Newswise — Repeated exposure to disinfection by-products in the air around indoor swimming pools may damage the outermost cells lining the smallest airways in the lungs of children, according to a study published today in the December issue of the peer-reviewed journal Environmental Health Perspectives (EHP). The Swedish study of 33 boys and 24 girls aged 10-11 years showed that blood levels of a lung-specific protein known as Clara cell protein (CC16) were significantly lower among children who regularly visited indoor pools compared to children who did not.
The research was part of a series of studies examining possible changes in CC16 serum levels in relation to ambient ozone exposure as well as other environmental exposures. The researchers began by looking for signs of an adverse effect on lung function or CC16 concentrations after light exercise in moderate levels of ozone. While no significant correlation was observed in the group as a whole, the researchers did find that a subset of children who regularly visited chlorinated indoor swimming pools showed significantly lower concentrations of CC16 in their blood both before and after ozone exposure, compared to those who didn't visit pools.
Clara cells are bronchiolar epithelium cells thought to help defend airways against damage. CC16 is thought to protect the respiratory tract from inflammation. These findings' suggestion that repeated exposure to the air around indoor chlorinated pools may damage Clara cell function is supported by previous studies. A previous study by one of the co-authors also found an increased incidence of asthma among children who regularly visited indoor pools.
"Our results indicate that repeated exposure to chlorination by-products in the air of indoor swimming pools has an adverse effect on the Clara cell function in children, such that the anti-inflammatory role of CC16 in the lung could be diminished," the study authors write. "A possible role of such influence on Clara cell function in inducing pulmonary morbidity (e.g., asthma) should be further studied."
The fairly low levels of ozone in the air where the children exercised for the study period may be part of the reason no significant changes were noted in lung function, according to Dr. Jim Burkhart, science editor for EHP. "The levels of ambient ozone in the study area were fairly moderate, and lower than those reported to impact lung function in other studies. But the potential link between the air around indoor chlorinated pools and asthma in children is worthy of further investigation," he said.
The lead author of this study was Birgitta Json Lagerkvist of the Department of Public Health and Clinical Medicine at Umea University in Umea, Sweden. Other authors included Alfred Bernard, Anders Blomberg, Erik Bergstrom, Bertil Forsberg, Karin Holmstrom, Kjell Karp, Nils-Goran Lundstrom, Bo Segerstedt, Mona Svensson, and Gunnar Nordberg. The article is available free of charge at http://ehp.niehs.nih.gov/members/2004/7027/7027.html.
EHP is published by the National Institute of Environmental Health Sciences, part of the U.S. Department of Health and Human Services. EHP is an Open Access journal. More information is available online at http://www.ehponline.org/.
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Environmental Health Perspectives (Dec-2004)
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