Detection of pleural plaques in workers exposed to inhalation of natural fluoro-edenite fibres.

Fluoro-edenite is a natural mineral species initially isolated in Biancavilla, Sicily. The fibres are similar in size and morphology to certain amphibolic asbestos fibres, the inhalation of which may cause chronic inflammation and cancer. Occupational asbestos exposure is known to be associated with pleural and lung diseases, including pleural plaques. The aim of this study was to report the pleural and lung parenchymal lesions detected by high-resolution computed tomography (HRCT) in a group of construction workers exposed to fluoro-edenite. Information regarding life habits and occupational history was collected from 43 workers enrolled into the study. The participants underwent physical examination, blood analysis, search for uncoated fibres and ferruginous bodies in the sputum, pulmonary function tests, including diffusion capacity for carbon monoxide (TLCO), and HRCT chest imaging. A general descriptive outcome analysis was also conducted; a prevalence ratio (PR) with 95% confidence interval and a two-tailed test P-value were calculated for pleural plaques using log-binomial regression, measuring plaque size and thickness, and cumulative exposure index (CEI). The mean values of the functional respiratory tests were within the normal range for all participants. A restrictive ventilatory defect was identified in two (5%) subjects and an obstructive ventilatory defect in three (7%) subjects. TLCO was reduced in two additional participants. Fibres were detected in 19 (44%) of subjects. Pleural involvement was documented in 39 (91%) workers, of whom 31 (72%) had bilateral plaques. Calcifications were detected in 25 (58%) of these participants. PR indicated a progressive increase in the risk of developing pleural lesions with rising CEI, i.e. length of exposure. The present findings demonstrate for the first time the presence of pleural plaques in the lungs of subjects exposed to fluoro-edenite fibres, and not to asbestos, through residing in Biancavilla and through their occupation.