New Study Shows Effects of Exposure To Swimming Pool Chlorine Equivalent to Smoking
PARIS -- Chlorine used to disinfect indoor swimming pools could be one of the causes behind an astonishing surge in childhood asthma in developed countries in the past few decades, a new study indicates. The suspected culprit is trichloramine, a gassy, easily inhalable irritant that is released in a complex process when chlorinated water reacts with urine, sweat or other organic matter brought by swimmers. Trichloramine has previously been pointed to as a trigger for three proteins that destroy the cellular barrier protecting the lungs, making it permeable and more prone to the passage of allergens, the substances that unleash an asthma attack. Belgian researchers, writing in the British research journal Occupational and Environmental Medicine, took blood samples from 226 young primary-school children who had swum regularly at indoor pools since early childhood. They also took samples from 29 adults and children both before and after a session in an indoor pool. The samples show that youngsters who regularly attend indoor pools accumulate these proteins, making them more at risk from asthma. Most frightening of all: The children who swam most frequently had protein levels of the kind found in regular smokers. Protein levels even rose measurably among people who had been sitting at the poolside and had not been swimming. "The increasing exposure of chlorination products in indoor pools might be an important cause of the rising incidence of childhood asthma and allergic disease in industrialized countries," say the scientists, led by Alfred Bernard, a toxicologist at Catholic University of Louvain in Brussels. The effects were the same for children wherever they lived, and remained after other environmental pollutants were accounted for. Levels of trichloramine -- chemical name nitrogen trichloride (NCl 3) -- vary considerably, however. They depend on how crowded the pool is, on the ventilation and on how clean the swimmers are. Chlorine has been used for several decades to kill bacteria in indoor pools. But the authors were astounded when they were unable to locate a single serious study to check whether this or other disinfectant chemicals pose a risk to swimmers, especially children, who are the most frequent users.
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