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November 9, 2016

OECD Publishes a Number of New Reports in Series on the Safety of Manufactured Nanomaterials, Including Nanosilver Case Study and Gold Nanoparticle Occupational Exposure Assessment in Pilot Scale Facility

Lynn L. Bergeson Carla N. Hutton

In November 2016, the Organization for Economic Cooperation and Development (OECD) published the following new reports in its Series on the Safety of Manufactured Nanomaterials:

  • Toxicokinetics of Manufactured Nanomaterials: Report from the OECD Expert Meeting:  As part of its Program on the Safety of Manufactured Nanomaterials, OECD initiated a series of expert meetings to discuss the applicability of the OECD Test Guidelines to nanomaterials.  The Working Party on Manufactured Nanomaterials (WPMN) agreed to organize an expert meeting to address the toxicokinetics of manufactured nanomaterials. The document presents a report of the discussion and recommendations derived from the workshop.
  • Exposure Assessment of Nano-Silver (AgNP): Case Study:  The main purpose of the Case Study was to identify existing data gaps regarding exposure assessment of nanomaterials and to make recommendations on how to address these data gaps.  The Case Study presents information on the materials selected, the approach used, as well as the measurement/modeling methods, and results for each endpoint.  The Case Study states that the main technical challenge was the lack of standardized protocols for exposure measurements.  Another challenge was the lack of consensus as to which measurement unit is preferred in measuring nanomaterials (weight, particle numbers, particle size distribution, surface area), and there may not be one unit that can be applied for each exposure scenario.  The Case Study includes suggestions intended to make collected exposure data more useful in risk assessment.
  • Future Challenges Related to the Safety of Manufactured Nanomaterials: Report from the Special Session:  The purpose of the special session was to provide delegations an opportunity to share their current and future priorities and challenges related to the safety of manufactured nanomaterials and their convergence with other technologies.  WPMN intended the discussion to facilitate better understanding of the issues facing delegations and also to identify areas of common concern to ensure the effective development of the regulatory arrangements in their respective countries.  WPMN also intended the session to identify areas of work that could be undertaken by WPMN in its future program of work that would assist delegations with the regulation/management of manufactured nanomaterials.  The report states that it has been recognized that delegations can work collaboratively to leverage the international expertise available to the WPMN to tackle those challenges.  This will in turn ensure that the regulatory agendas of member countries move forward in a timely way.
  • Grouping and Read-Across for the Hazard Assessment of Manufactured Nanomaterials: Report from the Expert Meeting:  The Report states that the April 13-14, 2016, meeting confirms the outcome of the workshop on the categorization of manufactured nanomaterials, where it was agreed that definitions and terminologies need to be clarified and consistently applied.  According to the Report, the general scheme for building and justifying groups and the read-across seems acceptable for nanomaterials.  The Report notes that there is need to develop guidance that addresses the specificities of manufactured nanomaterials, however.  Generic categories based on the ones presented at the workshop on the categorization of manufactured nanomaterials and the ones based on solubility, shape, and mode of action can be starting points for building the hypothesis for grouping and read-across.  The Report states that tiered approaches should be developed to address the specific data needs for the material and concerns being considered and this requires evaluating the available screening methods to assess their relevance and reliability.  According to the Report, there is still a need for reliable testing methods, and development of such methods should be further prioritized.  According to the Report, to illustrate their practical application, frameworks should be tested with case studies both for environmental and human health hazard assessment.  For (eco)toxicological screening purposes, high throughput systems and “-omics” methods should be explored, including development of additional such methods.
  • Grouping and Read-Across for the Hazard Assessment of Manufactured Nanomaterials: Participants List to the Expert Meeting.
  • Gold Nanoparticle Occupational Exposure Assessment in a Pilot Scale Facility: The main objective of the project was to identify tasks that may result in emissions of gold nanoparticles into the environment during their synthesis.  The study concludes that synthesis of gold nanoparticles in liquid suspension results in emission of/and exposure to gold nanoparticles.  Exposure during synthesis was not limited to the pristine gold nanoparticles (e., primary particles) but their aggregates/agglomerates, as well.  Time-weighted average (TWA) levels were very low and particle emission was less than the proposed nano reference values (NRV) and below the OECD excursion guidance criteria.  According to the study, further research needs to be undertaken to assess the adverse health effects of exposure of gold nanoparticles, however.  OECD notes that to its knowledge, this is the first study to suggest that engineered gold nanoparticles are emitted during their synthesis using the citrate reduction method, and the study has laid the basis for future exposure assessment of other nanoparticles/nanomaterials of interest in the country.
  • Developments on the Safety of Manufactured Nanomaterials Tour de Table from OECD Delegations (Nov. 2015-Oct. 2016): The document compiles information on developments on the safety of manufactured nanomaterials provided by OECD delegations during the period November 2015 to October 2016.  The document aims to summarize relevant information on activities related to manufactured nanomaterials, as well as other activities on nanotechnologies at the international level.
  • Strategy for Using Metal Impurities as Carbon Nanotube Tracers: The document describes practical and cost-effective monitoring approaches for using metal impurities in carbon nanotubes as indicators of their presence in the workplace.  Its goal is to supplement the “toolbox” of existing methods available for risk assessment and exposure mitigation.  The document states that advice on sampling techniques and off-line analysis will assist the occupational hygienist to identify situations where metal impurities in carbon nanotubes can be applied as a sensitive but qualitative indicator of the presence of process-related releases of carbon nanotubes in the workplace.

Although the OECD website lists an additional report, Titanium Dioxide:  Summary of the Dossier, its link does not work.