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September 7, 2018

IRSST Publishes Assessment of Methods of Sampling and Characterizing Engineered Nanomaterials in the Workplace in English

Lynn L. Bergeson Carla N. Hutton

The Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) recently published a report, in English, entitled An Assessment of Methods of Sampling and Characterizing Engineered Nanomaterials in the Air and on Surfaces in the Workplace.  As reported in our March 29, 2017, blog item, IRSST first published the report in French.  The research project has two complementary parts:  a laboratory investigation and a fieldwork component.  The laboratory investigation involved generating titanium dioxide nanoparticles under controlled laboratory conditions and studying different sampling and analysis devices.  The fieldwork comprised a series of nine interventions adapted to different workplaces and designed to test a variety of sampling devices and analytical procedures and to measure engineered nanomaterial exposure levels among Québec workers.  The workplace investigations covered a variety of industries (e.g., electronics, manufacturing, printing, construction, energy, research and development) and included both producers and users or integrators of engineered nanomaterials.  In the workplaces investigated, IRSST found nanometals or metal oxides, nanoclays, nanocellulose, and carbonaceous materials, including carbon nanofibers and carbon nanotubes.  Based on IRSST’s investigations, it proposes a strategy for more accurate assessment of exposure to engineered nanomaterials using methods that require a minimum of preanalytical handling.  The recommended strategy is a systematic two-step assessment of workplaces that produce and use engineered nanomaterials.  The first step involves testing with different direct-reading instruments, as well as sample collection and subsequent microscopic analysis, to identify clearly the work tasks that generate engineered nanomaterials.  The second step, once work exposure is confirmed, is specific quantification of the engineered nanomaterials detected.  IRSST states that the following findings are particularly helpful for detailed characterization of exposure to engineered nanomaterials:

  1. The first conclusive tests of a technique using inductively coupled plasma mass spectrometry (ICP-MS) to quantify the metal oxide content of samples collected in the workplace;
  2. The possibility of combining different sampling methods recommended by the National Institute for Occupational Safety and Health (NIOSH) to measure elemental carbon as an indicator of NTC/NFC, as well as demonstration of the limitation of this method stemming from observed interference with the black carbon particles required to synthesis carbon materials;
  3. The clear advantages of using an Mini Particle Sampler® (MPS), which allows quantification of materials;
  4. The major impact of sampling time: a long sampling time overloads electron microscopy grids and can lead to overestimation of average particle agglomerate size and underestimation of particle concentrations; and
  5. The feasibility and utility of surface sampling, either with sampling pumps or passively by diffusion onto the electron microscopy grids, to assess the dispersion of engineered nanomaterials in the workplace.

IRSST states that “[t]hese original findings suggest promising avenues for assessing ENM exposure, while also showing their limitations. Improvements to our sampling and analysis methods give us a better understanding of ENM exposure and help in adapting and implementing control measures that can minimize occupational exposure.”