NanoHarmony Work on Test Guidelines and Guidance Documents

An important aspect of NanoHarmony was the project’s work on OECD Test Guidelines (TGs) and Guidance Documents (GDs). Eight endpoints where nanomaterial-adapted test methods have been identified as regulatory priorities were worked upon during the project with the intention of them moving forward through the OECD process as either new or adapted TGs or GDs. A brief update of the various TGs and GDs supported through NanoHarmony is provided below.

Scoping review for a tiered approach for reliable bioaccumulation assessment of MNs in environmental organisms to minimising use of higher tier vertebrate tests (WPMN Project)

The aim in this work was to provide scientific evidence and data to support and facilitate the acceptance of a tiered approach to bioaccumulation testing in fish and to devise new guidance on how to waive the TG305 Bioaccumulation in Fish Test for MNs. Literature reviews and experimental studies were undertaken to develop a scoping review. Following from this a Standard Project Submission Form (SPSF) will be submitted to the Working Party of the National Coordinators to the Test Guidelines Programme (WNT) in November 2024 for the development of a GD.

New Test Guideline on toxicokinetics to accommodate testing of nano-particles (WNT Project 4.146)

New in vivo toxicokinetic studies have been performed,  existing toxicokinetic data evaluated and modelling studies undertaken to determine the optimal design  for toxicokinetic studies (e.g. dose levels, number of sampling points, number of animals per sampling point, organs / tissues to be analysed, duration of (post-)exposure). Several studies are ongoing, and a TG is anticipated to be prepared for 2025.

Development of a new Guidance Document on the determination of concentrations of nanoparticles in biological samples for (eco)toxicity studies (WNT Project 1.10)

Within the project the state of the art and data gaps in techniques and approaches for the determination of concentrations of nanoparticles in biological samples were identified and  experimental studies on spICP-MS and dark-field microscopy undertaken, alongside expert workshops to gather input. An outline GD will be sent to WNT in 2024 for commenting, with the aim of endorsement by WNT  in April 2025.

Guidance Document on determination of solubility and dissolution rate of nanomaterials in water and relevant synthetic biological media (WNT Project 1.5)

During the project available data and methods were assessed and  new data generated through organising an inter-laboratory comparison (ILC) and consulting relevant stakeholders. A GD will continue to be developed with submission for endorsement by the WNT planned during 2024.

Guidance Document on identification and quantification of the surface chemistry and coatings on nano- and microscale materials (WNT Project 1.6)

A tiered approach with standard operating procedures (SOPs) using a range of suitable techniques and the organisation of an ILC to validate this has been undertaken during the project. The GD will continue to be developed until the end of 2023, with final endorsement by the WNT planned for 2024.

TG on Determination of the dustiness of manufactured nanomaterials (WNT Project 1.8)

An ILC was organised to test the dustiness of fibres. The data will be developed into a TG for dustiness testing (including granular particles and fibres). In addition, the use of dustiness index of fibrous powders for ATEX safety assessment was evaluated. The information on dustiness testing will feed into two GDs, one on the use of dustiness data for exposure assessment and one for the use of dustiness data for ATEX. The TG and GDs will be shared with OECD expert groups during 2024 and aim for endorsement by the WNT in 2025.

New Guidance Document on IATA for intestinal fate of orally ingested nanomaterials (WNT Project 4.158)

The project undertook a literature review and analysis of the state-of-the-art and relevant gaps,  collected, further developed and consolidated SOPs and validated them in an ILC. A draft of the GD will be shared with OECD experts at the start of 2024, with the plan of a final WNT endorsement in 2025.

Revision of Guidance Document 317 on Aquatic Toxicity Testing of Nanomaterials (WNT Project 2.71)

The project identified and collated data, protocols and SOPs, as well as validating SOPs in an ILC. The draft of the GD will be shared with OECD experts during 2024, with final endorsement by the WNT foreseen in 2025.