Chemical sensitivity: Symptom, syndrome or mechanism for disease?

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78 Scopus citations


Several different meanings have been attached to the term 'chemical sensitivity' by those who use it. Feeling ill from odors is a symptom reported by approximately one-third of the population. The syndrome of chemical sensitivity, frequently called 'Multiple Chemical Sensitivity' or 'MCS' has been the subject of three federally sponsored workshops; at least five different case definitions for research on MCS have been proposed. In contrast, the hypothesis that chemical sensitivity may be a mechanism for disease posits that a broad spectrum of 'recognized' chronic illnesses, ranging from asthma and migraine to depression and chronic fatigue, may be the consequence of environmental chemical exposures. According to this theory, a two-step process occurs: (1) an initial salient exposure event(s) (for example, a one-time, intermittent, or continuous exposure to pesticides, solvents, or air contaminants in a sick building) interacts with a susceptible individual, causing loss of tolerance for everyday, low level chemical inhalants (car exhaust, fragrances, cleaning agents), as well as for foods, drugs, alcohol, and caffeine; (2) thereafter, such common, formerly well-tolerated substances trigger symptoms, thus perpetuating illness. 'Masking' (acclimatization, apposition, and addiction) may hide these exposure-symptom relationships, thus obfuscating the environmental etiology of the illness. Accumulating clinical observations lend credence to a view of chemical sensitivity as an emerging theory of disease causation and underscore the need for its testing in a rational, scientific manner. While chemical sensitivity may be the consequence of chemical exposure, the term 'toxicant- induced loss of tolerance' more fully describes the two-step process under scrutiny.

Original languageEnglish (US)
Pages (from-to)69-86
Number of pages18
Issue number1-3
StatePublished - 1996


  • Chemical sensitivity
  • Environmental etiology
  • Environmental exposure
  • Theory for disese
  • toxicant-induced loss of tolerance

ASJC Scopus subject areas

  • Toxicology


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