A Follow-up Study of the Grain Elevator Workers in the Port of Vancouver

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Abstract
A second respiratory survey was conducted on 587 grain elevator workers in the Port of Vancouver and on 111 civic workers, 25 years after the first health survey. The prevalence of respiratory symptoms and lung function findings among grain elevator workers in the second survey were almost identical with those in the first health survey, even though the dust concentration was lower in the elevators during the second survey. The longitudinal study in 396 grain workers showed that the prevalence of respiratory symptoms increased slightly during the second health survey among workers who had the same smoking habits during both surveys. Of the smokers who had respiratory symptoms or lung function impair-ment in the first survey, 23.5% followed our advice and gave up smoking; the prevalence of cough and sputum pro-duction decreased among these workers. The annual decline in function was greater for grain workers than civic workers particularly among workes over the age of 50 years when the differences in annual decline in forced expiratory volume in 1 sec (FEV1.0) and maximal mid-expiratory flow rate (MMF) between the two work groups became statistically significant. The annual decline in lung function was significantly correlated with age and smoking for both work groups. Cigarette smokers had a greater decline in lung function than nonsmokers,and older workers also showed a more rapid decline in lung function compared to younger workers. The relationship between FEV1.0 FVC, and MMF with age was quadratic rather than linear. Among grain workers the decline in lung function was not correlated with initial lung function, presence of respiratory symptoms, atopic status, or duration of exposure. It was, however, correlated with the acute changes in lung function over the course of one work shift and one work week. We conclude that grain dust has deleterious effects on the lung function of the workers and that it should not be regarded as a nuisance dust.