The Interagency Workgroup on
Multiple Chemical Sensitivity
August 24, 1998
Introduction and History
Table of Contents
I. Background and
Introduction and History
The condition now most commonly known as multiple
chemical sensitivity (MCS) was brought to the attention of the U.S. medical establishment
when the late Theron Randolph, a physician trained in allergy and immunology, reported
that a number of his patients reacted adversely to chemicals in their environment
(Randolph, 1952). He compared the condition to Selye's stress-oriented general adaptation
syndrome (Kurt, 1995) and linked the adverse effects of this "petrochemical
problem" to contact with chemicals found in commonly encountered substances such as
cosmetics, auto fuels, exhaust fumes, and food additives. He also observed that many of
his patients reacted to many industrial solvents found in small amounts in manufactured
products such as construction materials, newspaper and other ink-related products,
furniture, and carpet.
Although Randolph and other physicians who shared his theories published articles in
the medical literature during the 1950's and early 1960's, his views were not widely
accepted among physicians, particularly those trained in allergy and immunology. In 1965,
in response to this lack of acceptance within his specialty, he founded the Society for
Human Ecology and invited physicians of all specialties (who were later often referred to
as clinical ecologists) to take part. In 1985, the Society changed its name to the
American Academy of Environmental Medicine (AAEM, 1992). Today, members are referred to as
environmental physicians. However, the term clinical ecologist remains in use.
The American Academy of Environmental Medicine has stated that a wide variety of
symptoms, stemming from many different organs, "[m]ay all be the result of biologic
system dysfunctions triggered by environmental stressors in susceptible patients"
(AAEM, 1992). AAEM supports the application of a comprehensive model of environmental
medicine to elucidate the nature of these system dysfunctions. The model states the
Environmentally Triggered Illnesses (EI) result from a disruption of homeostasis by
environmental stressors. This disruption may result from a wide range of possible
exposures, ranging from a severe acute exposure to a single stressor to cumulative
relatively low grade exposures to many stressors over time. The disruption can affect any
part of the body via dysfunctioning of any number of the body's many biologic mechanisms
and systems. The ongoing manifestations of Environmentally Triggered Illnesses are shaped
by the nature of stressors and the timing of exposures to them, by the biochemical
individuality of the patient, and by the dynamic interactions over time resulting from
various governing principles such as the total load, the level of adaptation, the
bipolarity of responses, the spreading phenomenon, the switch phenomenon, and individual
susceptibility (biochemical individuality) (AAEM emphasis) (AAEM, 1992).
There has been increasing debate over MCS in the years since Randolph's publications. A
wide variety of symptoms have been reported, including fatigue, malaise, difficulty
concentrating, loss of memory, weakness, headaches, nausea, mucous membrane irritation,
and dizziness (Terr, 1986; Lax and Henneberger, 1995). MCS patients have associated their
symptoms with many substances, including colognes and perfumes, aerosol air freshener,
laundry detergent, gasoline exhaust, cleaners, insecticide sprays, and cigarette smoke
(Ziem, 1992; Lax and Henneberger, 1995). MCS has been associated with exposure to many
kinds of substances. These exposures may occur in workplaces, homes, and outdoors. In this
report, the environment in which MCS might occur comprises all these locations.
Topics that have been debated include: whether MCS is a distinct disease entity, its
etiology (or etiologies), its pathophysiology, how to define the condition, how it should
be treated, and how it should be approached in the legal and legislative arenas. The
condition has become more visible through increased media attention. One result of this
visibility has been an increase in the number of scientists and physicians taking part in
the debate. The discussions have, at times, become contentious, and there have been calls
for governmental action by MCS patients, advocacy groups, and legislators.
In recent years, federal agencies have increased their interagency cooperation on MCS
issues through sharing of current knowledge, development of research recommendations, and
cosponsorship of workshops and conferences. This report is part of that continuing effort.
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Many other names have been applied to the condition
called MCS. Among them are environmental illness (EI), ecological illness, total allergy
syndrome, the 20th Century disease (e.g., Hileman, 1991), and idiopathic environmental
intolerances (IPCS, 1996). The last term, which is discussed in Section VI, was
recommended by a MCS workshop that was organized by the International Program on Chemical
Safety (a program cosponsored by the United Nations Environmental Program, the
International Labor Office, and the World Health Organization).
Until more is known about the etiology of the condition, it is not possible to
determine what name would be both descriptive and physiologically correct. The workgroup
has elected to use the most commonly applied term "multiple chemical
sensitivity" ("MCS") throughout this report.
