Young Swimmers May Be at Increased Risk for Asthma

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Young Swimmers May Be at Increased Risk for Asthma

from Clinician Reviews ®

Posted 08/26/2003

Bernard A, Carbonnelle S, Michel O, et al. Lung hyperpermeability and

asthma prevalence in schoolchildren: unexpected associations with the

attendance at indoor chlorinated swimming pools. Occup Environ Med.

2003;60:385-394.

Swimmers who use indoor pools are exposed to potentially harmful chemical

compounds, such as nitrogen trichloride; what effect might this have on

their lungs? New research conducted by Belgian scientists suggests that

regular indoor pool use by children -- and the concomitant inhalation of

gases produced by chlorination agents -- is associated with an elevated

risk of asthma.

In three separate studies, Bernard et al measured blood levels of lung-

specific proteins that reflect the permeability or cellular integrity of

the lung epithelial barrier. Both the acute and chronic effects of indoor

pool exposure on lung epithelium were examined, as was the prevalence of

asthma among children who swam regularly.

In the chronic effects study, 226 children (mean age, 10) were recruited

from seven primary schools at which pool attendance was mandatory. Blood

samples were taken, and levels of lung-specific proteins were measured.

The children's cumulative pool exposure varied according to the amount of

time they spent in the water per week (30 to 60 minutes) and the age at

which they began swimming. The researchers found that pool exposure was

the one independent variable that consistently influenced serum

concentrations of lung-specific proteins; more time spent in the water

correlated with a greater likelihood of increased endothelial permeability.

The acute effects of indoor pool exposure were studied in 16 children

(ages 5 to 14) and 13 adults (ages 26 to 47) at a public swimming

facility. Blood samples were taken from all participants before they

entered the pool area and again after two hours of pool use for the

children; adults spent one hour at poolside without swimming, then swam in

the pool for the second hour. Concentrations of lung-specific proteins

increased during the study period; the increases among adults were

statistically significant after one hour of poolside exposure alone.

The third study was a retrospective analysis of data from an asthma

prevalence survey conducted in Brussels between 1996 and 1999. The study

involved 1,881 children (ages 7 to 14) who had been recruited from 15

urban primary schools. Parents completed a questionnaire about their

children's health status, respiratory symptoms, and

environmental/lifestyle variables. The schools provided information on

pool attendance. With parents' consent, children's peak expiratory flow

(PEF) was measured after six minutes of exercise. A decrease in PEF of 10%

or more five to 10 minutes after exertion indicated significant exercise-

induced bronchoconstriction. Total asthma prevalence ranged from 5.5% to

30.5%, depending on the school. Cumulative pool exposure was again the

only variable that significantly correlated with asthma indicators (ie,

prevalence of wheezing or other respiratory symptoms).

The authors suggest a future move toward non-chlorine-based disinfectants

in order to minimize pool users' exposure to potentially harmful chemicals.

Use of indoor pools may expose swimmers to harmful chemicals that could

compromise their lungs and increase their risk of asthma.

Becki

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