http://www.environmentalhealth.ca/w03mcs99.html

Multiple Chemical Sensitivity: A 1999 Consensus

ABSTRACT. Consensus criteria for the definition of multiple chemical
sensitivity (MCS) were first identified in a 1989 multidisciplinary
survey of 89 clinicians and researchers with extensive experience in,
but widely differing views of, MCS. A decade later, their top 5
consensus criteria (i.e., defining MCS as [1] a chronic condition [2]
with symptoms that recur reproducibly [3] in response to low levels of
exposure [4] to multiple unrelated chemicals and [5] improve or resolve
when incitants are removed) are still unrefuted in published
literature. Along with a 6th criterion that we now propose adding
(i.e., requiring that symptoms occur in multiple organ systems), these
criteria are all commonly encompassed by research definitions of MCS.
Nonetheless, their standardized use in clinical settings is still
lacking, long overdue, and greatly needed-especially in light of
government studies in the United States, United Kingdom, and Canada
that revealed 2-4 times as many cases of chemical sensitivity among
Gulf War veterans than undeployed controls. In addition, state health
department surveys of civilians in New Mexico and California showed
that 2-6%, respectively, already had been diagnosed with MCS and that
16% of the civilians reported an "unusual sensitivity" to common
everyday chemicals. Given this high prevalence, as well as the 1994
consensus of the American Lung Association, American Medical
Association, U.S. Environmental Protection Agency, and the U.S.
Consumer Product Safety Commission that "complaints [of MCS] should
not be dismissed as psychogenic, and a thorough workup is essential,"
we recommend that MCS be formally diagnosed-in addition to any other
disorders that may be present-in all cases in which the 6
aforementioned consensus criteria are met and no single other organic
disorder (e.g., mastocytosis) can account for all the signs and
symptoms associated with chemical exposure. The millions of civilians
and tens of thousands of Gulf War veterans who suffer from chemical
sensitivity should not be kept waiting any longer for a standardized
diagnosis while medical research continues to investigate the etiology
of their signs and symptoms.

AS RESEARCHERS AND CLINICIANS with experience in the study, evaluation,
diagnosis, and/or care of adults and children with chemical sensitivity
disorders, we support the stated goal of the National Institutes of
Health 1999 Atlanta Conference on the Health Impact of Chemical
Exposures During the Gulf War "to fully characterize the nature of
multiple chemical exposures within the Gulf War veteran population and
to relate this characterization to what is known about Multiple
Chemical Sensitivity (MCS) and related conditions and disorders within
civilian populations."(1) Based on research conducted by state and
federal government agencies, we already know that MCS is one of the
most commonly diagnosed chronic disorders in civilians and the most
common-but still largely undiagnosed-disorder of any kind in Gulf
War veterans of the United States.

In statewide telephone surveys of randomly selected adults, conducted
by health departments in California in 1995 and 1996 and New Mexico in
1997, investigators found that 6% of adults in California(2) and 2% of
adults in New Mexico(3) indicated that they had already been diagnosed
with MCS or Environmental Illness, whereas 16% in both states said they
were "unusually sensitive to everyday chemicals." When randomly
selected adults in other states were asked if they were "especially
sensitive" (instead of "unusually" sensitive), one-third
consistently maintained that they were.(4-6)

Among Gulf War era veterans, data from the largest random survey
presented by the U.S. Department of Veterans' Affairs (VA) in 1998
(based on questionnaires completed by 11 216 deployed to the Gulf and 9
761 nondeployed) show that 5% reported chemical sensitivity among the
nondeployed personnel and 15% reported the same among the deployed.(7)
Other VA researchers report much higher rates-but the same 3-fold
difference-in a smaller random sample of VA hospital outpatients: 86%
of ill veterans deployed to the Gulf complained of chemical
sensitivity, compared with 30% of undeployed ill veterans.(8) In the
only study in which MCS was specifically assessed among veterans
selected randomly from the VA Registry, investigators found 36% of 1
004 met common research criteria for MCS.(9) Among randomly selected
Department of Defense (DOD) personnel who remain on active duty, two
larger studies by the Centers for Disease Control found slightly
lower-but still significant-2.1- and 2.5-fold increases in the
prevalence of self-reported chemical sensitivity among those deployed
to the Gulf, compared with those who were not deployed. In the
"Iowa" study, in which the prevalence rates for deployed and
nondeployed individuals were 5.4% and 2.6%, respectively, investigators
used a detailed questionnaire to assess "probable MCS."(10) In the
"Pennsylvania" study,(11) in which prevalence rates were 5% versus
2%, respectively, only one "yes/no" question was asked about
chemical sensitivity. Canadian Gulf War veterans reported only
approximately one-half the prevalence of MCS (2.4%), but nevertheless
this was 4 times more than their controls.(12) Even in the United
Kingdom where MCS is little known, Gulf War veterans report being
diagnosed with MCS at 2.5 times the rate of military controls.(13)

