendance

Abstract

Swimming pool attendance and exposure to chlorination by-products showed adverse health effects on children. We assessed whether early swimming pool attendance, especially baby swimming, is related to higher rates of early infections and to the development of allergic diseases. In 2003–2005, 2192 children were analysed for the 6-year follow-up of a prospective birth cohort study. Data on early swimming pool attendance, other lifestyle factors and medical history were collected by parental-administered questionnaire. Bivariate and multivariate logistic regression analyses were used to evaluate associations.

Babies who did not participate in baby swimming had lower rates of infection in the 1st year of life (i) diarrhoea: OR 0.68 CI 95% 0.54–0.85; (ii) otitis media: OR 0.81 CI 95% 0.62–1.05; (iii) airway infections: OR 0.85 CI 95% 0.67–1.09. No clear association could be found between late or non-swimmers and atopic dermatitis or hay fever until the age of 6 years, while higher rates of asthma were found (OR 2.15 95% CI 1.16–3.99), however, potentially due to reverse causation.

The study indicates that, in terms of infections, baby swimming might not be as harmless as commonly thought. Further evidence is needed to make conclusions if the current regulations on chlorine in Germany might not protect swimming pool attendees from an increased risk of gastrointestinal infections. In terms of developing atopic diseases there is no verifiable detrimental effect of early swimming.

Introduction

Baby swimming, which became more and more popular since 1970, showed to increase the risk of recurrent respiratory tract infections and otitis media (Nystad et al., 2003) as well as to lead to airway changes potentially predisposing to respiratory diseases later in life (Bernard and Nickmilder, 2006b; Bernard et al., 2007). Chlorine compounds used for the disinfection of swimming pools do react with organic matter (e.g., urine, sweat) of swimmers resulting in potentially harmful inhalable by-products at the water surface. Although chlorine itself and most of its derivates are known toxic agents, it was pronounced as being safe as water disinfectant. Detailed analyses and extended studies only started recently, when more concern came up regarding their potential influences on human health. Chlorinated swimming pool attendance was found to increase lung hyperpermeability, exercise-induced bronchoconstriction (EIB) and asthma (Bernard et al., 2003). Thus, the hypothesis was generated that a repeated or chronic disruption of the lung epithelial barrier could facilitate the penetration of allergens in the lung (Bernard et al., 2003) and therefore could result in increased rates of allergic sensitization and atopic diseases. Furthermore, chlorine in bathing water showed to change the dermal barrier function, especially of atopic skin (Seki et al., 2003). Official directives on chlorine differ between countries, e.g., German maximum chlorine levels are 10 times lower than those in Belgium. The objective of this study was to assess whether early swimming pool attendance in Germany, especially baby swimming, could be related to higher rates of a variety of early infections and to the development of allergic diseases.