19 Exploring the variability of hazards behind the global epidemic of engineered stone-associated silicosis

Abstract The emergence of engineered stone (ES)--associated silicosis is a global health crisis. This ‘new’ version of silicosis is more severe than what is traditionally seen in workers. This suggests that non-silica components of ES potentiate disease. The aim of this study was to explore the physical and chemical characteristics of ES dust emissions, at a sufficient scale and specificity to enable subsequent risk factor analysis with toxicology assays. We established a unique repository of 50 ES products. We cut/processed these stones under real-world conditions, and captured dust emissions using conventional air sampling approaches. Dust particles were analysed for crystallinity by XRD, resin content by TGA, metal composition by XRF, particle size and charge by DLS technique, and morphology by SEM. In addition, generated volatile organic compounds (VOCs) were captured using appropriate sorbent tubes and analysed by liquid and/or gas chromatography. ES processing emitted very fine dust, ranging in aerodynamic size from 100 nm to 825 nm, of high surface area. These respirable dust particles comprised 90% crystalline silica in the form of quartz and cristobalite, and up to 25% resin by weight. Actively machining ES also released harmful VOCs such as phthalic anhydride, styrene, and benzene, which have been linked to adverse health effects. We suggest, for the first time, that occupational hygienists need to consider co-exposures to dust and VOCs in undertaking exposure assessment and management for ES workers. Work is in progress to elucidate the role of particle size and chemistry on the pathogenesis of ES-associated silicosis.