Clearly, there is a significant need for a standardized clinical
definition of MCS and a comprehensive clinical protocol that VA, DOD,
and other physicians can use to evaluate it. We recommend to our
colleagues and the sponsors of the Atlanta Conference-the Department
of Health and Human Services' Office of Public Health and Science,
the Centers for Disease Control and Prevention, the National Institutes
of Health, and the Agency for Toxic Substances and Disease
Registry-that MCS be formally defined for clinical purposes by the
top 5 "consensus criteria" identified in a 1989 survey of 89
clinicians and researchers who had extensive experience in MCS but who
also held widely divergent views about its etiology.(14) Included were
36 specialists in allergy, 23 in occupational medicine, 20 in
"clinical ecology," and 10 in internal medicine and otolaryngology.
We would add only that symptoms associated with chemical exposures must
involve multiple organ systems, thus distinguishing MCS from specific
single-organ system disorders (e.g., asthma, migraine) that also may
meet the first 5 criteria.

Consensus Criteria for MCS
The following consensus criteria for the diagnosis of MCS were gleaned
from the study by Nethercott et al.(14) (funded in part by grants from
US NIOSH and US NIEHS):

  1. "The symptoms are reproducible with [repeated chemical]
exposure."

  2. "The condition is chronic."

  3. "Low levels of exposure [lower than previously or commonly
tolerated] result in manifestations of the syndrome."

  4. "The symptoms improve or resolve when the incitants are
removed."

  5. "Responses occur to multiple chemically unrelated
substances."

  6. [Added in 1999]: Symptoms involve multiple organ systems.

Given the only other explicit consensus ever published on MCS-the
1994 statement of the American Lung Association, American Medical
Association, U.S. Environmental Protection Agency, and U.S. Consumer
Product Safety Commission, that "complaints [of MCS] should not be
dismissed as psychogenic, and a thorough workup is essential" (ALA
1994)-we recommend that MCS be diagnosed whenever all 6 of the
consensus criteria are met, along with any other disorders that also
may be present, such as asthma, allergy, migraine, chronic fatigue
syndrome (CFS), and fibromyalgia (FM). MCS should be excluded only if a
single other multi-organ disorder can account for both the entire
spectrum of signs and symptoms and their association with chemical
exposures, such as mastocytosis or porphyria, but not CFS or FM, which
are not so associated.

To assist physicians who are unfamiliar with the evaluation of MCS, we
recommend that clinical protocols include validated questionnaires for
screening and characterizing chemical sensitivity,(15,16) a list of
overlapping disorders to consider in the differential diagnosis of MCS,
and a list of signs and test abnormalities associated with MCS in the
peer-reviewed literature (summarized by Ashford and Miller(17) and
Donnay(18)). Although no single test is yet considered diagnostic of
MCS, those suggested by signs, symptoms, or history may be helpful in
treating and tracking the disorder.

The presentation of MCS may vary greatly among cases and over time.
Some individuals are totally disabled by severe symptoms suffered on a
daily basis, for example, whereas others are disabled only minimally by
mild symptoms suffered occasionally. We, therefore, recommend that any
clinical diagnosis of MCS be characterized and followed over time using
quantitative and/or qualitative indices of life impact or disability
(e.g., minimal, partial, total); symptom severity (e.g., mild,
moderate, severe); symptom frequency (e.g., daily, weekly, monthly);
and sensory involvement (identification of which sensory
pathways-olfactory, trigeminal, gustatory, auditory, visual and/or
touch, including perception of vibration, pain and heat or cold-show
altered (+/-) sensitivity and/or tolerance for normal levels of
stimuli, either chronically or in response to particular chemical
exposures).

