The OECD conceptual framework was developed to provide a framework for the testing and assessment of potential endocrine disrupters. It is intended to apply to both new and existing substances as different chemical sectors such as pharmaceuticals, industrial chemicals and pesticides.

Initially it was developed to guide the Task Force's deliberations in deciding which tests were suitable for OECD test development and validation work . It was developed taking into account:

• The views of Member countries as expressed through answers to a Questionnaire and the OECD's Appraisal of Test Methods for Sex Hormone&Disrupting Chemicals (OECD Monograph No.21)
• Proposed testing schemes such as those developed at relevant workshops notably the European Workshop on the Impact of Endocrine Disrupters on Human Health and Wildlife (the Weybridge Workshop) and the Joint SETAC&Europe/OECD/EC Expert Workshop on Endocrine Modulators and Wildlife: Assessment and Testing (the EMWAT Workshop);
• The work of national activities such as the USEPA's Endocrine Disrupter's Screening and Testing Advisory Committee (EDSTAC) and research activities in Japan;
• Industry initiatives such as being undertaken by the European Chemical Industry (CEFIC).

The initial framework has been revised by the EDTA Task Force at its meetings to reflect OECD member countries' views.  The conceptual framework agreed by the EDTA6 in 2002 is not a testing scheme but rather a tool box in which the various tests that can contribute information for the detection of the hazards of endocrine disruption are placed. The tool box is organised into a 5 compartments or levels each corresponding to a different level of biological complexity (for both toxicological and ecotoxicological areas).  A series of important notes are attaced to the framework.  Even though the conceptual framework may be full of testing tools this does not imply that they all will be needed for assessment purposes. Tools (assays and tests) will be added as they are validated in future.

The conceptual framework is subject to further elaboration and discussion as the work on endocrine disrupters proceeds.