For some people with multiple chemical sensitivities (MCS), the problem begins after accidental exposure to a chemical, perhaps at work. For others, it takes exposure to low levels of chemicals over months or years before symptoms begin. The result is sensitivity to many different types of chemicals even in small amounts, and in things that usually don't bother people, such as perfumes, laundry detergent, or cleaning products. This sensitivity isn't an allergy in the usual sense, but like an allergy it causes particular physical symptoms.
The symptoms
When someone with MCS comes in contact with a substance to which he or she is sensitive, either by breathing it in, eating it, or touching it, he or she has a physical reaction to it. Each person affected has his or her own type of reaction, which can range from mild and uncomfortable to severe and life-threatening. The most common reactions are headache, fatigue, dizziness, nausea, memory problems, breathing problems, feeling like you have the flu, rashes, and hives. Usually the symptoms fade between exposures, but some people have the symptoms all the time.
Research still needed
What exactly causes MCS--in other words, what the physical processes are that bring it on--is not completely clear. Researchers are studying how chemical exposure and sensitivity can affect brain chemistry and cause emotional and central nervous system disorders, such as brain inflammation (toxic encephalopathy). Other researchers are looking at the immune system and how reaction to one chemical "crosses over" into a reaction to many chemicals.
However, there are also questions by some in the medical community as to whether MCS exists. Yet try telling someone with MCS that the symptoms he or she is experiencing only happen because he or she believes they will. People affected describe not being able to stand in line behind people wearing perfume without getting a severe headache, or walk through the laundry detergent aisle in the supermarket without having trouble breathing, or being unable to pump gas because they feel dizzy and nauseous.
The big picture
It took several years before "sick building syndrome," a situation in which people working or living in a building become ill from chemical exposure, was recognized and accepted as truly existing. So too with multiple chemical sensitivity. Like chronic fatigue syndrome and fibromyalgia (both of which can coexist with MCS), MCS is finally being recognized by the general public, the media and the U.S. government. Since 1991 MCS could be considered a disability under the Americans with Disabilities Act. Many states have established registries for chemically sensitive individuals who, for example, will be notified of pesticide applications.
Understanding MCS
The next step in understanding MCS would seem to be the establishment of a clearinghouse for scientific information on the disorder (either by a national government or a private foundation). Techniques for alleviating MCS need to be established and the medical community informed of what proven therapeutic measures exist and where they are available. The public also needs to be made aware of the potential misuse of science by lawyers, salesmen, and others who wish to benefit financially from people suffering from MCS.
There is hope for people with MCS, and as time goes by science will understand even better how to deal with the disorder, and perhaps even eliminate it.
Information for this article was taken from:
- Chemical Injury Resource Association of Minnesota. What is EI/MCS?
- Nelson, Eric. The MCS Debate: A Medical Streetfight. The Free Press, Feb/Mar 1994.