For research purposes that require greater homogeneity, we encourage
investigators to refine the consensus criteria for MCS with whatever
additional inclusion or exclusion criteria they believe are needed to
test their hypotheses. The indices and domains that are used to
characterize and select both cases and controls in MCS research should
be fully reported so that results from different studies can be
compared and their broader applicability assessed.

Given the significant overlap in clinic populations of MCS with both
CFS and FM, as well as the need to better understand the relationships
between these disorders,(19-21) we recommend that all
"solicitations" and "requests for applications" issued by
federal agencies for human research into any one of CFS, FM, or MCS
direct investigators to screen for all three (regardless of their
selection criteria, which need not be affected) and to report their
results in these terms. There is a precedent for this: the National
Institute of Arthritis and Musculoskeletal Disorders routinely requires
that in studies of fibromyalgia investigators must screen for and
report any overlap with temporo-mandibular joint disorder. CFS, FM, and
MCS research could all benefit from greater collaboration, and so we
welcome the Congressional initiative of Senator Tom Harkin to earmark
$3 million of the DOD's 1999 Gulf War illnesses research budget for
multidisciplinary studies of CFS, FM, and MCS together (solicitation
074&&&-9902-0005 issued 2/12/99) to better understand both their
overlaps and differences. We recommend that such three-way studies be
solicited by all federal agencies funding CFS, FM or MCS research.

References

  1. Eisenberg J. Report to Congress on Research on Multiple Chemical
Exposures and Veterans with Gulf War Illnesses. Washington DC: US
Department of Health and Human Services, Office of Public Health and
Science. 15 January 1998.

  2. Kreutzer R, Neutra R, Lashuay N. The prevalence of people
reporting sensitivities to chemicals in a population-based survey. Am J
Epidemiol (in press).

  3. Voorhees RE. Memorandum from New Mexico Deputy State
Epidemiologist to Joe Thompson, Special Counsel, Office of the
Governor; 13 March 1998.

  4. Bell IR, Schwartz GE, Amend D, et al. Psychological
characteristics and subjective intolerance for xenobiotic agents of
normal young adults with trait shyness and defensiveness. A
parkinsonian-like personality type? J Nerv Ment Dis 1998; 182:367-74.

  5. Bell IR, Miller CS, Schwartz GE, et al. Neuropsychiatric and
somatic characteristics of young adults with and without self-reported
chemical odor intolerance and chemical sensitivity. Arch Environ Health
1996; 51:9-21.

  6. Meggs WJ, Dunn KA, Bloch RM, et al. Prevalence and nature of
allergy and chemical sensitivity in a general population. Arch Environ
Health 1996; 51(4):275-82.

  7. Kang HK, Mahan CM, Lee KY, et al. Prevalence of chronic fatigue
syndrome among US Gulf War veterans. Boston, MA: Fourth International
AACFS Conference on CFIDS, 10 October 1998 (abstract and presentation).

  8. Bell IR., Warg-Damiani L, Baldwin CM, et al. Self-reported
chemical sensitivity and wartime chemical exposures in Gulf War
veterans with and without decreased global health ratings. Mil Med
1998; 163:725-32.

  9. Fiedler N, Kipen H, Natelson B. Civilian and veteran studies of
multiple chemical sensitivity. Boston, MA: 216th Annual Meeting of
American Chemical Society, Symposium on Multiple Chemical Sensitivity:
Problems for Scientists and Society, 26 August 1998 (abstract and
presentation).

 10. Black DW, Doebbing BN, Voelker MD, et al. Multiple Chemical
Sensitivity Syndrome: Symptom Prevalence and Risk Factors in a Military
Population. Atlanta, GA: The Health Impact of Chemical Exposures During
the Gulf War-A Research Planning Conference. 28 February 1999
(presentation, manuscript submitted).

 11. Fukuda K, Nisenbaum R, et al. 1998. Chronic multisymptom illness
affecting Air Force veterans of the Gulf War. JAMA 1998; 280:981-88.

