The OECD Working Party on Manufactured Nanomaterials (WPMN) and the OECD Working Party of National Coordinators of the Test Guidelines Programme (WNT) have been working collaboratively to address the specific challenges of nanomaterials safety testing. Over recent years, they have developed and continue to refine OECD Test Guidelines (TGs) and Guidance Documents (GDs) to produce reliable safety data for nanomaterials. The dedicated OECD webpage provides more background information.
Draft Test Guideline on Determination of the Solubility and Dissolution Rate of Nanomaterials for Environmental Fate Assessment
- Submission period
- 30 September - 11 November 2025
Public consultation
Project description
In 2013, the United States submitted a Standard Project Submission Form (SPSF) to develop a new TG on the dissolution rate of nanomaterials in the aquatic environment. The project was added to the WNT work plan in 2014. Over the years, Austria and Germany have taken the lead on the project, and the TG has been discussed and further developed within WNT-WPMN Joint Expert Group (JEG) on environmental fate and ecotoxicity of nanomaterials. The current draft TG was reviewed during two rounds of comments by the JEG in March and June 2025. The feedback received was implemented in the presented documents.
The scope of this TG is to provide cost-efficient and easy to implement methodologies to determine nanomaterials solubility and dissolution rate in water at different environmentally relevant pH values with a passive pH control (buffers) for environmental fate assessment. This TG consists of two parts: part A is a batch test that delivers the apparent solubility of a nanomaterial after 24h at pH 7 (as default; in addition, pH values between 5 and 8 can be applied). Part B is a time-resolved batch test that delivers the apparent solubility of a nanomaterial after 72h at pH 5, 7 and 8, and the dissolution rate as long as depletion of the nanomaterial or saturation of the solution is not reached before 4h. It must be noted that due to the given starting concentrations of the tests (Part A 100 mg/L, Part B 10 mg/l) the highest solubilities that can be correctly determined are 100 mg/L (Part A) and 10 mg/L (Part B).
How to contribute
The draft TG is currently under a commenting round by the Working Party of the National Coordinators of the Test Guidelines Programmes (WNT) and open for comments from the public at the same time. Interested parties are invited to contact their National Coordinators at least a week before 11 November 2025.
