OCCUPATIONAL ASTHMA IN NEW-ZEALANDERS - A POPULATION-BASED STUDY

Objectives--To examine the effect of occupation on respiratory symptom s in a randomly selected adult population aged 20-44 years. Methods--I t is based on the phase II sampling of the New Zealand part of the Eur opean Community respiratory health survey. 1609 people (63.9% response rate) completed a detailed respiratory questionnaire. Of those respon ding, 1174 (73%) underwent skin tests and 1126 (70%) attended to under go methacholine bronchial challenge. Current occupation was recorded a nd a previous occupation was also recorded if it had led to respirator y problems. 21 occupational groups were used for analysis for the five definitions of asthma: wheezing in the previous 12 months; symptoms r elated to asthma; bronchial hyperresponsiveness (BHR); BHR with wheezi ng in the previous 12 months; and BHR with symptoms related to asthma. Results--Prevalence odds ratios (ORs) were significantly increased fo r farmers and farm workers (OR 4.16, 95% confidence interval (95% CI) 1.33 to 13.1 for the combination of wheezing and BHR). Increased risks of prevalence of asthma were also found for laboratory technicians, f ood processors (other than bakers), chemical workers, and plastic and rubber workers. Workers had also been divided into high and low risk e xposure categories according to relevant publications. The prevalence of wheezing was greater in the high risk group (OR 1.57, 95% CI 0.83 t o 2.95) than in the low risk group. Atopy was associated with asthma, but the prevalence of atopy did not differ significantly between occup ational exposure groups. The attributable risk of wheezing that occurr ed after the age of 15 years and that was estimated to be due to occup ational exposure (based on the defined high risk group) was 1.9%, but this increased to 3.1% when farmers and food processors (other than ba kers) were also included in the high risk group. Conclusions--This pop ulation based study has identified certain occupations significantly a ssociated with combinations of asthmatic symptoms and BHR.