Future improvements: replacement in vitro methods.

Revolutions in thinking and practice are essential in regulatory toxicology if genuine protection of human beings and the environment is truly to be improved. New test development is the key: Tests should have greater relevance than the current animal procedures based on (1) a mechanistic understanding of the basis of the test method itself and of the toxic phenomenon of concern, (2) taking advantage of new developments in cell and molecular biology and computer systems of various kinds, and (3) a clear understanding of the value of good prediction models. In the not-too-distant future, current research in genomics, proteomics, and metabolomics should provide opportunities for the development of valuable new tests. An inescapable requirement of tests intended to be used for regulatory purposes is validation (i.e., an independent assessment of relevance and reliability for stated purposes according to internationally agreed-upon criteria). However, there is no standard validation scheme; a case-by-case approach is essential. It is important to take advantage of experience, which reveals that prevalidation makes formal validation studies faster, less expensive, and more likely to succeed, and that the procedures for independent assessment used by the European Centre for the Validation of Alternative Methods (ECVAM) and the Interagency Coordinating Committee for the Validation of Alternative Methods (ICCVAM) are effective in practice.