Rapid clinical progression of silicosis in quartz conglomerate workers in Southern Spain

Background: Cases of silicosis among workers involved in the manufacturing of quartz conglomerates (QC) products used in kitchen countertops have been widely reported in the last years. Research suggests a more rapid evolution of the disease compared to classical form in miners. Objective: To evaluate clinical and functional progression of silicosis in QC workers in a cohort of patients from the province of Cadiz. Methods: We collected information on all patients diagnosed with silicosis in our area between 2009 and 2016. All of them had worked manufacturing QC countertops. Two radiologists confirmed diagnoses by chest X-ray and/or HRCT. Results: Ninety five workers were diagnosed in the study period. All were men, with mean age at diagnosis 35,1±6,9 (mean±SD) years. Length of exposure to silica dust was 12,9±5,5 years. Most cases (81%) were detected between 2010 and 2013. At the time of diagnosis, 88 cases were classified as Simple Chronic Silicosis (SCS) and 7 cases as Complicated Chronic Silicosis (CCS). After an average follow-up time of 3,4±1,7 years 21/88 patients with SCS developed CCS yielding 28 a total of CCS cases (29,5%). Four patients died, two of them after lung transplantation. At diagnosis 71% of patients had FVC in a normal range (ATS/ERS classification) and 30,2% of patients had normal values of DLCO. After follow-up, 57% and 26,7% of patients presented FVC and DLCO, respectively, in a normal range. Conclusions: Silicosis caused by inhalation of dust from quartz engineered stone is an aggressive and rapidly progressive disease. Due to the extensive use of this material, there is urgent need to foster active surveillance and to promote basic and applied research.