1. 1990-2000: Co-operative studies among member countries
International co-operation among OECD member countries on (Q)SARs started in the early 1990s. One of the recommendations of the OECD workshop on notification schemes for new chemicals held in 1989 focused upon the need to evaluate the predictive power of the (Q)SAR models used by the United States by comparing the results of the (Q)SAR assessment with those obtained from the base-set testing of new chemicals required by the European Commission.
In accordance with the recommendation, the "Structure Activity Relationship/Minimum Premarketing dataset" (SAR/MPD) study was undertaken from 1991 to 1993, which compared (Q)SAR predictions done with base-set test data for 175 chemicals. The results of the study were jointly published in 1994 by the US EPA and the OECD. ENV Monograph No. 88: pages 1-81, pages 82-181, pages 182-296, pages 297-366.
In the early to mid-1990’s, the OECD undertook several additional efforts to assess a variety of (Q)SAR methodologies such as the OECD Workshop on QSARs in Aquatic Effects Assessment held in 1990. The outcomes of the workshop (ENV Monograph No. 58) was used in the development and publication of the OECD Guidance Document for Aquatic Effects Assessment (ENV Monograph No. 92).
The OECD also published two other documents related to (Q)SARs that were based upon member country-led projects. The first was on the Application of Structure Activity Relationships to the Estimation of Properties Important in Exposure Assessment (ENV Monograph No. 67), and the second was on Structure Activity Relationships for Biodegradation (ENV Monograph No. 68).
2. Early 2000s: Development of the OECD principles for the validation of (Q)SAR models
In March 2002, a workshop organized by CEFIC and ICCA on “Regulatory Use of (Q)SARs for Human Health and Environmental Endpoints” was held in Setubal, Portugal, and the recommendations from the workshop were then submitted to the OECD. In November 2002, the OECD 34th Joint Meeting of the Chemical Committee and the Working Party on Chemicals, Pesticides and Biotechnology held a Special Session on (Q)SARs to review and discuss the workshop’s recommendations as well as information submitted from the OECD member countries and other organizations.
The Special Session pointed out the need for transparency in (Q)SAR models and clear procedures for applicability evaluation and validation for (Q)SARs. Based upon such need, the OECD member countries agreed to initiate an activity to develop an internationally accepted set of criteria, as well as procedures for the evaluation of existing and promising (Q)SAR models. An OECD Expert Group on (Q)SARs was subsequently established in early 2003.
The OECD principles for the validation of (Q)SAR models were agreed upon in 2004, and a relevant guidance document was published in 2007.
The OECD also published a case study report compiling current and prospective regulatory applications in 11 OECD member countries in August 2006.
3. Since 2004: Development of the (Q)SAR Toolbox
In November 2004, member countries recognized that the focus of the work should shift to the regulatory use and application of (Q)SARs. The (Q)SAR Project now focuses on facilitating the acceptance of (Q)SAR approaches in the assessment of chemicals. The major work item is the development of the OECD (Q)SAR Toolbox firstly released in March 2008. Version 2.0 was released in October 2010.