Section A of Guidance Document 150 provides background and history, defines terms used in the document, and describes the objectives, scope and limitations. Guidance Document 150 was developed to be a resource for regulators and because of substantial regional differences in the regulatory policies on endocrine disrupters, the document offers guidance for identifying hazard of chemicals that may interact with the endocrine system but does not consider exposure herein. A table of all endocrine disrupter screens and tests for which guidance is provided, and includes the standardised test methods that are available at the international and national levels, as well as those under development. This section also describes the Conceptual Framework for Testing and Assessment of Endocrine Disrupting chemicals. The Conceptual framework includes five levels that increase in biological complexity. Level 1 of the framework is existing and non-test data; Level 2 covers mechanistic in vitro assays; Level 3 covers in vivo assays that provide limited data regarding select endocrine mechanisms or pathways; Level 4 covers in vivo assays providing limited data on adverse effects; and Level 5 covers in vivo assays which provide more complete data on adverse effects and an organism’s life cycle.

Section B of Guidance Document 150 provides general guidance on endocrine assessment, assays, and endpoints. The section also provides considerations for information collected at each level of the Conceptual Framework. In this section is a table of all endpoints in the assays included the Conceptual Framework, along identification of those endpoints that are relevant to the estrogen, androgen, thyroid, and steroidogenesis modalities of vertebrates and juvenile hormone of invertebrates are include for each assay. Guidance is also provided for cross-species extrapolation among the well conserved endocrine pathways of vertebrates, consideration of chemicals with potential multiple endocrine modes of action, and recognition that no single assay provides definitive evidence of endocrine disruption, but rather a weight of evidence approach is needed. A table describing evidence approaches for considering chemicals as endocrine disrupters is included, along with experiences using test methods for endocrine assessment of chemicals in a regulatory context.