Physico-chemical properties of quartz from industrial manufacturing and its cytotoxic effects on alveolar macrophages: The case of green sand mould casting for iron production

• Published in: Journal of hazardous materials Vol. 312; pp. 18 - 27
• Main Authors: Di Benedetto, Francesco, Gazzano, Elena, Tomatis, Maura, Turci, Francesco, Pardi, Luca A., Bronco, Simona, Fornaciai, Gabriele, Innocenti, Massimo, Montegrossi, Giordano, Muniz Miranda, Maurizio, Zoleo, Alfonso, Capacci, Fabio, Fubini, Bice, Ghigo, Dario, Romanelli, Maurizio
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.07.2016
• Subjects: Animals; Carbon; Carbon coating; Cytotoxicity; Dust; EPR/ESEEM; Free radicals; Health effects; Hole and Al centres; Iron; Iron and steel making; Macrophages; Macrophages, Alveolar - drug effects; Mice; Morphology; Nitric Oxide - metabolism; Quartz; Quartz - chemistry; Raw; Reactive Oxygen Species - metabolism; ROS; Sand; Silicon Dioxide; NO; EPR/ESEEM; Free radicals; ROS; Cytotoxicity; Health effects; Quartz; Macrophages; Hole and Al centres; Carbon coating
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2016.03.016

[Display omitted] •Industrial processing of SiO2 contributes to the variability of its hazard.•Modifications affecting a SiO2-rich sand in cast iron production were investigated.•Numerous changes in sample morphology and surface reactivity were traced.•No cellular responses were observed with the processed powder.•Temperature change and contamination by C represent critical steps in the process. Industrial processing of materials containing quartz induces physico-chemical modifications that contribute to the variability of quartz hazard in different plants. Here, modifications affecting a quartz-rich sand during cast iron production, have been investigated. Composition, morphology, presence of radicals associated to quartz and reactivity in free radical generation were studied on a raw sand and on a dust recovered after mould dismantling. Additionally, cytotoxicity of the processed dust and ROS and NO generation were evaluated on MH-S macrophages. Particle morphology and size were marginally affected by casting processing, which caused only a slight increase of the amount of respirable fraction. The raw sand was able to catalyze OH and CO2− generation in cell-free test, even if in a lesser extent than the reference quartz (Min-U-Sil), and shows hAl radicals, conventionally found in any quartz-bearing raw materials. Enrichment in iron and extensive coverage with amorphous carbon were observed during processing. They likely contributed, respectively, to increasing the ability of processed dust to release CO2− and to suppressing OH generation respect to the raw sand. Carbon coverage and repeated thermal treatments during industrial processing also caused annealing of radiogenic hAl defects. Finally, no cellular responses were observed with the respirable fraction of the processed powder.