OCCUPATIONAL ASTHMA AND RHINITIS DUE TO WESTERN (CANADIAN) RED CEDAR (THUJA PLICATA)

Western or Canadian red cedar is proving to be a relatively common cause of occupational asthma and rhinitis; this paper summarizes our experience of 35 patients with this condition, which has not previously been fully described. In milder cases with intermittent exposure, or with recurring improvement at weekends or on vacation, the patient usually becomes aware of an occupational factor; nevertheless, both patient and doctor may be misled by the predominantly nocturnal character of the cough and asthma. In more severe cases, symptoms may persist either nocturnally or continuously for days or weeks after exposure has ceased. Diagnosis may be difficult in these circumstances, and requires an awareness of the hazard and the taking of a comprehensive occupational history. Some benefit may be obtained from symptomatic therapy, but avoidance of the timber is the only effective treatment in most cases, and should be recommended in all.