Distinguishing between adverse and non-adverse effects – Session summarySession Report from the Joint STP/IFSTP International Symposium “Toxicologic Pathology in the New Millenium” June 24–28, 2001, in Orlando, Florida

Abstract

Summary We in toxicologic pathology have to make decisions on various levels: Firstly, we decide whether there is a lesion, secondly we have to diagnose it and give it the appropriate name, thirdly we have to find out whether it is induced, fourthly to judge whether the lesion is adverse or non-adverse, and lastly decide whether the induced lesion has relevance to man. In this session we are concerned with the characterization of adverse and especially of non-adverse effects. We have to be able to distinguish between the two in toxicity studies to determine the non-adverse effect level (NOAEL). The NOAEL is needed to set the initial dose in phase I studies with regard to drugs and to calculate the admissible daily intake of environmental chemicals. Thus, the topic of our session is important for hazard identification and risk assessment. There is, however, a paucity of references in the literature specifically dealing with this issue. Therefore, the chairmen of this session were pleased that our session topic was accepted in the overall program, since there appears to be an urgent need to present and discuss this issue in a large international forum. The objective of this session is to give some guidance to toxicologic pathologists, study directors, and their colleagues in governmental agencies, on how to define non-adverse effects and to establish the NOAEL in toxicity studies.