Key takeaway
What This Development Means
ECHA’s PBT Expert Group discussed bioaccumulation assessment strategies that expand beyond fish-centric evidence, with greater use of NAMs and broader organism coverage, influencing how evidence may be assembled under REACH and CLP.
What are bioaccumulation assessment strategies in EU chemicals regulation?
Bioaccumulation assessment strategies set out how to judge whether a substance builds up in organisms, supporting PBT/vPvB and PMT/vPvM conclusions under REACH and CLP. Evidence may include screening criteria, QSAR predictions, laboratory tests, and kinetic data. The aim is consistent, traceable decisions for environmental hazards across the EU regulatory system.
How should companies prepare for ECHA’s evolving bioaccumulation assessment strategies?
Start by identifying substances where your dossiers rely mainly on fish studies for bioaccumulation. Check whether alternative methods, such as OECD TG 319A/B or 321, could be relevant and document applicability limits. Record how you combine predictions and test results, and align updates with current ECHA guidance before submission deadlines.
Source basis: ECHA PBT Expert Group scientific discussions: bioaccumulation assessment strategies (8 December 2025)
ECHA’s PBT Expert Group says bioaccumulation assessment strategies are evolving, with more reliance on New Approach Methodologies (NAMs) and broader organism coverage, affecting how PBT/vPvB and PMT/vPvM evidence is built for regulatory decisions under REACH and CLP.
Why Bioaccumulation Assessment Strategies Are Changing
ECHA notes that the approach needs to work for substances that are hard to test, including cases where fish studies may not capture broader bioaccumulation concerns. Guidance updates in 2023 and 2024 add Hyalella as a test organism and incorporate toxicokinetic data to support evaluation in air-breathing organisms such as mammals.
What Was Discussed: NAMs And Tiered Testing Options
At the 41st PBT Expert Group meeting, ECHA reports presentations on an “Integrated strategy for the assessment of aquatic and terrestrial bioaccumulation” project. The project analysed 231 chemicals and recommended consensus values for log Kow and log Koa.
The tiered approach discussed screening criteria and QSAR predictions alongside an in vitro clearance assay with fish cell lines (OECD TG 319A/B) and an invertebrate bioconcentration test (OECD TG 321). For air-breathing organisms, an in vitro intrinsic clearance assay using rat hepatocytes or S9 was discussed in combination with IVIVE, with in vivo testing positioned as a later step when results remain inconclusive. Caren Rauert (UBA) is quoted as saying: “For most substances a non-vertebrate test option would already be available”.
Implications For Compliance Teams Across The Value Chain
The note is non-binding, but it signals expectations for dossier evidence. Teams preparing REACH registrations, updates, or risk assessments can review fish-only rationales, document applicability domains for any NAMs used, and capture decision logic for combining predictions and test results. ECHA notes the project report will be published early 2026 on the UBA website.
Summary
ECHA’s PBT Expert Group says bioaccumulation assessment strategies are moving beyond fish centred evidence, with Hyalella testing, toxicokinetic data, and greater use of NAMs. A tiered approach combining QSAR, in vitro assays, and targeted follow up testing may shape future dossier expectations under REACH and CLP for regulated companies today.
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