Letting Babies Swim in Chlorinated Pools Harms Their Health For Life

"This suggests that chlorinated pool attendance can increase the risk of asthma and respiratory allergies by making the airways more sensitive not only to allergens but also to infectious agents," senior researcher Alfred Bernard said.

Researchers conducted health tests on 430 Belgian kindergarteners and had their parents fill out questionnaires about their health history and swimming habits. They found that while 36 percent of children who had been exposed to chlorinated pools before the age of two had a history of the lung infection known as bronchiolitis, compared with only 24 percent of children who had not been exposed.

Bronchiolitis is a usually viral infection of the small airways of the lungs. Researchers believe that chlorine in swimming pools may combine with sweat, saliva and urine from swimmers to produce chemicals that irritate and weaken the lungs. In the weaker, developing lungs of children, this can raise the risk of infection.

Supporting this hypothesis, researchers found that indoor pools increased infection risk more than outdoor pools. Children who had been to chlorinated outdoor pools for 20 or more hours by age two are twice as likely to suffer from bronchiolitis as children who had not been to chlorinated pools at all. Children who had been to indoor pools were 3.5 times as likely to have a history of the infection.

Researchers found that while neither swimming nor a history of bronchiolitis appeared to raise the risk of asthma or respiratory allergies by age five on their own, the combination of these factors led to a significantly higher risk.

Bernard noted that swimming is an "enjoyable" way to get kids exercise, but that chlorinated pools carry risks. He suggested that children use pools disinfected without chlorine whenever possible.