Longitudinal decline in lung function measurements among Saskatchewan grain workers.
OBJECTIVE
To evaluate the relationship between the long term effects of grain dust and decline in lung function among grain elevator workers in Saskatchewan, studied over a 15-year period.


METHODS
The Grain Dust Medical Surveillance Program was started by Labour Canada in 1978 and longitudinally studied the respiratory health of Canadian grain elevator workers over a 15-year period (1978 to 1993). Data on respiratory symptoms and pulmonary function tests (forced expiratory volume in 1 s [FEV1], forced vital capacity [FVC]) were collected once every three years; each three-year interval was called a 'cycle'. Data from Saskatchewan were analyzed for this report. A transitional model using the generalized estimating equations approach was fitted using a SAS macro to predict the annual decline in FEV1 and FVC.


RESULTS
Previous lung function, as one of the covariates in the transitional model, played an important role. Significant predictors of FEV1 were previous FEV1, base height, weight, years in the grain industry, current smoking status, cycle II, cycle III and cycle V. Significant predictors of FVC were previous FVC, base height, weight, years in the grain industry, cycle II, cycle III and cycle IV.


CONCLUSIONS
The estimated annual decline in FEV1 and FVC increased according to length of time in the grain industry among nonsmoking, ex-smoking and smoking grain elevator workers. Lung function values improved after dust control, and yearly declines in FEV1 and FVC after dust control were smaller compared with yearly losses before dust control.
Pahwa
Punam
P
Department of Community Health andEpidemiology, Institute of Agricultural, Rural andEnvironmental Health, University of Saskatchewan, Saskatoon, Canada. pahwa@sask.usask.ca
Senthilselvan
Ambikaipakan
A
McDuffie
Helen H
HH
Dosman
James A
JA
D000328:Adult; D000382:Agricultural Workers' Diseases / Q000453:epidemiology*; D004391:Dust; D002523:Edible Grain; D006801:Humans; D019570:Inhalation Exposure / Q000706:statistics & numerical data; D016015:Logistic Models; D015999:Multivariate Analysis; D016273:Occupational Exposure / Q000706:statistics & numerical data*; D011159:Population Surveillance; D012129:Respiratory Function Tests / Q000706:statistics & numerical data*; D012525:Saskatchewan / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology; D013995:Time
D004391:Dust