Some preliminary thoughts on the potential contribution of epidemiology to the question of multiple chemical sensitivity.

Epidemiology has played a role in clarifying mysterious symptom complexes such as AIDS, Chronic Fatigue Syndrome, and Psychiatric Disease. Is Multiple Chemical Sensitivity a new environmental disease or another in the parade of psychosomatic syndromes which have come and gone in history. It is proposed that epidemiology can: (1) Describe quantitatively the relative frequency of presenting symptoms and natural history. (2) Work with experimental psychologists to develop double-blind protocols for the "environmental unit" where chemical challenges are said to reveal chemical etiology. (3) Develop an epidemiological definition in a clinical series. (4) Develop an epidemiological definition in cohorts recently exposed to chemicals. (5) Apply the epidemiological definitions in descriptive studies and around hazardous waste sites.