 12. Canadian Department of National Defense (CDND). Health Study of
Canadian Forces Personnel Involved in the 1991 Conflict in the Persian
Gulf. Ottawa, Canada: Goss Gilroy; 20 April 1998. [Online at:
http://www.DND.ca/menu/press/Reports/Health/health_study_e_vol1_TOC.htm]

 13. Unwin C, Blatchley N, Coker W, et al. Health of UK servicemen who
served in the Persian Gulf War. Lancet 1999; 353:169-78.

 14. Nethercott JR, Davidoff LL, Curbow B, et al. Multiple chemical
sensitivities syndrome: toward a working case definition. Arch Environ
Health 1993; 48:19-26.

 15. Szarek MJ, Bell IR, Schwartz GE. Validation of a brief screening
measure of environmental chemical sensitivity: the chemical odor
intolerance index. J Environ Psychol 1997; 17:345-51.

 16. Miller CS, Prihoda TJ. The Environmental Exposure and Sensitivity
Inventory (EESI): a standardized approach for quantifying symptoms and
intolerances for research and clinical applications. Toxicol Ind Health
(in press).

 17. Ashford NA, Miller CS. Chemical Exposures: Low Levels and High
Stakes (2nd ed). New York: John Wiley, 1998.

 18. Donnay A. A Resource Manual for Screening and Evaluating Multiple
Chemical Sensitivity. Baltimore MD: MCS Referral and Resources, 1999.

 19. Buchwald D, Garrity D. Comparison of patients with chronic
fatigue syndrome, fibromyalgia, and multiple chemical sensitivities.
Arch Int Med 1994; 154:2049-53.

 20. Slotkoff AT, Radulovic DA, Clauw DJ. The relationship between
fibromyalgia and the multiple chemical sensitivity syndrome. Scand J
Rheumatol 1997; 26:364-67.

 21. Donnay A, Ziem G. Prevalence and overlap of chronic fatigue
syndrome and fibromyalgia syndrome among 100 new patients with multiple
chemical sensitivity syndrome. J Chron Fatigue Syndrome 5(2):(in
press).

Signatories to the 1999 Consensus on Multiple Chemical Sensitivity

Liliane Bartha, M.D.
William Baumzweiger, M.D.
David S. Buscher, M.D.
Thomas Callender, M.D., M.P.H.
Kristina A. Dahl, M.D.
Ann Davidoff, Ph.D.
Albert Donnay, M.H.S.
Stephen B. Edelson, M.D., F.A.A.F.P., F.A.A.E.M.
Barry D. Elson, M.D.
Erica Elliott, M.D.
Donna P. Flayhan, Ph.D.
Gunnar Heuser, M.D., Ph.D., F.A.C.P.
Penelope M. Keyl, M.Sc., Ph.D.
Kaye H. Kilburn, M.D.
Pamela Gibson, Ph.D.
Leonard A. Jason, Ph.D.
Jozef Krop, M.D.
Roger D. Mazlen, M.D.
Ruth G. McGill, M.D.
James McTamney, Ph.D.
William J. Meggs, M.D., Ph.D., F.A.C.E.P.
William Morton, M.D., Dr.P.H.
Meryl Nass, M.D.
L. Christine Oliver, M.D., M.P.H., F.A.C.P.M.
Dilkhush D. Panjwani, M.D., D.P.M., F.R.C.P.C.
Lawrence A. Plumlee, M.D.
Doris Rapp, M.D., F.A.A.A., F.A.A.P., F.A.A.E.M.
Myra B. Shayevitz, M.D., F.C.C.P., F.A.C.P.
Janette Sherman, M.D.
Raymond M. Singer, Ph.D., A.B.P.N.
Anne Solomon, Ph.D., M.A.
Aristo Vodjani, Ph.D.
Joyce M. Woods, Ph.D., R.N.
Grace Ziem, M.D., Dr.P.H., M.P.H.
This article was published in the May/June 1999 issue of Archives of
Environmental Health, Vol. 54, No. 3, pp. 147-149.  Heldref
Publications, Helen Dwight Reid Educational Foundation
http://www.heldref.org. The publisher grants permission for the free
reprinting and distribution of this statement.