Multiple chemical sensitivities syndrome: toward a working case definition.

A study was conducted to identify clinical diagnostic criteria that experts regarded as major for categorizing patients as having multiple chemical sensitivities (MCS) syndrome. A cross-sectional survey of 148 medical practitioners with an interest in, or familiarity with, the condition was performed scoreable questionnaires were returned by 60.1% of those surveyed. The following five criteria, all based on self-reports, were selected as major for diagnosing the syndrome by more than 50% of the respondents: (1) symptoms are reproducible with exposure; (2) condition is chronic; (3) low levels of exposure result in manifestations of the syndrome; (4) symptoms resolve with removal of incitants; and (5) responses occur to multiple, chemically unrelated substances. It is proposed that the major criteria accepted by the majority of survey respondents be used provisionally as the basis for categorizing cases in investigations of MCS syndrome.