Multi‑Laboratory Ring Trial to Support Development of OECD Test Guideline 321 on Hyalella Azteca Bioconcentration Test (HYBIT)

This document contains the validation report of the H. azteca bioconcentration test (HYBIT), prepared by Germany in 2023 and approved as Test Guideline 321 by the Working Party of the National Coordinators of the Test Guidelines Programme. This was a project on the work plan of the Test Guidelines Programme until 2024.