The evolution of validation: a commentary

Validation was first referenced as an English word in 1656, and is defined in one dictionary as "an act, process or instance of validating, especially: the determination of the degree of validity of a measuring device." To contemporary toxicologists, the word is most commonly encountered during discussions of the status of new or proposed test methods. Progress toward the reduction, refinement, and ultimate replacement of animals in toxicity testing would be facilitated and accelerated by a number of factors. Among these is recognition that the validity of a new method or approach can be enhanced substantially by an appreciation of strengths and limitations, the domain(s) of chemical applicability, and the judicious use of expert opinion. Ultimately, however, the major limitation to progress may be an unwillingness by regulators to operate outside their comfort zone.</.