Developing OECD test guidelines for regulatory testing of nanomaterials to ensure mutual acceptance of test data.

The OECD Working Party on Manufactured Nanomaterials (WPMN) provides a global forum for discussion of nano-safety issues. Together with the OECD Test Guidelines Programme (TGP) the WPMN has explored the need for adaptation of some of the existing OECD Test Guidelines (TGs) and Guidance Documents (GDs) as well as developing new TGs and GDs to specifically address NM issues. An overview is provided of progress in the TGP and WPMN, and information on supporting initiatives, regarding the development of TGs for nanomaterials addressing Physical Chemical Properties, Effects on Biotic Systems, Environmental Fate and Behaviour, and Health Effects. Three TGs specifically addressing manufactured nanomaterials have been adopted: a new TG318 ″Dispersion Stability of Nanomaterials in Simulated Environmental Media", and adaptation of TG412 and TG413 on Subacute Inhalation Toxicity: 28-Day Study/90-day Study. The associated GD39 on Inhalation Toxicity Testing has also been revised. The TGP current develops four new TGs and four GDs. One new TG and six GDs are developed in the WPMN. Six new proposals were submitted to the TGP in 2018. Furthermore, as TGs are accompanied by OECD harmonised templates (OHTs) for data collection, an outline of recently developed OHTs particularly relevant for NMs is also included.

Physico-chemical properties of manufactured nanomaterials - Characterisation and relevant methods. An outlook based on the OECD Testing Programme.

Identifying and characterising nanomaterials require additional information on physico-chemical properties and test methods, compared to chemicals in general. Furthermore, regulatory decisions for chemicals are usually based upon certain toxicological properties, and these effects may not be equivalent to those for nanomaterials. However, regulatory agencies lack an authoritative decision framework for nanomaterials that links the relevance of certain physico-chemical endpoints to toxicological effects. This paper investigates various physico-chemical endpoints and available test methods that could be used to produce such a decision framework for nanomaterials. It presents an overview of regulatory relevance and methods used for testing fifteen proposed physico-chemical properties of eleven nanomaterials in the OECD Working Party on Manufactured Nanomaterials' Testing Programme, complemented with methods from literature, and assesses the methods' adequacy and applications limits. Most endpoints are of regulatory relevance, though the specific parameters depend on the nanomaterial and type of assessment. Size (distribution) is the common characteristic of all nanomaterials and is decisive information for classifying a material as a nanomaterial. Shape is an important particle descriptor. The octanol-water partitioning coefficient is undefined for particulate nanomaterials. Methods, including sample preparation, need to be further standardised, and some new methods are needed. The current work of OECD's Test Guidelines Programme regarding physico-chemical properties is highlighted.

Review of achievements of the OECD Working Party on Manufactured Nanomaterials' Testing and Assessment Programme. From exploratory testing to test guidelines.

This paper charts the almost ten years of history of OECD's work on nanosafety, during which the programme of the OECD on the Testing and Assessment of Manufactured Nanomaterials covered the testing of eleven nanomaterials for about 59 end-points addressing physical-chemical properties, mammalian and environmental toxicity, environmental fate and material safety. An overview of the materials tested, the test methods applied and the discussions regarding the applicability of the OECD test guidelines, which are recognised methods for regulatory testing of chemicals, are given. The results indicate that many existing OECD test guidelines are suitable for nanomaterials and consequently, hazard data collected using such guidelines will fall under OECD's system of Mutual Acceptance of Data (MAD) which is a legally binding instrument to facilitate the international acceptance of information for the regulatory safety assessment of chemicals. At the same time, some OECD test guidelines and guidance documents need to be adapted to address nanomaterials while new test guidelines and guidance documents may be needed to address endpoints that are more relevant to nanomaterials. This paper presents examples of areas where test guidelines or guidance for nanomaterials are under development.