Dustiness of nanomaterial in powder: outcomes of the prenormative research project carried out under the M461 European mandate

Konferenceabstrakt til konference - 2018

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In recent years, dustiness has become an input parameter for control banding tools developed for nanomaterials. In Europe, dustiness is also considered relevant, as in the context of REACH registration dossiers. In addition, some recently developed strategies to measure exposure by inhalation require that information on dustiness be provided. In this context, considering that it was important that validated and harmonized methods should be proposed in the near future a pre-normative research program was set up with the ultimate objective of proposing standards. In this project involving six European reference institutes in occupational health, a harmonized approach was elaborated and applied to four dustiness methods that coexist in Europe, that is the RD, the CD, the small rotating drum (SRD) and the vortex shaker (VS) methods. The harmonization concerned the conditioning and preparation of the powder test samples, the aerosol sampling line, the measurement strategy, the sequence of the tests and the data processing. The strategy makes it possible to determine, in addition to the classical respirable dustiness mass fraction (mg/kg), two new pertinent dustiness indices based on the number (particle/mg) and surface metrics (m2/kg). In addition, it qualifies the size distribution of the emitted aerosol as well as the morphology and chemical characterization of the particles. To test the four dustiness methods, ten candidate powders manufactured and used on an industrial scale have been selected. These powders have different chemical natures (TiO2, SiO2, CaCO3 and BaSO4) and are characterized by properties covering wide ranges. For example, their volume-specific surface area ranges from 15 m2/cm3 to about 1850 m2/cm3. As a result, a database consisting of approximately 250 values for each metric (mass, surface and number) was generated. The results obtained were repeatable, with CV of the order of 20%. For each of the metrics, the indices obtained typically extend over several orders of magnitude, which clearly make it possible to differentiate the powders between them. Despite the great diversity of the tested powders, the number size distributions were relatively close to each other with modes that range from 0.9 μm to 2.4 μm. This project has led to draft standards, currently under revision: prEN 17199 (2018) Workplace exposure - Measurement of dustiness of bulk materials that contain or release nano-objects or submicrometer particles, Part 1 to 5.

Reference

Dustiness of nanomaterial in powder: outcomes of the prenormative research project carried out under the M461 European mandate. 2018.

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