Abstract
With the increasing interest in the potential benefits of nanotechnologies, concern is still growing that they may present emerging risks for workers. Various strategies have been developed to assess the exposure to nano-objects and their agglomerates and aggregates (NOAA) in the workplace, integrating different aerosol measurement instruments and taking into account multiple parameters that may influence NOAA toxicity. The present study proposes a multi-metric approach for measuring and sampling NOAA in the workplace, applied to three case studies in laboratories each dedicated to materials with different shapes and dimensionalities: graphene, nanowires, and nanoparticles. The study is part of a larger project with the aim of improving risk management tools in nanomaterials research laboratories. The harmonized methodology proposed by the Organization for Economic Cooperation and Development (OECD) has been applied, including information gathering about materials and processes, measurements with easy-to-use and hand-held real-time devices, air sampling with personal samplers, and off-line analysis using scanning electron microscopy. Significant values beyond which an emission can be attributed to the NOAA production process were identified by comparison of the particle number concentration (PNC) time series and the corresponding background levels in the three laboratories. We explored the relations between background PNC and microclimatic parameters. Morphological and elemental analysis of sampled filters was done to identify possible emission sources of NOAA during the production processes: rare particles, spherical, with average diameter similar to the produced NOAA were identified in the nanoparticles laboratory, so further investigation is recommended to confirm the potential for worker exposure. In conclusion, the information obtained should provide a valuable basis for improving risk management strategies in the laboratory at work.
Highlights
In the last decade nanotechnologies (NTs) and nanomaterials (NMs) have seen rapid development worldwide, as seen in the growing numbers of R&D investments [1], nanotech enterprises [2], and nano-related products on the market [3]
The three nano-objects and their agglomerates and aggregates (NOAA) were chosen for their characteristics common in the nanosystems widely employed in research laboratories and including some peculiarities to distinguish the NOAA produced “on purpose” from the background
Two SEM images of G are reported in Figure 2a: in the left-hand panel the darker areas are the G terraces grown on silicon carbide (SiC) substrate; in the right-hand panel the entire surface is covered by a monolayer of G grown on copper (Cu) foil
Summary
In the last decade nanotechnologies (NTs) and nanomaterials (NMs) have seen rapid development worldwide, as seen in the growing numbers of R&D investments [1], nanotech enterprises (about 4000) [2], and nano-related products on the market (up to 1800) [3]. The toxicological literature suggests that multiple parameters may influence NMs health effects: their size, shape, particle number and mass concentration, surface area, aggregation and agglomeration, water solubility, and surface chemistry are the most important metrics in exposure studies [8,9,10]. Sample Preparation and Recator 2 Opening 1. Sample Preparation and Recator 1 Opening 3.1 Cleaning 3.2 Cleaning: Graphite Spraying 0. Shell Building 4.1 Drying: Vacuum Pump Turned on 4.2 Drying. Synthesis 4.1 Drying: Vacuum Pump Turned off (NP produced during day 7) 2.
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