Multiple Chemical Sensitivity: An Illness Often Misunderstood

What MCS is
What causes MCS

What Multiple Chemical Sensitivity Is 

The diagnosis of multiple chemical sensitivity (MCS) is being applied, although definition of this "medical phenomenon" is elusive and not well defined or understood. Many of the physicians who diagnose "MCS" are clinical ecologists who are members of the American Academy of Environmental Medicine. This organization defines MCS as "An ecologic illness of poly-symptomatic, multi-system chronic disorder manifested by adverse reactions to environmental excitants, as they are modified by individual susceptibility in terms of specific adaption."¹ Another recent definition was proposed, "MCS is an acquired (meaning not inherited) disorder characterized by recurrent symptoms, referable to multiple organ systems, occurring in response to demonstrable exposure to many chemically unrelated compounds at doses far below those established in the general population to cause harmful effects. No single widely accepted test of physiologic function can be correlated with symptoms."² Other recognizable names for MCS include: Environmental Illness, Total Allergy Syndrome, Idiopathic Environmental Illness and Chemical AIDS.

Multiple chemical sensitivity is a controversial topic and debate rages on whether MCS is classifiable as an illness. The reasons for this are:

• There is no consistent pattern of symptoms.

• Information on frequency and history is lacking.

• There are no consistent diagnostic test results; MCS patients typically have normal medical test results.

• There is no known mechanism of illness (specific triggers).

• Many of the patients have psychiatric problems.

• Treatments do not work.

• Levels of chemicals that trigger it are much lower than is thought to cause any health problems.

In summary, the diagnosis of multiple chemical sensitivities provides the patient with little information concerning the cause, prognosis, or treatment of the symptoms.

The number of people in the United States who have been diagnosed with MCS is unknown; but in a 1996 survey of 4000 adults in California carried out by the California Health Services Department, 6.3% of respondents reported a diagnosis of multiple chemical sensitivity. An additional 15.9% reported "chemical sensitivity" associated with multiple reactions, without a specific diagnosis of MCS.³

What Causes MCS

In a recent survey of occupational physicians, 62 percent stated that MCS is mostly psychological, and 83 percent said that MCS is due to some combination of psychological and physical causes. The occupational physicians who saw these patients referred them to psychiatrists and psychologists much more often than they did to allergists and neurologists. Only 9 percent believed that MCS primarily is due to physical causes.⁴

Some researchers have suggested that the psychiatric problems are not the cause of MCS, but that the health problems caused by MCS might make one more depressed, stressed, or fearful.

The National Research Council, at the request of the US Environmental Protection Agency, conducted a workshop to discuss the issue and to identify backing scientific information. Results of this workshop present approaches for evaluating and treating the patients.¹

References

1. National Research Council. Multiple Chemical Sensitivities. Washington, DC 1992.

2. Cullen MR. The worker with multiple chemical sensitivities: an overview. Occ. Med State Art Rev. 1987;2:655-661.

3. Blank DM. What's in the office air? Workers smell trouble: trying to define an on-the-job malady. New York Times. 1998 Feb 22;Sect. BU: 11.

4. Ross HL. The behavioral effects of indoor air pollutants. Occupational Medicine: State of the Art Reviews. Philadelphia, Hanley and Belfus, Inc. 1995 Jan-Mar;10(1):158.