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The most basic disagreement surrounding the study of MCS
has been how to define the condition in ways acceptable to the many interested parties. In
1987, Mark Cullen, M.D., a professor of medicine and epidemiology at Yale University,
edited an issue of Occupational Medicine State of the Art Reviews entitled
"Workers With Multiple Chemical Sensitivities" (Cullen, 1987). He described the
case of a middle-aged man who had developed sensitivities to a wide variety of chemicals,
including common household products. This occurred after the patient had developed
pneumonia following exposure to a chemical spilled at work. Cullen reported his lack of
success in treating the patient and noted that there were other patients in whom the same
symptoms developed following similar situations. From this experience, Cullen proposed a
definition that has become the one most commonly referenced, and is, for some, the de
facto definition of MCS.
1 presents Cullen's definition and others that have been proposed. Common elements in
the definitions are summarized in Table
2. Not shown in Table
2 is the definition used by Kurt (1995) in his research. He defined MCS as "[a]
symptom complex triggered by odor or a perceived exposure; occurring at exposure levels
below those of allergic sensitivity or irritation; analogous to the symptoms of panic
disorder as defined by (DSM-III-R); lacking objective clinical pathologic criteria; and
responsive to panic disorder management." This definition is distinctly different
from those in Table
2, (i.e., it is primarily based on psychological criteria); therefore it was not
included in the table.
The elements most common among the definitions in Table 2 include multiple environmental causes, chronicity,
multiorgan symptoms, and symptoms at very low levels of chemical exposure. It is also
apparent that Cullen's definition contains the most individual elements. The definition
most clinically oriented because of its specificity about symptoms is that of the
Association of Occupational and Environmental Clinics (AOEC), a group of primarily
university-based clinics that specialize in occupational and environmental medicine. Their
definition contains all of Cullen's elements but one (demonstrable exposure).
The California Department of Health Services (CDHS) has proposed the development of a
descriptive scale for use in population-based research that could reduce the necessity of
prematurely finding one, widely agreed-to case definition. The scale would be based on
such factors as the number of substances eliciting responses at low doses, the number of
organ systems involved, symptom severity, symptom chronicity, and initiating events. Each
item would be scored individually in multidimensional scale or combined to create a
composite monodimensional scale. Subjects' scores would be based on responses to
standardized questionnaires (CDHS, 1996). CDHS suggested that this approach would allow
the placement of patients along a continuum to create descriptive categories, such as (1)
patients with very suggestive scale scores (with or without the presence of confounding
medical and psychiatric conditions); (2) respondents with moderately suggestive scores;
and (3) respondents with scale scores unlikely to represent MCS. Response scaling allows
for maximal use of all respondents, allows for the identification of a subset of
respondents who represent the most likely persons to be afflicted, and may prove useful in
describing the natural history of the condition. Other subjects can be chosen from along
the continuum for a comparison group (see Section II, Epidemiologic Considerations).
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Federal and state government interest in MCS has a relatively long
history, as documented by Hileman (1991), from which Table 3 is adapted. Selected legal cases are also included in Table
3 because they have occasionally led to action by government agencies. Although not
intended to be all-inclusive, the list gives examples of how MCS has been addressed in
legal and governmental forums.
In addition to the items in Table
3, there have been a number of other state actions. California, Louisiana, Minnesota,
Ohio, Oregon, and Pennsylvania have ruled in favor of MCS claimants in workers'
compensation cases, but this situation can and does change with shifts of policy and
personnel in the states. Gots (1995) has stated that the number of MCS claims continues to
rise. New Hampshire has a workers' compensation act that recognizes the condition; in
addition, several state court decisions in California, Ohio, and other jurisdictions have
found that MCS conditions qualify as handicaps for purposes of state employment
discrimination statutes (Lieberman et al., 1995).
Florida was the first state to pass legislation creating a pesticide notification
registry for persons claiming chemically related illness. Typically, these registries
require that notice of impending pesticide application to abutting property be given to
persons listed on the registry. Some registries also require notification for painting,
repair, and construction. A physician's certification of sensitivity to chemicals is
usually required before a person can be enrolled in a registry. Currently, 10 states
(Colorado, Connecticut, Florida, Louisiana, Maryland, Michigan, Pennsylvania, Washington,
West Virginia, and Wisconsin) have created notification registries through legislation.
There have also been successful efforts to reduce the medical requirements needed for
persons to be placed on state registries. Colorado, for example, may allow admittance to
its pesticide sensitivity registry through a document signed by licensed physicians
regardless of the geographic areas in which they practice medicine (Langley, 1995).
Perhaps the most significant MCS legislation passed by a state was enacted by
Washington State in 1994. Several medical centers were funded to diagnose and treat
chemically related illness or porphyrinopathy (Langley, 1995). In addition, Washington
State announced in 1996 the funding of six projects on chemically related illness totaling
$1.4 million. The projects included research on the validity of immune and lymphocyte
tests in MCS patients and controls, the relationship of brain function to MCS, and the
development of objective tests for evaluation of MCS patients. Related projects included
investigation of (1) the relationship between low levels of volatile organic compounds and
functional/inflammatory changes in the lungs or sinuses and (2) the potential health
effects of exposure to the dusts of various tree species and to certain metals (Washington
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