Experimental approaches to chemical sensitivity: introduction and overview.

Multiple chemical sensitivity (MCS) or environmental illness has been the subject of numerous conferences (1,2), several research papers (3), and much controversy. What is the purpose of yet another workshop on this topic? Patients report that low-level chemical exposures are making them ill, yet these reports of illness are not well supported by the knowledge bases of toxicology or medicine. IfMCS is not classical toxicity, perhaps the next logical assumption is that this illness has more to do with the individual susceptibility than with chemical toxicity. But what are the mechanisms for this clinical phenomenon and how can we begin to test objectively the interaction of susceptibility factors, chemical exposures, and illness? This was the purpose of our workshop. Unlike previous conferences, this conference was conducted as a workshop in which experienced MCS clinicians who could document patient characteristics worked with experimental investigators from scientific disciplines related to MCS to develop experimental approaches. This supplement is a compilation of papers given by invited speakers, both clinical and methodologic, along with assigned commentaries in response to some of the papers. These papers reflect the background and the diversity of opinion that exists in this area of inquiry. The paper by Fiedler and Kipen (3) is an overview of published studies that have