Notified cases of occupational asthma in Norway: exposure and consequences for health and income.

Background: Estimates of occupational asthma (OA) may vary between countries and within countries. An overview of cases of occupational asthma in Norway has not been presented previously. Norwegian physicians are obliged to report occupational diseases to the Labor Inspection Authority. The registry of these notifications was used to study the cases of OA.

Methods: Data were collected from the notifications for respiratory disease for the period 1995-1999. A postal questionnaire inquiring into work, respiratory symptoms, smoking, and socioeconomic consequences of the disease was sent to 1,239 workers with a physician's diagnosis of obstructive respiratory disease.

Results: The response rate to the questionnaire was 81% (1,000 workers of whom 723 had OA). On an average, 223 annual cases of OA were reported in the study period (1995-1999). The highest incidence of notifications was found in the primary aluminum industry and in bakers, car painters, and welders. At the time of notification, more than half of the workers had left their original jobs. At the time of this study 2-6 years later, approximately the same proportion of workers had experienced a reduction in income and had received financial compensation; 60-78% were still on antiasthmatic medication.

Discussion: The notification of OA by Norwegian physicians may underestimate the true incidence considerably. A majority of the notified cases seemed to become chronic despite medical treatment.

Conclusions: More emphasis should be put on early recognition of OA and on the reduction or cessation of exposure after the diagnosis of OA.