Prevalence of occupational asthma among workers exposed to eastern white cedar.
We assessed the prevalence of occupational asthma among current (n = 29/31, 94%) and former (n = 13/49, 27%) employees of a sawmill in which eastern white cedar has been made into shingles during the past 3 yr. All participants answered a respiratory questionnaire, and all except one underwent spirometry and methacholine inhalation tests. All those with bronchial hyperresponsiveness (PC20 methacholine < or = 19 mg/ml) were invited to undergo specific inhalation challenges. Mean duration of exposure was 13 mo (19 workers > 12 mo). Twenty-eight workers (65%) reported a history compatible with asthma, and 25 (58%) had symptoms that were suggestive of occupational asthma. Only two subjects had significant airway obstruction (FEV1 < 80% pred) (mean value = 98% pred). Eighteen subjects (42%) had a PC20 < or = 16 mg/ml. Specific inhalation tests with plicatic acid and/or western red cedar (which contains twice as much plicatic acid as eastern white cedar), were done on 12 subjects who had a PC20 < or = 16 mg/ml when they were assessed. Three subjects were considered to have positive tests (one had an isolated immediate reaction, one had a late reaction, and one had significant changes in PC20 each time he was exposed but no changes in FEV1). Environmental monitoring showed concentrations of total dusts above 2 mg/m3 in half of the samples. The prevalence of occupational asthma in this workplace was three of 42 participants (7%) or at least three of 80 (3.8%) of all current or ex-workers. This is comparable to the prevalence of occupational asthma in subjects exposed to western red cedar.
Department of Chest Medicine, Hôpital du Sacré-Coeur, Montreal, Quebec, Canada.
J L
JL
Malo
A
A
Cartier
J
J
L'Archeveque
C
C
Trudeau
J P
JP
Courteau
L
L
Bherer
D000328:Adult; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D004391:Dust / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D009784:Occupational Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D015995:Prevalence; D011792:Quebec / Q000453:epidemiology; D012129:Respiratory Function Tests / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D014934:Wood
D004391:Dust