Multiple Chemical Sensitivity (synonyms: Chemical Intolerance; Multiple Chemical Sensitivity; Idiopathic Environmental Intolerances (IEI); Idiopathic Chemical Sensitivity; MCS; MCS Syndrome; Multiple Chemical Intolerance; ICD-10-GM T78.4: Allergy, unspecified) is a disorder that is a reaction of the central nervous system. It refers to a patient’s hypersensitivity to various chemicals and environmental pollutants, such as:
- Fragrances
- Solvents
- Formaldehyde
- Pesticides
- Polychlorinated biphenyls (PCBs)
- Heavy metals
- Detergent
- Residential poisons
In MCS syndrome is usually no acute poisoning (noxe), but it is characterized by an “initial noxe” or a “toxic induced loss of tolerance” (TILT).
Chemical substances in concentrations in which the general population hardly notices them lead to different, unspecific symptoms in people with MCS.
Gender ratio: Women are affected significantly more often than men.
Frequency peak: The disease occurs predominantly between the 20th and 60th year of life. An age peak is around the age of 40.
The prevalence (disease incidence) is between 0.5 and 3.9% (in the world). For individual countries, the prevalence is distributed as follows:
- Germany: 0.5 %
- Australia: 0.9 %
- Sweden: 3.7
- Japan: 3.8
- USA: 3.9
Moderate (moderate) chemical intolerance is found in 9-33%.
Course and prognosis: Since the central nervous system is affected in MCS syndrome, disease symptoms can occur throughout the body and in all organs. Affected individuals may be severely disabled and unable to work.
