Why are Silica Dust Exposures and Silica-Related Health Effects Still a Global Concern?

Abstract

Background and aim Epidemiology studies of workers exposed to silica dust demonstrate that crystalline SiO2 is a multipotential hazard. Research among construction workers, miners, ceramic and brick workers, countertops workers, and sandblasters where respirable silica dust levels has been measured has demonstrated excess risk for silicosis, cor pulmopale, silica-tuberculosis (SiTB), several chronic respiratory conditions, coal workers pneumoconiosis (CWP), several auto-immune diseases, and cancers of the lung and gastro-intestinal tract. Methods Despite knowledge of these links over the past decades, occupational and environmental health professionals have not been able to address three new silica-related health issues. They are silicosis and CWP among US coal miners, severe silicosis and auto-immune ailments among countertop workers; and ongoing risk for SiTB among Africa miners. The author examined the literature for other novel silica-related health risks. Results Current workers and their managers seem to not have sufficient awareness of the occupational hazards of silica dust. There are new silica dust concerns including fracking sand, railroad ballast, and dust control in countertop machining. There are new cancer links with silica, including women and nonsmokers with excess lung cancer; excess lung cancer among patients with CWP; children’s dust exposure in small-scale gold mining; and excess lung diseases and pulmonary cancer among railroad workers. There is need for research on improved silica sampling techniques and protective gear. Pathologists should explore whether silicosis leads to differences in cell characteristics that produce silica-linked lung cancers compared to ‘garden variety’ malignancies. Conclusion Despite promises that global silica problems were controlled, that seems to be countered by excesses of CWP and SiTB that still bedevil the occupational medicine and public health communities. We need more worker education, prevention or regulatory policy, and basic silica biology and pathology to effectively intervene. Keywords Silica health effects, future prevention efforts; improved sampling methods