Can the occurrence of bronchial asthma in potroom workers be prevented?

Bronchial reactivity was evaluated in a group of 35 workers at preemployment examination using the metacholine test. Three workers showed an increased bronchial reactivity, the rate being in accordance with the previous experience. Ten randomly chosen subjects with normal reactivity, who were engaged as potroom workers, were followed up during a two-to-five-year period. None of them experienced any significant respiratory complaints and their bronchial reactivity also remained normal. Only one worker had a borderline finding (PD20FEV1). Although selection at preemployment medical examination is a measure that has to be used only exceptionally, based on the finding obtained by non-specific bronchoprovocation challenge it seems that it can be recommended in the case of that particular exposure.

Follow-up of airway reactivity in potroom workers in relation to exposure.

Two groups of workers were studied: a) 24 workers with respiratory complaints--7 of whom were light and 4 borderline hyper-reactors--who continued to work on the electrolytic reduction of aluminium for up to two years; b) 30 workers with increased bronchial reactivity who ceased to work in potrooms for 3.7 years on average (range 2-11 years) because of respiratory complaints. Subjective respiratory complaints were recorded and a non specific bronchial reactivity test was performed one or two times during the follow-up period. A sustained level of airway reactivity was recorded in both groups of workers regardless of exposure conditions. In workers with dyspnoea and airway obstruction, bronchial reactivity did not worsen in spite of continued exposure. On the other hand cessation of exposure was not followed by normalization of bronchial reactivity. The potential role of atopy, smoking habits and length of previous exposure was analyzed. It appears that increased bronchial reactivity, once induced, has a tendency to persist. An improvement in subjective complaints may be expected after cessation of exposure.

Bronchial hyperreactivity in potroom workers and prognosis after stopping exposure.

A group of 30 potroom workers who developed an asthma-like syndrome during their work in the electrolytic extraction of aluminium (Alu-Swiss process with prebacked anodes) was followed up after stopping exposure. Subjective respiratory complaints were registered and a non-specific bronchial reactivity test using methacholine was performed once or twice during the follow up period (1984-9). After transfer to other work most workers either had an improvement in respiratory symptoms (60%) or even normalisation (27%); only 13% did not show changes. Bronchial hyperreactivity remained unchanged in 67% of workers, was less pronounced in 13%, normalised in 13%, and deteriorated in 7%. Smoking habits, atopy, and duration of exposure did not seem to have influenced the results obtained. No significant correlation was found between duration of exposure and the speed of onset of respiratory symptoms and the later prognosis of the syndrome. Based on the information collected during the period of observation it appears that reactive airway dysfunction syndrome, once induced, has a tendency to persist. An improvement in subjective complaints may be expected, however, after stopping exposure.