ABSTRACT
From time to time, physicians encounter patients with a chief complaint of hyperosmia accompanied by multisystem symptoms and intolerances for a wide variety of chemicals, foods, and/or drugs (Ashford and Miller, 1998; Berglund et al., 1992; Doty et al., 1998). Often these patients say they become ill when exposed to various odors, often in response to cacosmia (Ryan et al., 1988) or dysosmia (Miller, 1996). For example, they may describe everyday exposures to fragrances, diesel exhaust, new plastic car interiors, household cleaners, etc. (Table 1), as being overpowering, “stronger than ever before,” or “extremely irritating” and triggering symptoms such as headaches, fatigue, memory difficulties, mental confusion, anxiety, irritability, depression, myalgias, arrhythmias, dyspnea, and every sort of gastrointestinal problem (Table 2). This clinical presentation has come to be known as multiple chemical sensitivity (MCS) or multiple chemical intolerance. Patients presenting with this peculiar combination of subjective hyperosmia, multisystem symptoms, and multiple intolerances appear to be on the increase (AOEC, 1992; NIEHS, 1997; NRC, 1992). Later in this chapter, epidemiological and clinical studies of this phenomenon will be reviewed.
