Under recent EU requirements, endocrine disruption (ED) assessment is now required for chemicals including UVCBs: substances of unknown or variable composition, complex reaction products or biological materials. Their complex composition, limited data on many constituents and the lack of validated frameworks tailored to UVCBs make linking endocrine activity to adversity especially challenging.
On behalf of the Lower Olefins and Aromatics (LOA) REACH Consortium, which registers around 143 substances, the authors screened LOA UVCB constituents for potential endocrine activity. The screening covered the estrogenic, androgenic, thyroid and steroidogenic (EATS) pathways, along with other relevant targets. A virtual screening workflow combined several validated QSAR tools (OPERA, VEGA, Percepta and the OECD QSAR Toolbox) through rule-based consensus scoring. Each constituent was rated for predicted activity and for confidence in that prediction.
Of the 149 constituents assessed, 104 were identified as low priority and 12 as high priority, with 19 showing weak activity. Mapping these results onto each LOA category pinpointed the specific UVCB groups needing further ED evaluation. The approach is a transparent, reproducible and resource-efficient way to prioritise, focusing weight of evidence assessment on the substances with the highest potential for ED activity.
Authors
C. Haines, L. G. Higgins, E. M. Maloney, M. Rooseboom, N. Aygun Kocabas, S. Barber, D. Bermudez, N. Ranggasami, E. Fioravanzo, P. Russell, E. K. Rushton
EUROTOX 2026, Poster P27-12 (Session PV02, Regulatory Toxicology (REACH)), Abstract ID 1287