Occupational asthma due to persulfate salts: diagnosis and follow-up.

BACKGROUND Persulfate salts have been identified as a cause of occupational asthma (OA). The aim of the present study was to describe the clinical characteristics, diagnostic testing results, and follow-up of eight patients with OA that was triggered by these chemical compounds. METHODS Eight patients with OA due to exposure to persulfate salts were studied. Immunologic, lung function, and specific bronchial challenge tests (SBCTs) were performed in all patients. Once their condition had been diagnosed, the patients were seen every 1, 3, and 6 months for a mean duration of 18 months. RESULTS The mean time of exposure to persulfate salts up to diagnosis was 15 years (range, 3 to 27 years), and mean time that had elapsed between symptom onset and diagnosis was 38 months (range, 3 to 120 months). Three patients were smokers, six patients presented with rhinitis prior to asthma in relation to persulfate exposure, and three presented with dermatitis. The results of total IgE tests were positive in six patients, and the results of skin-prick tests for detection of persulfate salts were positive in five of these patients. The results of a SBCT was positive in the seven patients in whom it was performed. Symptoms persisted in all but one patient and required medical treatment. CONCLUSIONS The results suggest that the reliable diagnosis of OA due to persulfate salts must be based on the specific challenge test until further experience has been acquired. Despite avoiding exposure, patients continued with symptoms and required treatment for the control of symptoms. Finally, a dependent IgE mechanism appears to be implicated in the pathogenesis of OA due to exposure to persulfate salts.