Developing a weight-of-evidence approach for persistence assessments

I am writing to share some exciting news about a new publication in Integrated Environmental Assessment and Management:

Developing a weight-of-evidence methodology for persistence assessment of substances in the environment

Environmental persistence is fast becoming one of the most critical and decisive issues in chemicals management. The introduction of "persistent, mobile and toxic" (PMT) and "very persistent, very mobile" (vPvM) hazard classes in the EU have brought a vast swathe of new chemicals under scrutiny. Meanwhile, the changes under the EU Classification Labelling and Packaging (CLP) regulation mean that ever more actors in the supply chain are having to evaluate and classify their products for persistence (incidentally, the 1st May deadline for the mandatory classification of mixtures is fast approaching).

With the increasing emphasis on persistence, these assessments are no longer a niche issue, confined to the purview of a limited pool of experts. They are now a core part of regulatory compliance, needing to be carried out at scale.

This is one of the key reasons for developing the Persistence Assessment Tool (PAT). The PAT is the product of a multi-sector initiative to develop a software tool that can guide assessors through the complex process of evaluating and weighing information relevant to a chemical's persistence and arriving at robust, transparent and predictable conclusions. This new publication in IEAM is a companion to the PAT, providing details of the background and underpinning methodology, and demonstrating its performance with an example substance.

It may surprise you to hear that there is a lot about persistence assessments that remains unresolved. While EU policy is moving fast and the ECHA guidance has continuously expanded, the process of bringing together complex and disparate information in what's called a weight-of-evidence determination still remains opaque. The work we did on the PAT attempted to bridge that gap and provide a clear methodology for data quality evaluation and weight-of-evidence that could readily be implemented. These steps aimed to fully incorporate the rules and spirit of the current REACH framework whilst remaining flexible for other frameworks that are known carry out these assessments differently. These aspects are further discussed in the paper.

I hope that you will find this paper both interesting and useful. Whether you are new to persistence assessments or a seasoned practitioner, there should be something in there for you. I want to acknowledge my co-authors, the project sponsors Concawe and the International Collaboration on Cosmetics Safety (supported by Cefic-LRI and ECETOC), and the many other contributors. The PAT was several years in the making and drew from numerous previous activities at both Cefic-LRI and ECETOC. We look forward to now seeing the tool taken up and used by regulatory professionals, and further developed by the scientific and regulatory community!

Once again, here is the link to the publication, which includes a downloadable version of the PAT in the supplementary information. You can download the latest version of the PAT from the Ricardo website here.

Stay tuned for some more persistence-related updates soon. Feel free to reach out to me if you'd like to discuss these assessments, or if you have any questions or feedback on the PAT.