Multiple Chemical Sensitivity-What is It?
Roy L. DeHart
"If you don't know where you are going any road will get you there."
-Anonymous
This workshop on multiple chemical sensitivity accomplishes many objectives; perhaps most significant was gathering many professionals with widely divergent opinions regarding MCS together. One important objective unfortunately must await another time: the definition of MCS.
The inability to reach concensus of such an important aspect of this phenomenon speaks volumes on the controversy that is MCS. This controversy is neither new nor unstated. Several disciplines in organized medicine have addressed the issues and contributed to the controversy. Four of these positions are presented for review.
The California Medical Association established a Task Force on Clinical Ecology under its Scientific Board. The report of the Task Force was published in February, 1986 which in part states:
The task force collected material as for any subject review and included all information supplied by individual clinical ecologists and by their professional organizations. There was extensive description of the basic hypotheses of clinical ecology, and an ample and varied collection of anecdotal reports and individual patient testimonials. In contrast, there was a surprising paucity of published studies to prove or disprove clinical ecology hypotheses. Critical analyses of patients and cohorts, detailed data collection, validation and confirming laboratory assays were not provided.
No convincing evidence was found that patients treated by clinical ecologists have unique, recognizable syndromes, that the diagnostic tests employed are efficacious and reliable or that the treatments used are effective. Even though clinical ecology has existed for approximately 50 years, only a few studies have been conducted that are scientifically sound. Most have such serious methodological flaws as to make their conclusions unacceptable. Those few studies that used scientifically sound methods have provided evidence that the effectiveness of certain treatment methods used by clinical ecologists is based principally on placebo response.
Undoubtedly, some patients suffer from illnesses that cannot be readily diagnosed and
for which only supportive treatments exist. It may even be true that some or all of the hypotheses and treatments proposed by clinical ecologists are valid but we found no evidence to support them. These hypotheses and treatments should be subjected to modern, scientific methods of evaluation. We think that this can be done provided genuine interest exists.
The task force is concerned that unproved diagnostic tests are being widely used by clinical ecologists in what may be incorrect or inappropriate applications. Decisions made on the basis of these tests can lead to misdiagnosis, resulting in patients being denied other supportive treatments and becoming psychologically dependent, believing themselves seriously and chronically impaired. This possibility underscores-the need for more adequate scientific studies to prove or disprove the value of clinical ecology tests and treatments. To consider the current practice of clinical ecology experimental is misleading, however. It can only be considered experimental when its practitioners adhere to scientifically sound research protocols and inform their patients about the investigative nature of then' practice.)1
The same year the Executive Committee of the American Academy of Allergy and Immunology issued a position statement on Clinical Ecology. The critique follows:
The environment is very important in the lives of every human being. Environmental factors, such as chemicals and pollutants, have been demonstrated to influence health. The idea that the environment is responsible for a multitude of human health problems is most appealing. However, to present such ideas as facts, conclusions, or even likely mechanisms without adequate support, is poor medical practice.
The theoretical basis for ecologic illness in the present context has not been established as factual, nor is there satisfactory evidence to support the actual existence of "immune system disregulation" or maladaptation. There is no dear evidence that many of the symptoms noted above are related to allergy, sensitivity, toxicity, or any other type of reaction from foods, water, chemicals, pollutants, viruses, and bacteria in the context presented. Properly controlled studies defining objective parameters of illness, properly controlled evaluation of the treatment modalities, and appropriate patient assessment have not been done. Anecdotal articles do not constitute sufficient evidence of a cause-and-effect relationship between symptoms and environmental exposure. The major techniques used by the clinical ecologists are controversial and unproven. The American Academy of Allergy and Immunology has previously published position statements concerning subcutaneous and sublingual provocation neutralization procedures and found them to be unproven. More recent review of new data submitted by a number of clinical ecologists to the Practice Standards Committee of the Academy has not changed that recommendation. There are no adequate studies of the cyclic diets, elimination diets, injection therapy with chemicals, or even the environmentally controlled units to substantiate their use. Many of the patients are reported to have a normal physical examination and normal laboratory tests.
There are no immunologic data to support the dogma of the clinical ecologists. To suggest that these patients lack suppressor T cell function has not been supported by published data. The suggestion that neutralization therapy can provide rapid relief witch minutes or hours cannot be supported by controlled clinical studies or immunologic data.2
The American College of Physicians published a position paper on Clinical Ecology in 1989. The summary from that publication is quoted:
Clinical ecologists propose the existence of a unique illness in which multiple environmental chemicals, foods, drugs, and endogenous C. albicans have a toxic effect on the immune system, thereby adversely affecting other bodily functions. The proposal uses some concepts that superficially resemble those that apply to clinical allergy and toxicology and others that are novel.
