Currently available in vitro methods used in the regulatory toxicology

About two decades ago in vitro mutagenicity tests were adopted as the first in vitro methods in regulatory toxicology. For reasons of animal welfare and better science, many validation studies of various in vitro methods were performed between 1985 and 1995 for their potential to replace the Draize eye irritation test. Albeit the fact that four in vitro methods (HET-CAM, BCOP, IRE, and ECE) have gained regulatory tolerance in Europe for the classification of severe eye irritants, the lessons learned mainly from these validation studies led to the definition of internationally harmonised OECD validation principles and acceptance criteria (Final Report of the OECD Workshop on Harmonization of Validation and Acceptance Criteria for Alternative Toxicological Tests Methods, 1996. OECD Publication Office, Paris, France). Application of these principles to prevalidation and validation studies, and additional special studies performed in Europe with the support of ECVAM, ended in the scientific validation of new in vitro methods for the prediction of skin corrosivity and phototoxicity. They were accepted for regulatory use in Europe and adopted on 8 June 2000 as test methods B. 40 and B. 41 of Annex V of Directive 67/548/EEC. In quite a different approach, European industry has submitted in-house validation data to support a Draft OECD Test Guideline for in vitro dermal absorption testing, which-after peer review and a long lasting international discussion-will now be adopted by the OECD. The increasing importance of regulatory measures derived from quantitative cytotoxicity tests, and some examples of regulatory accepted in vitro methods, where the specific purpose is restricted to a specific regulation (e.g. testing of medicinal products, or medical devices), are also addressed.