Effect on pulmonary functions of dust exposed rice mill workers in comparison to an unexposed population.

Abstract

Paddy milling is the oldest and largest agro-processing industry in India. A large number of workers are employed in the rice mills where they are potentially exposed to dust. It has been shown that exposure to dust results in a high prevalence of respiratory diseases, such as asthma, chronic bronchitis, extrinsic allergic alveoli ties, toxic syndrome, and interstitial lung disease. The aim of this study was to investigate the effect of dust on rice mill workers' health using lung function tests with comparison to an unexposed population. Two hundred eighteen rice mill workers (exposed volunteers) were randomly selected from 25 rice mills in Assam, India. Participants were 18-60 years with at least one year of work experience. Further, 377 volunteers who were not exposed to dust and having similar demographic characteristics also participated as a control group. Pulmonary function tests were conducted for all participants by spirometry. The tests included forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC (%), peak expiratory flow (PEF) and forced expiratory flow during the middle half of a forced vital capacity (FEF25-75%). Values from exposed workers were compared with the unexposed volunteers. It was observed that the lung function parameters FVC, FEV1, PEF and FEF25-75% in exposed workers were significantly decreased compared with unexposed volunteers. There were also significantly decreased FVC, FEV1, FEV1/FVC%, PEF and FEF25-75% with increase in age and duration of dust exposure. It was further observed that 48% and 32% of the total male and female volunteers, respectively, had evidence of lung disease. Irrespective of gender, approximately 45% of mill workers had evidence of lung disease, of which 21% was restrictive and 24% was obstructive. Compared with unexposed controls, rice mill workers have a greater prevalence of respiratory disease based on pulmonary function tests.