http://www.ivillagehealth.com/news/topnews/content/0,,418445_582439,00.html

Study looks at asthma risk, indoor pools

By Keith Mulvihill

Last Updated: 2003-05-29 15:23:48 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Repeated inhalation of chemical-laden air near indoor swimming pools may cause harm to the lungs of children and increase their risk for asthma, according to Belgian researchers.

However, one asthma expert not involved in the study cautions that such an effect is unlikely to play a role in the rising number of childhood asthma cases in the U.S. And it's not clear how important the risk of indoor pools is in the big picture, she said.

"I wouldn't want people to get the idea that pools cause asthma," Dr. Luz Claudio of Mount Sinai School of Medicine in New York told Reuters Health. "And parents should be aware that there are other environmental factors, with much stronger evidence, that are linked to asthma -- indoor tobacco smoke, mold and dust mites are very strongly associated with asthma in children."

In the new study, Dr. Alfred Bernard of Catholic University of Louvain in Brussels and colleagues measured blood levels of lung proteins in 226 healthy children who did not have asthma. An increase in such proteins in the blood may be a sign that the cells lining the lungs have been damaged.

All of the children regularly swam in an indoor pool as part of a school program at least every other week for several years. The researchers also measured lung proteins in 16 children and 13 adults immediately before and after they sat near or used an indoor pool.

In addition, they analyzed data from 1,881 children to determine if there was a relationship between pool use and asthma risk. The researchers also considered other factors such as overall exercise and mold on bedroom walls.

Cumulative pool attendance was the factor most consistently related to increased blood levels of the lung proteins, the report indicates.

The investigators also found that lung proteins increased in both children and adults after spending time near a pool, according to the report published in the June issue of the journal Occupational and Environmental Medicine.

The researchers note that when chlorine reacts with organic matter, such as urine or sweat, in a swimming pool, it forms a mixture of chemicals that can be inhaled by swimmers as gases or aerosols. Chief among them is a chemical called nitrogen trichloride, or trichloramine -- the same harmful chemical that is produced when household bleach and ammonia are combined.

Small amounts of the chemical may cause mild irritation and harm the tissues of the lung and damage the cells.

Based on their findings, Bernard's team suggests that exposure to chlorination products in indoor pools may be an important reason why asthma rates have been rising in developed countries.

"This study is the first to report evidence that exposure to chlorination products in indoor swimming pools may cause adverse effects on the lungs ... of recreational swimmers," Bernard and colleagues write.

"The question needs to be raised as to whether it would not be prudent in the future to move towards non-chlorine based disinfectants, or at least to reinforce water and air quality control in indoor pools," they add.

However, Claudio said very few studies have validated the specific proteins measured in the current study as definitive markers for lung health.

"How well these makers correlate with lung damage hasn't been completely figured out," said Claudio, during a telephone interview.

What's more, she notes that the Belgian children in the study have much higher levels of indoor pool exposure than children in other countries. Indoor swimming is a compulsory part of such youngsters' education, unlike children in the U.S.

Claudio noted that trichloramine is a well-known lung irritant and "one would expect to see some level of lung damage," but the relationship described in the current study "is not that striking."

"To say that chronic exposure to indoor pool environments is a major contributor to the rising rates of asthma, I don't think that this is the case, at least based on my experiences here in the U.S., and New York City in particular," she added.

Copyright 2002 Reuters.