Historical Perspective From the Definition of Silicosis at the 1930 Johannesburg Conference to the Blurred Boundaries Between Pneumoconioses, Sarcoidosis, and Pulmonary Alveolar Proteinosis (PAP) Michel Vincent, 1,2Ã Cecile Chemarin, 1 Catherine Cavalin, 2,3,4 Mikael Catinon, 1,2 and Paul-Andre  Rosental 2,3,5 The 1930 International Labour Office Conference on silicosis in Johannesburg identified silicosis by setting a medicolegal framework to its nosology: as with other occupational illnesses, its medical content was fixed under economic pressure. This article follows a reading of all the proceedings of this conference (debates and reports of experts) to examine their potential impact on the etiology and nosology of other diseases, specifically sarcoidosis and pulmonary alveolar proteinosis (PAP), “idiopathic” diseases in which inorganic particles may be involved. Wepropose renewed study of the role of inorganic particles in these diseases. To do this, we propose to mobilize detection means such as mineralogical analysis and electron microscopy and in depth interviewing that are currently seldom used in France, in order to establish diagnosis and the potential occupational and environmental origin of these diseases. Am. J. Ind. Med. 58:S31–S38, 2015. ß 2015 Wiley Periodicals, Inc. KEY WORDS: pneumoconiosis; sarcoidosis; pulmonary alveolar proteinosis; in-depth interview; mineralogical analysis INTRODUCTION Since the twentieth century, the leading causes of illness have been attributed to nutritional deficiencies, to exposure to toxic substances and infectious agents, to psychological dysfunction, and/or to genetic predisposition [Genuis, 2012]. A review of the 1930 International Labour Office Conference on silicosis in Johannesburg proceed- ings [ILO, 1930] opens the way for new avenues of research on possible environmental causes of diseases that are considered to be of undetermined etiology. We concentrate here on sarcoidosis and acute pulmonary alveolar proteinosis (PAP) [Blanc, 2015] to show how these idiopathic diseases may be revisited from an understanding of silica-induced lung pathologies as expressed by the 1930 Johannesburg Conference. 1 Pneumology Unit and Laboratory of mineral pathologies at the Centre Hospitalier Saint Joseph Saint Luc, Lyon, France 2 Centre for European Studies, ERC Grant Silicosis Sciences Po, Paris, France 3 Interdisciplinary Laboratory for Evaluation of Public Policies (LIEPP), Sciences Po, Paris, France 4 Centre for Employment Studies, Noisy-le-Grand, France 5 National Institute for Demographic Studies (INED), Paris, France Contract grant sponsor: European Research Council (ERC)/SILICOSIS project/ Principal investigator: Paul-Andr e Rosental; Contract grant number: ERC-2011- ADG_20110406^Project ID: 295817; Contract grant sponsor: Sciences Po 2013 Scien- tific Advisory Board, Les poussi  eres de Givors/Principal investigator: Paul-Andr  e Rosental. Correspondence to: Dr. Michel Vincent, Pneumology Unit and Laboratory of mineral pathologies at the Centre Hospitalier Saint Joseph Saint Luc, 20 Quai Claude Bernard, 69007 Lyon, France. E-mail: mvincent@ch-stjoseph-stluc-lyon.fr Accepted 17 July 2015 DOI 10.1002/ajim.22518. Published online in Wiley Online Library (wileyonlinelibrary.com). AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 58:S31–S38 (2015) ß 2015 Wiley Periodicals, Inc.