Multiple chemical sensitivity syndrome is characterized by recurrent, nonspecific symptoms attributed to low-level exposure to chemically unrelated substances commonly occurring in the environment. Symptoms are numerous, often involving multiple organ systems, but physical findings are unremarkable. Diagnosis is by exclusion. Treatment is psychologic support and avoidance of perceived triggers, although triggers rarely can be defined.
No universally accepted definition exists, but multiple chemical sensitivity syndrome is generally defined as the development of multiple symptoms attributed to exposure to any number of identifiable or unidentifiable chemical substances (inhaled, touched, or ingested) in the absence of clinically detectable organ dysfunction or related physical signs.
Reported triggers for multiple chemical sensitivity include
Many theories—immunologic and nonimmunologic—have been proposed. These theories are all hampered by lack of a consistent dose response to proposed causative substances; ie, symptoms may not be replicated after exposure to high levels of a substance that previously, at much lower levels, seemed to provoke a reaction. Similarly, consistent objective evidence of systemic inflammation, cytokine excess, or immune system activation in relation to symptoms is lacking. Many physicians consider the etiology to be psychologic, probably a form of somatization disorder (see Somatoform and Factitious Disorders: Somatization Disorder). Others suggest that the syndrome is a type of panic attack (see Anxiety Disorders: Panic Attacks and Panic Disorder) or agoraphobia (see Anxiety Disorders: Agoraphobia). Some facets of the syndrome resemble the no-longer-used psychologic diagnosis of neurasthenia.
Multiple chemical sensitivity syndrome develops in 40% of people with chronic fatigue syndrome and in 16% of people with fibromyalgia.
Although measurable biologic abnormalities (eg, decreased levels of B cells, elevated levels of IgE) are rare, some patients have such abnormalities. However, these abnormalities appear without a consistent pattern, and their significance is uncertain.
Symptoms and Signs
Symptoms (eg, palpitations, chest pain, sweating, shortness of breath, fatigue, flushing, dizziness, nausea, choking, trembling, numbness, coughing, hoarseness, difficulty concentrating) are numerous and usually involve more than one organ system. Most patients present with a long list of suspected agents, self-identified or identified by a physician during previous testing. Such patients often go to great lengths to avoid these agents by changing residence and employment, avoiding all foods containing “chemicals,” sometimes wearing masks in public, or avoiding public settings altogether. Physical examination is characteristically unremarkable.
Diagnosis initially involves exclusion of demonstrable allergies and other known disorders with similar manifestation (eg, atopic disorders such as asthma, allergic rhinitis, food allergies, and angioedema). Atopic disorders are excluded based on a typical clinical history, skin-prick testing, serum assays of specific IgE, or all 3. Consultation with an allergy specialist may be necessary. Building-related illnesses, including sick building syndrome, in which many people who spend time in the same building develop symptoms (see Environmental Pulmonary Diseases: Specific BRIs), should be considered.
Despite an uncertain cause-and-effect relationship, treatment is usually aimed at avoiding the suspected precipitating agents, which may be difficult because many are ubiquitous. However, social isolation and costly and highly disruptive avoidance behaviors should be discouraged.
Psychologic evaluation and intervention may help, but characteristically many patients resist this approach. However, the point of this approach is not to show that the cause is psychologic but rather to help patients cope with their symptoms.
Last full review/revision December 2008 by Margaret-Mary G. Wilson, MD