We are grateful for the opportunity to respond to the comments of Martínez González et al.1 regarding our earlier communication2 on the detection and description of a cluster of silicosis cases among young quartz agglomerate workers in Chiclana de la Frontera (Cádiz).3 We will try to address the main points raised, despite the limitations imposed by some imprecise statements, which we, for our part, may have misinterpreted. We are concerned that our findings – and the conclusions drawn from them – have been described as mere opinions. The authors, by using only the International Classification of Radiographs in Pneumoconiosis of the International Labor Organization to argue against the validity of our results, appear to overlook the fact that the diagnosis were based primarily on the anatomical pathology results of four lung biopsies obtained by video-assisted thoracoscopy. When confirmation of a cluster of silicosis cases was received from the pathology department, high-resolution computed tomography (HRCT) was used to confirm the diagnosis in patients who were already symptomatic, nine of whom showed no changes on standard chest X-ray (CXR). Eight of these patients have currently been diagnosed with silicosis, including two who have developed complicated chronic silicosis.

In our procedures for screening and monitoring exposed workers, we do not underestimate the historically proven value of CXR. Nevertheless, after the appearance of several very severe cases, one terminating in death and another two waitlisted for lung transplantation, and in the context of the cluster described, HRCT, an accessible test with a very high positive predictive value, was used to improve the quality of the diagnosis. In an original article,3 we raise the issue of difficulty in interpreting CXR, which were initially judged normal in some patients. Other authors have mentioned limitations such as wide inter-evaluator variability and underdetection in the diagnosis of silicosis.4 In contrast, HRCT provides more information than CXR, particularly in the early stages of the disease,5 as we were able to confirm in our series. HRCT is more sensitive and specific in the diagnosis of silicosis, revealing early subpleural rounded opacities in the lower lobes or mediastinal lymph nodes that could not be visualized on CXR.6 The advantages of HRCT are substantial, since if silicosis is detected early in an exposed worker, quicker action can be taken to adapt the subject's employment and to reduce the chances of disease progression.

Thus, it seems unreasonable to dismiss as alarmist the publication of this series of cases associated with preventable exposure and serious consequences for public health, simply because they do not follow a standard diagnostic protocol. Indeed, standard diagnostic procedures were not ignored, they were only improved under the specific conditions of our clinical investigation. We are convinced that our study, and both the reflections that arose a posteriori and the general hypotheses generated from our initial findings are ethically correct, do not involve any conflict of interest, and respond to society's expectations of scientists. In this respect, one of the aims of the article was to combine our efforts with those of other clinicians and researchers interested in broadening our understanding of both the disease and the multiple interventions needed to reduce the impact of this form of silicosis in synthetic stone workers,7 some of which have already been put into practice. We hope that these additional clarifications will be useful for advancing on both fronts.