INTRODUCTION

Edward J Calabrese

Hormesis is a general dose-response phenomenon characterized by a stimulatory response at low doses and an inhibitory response at higher doses. While this phenomenon is reported in all biological fields (often by the use of different but essentially similar meaning terms) and appears to occur without restriction to chemical/physical stressor agent, endpoint measured and biological model system, its utility and application may be quite different according to the specific field of study (i.e., clinical medicine, experimental psychology, range management, human risk assessment, ecological risk assessment, and others).

The past several decades have witnessed a progressive increase of experimentally derived findings demonstrating the reproducibility of hormetic effects and their quantitative dose-response similarities. Likewise, generalizable mechanistic frameworks, based on experimental data, have begun to clarify and explain hormetic dose-response relationships. As a result of these cumulative developments, it is not unexpected that preliminary discussions on the role of hormesis in the area of ecological risk assessment have begun to emerge within academia, government and the private-sector. This issue of the BELLE Newsletter is designed to both focus and clarify the current status of this topic and to provide a blueprint for future activities. In this issue Dr. Peter Chapman offers a broadly based, challenging and cogent perspective on the role of hormesis in ecotoxicology and ecological risk assessment. The paper of Dr. Chapman was then subjected to seven independent expert commentaries that were designed to reflect a broad spectrum of high-level technical expertise. The Newsletter concludes by a response from Dr. Chapman to the seven expert commentaries.