Challenges for assessing and managing PMT/vPvM substances Based on the criteria for persistence, mobility and toxicity, many chemicals (as shown from the prediction results above) may be PMT/vPvM substances, warranting further assessments and management (see Table ). One of the major challenges of dealing with PMT/vPvM substances is the lack of high-quality data. As shown above, there is a growing need for computational modelling to complement experimental approaches as the number of substances to be tested increases, yet efficient computational methods rely on high quality and sufficient experimental data availability, which is a major limiting factor. Structurally diverse substances with multiple functional groups and stereochemistry can lead to unexpected behaviour, posing a critical challenge . However, developing high-throughput screening (HTS) methods for toxicity testing may be difficult for these diverse substances and toxicological endpoints, which produce large amounts of data, and require expert knowledge to interpret and manage .