Occupational asthma in Finland

Abstract

Summary In Finland occupational asthma caused by protein allergens and reactive chemicals present in the air of work environments is increasing. This communication describes provocative challenge tests and methods for measuring exposure under simulated work conditions. The importance of lung function measurements during non‐exposure and placebo periods is stressed. Especially late reactions are difficult to assess because of the great circadian variation in the lung function parameters of asthmatics. For a positive challenge test, a decrease in peak flow values of at least 15% and a clear deviation from normal circadian variation and placebo periods is required. The allergens of vegetable or animal origin primarily affect patients with an atopic constitution. Chemical allergens seem to attack all exposed workers in the same way. The report lists the occupations with risk for asthma and refers to the population at risk; bakers seem to be the group with the most risk. The importance of early diagnosis, removal of the worker from exposure and improvement of the hygienic aspects of the work environment are stressed.

Supplement

“…According to provocation tests two cases from the latter group were caused by cobalt. In 1976, 17 new cases of occupational asthma were reported from the Finnish metal products and machine manufacturing industries, where the population at risk was about 140,000 (29). Former morbidity rates for asthma from the Finnish metallurgic industry are not known.…”

“…If a previously healthy person becomes sensitized to agents encountered in his work environment and the outcome is asthma, the person is usually eligible for compensation for an occupational disease. A positive specific provocation test is normally required (29).…”

“…The Institute uses the following clinical criteria for occupational asthma (3,29): (a) a 15 % or more decrease in forced expiratory volume in 1 s (FEV t ) after histamine challenge or after provocation with 1 Ofo methacholine vapor and (b) a 15 Ofo or more decrease in peak flow after challenge with a specific occupational agent and a clear distinction of the normal peak flow from normal circadian variation after a specific challenge test.…”

“…They suggested that exposure to 1.0-2.5 ppm (cm 3 /m 3 ) of sulfur dioxide caused a significant loss of FEV 1 (79 ml/a) in a susceptible subgroup. In the normal US male population the yearly decrease in FEV I is [25][26][27][28][29][30][31][32][33][34][35] There is evidence from controlled laboratory studies that sulfur dioxide concentrations of 3-5 ppm (cm 3 /m 3 ) decrease bronchiall air flow already after 3-5 min of exposure (31). It also causes throat irritation and a cough at these concentrations.…”

Impact of occupation on respiratory disease

“…The SWORD project in Britain (2) and the SENSOR system in the United States (3) are such examples. Sweden (4) and Finland ( 5 ) have similar surveillance systems.…”