The Role of IARC in Causation of Occupational Diseases: Case Study of the Carcinogenic Evaluation of Crystalline Silica

The importance of causation of occupational diseases and the role of the International Agency for Research on Cancer (IARC) are discussed in this chapter. As a case study, the process by which silica dust was judged a known human carcinogen by IARC is reviewed. Silicosis is a chronic occupational lung disease known to be caused by inhaling crystalline silica, and the pulmonary cancer risk after the diagnosis of silicosis is a part of the IARC review of evidence. Laboratory animal evidence and mechanistic findings supporting IARC evaluation are also described. There remains a need to explore the association between silica exposure and other nonlung tumors, especially gastrointestinal cancers. The Occupational Safety and Health Administration (OSHA) developed a new regulatory standard that lowered the permissible exposure to 50ug/m3 in 2016. OSHA labeled silica as a known human carcinogen because of the IARC assessment. Occupational medicine leaders need to address several current silica dust problems such as silicosis/coal workers pneumoconiosis among coal miners, acute silicosis and auto-immune diseases among countertop workers, and intervention programs to lower silico-tuberculosis among South African miners. Future research studies need good silica dust monitoring estimates and high-quality industrial hygiene samples to evaluate the associations between silica exposure and many diverse diseases.

Keywords: Artisanal gold mining, Auto-immune ailments, Countertop manufacturing, Crystalline silica, History of causation assessment, Human cancer assessment, International Agency for Research on Cancer, Silico-tuberculosis, Silicosis, Lung cancer, National Institute for Occupational Safety and Health, Occupational diseases, Occupational Safety and Health Administration, Quartz epidemiology, Prevention, Quartz exposure in coal mines.