Section C of Guidance Document 150 provides guidance on all assays covered in the document, including OECD validated test guidelines, test guidelines that have been validated at a national level, test guidelines described in other OECD guidance documents, and test methods that have been proposed as OECD guidelines or are currently in the OECD validation process. Description of each assay includes a discussion of the basis for the assay, special considerations, limitations, when the assay is likely to be used, and guidance for interpretation for positive, negative, and equivocal results. For each specific guideline, a table illustrating a variety of data scenarios is also included, as is guidance for a next testing step if a conclusion cannot be drawn from existing data.

Specific guidance is provided for validated OECD in vitro screens, including the Performance-based Test Guideline (TG 493) for Human Recombinant Estrogen Receptor (hrER) assay to detect chemicals that bind the estrogen receptor (ER), the Performance-based Test Guideline (TG 455) for ER capable of detecting estrogen agonsits and antagonists, the Androgen Receptor (AR) Transactivation Assay (TG 458) capable of detecting androgen agonists and antagonists, and the H295R Steroidogenesis Assay (TG 456) to screen for chemicals that interfere with the synthesis of androgens and estrogens. For each assay, background, considerations, limitations, and when the assay might be used are discussed. Scenarios for interpreting positive, negative, and equivocal results, along with other endocrine test guideline data are also provided.

Specific guidance is provided for in vitro screening assays that have been validated at a national level by the US Environmental Protection Agency (Androgen Receptor Binding Assay and the Aromatase Assay). Though these assays are not validated OECD test guidelines, they provide information on the potential mechanism of test chemicals and may be useful for evaluating chemicals as endocrine disrupters in a weight of evidence approach. For each assay, background, considerations, limitations, and when the assay might be used are discussed. Scenarios for interpreting positive, negative, and equivocal results, along with other endocrine test guideline data are also provided