On the heels of a number of studies linking swimming to respiratory issues, a German agency has become the first to recommend that children younger than 2 years old with a family history of allergies avoid indoor pools.

“The Federal Environment Agency (UBA) recommends, for the sake of precaution, that concerned parents of children under the age of 2 from families that suffer allergies not go to baby swimming until the suspicion is confirmed,” according to an official press release.

The warning is based on a number of studies that suggest disinfection byproducts formed from the reaction of chlorine when combined with organic compounds — including human sweat and other body fluids — may contribute to respiratory issues.

UBA tests detected airborne trichloramine concentrations at German indoor pools of up to 18.8 milligrams/ cubic meter of air (mg/m3); however, 90 percent of all measured levels fell below the concentration of 0.50 mg/m3 recommended by the World Health Organization. Researchers found that in pools with high concentrations, ventilation did not comply with generally accepted technical rules and standards.

Agency officials are hoping to eventually get more information on whether or not lung damage is actually done in early childhood and the extent to which it might lead to asthma.

“Trichloramine (TCA) is a strong irritant, with biochemical data as well as epidemiological evidence indicating it to possibly play a role in the induction of asthma, particularly if highly sensitive children under 2 years are exposed regularly. Scientific, i.e., toxicological, understanding is not quite at the point where a safe level of TCA can be given," said Dr. Ingrid Chorus, with the UBA.

Also in the announcement, UBA President Jochen Flasbarth reiterated the importance of healthy swimming. “Swimming is healthy for children and adults alike, and so that it stays that way, a thorough shower should be taken by everybody before swimming to help avert the health risks posed by trichloramine,” he said.

Flasbarth also called on indoor pool operators to use available water treatment technology. “Modern technology and public education to raise awareness can solve the problem insofar as to minimize the health risks posed by chlorine reaction products,” he said.

Echoing the German position that more information is needed, U.S. experts’ reaction to the warning was mixed.

“We are not aware of any data showing a strong link between asthma in U.S. children and indoor swimming, or that existing data from Europe on such a potential link is strong enough to warrant telling parents not to allow their young children to use indoor swimming environments,” said Michael J. Beach, Ph.D., associate director for healthy water, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention. “However, writers of the Model Aquatic Health Code are acutely aware of the need for improved water and air quality in indoor swimming environments, and the acute health effects due to exposure to these air contaminants are well documented.”

Mary Ostrowski, director, chlorine issues for the American Chemistry Council's Chlorine Chemistry Division in Washington, D.C., reiterated Flasbarth’s call for healthy swimming and education. But Ostrowski said the German advisory is “highly precautionary.”

“As we state on the ACC Web site ... there is no convincing evidence that swimming in chlorinated pools causes asthma in otherwise healthy people,” she added.

For his part, aquatics expert Tom Griffiths was not surprised to hear of the warning.

“While early swimming lessons may in fact reduce drowning, I do believe it can cause a host of [ear, nose and throat] and other problems …” said the founder of Aquatic Safety Research Group in State College, Pa.