Multiple Chemical Sensitivity


Multiple chemical sensitivity (MCS) is a highly controversial disorder associated with unusually extreme sensitivity or allergy-like reaction in response to low-level exposure to chemicals, solvents, petroleum products, smoke, pollen, pet fur, perfumes, and volatile organic chemicals (VOCs) in particular. The disorder is also referred to as multiple chemical sensitivity syndrome, chemical injury, chemical sensitivity, environmental illness, multiple allergy, and total allergy syndrome, along with many other related terms.


Unlike true allergies, MCS does not have an underlying cause that is relatively well understood. Consequently, it is generally regarded as idiopathic—meaning that it does not have a known mechanism of causation. As of 2012, MCS is not recognized as an “established organic disease” by the American Medical Association, the American Academy of Allergy and Immunology, the American College of Physicians, the International Society of Regulatory Toxicology and Pharmacology, and many other medical organizations.

In 1987, Dr. Mark R. Cullen defined MCS within the paper “The Worker with Multiple Chemical Sensitivities: An Overview” (2:655–661) within the journal Occupational Medicine. Cullen's definition states that MCS is a disorder:

In 2005, Dr. Michael Lacour and colleagues expanded the definition made by Cullen within the article “Multiple Chemical Sensitivity Syndrome (MCS)—Suggestions for an Extension of the U.S. MCS-case” (208, 141–151) in the journal International Journal of Hygiene and Environmental Medicine. Lacour includes these six fundamentals for MCS: (1) it is a chronic condition, (2) its symptoms recur reproducibly, (3) it occurs in multiple organ systems, (4) it occurs in response to low levels of exposure, (5) it occurs because of multiple unrelated chemicals, and (6) it improves or is resolved when incitants are removed. Lacour also adds the following symptoms:

Risk factors

MSC has been cited to occur due to a multitude of chemicals. Some of the more common include:


Causes and symptoms

MCS has no uniform cause or consistent, measurable features. Insufficient medical evidence has yet to confirm a relationship between any of the various possible causes of MCS and the symptoms that individuals report. Individuals who have been diagnosed with MCS report widely varied symptoms. This makes it very difficult for MCS to be treated. Further, medical professionals contend it is a chronic condition identified by increased sensitivity to even slight exposure to chemicals, and that multiple symptoms occur in multiple organ systems. An episode of MCS is often caused by exposure to a newly introduced consumer product, such as new carpet. Proposed theories regarding the cause of MCS usually center around allergies, immune system dysfunction, neurobiological sensitization, and various psychological theories.

People with MCS often experience some of the following symptoms:

Sometimes these symptoms are so disabled that the person cannot live or work except in an environment completely devoid of chemicals.

Critics argue that this condition should not receive clinical recognition as a disease, insisting that there is no conclusive scientific evidence to link the causes to the symptoms of the condition.

Somatoform disorders—
Any mental disorder characterized by symptoms that suggest physical illness or injury; however, with symptoms that cannot be completely explained by a medical condition, from exposure with a substance, or attributable to another mental disorder.
Any type of poison made by humans or introduced into the environment by human activity, such as insecticides.
Volatile organic chemicals—
Any organic chemicals with a high vapor pressure at ordinary, room-temperatures.


Cases of MCS are usually diagnosed and evaluated based on the patient's description of symptoms and their connection to environmental exposures. Although it is clear that some people are very sensitive to various microorganisms, noxious chemicals, and common foods, there is little evidence that an immunologic basis exists for generalized allergy to environmental substances.

A medical professional will usually diagnosis MCS when observing all of the following:



Public health role and response

Because MCS is not recognized as a valid medical condition, little has been done with respect to a public response. The medical community treats MCS as best as it can under these limited circumstances.


For the most part, the prognosis for sufferers of MCS is best when they avoid pollutants and toxicants.


One can prevent MCS by avoiding all chemicals that are known to adversely affect one's health. Although difficult at best, it is advised to live in an environment that is absent of pollutants and irritants of any kind—that is, a chemical-free environment.

See also Toxicology ; Volatile organic compound .



Larsen, Laura, editor. Environmental Health Sourcebook. Detroit: Omnigraphics, 2010.

Matthews, Bonnye L. Defining Multiple Chemical Sensitivity. Jefferson, NC: McFarland, 2008.

Natelson, Benjamin H. Your Symptoms Are Real: What to Do When Your Doctor Says Nothing Is Wrong. Hoboken, NJ: John Wiley, 2008.

Pall, Martin L. Explaining “Unexplained Illnesses”: Disease Paradigm for Chronic Fatigue Syndrome, Multiple Chemical Sensitivity, Fibromyalgia, Post-Traumatic Stress Disorder, Gulf War Syndrome, and Others. New York: Harrington Park Press, 2007.

Preston, Flora. Convenient, “Safe” and Deadly: The True Costs of Our Chemical Lifestyle. Lanark, ONT, Canada: Health Risk Navigation, 2006.

Sutton, Amy L. Allergies Sourcebook: Basic Consumer Health Information About Allergic Disorders, such as Anaphylaxis. Detroit: Omnigraphics, 2007.

Valkenburg, Els. Understanding Multiple Chemical Sensitivity: Causes, Effects, Personal Experiences and Resources. Jefferson, NC: McFarland, 2010.


“Definitions of MCS.” Danish Research Centre for Chemical Sensitivities. (accessed September 18, 2012).

Magill, Michael K., and Anthony Suruda. “Multiple Chemical Sensitivity Syndrome.” American Academy of Family Physicians. (September 1, 1998). (accessed September 18, 2012).

“Multiple Chemical Sensitivity (MCS).” Ecos Organic Paints and Biosis Ltd. (accessed September 18, 2012).

“Multiple Chemical Sensitivities.” Occupational Safety and Health Administration, U.S. Department of Labor. (accessed September 18, 2012).


Agency for Toxic Substances and Disease Registry, Centers for Disease Control and Prevention, 4770 Buford Hwy N.E., Atlanta, GA, 30341, (800) 232-4636, .

American Academy of Environmental Medicine, 6505 E. Central Ave., #296, Wichita, KS, 67206, 1(316) 684-5500, Fax: 1(316) 684-5709, administrator@aaemonline. org, .

American Medical Association, 515 N. State St., Chicago, IL, 60654, (800) 621-8335, .

Environmental Defense Fund, 1875 Connecticut Ave. N.W., Ste. 600., Washington, D.C., 20009, (800) 684-3322, .

Environmental Protection Agency, 1200 Pennsylvania Ave., N.W.; Ariel Rios Bldg., Washington, D.C., 20460, 1(202) 272-0167, .

Environmental Research Foundation, PO Box 160, New Brunswick, NJ, 08908, 1(732) 828-9995,, .

National Institute of Occupational Safety and Health, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, 30333, (800) 232-4636,, .

Occupational Safety and Health Organization, U.S. Department of Labor, 200 Constitution Ave., N.W., Washington, D.C., 20210, (800) 321-6742, .

William A. Atkins, BB, BS, MBA

  This information is not a tool for self-diagnosis or a substitute for professional care.