Research Center for MCS

The Danish Research Centre for Chemical Sensitivities is a national centre engaged into research in and information about Multiple Chemical Sensitivity. The condition is called Multiple Chemical Sensitivity (MCS) or Idiopathic Environmental Intolerance (IEI).

The Centre’s research on Multiple Chemical Sensitivity is based on a bio-psychosocial disease model and is organised in seven main areas.

To learn more about what they know about MCS and what more is being learned, go to–

A PhD thesis on Multiple Chemical Sensitivity

Click on their sidebar links, too.

Mask (Photo credit: live w mcs)


Different factors have been associated with development of multiple chemical sensitivity (MCS):

  • Some MCS patients report that their symptoms started after having been exposed to sudden high doses of chemicals, after spills or accidents involving solvents or pesticides
  • Others describe symptoms occurring after having been exposed to prolonged low doses of chemicals, for example degassing of chemicals in buildings with indoor climate problems, or from surfaces that have been inappropriately treated, e.g. by indoor use of fungicides
  • Factors such as infections, stress, psychological and physical trauma have also been described as important to the development of MCS
  • However, for many with severe MCS, the symptoms have evolved gradually, and it is not possible to identify a specific exposure as a cause.

Several theories 
Several theories as to why some people experience symptoms when exposed to common airborne chemicals have been suggested, but no theory is documented well enough to be able to say that we know the cause.

Various studies have suggested that MCS could be linked to:

  • Nervous system response to chemical substances, including, for example, an abnormal response to sensory stimuli, i.e. central sensitization.
  • Emotional or cognitive factors, such as anxiety or recollection of past unpleasant experiences involving scents.
  • Stress
  • Immune response to exposure to chemicals.
  • Genetic factors.

It is likely that the cause of MCS is multifactorial and that several of the above factors influence the development and maintenance of the condition.

The Research Centre’s research is based on a mulitfactorial model. Read more about their research.

What MCS is not
Although the MCS symptoms may be similar to symptoms of allergy or intoxication, the mechanisms are likely different.

Read more about why MCS cannot be described as an allergy or intoxication.

MCS as a functional disorder
Multiple Chemical Sensitivity is classified as a functional disorder in some contexts.

Functional disorders are defined as conditions where the patients experience symptoms without an identifiable medical explanation, resulting in impairment of the patient.

Other links:



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From a Yellow Canary of the 21st century, living in our disabling biosphere

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