A STUDY OF SPANISH SEPIOLITE WORKERS

Background-Sepiolite is an absorbent clay that is used as pet litter. It form thin crystals, which are a transition between chain and layere d silicates Inhalation studies in animals have shown no evidence of pu lmonary damage. This paper reports a cross sectional study o the total work force of the largest sepiolite production plant in the world. Me thods-Two hundred and eighteen workers (210 men and eight women) were studied. Height, age, and smoking history were recorded. Chest radiogr aphs were read according to the International Labour Office (ILO) clas sification by two readers. Readings were used to construct a numerical score, which was then used in statistical analyses. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were divi ded by the square of the height. Casella size selective personal sampl ers were used in randomly selected operatives to collect dust eight ye ars before the rest of the study was carried out. These samples were e valuated gravimetrically. Total dust samples were examined by optical and electron microscopes. Results were analysed by bivariate linear re gression, chi2 tests, and analysis of variance. Results-When allowance was made for smoking habit workers exposed to dry dust showed a signi ficantly greater decline in FEV1 with age than workers with little exp osure to dry dust. A similar pattern applied to FVC. Radiographic scor e showed deterioration with age but no clear differences from other va riables. High concentrations of dust were found in the bagging departm ent and also in the classifier shed. Conclusions-The major finding was that lung function deteriorated more rapidly in those who had had mor e exposure to dust, but there was no evidence of any accompanying radi ographic change.