Assessments of exposure to nanoparticles are currently based upon a number of different national and international recommendations. Only limited experience has been gained with these approaches and comparison made between them, if at all. This project had the objective of achieving harmonization at European level, and led to a draft recommendation for the assessment of inhalation exposure to nano-objects and their agglomerates and aggregates.
The standard under development addresses the objectives of assessment of inhalation exposure to nano-objects. Although the focus of the standard lies upon the assessment of nano-objects, the approach also applies to exposure to associated aggregates and agglomerates and to particles released from nanocomposites and nanotechnological products. For this purpose, existing approaches were considered, methods (including measurement methods) categorized, requirements and conditions of use identified, and consideration also given in the discussion to the documentation and interpretation of results.
In this approach, exposure is determined in successive stages. A critical point was that the criteria for progression to the next stage were not clear and scientifically reasoned. The last point in particular necessitated more far-reaching pre-normative research, in conjunction with detailed discussions at workshops between experts from the countries involved, in addition to the meetings of CEN/TC137/WG3.
The reasons for the performance of exposure assessment may vary. They include determining of exposure, evaluation of the efficacy of protective measures, review of conformity with existing occupational exposure limits or other benchmarks, and supporting risk assessments and epidemiological studies.
The multi-stage approach serving as the generic underlying structure already existed in the form of both a German proposal and an OECD proposal. It has now been summarized in a single document in European standard EN 17058:2018, Workplace exposure - Assessment of inhalation exposure to nano-objects and their agglomerates and aggregates, which is scheduled for publication in 2018. The standard describes recommendations and procedural specifications, such as measurement methods. The first stage comprises the procurement and interpretation of information. Should the result of this interpretation be positive, the procedure progresses to the second stage. This comprises measurement at the workplace by means of direct-reading instruments, by which the atmospheric concentration of particles under 1 µm can be determined in consideration of the background exposure. Should this yield a significant incidence of nanoscale particles, the third stage can be applied. In this stage, detailed studies of the workplace aerosols are conducted by experts. This includes size distributions of the aerosols, and the collection of aerosols for subsequent analysis and for study by electron microscopy, by which for example the presence of nanofibres is demonstrated.
-cross sectoral-Type of hazard:
chemical working substances, exposure, dust, fibers, particlesDescription, key words:
nanoparticle, inhalation, exposure assessment, European standard