Medline ® Abstracts for References 20,45
of 'Reactive airways dysfunction syndrome and irritant-induced asthma'
Cross-sectional assessment of workers with repeated exposure to chlorine over a three year period.
Gautrin D, Leroyer C, L'Archevêque J, Dufour JG, Girard D, Malo JL
Eur Respir J. 1995;8(12):2046.
Airflow obstruction has been described in workers who experienced symptoms after acute exposure to chlorine. Persistent bronchial hyperresponsiveness has also been assessed, but mainly in case studies. In this cross-sectional study, we have assessed the relationship between inhalational accidents ("puffs") involving chlorine and persistent symptoms as well as hyperresponsiveness in 239 out of 255 at-risk workers (94%). No relationship was found between persistent symptoms and the exposure variables studied. Forced vital capacity (FVC) was higher in subjects who had had no symptoms after a "puff", compared with those who had experienced mild symptoms. Forced expiratory volume in one second (FEV1) and FVC were significantly lower in subjects who experienced more than 10 puffs with mild symptoms than in subjects who reported no symptomatic puff. The presence of bronchial hyperresponsiveness was not related to exposure, but the methacholine dose-response slope showed a tendency to increased bronchial responsiveness with increased exposure. A significant difference was shown in subjects who experienced more than 10 puffs with mild symptoms. In this group of workers, repeated exposure to chlorine with acute respiratory symptoms was associated with a slight but significant reduction in expiratory flow rates, together with an increase in bronchial responsiveness, without long-term symptoms.
Dept of Chest Medicine, Hôpital du Sacré-Coeur, Montreal, Canada.
Effects of dexamethasone on functional and pathological changes in rat bronchi caused by high acute exposure to chlorine.
Demnati R, Fraser R, Martin JG, Plaa G, Malo JL
Toxicol Sci. 1998;45(2):242.
We assessed the effects of dexamethasone on functional and histological changes after acute exposure to a high level of chlorine gas in an animal model of reactive airways dysfunction syndrome (RADS). Sprague-Dawley male rats were exposed to 1500 ppm of chlorine for 5 min and treated with either dexamethasone (dex; 300 micrograms/kg/day) or saline intraperitoneally for 7 days. Lung resistance (RL), airway responsiveness to inhaled methacholine (MCh), airway wall morphometric measurements, and bronchoalveolar lavage (BAL) cells were assessed over a 2-week period after exposure. Dex administration significantly attenuated both chlorine-induced increased RL and chlorine-induced increased responsiveness to methacholine compared with saline: -2.7 +/- 6.8% vs 102.3 +/- 36.6% change from baseline RL (P<0.01) and 2.5 +/- 0.6 mg/ml vs 1.2 +/- 0.7 mg/ml in the MCh concentration required to double the RL from baseline (P<0.01). There was a tendency, albeit nonsignificant, for improvement in some indices of epithelial injury. Dex significantly attenuated the postexposure neutrophilic cellular response in BAL 1 day after exposure (15.8 +/- 4.9% neutrophils in the dex group vs 49.8 +/- 2.7% neutrophils in the saline group) (P<or = 0.001). Our results show that dex administration helps maintain pulmonary function, reduces BAL inflammatory cell number, and tends to improve some morphometric airway wall structure parameters in rats exposed to chlorine.
Department of Chest Medicine, Hôpital du Sacré-Coeur, Montreal, Quebec, Canada.