The SILICOAT project: In vitro and in vivo toxicity screening of quartz varieties from traditional ceramics industry and approaches for an effective quartz surface coating

The International Agency for Research on Cancer (IARC) has classified respirable crystalline silica (RCS) in the form of quartz or cristobalite from occupational sources as human carcinogens (category 1; 1997), however, acknowledging differences depending on source, as well as chemical, thermal and mechanical history of RCS. In the traditional ceramics industry, quartz containing raw materials are indispensable for manufacture and workers exposed to higher RCS concentrations in the air are potentially at risk for lung inflammation, silicosis or even lung tumors. The SILICOAT project thus aims at increasing workers' safety by developing and implementing cost-effective RCS coating technologies into ceramic processes which should saturate reactive surface silanol groups and inhibit quartz-specific toxic effects. Initially, 25 quartz-containing or -free raw materials from four ceramic producers (bulk powders or dried after wet milling) were screened in vitro (primary rat alveolar macrophages, 4 h of incubation, 75 coating strategies. In conclusion, toxicity screening demonstrated gradually different quartz-specific but also quartz-independent biological activities of ceramic raw materials and indicated attenuation of quartz effects by wet milling with alumina balls. The project has received funding by the European Union's 7th Framework Programme (FP7/2007-2013) under grant agreement n° 285787.