Authors' Response

Abstract

To the Editor: We thank Drs. Attfield et al for their thoughtful review of our article.1 We also appreciate their comments about risks of silicosis among coal miners who perform certain types of coal mining activities such as drilling through siliceous rock and that they may experience higher levels of crystalline silica exposures. We also note the occurrence of a mixed dust pneumoconiosis2 among coal miners that has been described as anthracosilicosis.3 The purpose of our report, however, was not to address all the pulmonary hazards potentially associated with coal mining but “to assess the scientific literature related to studies that have investigated the active agent(s) within coal responsible for causing CWP.” Any “downplaying” of risks of silica exposure among coal miners was not only unintended but also inadvertent. We mentioned explicitly [1, p465] the observations of Miller et al4 from the Scottish coalmine and concluded in the summary of our article: “The link between quartz and the development of CWP is minimal, aside from circumstances associated with high concentrations of quartz (usually >10%) in which the pulmonary response is more typical of silicosis as opposed to CWP” [1, p470]. We hope that critical readers would not be confused and that they will understand that the clear focus of the report was to identify features of coal associated with coal workers' pneumoconiosis (CWP), not downplay silica. In light of increased energy demands in a growing world economy, we hoped to identify features of coal associated with CWP such that preventive efforts may be enhanced. Robert J. McCunney, MD, MPH Department of Biological Engineering Massachusetts Institute of Technology Cambridge, MA Peter Morfeld, PhD Institute for Occupational Epidemiology and Risk Assessment Evonik Industries Essen, Germany and Institute for Occupational Medicine Cologne University North Rhine-Westphalia, Germany Stephen Payne, BS Department of Biological Engineering Massachusetts Institute of Technology Cambridge, MA