The respiratory symptoms and ventilatory lung functions of the production-line workers (F-exposed) at an aluminum plant in China have been studied. The data were compared with those obtained from the office workers (controls). F-exposed groups had a higher prevalence of respiratory symptoms than controls and their complaints of phlegm were significantly increased in the older subjects. Whereas several cases of chronic bronchitis were observed in the F-exposed groups, none could be found in the controls. The expiratory flow rate at 25% of the vital capacity/height (V25), which is sensitive in the detection of small airway obstruction, was decreased.
The present epidemiological study on the prevalence of respiratory disease was carried out according t o t h e most widely and comprehensively validated MRC questionnaire. The questionnaire is characterized by its making group comparison of the prevalence of individual symptoms singly or in combination, instead of searching for names of specific diseases such as bronchitis. The results obtained from this study clearly indicate the effect of working environment on the respiratory system of workers (Tables 1 and 2) and confirm the earlier findings reported on Japanese aluminum refinery workers (4). A greater number of the pot-line workers had cough and phlegm than office workers at the refinery. This is particularly true in Group D with an average age of 50.4 years. Compared with the controls, a higher percentage of subjects in this group complained of cough and phlegm.
The means of ‘?25/HT given by the F-exposed group (Table 2) were lower than that reported elsewhere (5). It is important that this criterion reflects the severity of the small airway obstruction resulting from F-exposure, an observation supported by the high prevalence of chronic bronchitis syndrome found in the F-exposed group (Table 1). Saric et al. (6) reported bronche constrictive symptoms among workers employed at an aluminum plant in Yugoslavia. Similarly, Wergeland et al. (7) observed persons working in the potrooms in a primary aluminum production plant in Norway to suffer from “potroom asthma.” After cessation of exposure, these workers still had respiratory dysfunction such as morning cough, dyspnea on exertion, and wheezing.
Further evidence of the linkage between fluoride air pollution and respiratory symptoms and lung function was shown in a study which surveyed North American Indian children living on a reservation adjacent to an aluminum smelter (8).
Results of the interviews in this study showed that about two-thirds of the subjects were cigarette smokers Analysis of our data did not show that smoking itself contributed to the prevalence of respiratory symptoms or impairment of ventilatory function.