Longitudinal assessment of airway caliber and responsiveness in workers exposed to chlorine

This longitudinal study (1992-1994) was performed to determine the relation between accidental chlorine exposure and changes in lung function and airway responsiveness in 239 workers in a metal production plant. These workers had taken part in a cross-sectional survey in 1992. In both the initial and the follow-up surveys, history of exposure to chlorine ("puffs"), accidental chlorine inhalation reported to the first-aid unit (gassing incidents), and of chronic symptoms were documented; spirometry and methacholine challenge tests were performed. At follow-up, 211 workers (88.3%) were seen. In workers with 20 pack-years or more of cigarette smoking, the fall in FEV(1) was associated with having had a gassing incident during the follow-up period; the fall in FEV(1)/FVC (%) was predicted by the number of puffs causing mild symptoms between the two assessments. An increase in airway responsiveness (PC(20) decrease > 1.5-fold) was present in 19 workers; it was associated with accidents reported to the first-aid unit during the previous 2 yr (OR: 5.9, 95% CI: 1.1 to 32.3). These findings suggest: (1) an effect on airway function related to the estimated number of puffs with mild symptoms and gassing incidents, mostly among smokers; (2) a detectable increase in airway responsiveness associated with gassing incidents.

Chronic rhinitis in workers at risk of reactive airways dysfunction syndrome due to exposure to chlorine

BACKGROUND

To assess the frequency of chronic upper airways symptoms and to relate the presence of these symptoms to accidental exposure to chlorine and changes in lower airways symptoms, airway function, and bronchial responsiveness in a cohort of workers at risk of sporadic occupational exposure to high concentrations of chlorine.

METHODS

Data were collected on symptom assessment, spirometry, and methacholine challenge tests from 211 workers seen twice at a 2 year interval (1992-4).

RESULTS

The proportion of workers reporting chronic rhinitis was 46.9% in 1992 and 42.2% in 1994. Chronic rhinitis reported in 1994 was significantly associated with acute exposure to chlorine (self reports, p = 0.02; first aid reports, p = 0.001). In a multivariate logistic regression analysis the presence of reported accidents at the first aid unit (one accident, odds ratio (OR) 3.1, 95% confidence interval (95% CI) 1.3 to 7.5; two or more accidents, OR 6.2, 1.1 to 35.8) and of personal atopy (OR 5.5, 2.2 to 10.8) were significant predictors of chronic rhinitis in 1994. Chronic lower airways symptoms were more frequent in 1994 among workers reporting chronic rhinitis on both assessments than in others (p = 0.03) and changes in bronchial responsiveness were more pronounced in those with persistent rhinitis (p = 0.09).

CONCLUSIONS

These results suggest that persistent nasal symptoms in workers at risk of reactive airways dysfunction syndrome could be a useful marker of lower respiratory tract abnormalities.

Changes in airway function and bronchial responsiveness after acute occupational exposure to chlorine leading to treatment in a first aid unit

OBJECTIVES

To describe the baseline characteristics and the time course of changes in lung function in workers accidentally inhaling high concentrations of chlorine in a prospective study.

METHODS

Baseline spirometry and methacholine challenge test were performed in a cohort of 278 workers at risk of accidental inhalation of chlorine. Workers in whom accidental inhalation led to intervention in a first aid unit were reassessed five to 25 days after the accident and serially thereafter when there where notable changes.

RESULTS

During a four year follow up period, 13 workers were seen at the first aid unit after a symptomatic accidental inhalation. Three of them experienced notable functional changes: one worker experienced a 10% fall in forced expiratory volume in one second (FEV1), and the other two had a notable fall in the concentration of methacholine that caused a 20% fall in FEV1 (PC20). Two workers were smokers and one had a personal history of atopy. Baseline assessment was within the normal range in these three workers. Recovery was complete three months after the accidental inhalation.

CONCLUSION

Transient but notable decreases in airway function or increases in bronchial responsiveness can occur after an accidental inhalation of high concentrations of chlorine in workers at risk.

Cross-sectional assessment of workers with repeated exposure to chlorine over a three year period

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.