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BMJ Open. 2012; 2(5): e000973.
Published online Oct 8, 2012. doi:  10.1136/bmjopen-2012-000973
PMCID: PMC3488741
Lung function in volunteers before and after exposure to trichloramine in indoor pool environments and asthma in a cohort of pool workers
Gunnar F Nordberg,1 Nils-Goran Lundstrom,1 Bertil Forsberg,1 Annika Hagenbjork-Gustafsson,1 Birgitta J-son Lagerkvist,1 Johan Nilsson,1 Mona Svensson,1 Anders Blomberg,2 Leif Nilsson,1,3 Alfred Bernard,4 Xavier Dumont,4 Helen Bertilsson,1 and Kare Eriksson1
1Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine, Umea University, SE-90187 Umea, Sweden
2Department of Public Health and Clinical Medicine, Medicine/Respiratory Medicine, Umea University, Umea, Sweden
3Department of Mathematical Statistics, Umea University, Umea, Sweden
4Unit of Industrial Toxicology and Occupational Health, Catholic University of Louvain, Brussels, Belgium
Correspondence to Dr  Gunnar F Nordberg; gunnar.nordberg/at/envmed.umu.se
Received March 31, 2012; Accepted August 21, 2012.
Abstract
Objectives
Exposure to trichloramine (NCl3) in indoor swimming-pool environments is known to cause mucous membrane irritation, but if it gives rise to changes in lung function or asthma in adults is not known. (1) We determined lung function in volunteers before and after exposure to indoor pool environments. (2) We studied the occurrence of respiratory symptoms and asthma in a cohort of pool workers.
Design/methods/participants
(1) We studied two groups of volunteers, 37 previously non-exposed healthy persons and 14 pool workers, who performed exercise for 2 h in an indoor pool environment. NCl3 in air was measured during pool exposures and in 10 other pool environments. Filtered air exposures were used as controls. Lung function and biomarkers of pulmonary epithelial integrity were measured before and after exposure. (2) We mailed a questionnaire to 1741 persons who indicated in the Swedish census 1990 that they worked at indoor swimming-pools.
Results
(1) In previously non-exposed volunteers, statistically significant decreases in FEV1 (forced expiratory volume) and FEV% (p=0.01 and 0.05, respectively) were found after exposure to pool air (0.23 mg/m3 of NCl3). In pool workers, a statistically significant decrease in FEV% (p=0.003) was seen (but no significant change of FEV1). In the 10 other pool environments the median NCl3 concentration was 0.18 mg/m3. (2) Our nested case/control study in pool workers found an OR for asthma of 2.31 (95% CI 0.79 to 6.74) among those with the highest exposure. Exposure-related acute mucous membrane and respiratory symptoms were also found.
Conclusions
This is the first study in adults showing statistically significant decreases in lung function after exposure to NCl3. An increased OR for asthma among highly exposed pool workers did not reach statistical significance, but the combined evidence supports the notion that current workroom exposures may contribute to asthma development. Further research on sensitive groups is warranted.
Keywords: Public Health, Respiratory Medicine (See Thoracic Medicine), Occupational & Industrial Medicine
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