Information derived from sensitization test methods: test sensitivity, false positives and false negatives.

Predictive toxicology tests for the prospective identification of skin-sensitizing chemicals are well known and have been used for many years. However, of these, only the local lymph node assay (LLNA) has actually undergone formal independent assessment to determine the accuracy of the predictions, particularly with respect to the likelihood of false positives and false negatives. Often, efforts to increase the sensitivity of a test (reducing false negatives) tend to increase the number of false positives. In this short review, these issues are discussed in particular relation to the 3 predictive tests available in regulatory toxicology, the guinea-pig maximization test, the occluded patch test of Buehler and the LLNA. A key perspective is that no predictive test is without limitations; having a good appreciation of these limitations is necessary for making the best use of the information derived from these methods.