Particle Emissions by Mechanical Treatment of Nanocomposites: Emission Library and Applications in Exposure and Risk Assessment

<ns3:p>Background Reworking and use of nanocomposites (materials with incorporated or embedded nanomaterials) are shown to release relevant quantities of particles that can cause risk for the workers or product users. It is mandatory to provide Conditions of Use (CoU) in Exposure Scenarios for the REACH legislation. This requires information on emissions that the registrant is required to report. Regardless of the REACH legislation, emissions are rarely studied or reported. Here, we revised the available emission/release studies considering the mechanical treatment of nanocomposites. Methods A literature review of mechanical treatment emissions measurements was conducted for the years 2017 – 2024. Emission scaling and CoU assessment were demonstrated for sanding, drilling, milling, sawing, and abrasion scenarios. Exposure model performance testing was performed by comparing predicted concentration levels with concentration levels measured in an industrial sanding scenario. Results One out of 32 studies reported emissions and 12 studies contained sufficient contextual information to calculate the emissions. We developed guidelines and created a data collection sheet to help researchers and developers report the emissions from mechanical stress tests. Most studies reported particle number concentrations that are insufficient for risk assessment, where hazard profiles are given in mass dose/concentration. Modelled concentrations were 2.4 times higher than measured concentrations in the industrial sanding scenario. However, due to differences in materials and measurement techniques, uncertainty assessment was not possible to conduct, and the model applicability was not confirmed. Conclusions In REACH legislation, reporting emissions and quantifying CoU for emissions containing nanomaterials is mandatory. Regardless of this, emissions are rarely reported. Emissions are the key factor in predictive exposure modelling and risk assessment. Here, we provide guidance and emission reporting templates and demonstrate how CoU can be quantified efficiently.</ns3:p>