Multiple chemical sensitivity: state of the art symposium. The role of chemical allergens.

Multiple chemical sensitivity (MCS) has been defined as "an acquired disorder of recurrent symptoms, referable to multiple organ systems, occurring in response to chemically unrelated compounds at doses far below those established in the general population to cause harmful effects" [Cullen, State Art Rev. Occup. Med. 2, 655 (1987)]. The pathophysiologic basis for the MCS syndrome has not been clearly defined. However, allergic reactions to specific chemicals encountered in the environment are much better understood.