Swimmers training in heated pools with chlorine would suffer lung changes similar to those of people with asthma.
Competitive swimmers who train in heated pools with chlorine would suffer lung changes similar to those of people with asthma.
A team from France and Canada compared lung tissue and respiratory tests of 23 Canadian swimmers in their 21s with 10 people with mild asthma and 10 healthy people, without allergies, of the same age. Tissue samples and tests were taken outside the competition season.
Valérie Bougault’s team, from the Lille 2 University of Health and Law, in France, found that swimmers’ lung tissue had almost six times more immune cells associated with asthma and allergies than tissue samples from healthy participants and an amount similar to that of the asthmatic group.
Swimmers and asthmatics also had scars in lung tissue, unlike those who did not swim.
“This study is the first to reveal direct evidence of respiratory tract damage associated with swimming in chlorinated pools , “ said Alfred Bernard, a toxicologist at the Catholic University of Leuven in Brussels, Belgium, who was not involved in the study.
“There is no evidence to suggest that these changes cause asthma in the long term,” said Dr. Sally Wenzel, a pulmonologist at the University of Pittsburgh.
Inflammation of the lung tissue was not associated with asthma symptoms, such as cough and wheezing, or with dyspnea during clinical evaluation to determine lung function.
In addition to the disinfectant function, chlorine reacts with a large amount of chemicals from human sweat, urine and hair. That induces the formation of by-products, some of which are dangerous to human health.
These by-products are very volatile and can evaporate into the pool air, according to Ernest Blatchley, an environmental engineer and water chemistry expert at Purdue University in Indiana, United States.
Elite swimmers inhale large amounts of those chlorine derivatives while doing strenuous exercises in the pool.
Exposure to chlorine substances in indoor pools would increase the sensitivity of swimmers to allergens, such as pet dander, pollen and dust, Bernard explained.
In fact, between 50 and 65 percent of competitive swimmers are sensitive to common allergens, compared with between 29 and 36 percent of the general population, Bougault said.
In the study published in the Journal of Allergy and Clinical Immunology , 18 of the 23 swimmers had at least one allergy. While exposure to allergens can modify lung tissue, “we also detect tissue changes in swimmers without allergies,” he added.
That suggests that exposure to chlorine derivatives would cause lung damage, Bougault concluded, which integrates the advisory councils of several industry companies, such as GlaxoSmithKline and MerckFrosst, which produce Advair and Singulair asthma drugs.
The authors cannot assure that repeated exposure to pool chemicals damages lung tissue.
However, they are sure that there are certain precautions that can be taken to reduce this exposure, such as avoiding swimming pools with a strong odor of chlorine in the air, a sign of mishandling of chemicals in the water.