The revised edition of Guidance Document (GD) 150 includes new and updated test guidelines that have been validated, or are currently in the validation process. Updates to the test guidelines concern all levels in the OECD Conceptual Framework for Testing and Assessment of Endocrine Disrupting Chemicals, and the Conceptual Framework itself has been updated. The revised GD includes various cross-cutting issues and a summary of some experiences gained from using the guidance in the first edition.

Of the five levels of the Conceptual Framework, Level 1 considers existing data and existing or new non-test information and Level 2 considers in vitro assays providing data about selected endocrine mechanism(s)/pathway(s). Levels 3-5 consider in vivo assays on endocrine mechanism(s)/pathway(s), on adverse effects on endocrine-relevant endpoints, and more comprehensive data on adverse effects on endocrine-relevant endpoints over move extensive parts of the life cycle or the organism.

The tests included in Level 2 are:
– Estrogen (OECD TG 493) or androgen receptor binding affinity (US EPA TG OPPTS 890.1150)
– Estrogen receptor transactivation (OECD TG 455, ISO 19040-3), yeast estrogen screen (ISO 19040-1 & 2)
– Androgen receptor transactivation (OECD TG 458)
– Steroidogenesis in vitro (OECD TG 456)
– Aromatase assay (US EPA TG OPPTS 890.1200)
– Thyroid disruption assays (e.g. thyroperoxidase inhibition, transthyretin binding)
– Retinoid receptor transactivation assays
– Other hormone receptors assays as appropriate
– High throughput screens