Am. J. Respir. Crit. Care Med., Vol 150, No. 4, Oct 1994, 1142-1145.
Bronchial hyperresponsiveness can improve while spirometry plateaus two to three years after repeated exposure to chlorine causing respiratory symptoms
JL Malo, A Cartier, LP Boulet, J L'Archeveque, F Saint-Denis, L Bherer and JP Courteau
Department of Chest Medicine, Hopital du Sacre-Coeur, Montreal, Hopital Laval, Quebec City, Canada.
Repeated exposure to chlorine in pulp mills and paper can induce persistent
asthma-like symptoms such as bronchial hyperresponsiveness and variable
changes in airway caliber. The long-term time course of bronchial
hyperresponsiveness has not been examined. We studied 20 of 29 subjects
(69% participation rate) who demonstrated bronchial hyperresponsiveness to
methacholine when they were first assessed, 18 to 24 mo after repeatedly
inhaling "puffs" of high concentrations of chlorine in a paper mill over a
3-mo period. Each subject answered a respiratory questionnaire and
underwent spirometry and a methacholine inhalation test 12 mo after the
initial survey, 30 to 36 mo after the chlorine inhalations. Three subjects
required inhaled steroids at the time of the initial survey and three at
the time of the second, including two who carried on using these
preparations. Only one subject changed smoking habits. There were no
significant overall changes in FEV1 on the two occasions, nine subjects
having a FEV1 < 80% on the first occasion and eight on the second. Six
of the 18 subjects (33%) who underwent a methacholine inhalation test on
both occasions had significantly improved PC20 results, including five for
whom the PC20 value was within the normal range. All six subjects had
normal FEV1 values on both assessments. Although changes in spirometry
induced by repeated exposure to chlorine seem to persist, bronchial
hyperresponsiveness can improve significantly in those with normal airway
caliber. This suggests that less pronounced bronchial alterations induced
by repeated exposures to chlorine may be reversible.
