A catalogue of generic and specific exposure scenarios (ESs) has been developed for engineered nanomaterials (ENM), taking into account the release scenarios over the entire life-cycle of these materials (Brouwer et al., 2010 and Clark et al., 2012). For occupational exposure scenarios, published measurement data and contextual information were collected. These were reviewed to describe and characterize occupational exposure and the available tools and models to predict occupational exposure

to the ENMs. For the development of generic exposure scenario descriptions, a library for the collection of exposure scenarios according to REACH Guidance was developed. From the 57 occupational exposure scenarios Protease Inhibitor Library in vitro (Brouwer et al., 2010), 14 are related to carbon-based nanomaterials, generating 35 contributing

exposure scenarios describing some facet of occupational exposure. Most of the ESs were from the production/synthesis of carbon-based nanomaterials or from handling materials (weighting, removing, sonication, etc.); two scenarios addressed tasks related to the machining of composites containing CNT. Based on the process of developing these ESs, several main conclusions could be drawn (Clark selleck et al., 2012): Most studies reported had an explorative character and were focused on concentration/emission analysis. Therefore, the reports from these studies did not include most of the information necessary to build ESs, e.g. amount used and frequency of activities. Basic characterization of the products used was often not available and operational conditions were often not described. Most concentration/emission-related measurement results were task-based. An important observation was the

lack of harmonization of either the measurement strategy including distinction between manufactured nanoaerosols and ‘background’ aerosols, or the ADAM7 analysis and reporting of measurement data. ENM-release during synthesis is best described by an emission factor (EF), which is defined as number, surface area and/or mass (volume) per unit of time released to the environment (Fissan and Horn, 2013). The ENM-release per unit of mass of produced material is best described by a release factor (RF), defined as number, surface area and/or mass (volume) per unit of mass of nanostructured material (Fissan and Horn, 2013). This depends on nanostructured material properties and the amount and kind of energy input during the different kinds of treatments of the material. The ENM emission and release factors can be considered to be important process and material properties, since without emission and release there is no exposure and therefore no risk.