1999 MCS consensus statement
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.
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.