Introduction to Multiple Chemical Sensitivities:
Multiple Chemical Sensitivity (MCS), also known as Idiopathic Environmental Intolerances (IEI), Chemical Sensitivity (CS), and Environmental Illness (EI), is a chronic condition experienced as a range of physical, mental, or emotional symptoms provoked by exposure of low concentrations of commonly used chemical, biologic or physical agents. These include fragrances, pesticides, solvents, electromagnetic frequency, and many more which have demonstrated effects in higher doses considered toxic. The symptoms of MCS include headaches, fatigue, nausea, dizziness, and are subjective, vague, and non-specific, meaning they can be attributed to many diseases and conditions.
Historical Background:
MCS was first defined in 1987 as an acquired disorder that developed after an identifiable chemical exposure. In 1994, several organizations including the American Medical Association, American Lung Association, U.S. Environmental Protection Agency agreed that “complaints of MCS should not be dismissed as psychogenic, and a thorough workup is essential.” In 1999, the criteria described below were published in Archives of Environmental Health:
"MCS is a chronic condition with symptoms that occur in multiple organ systems and recur reproducibly in response to low levels of exposure to multiple unrelated chemicals and improve or resolve when incitants are removed"
However, there is much disagreement about the cause and validity of MCS as its own disease.
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Published case studies have documented the existence of the shared characteristics above. Additional features of the symptoms common among MCS patients are nervous system involvement, addictive behaviors, and symptom provocation by an escalating number of exposures. A recent survey conducted with MCS patients achieved good reproducibility regarding self-report of symptoms described in published case definitions. In other words, there seems to be a shared experience common to all MCS patients.
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Others argue there is a lack of consistency both among patients and among the research. The conventional medical database UpToDate has the standpoint that MCS or IEI is not a distinct medical entity in and of itself, due to the lack of consistent objective physical findings or lab tests. There are no specific diagnostic criteria to define MCS. The prevailing theory in conventional medicine is that the current evidence does not support any immunological or biologic basis for IEI.
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Instead, MCS is considered a functional somatic syndrome, attributed to psychological factors, by conventional definition. MCS is currently classified as a Somatoform disorder, which is an umbrella term for mental illnesses that manifest with physical symptoms which are otherwise unexplained medically.
It is possible that MCS/IEI is an emerging condition brought on in age of increasing use of chemical substances that simply requires more research to understand fully. Experts in environmental medicine report that MCS is a modern phenomenon that is present in up to 20% of the population.
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Indoor Volatile
Compounds
Plastics
New Carpets
Mold
Fragrance & Cosmetics
Solvents
Gasoline
Nail Polish
Paints
Pesticides
Insecticides
Herbicides
Disinfectants
Drugs
Antibiotics
Anaesthetics
Implants
Chemotherapy
Cleaning Agents
Bleach
Ammonia
Disinfectants
Combustion
Engine Exhaust
Tobacco Smoke
Fire Smoke
Natural Gas
References:
Black DW, Temple S. Idiopathic environmental intolerance (multiple chemical sensitivity). In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on January 28, 2021.)
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Crinnion W, Pizzorno J. Clinical Environmental Medicine.; 2019.
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McKeown-Eyssen GE, Sokoloff ER, Jazmaji V, Marshall LM, Baines CJ. Reproducibility of the University of Toronto self-administered questionnaire used to assess environmental sensitivity. Am J Epidemiol. 2000 Jun 15;151(12):1216-22. doi: 10.1093/oxfordjournals.aje.a010172. PMID: 10905534.