Review of the clinical ecology literature provides inadequate support for the beliefs and practices of clinical ecology. The existence of an environmental illness as presented in clinical ecology theory must be questioned because of the lack of a clinical definition. Diagnoses and treatments involve procedures of no proven efficacy.
Case reports by clinical ecologists and evaluation of these patients by other physicians indicate that this diagnosis is applied most frequently to persons with symptoms of physiologic (somatic) or psychologic dysfunction, or both. Proof of cause-effect relations between environmental factors and symptoms of "environmental illness" is particularly difficult because clinical ecologists implicate such a broad range of agents, including chemicals, foods, hormones, and microorganisms. Most patients are believed to react to multiple environmental substances by any route of exposure, and some are said to be intolerant to the entire environment, the so-called "total allergy syndrome."
The principal method of proof cited by clinical ecologists for the existence of "environmental illness" is the symptom-provocation test used in diagnosis of individual cases after the condition is suspected because of a history of symptoms and suspected causes. Published studies on the provocation test employed widely different subject-selection methods and outcome-measurement criteria. All were seriously flawed by the absence of matched patient-control groups, absence or inadequacy of placebo, and failure to achieve or document randomness of trials. Not surprisingly, therefore, the conclusions from these studies are conflicting.
Those studies reporting results of immunologic tests are insufficient to address theories of environmental illness; the number of cases is small and selection criteria are not dear. Enumeration of lymphocyte subsets and quantitation of serum immunoglobulin and complement levels in patients with "environmental illness" have not yielded dear-cut evidence of immunologic abnormality.
Clinical ecologists use a treatment program that includes avoidance of environmental chemicals, rotation of foods in the diet, and neutralization of symptoms with injected or sublingual extracts. Except for small-dose oral nystatin, which is used for treatment of patients with the candida hypersensitivity syndrome, drug therapy is intentionally avoided, although some clinical ecologists recommend mineral salts, oxygen, vitamins minerals, and antioxidants for relief of symptoms. There are only two controlled studies on neutralization therapy. One evaluated only eight patients for 20 days; the other was a study of dust allergy in patients With allergic rhinitis, not "environmental illness." To date, there have been no controlled studies on diet therapy, environmental elimination therapy, or nystatin in patients with candida hypersensitivity. Thus there is no body of evidence that clinical ecology treatment measures, singly or in combination, are effective.
Others who have reviewed the diagnostic and therapeutic methods of clinical ecology have also arrived at the conclusion that these methods are of unproven value. Potential adverse effects from these procedures and the costs of clinical ecology diagnosis and treatment have not been evaluated.3 More recently, on April 28, 1991, the American College of Occupational Medicine issued the following position statement on multiple chemical hypersensitivity syndrome:
Multiple Chemical Hypersensitivity Syndrome is one of over 20 names or descriptions (20th century disease, Environmental Illness, Total Allergy syndrome, Chemical AIDS, etc.) given to a clinical complex characterized by recurrent polysystem symptoms often without observable physical findings or laboratory abnormalities believed to be associated with repeated exposure to specific biological, chemical or physical agents. Practitioners involved in the diagnosis and treatment of this phenomenon may identify themselves as clinical ecologists or environmental medicine specialists.
The pathophysiological mechanism described by these practitioners do not, in general, conform to what is currently known of human biological functions. To explain the phenomenon, these practitioners draw on new or modified mechanisms such as "total body load, spreading, and switching." The scientific foundation for managing patients with this syndrome has yet to be established by traditional clinical investigative activities that withstand critical peer review.
The following medical associations have carefully reviewed the available scientific evidence regarding this phenomenon:
The American Academy of Allergy and Immunology
The California Medical Association
The American College of Physicians
Their conclusions have been similar and state that the scientific and clinical evidence supporting the pathophysiological mechanisms and treatment regimens as articulated by these practitioners is lacking. It is the position of the American College of Occupational Medicine that the Multiple Chemical Hypersensitivity Syndrome is presently an unproven hypothesis and current treatment methods represent an experimental methodology. The College supports scientific research into the phenomenon to help explain and better describe its pathophysiological features and define appropriate clinical interventions. This research should adhere to established principles of scientific inquiry and the results submitted for publication in recognized peer-reviewed journals.4
In each of these position statements there is one integrating theme-the clear need for rigorous scientific placebo-controlled, double-blind investigations that are subject to exacting peer review. Although the working group was unable to characterize the patient with multiple chemical sensitivity, the investigators and scientists must provide a definition as part of protocol development. Case definition and criteria for a diagnosis must be explicit if the study population is to be appropriately identified. Further, if one is to define the mechanism of MCS or to conduct epidemiological research focused on MCS, case definition is not an option, but a necessity.
If the question cannot be answered as to what MCS is, how can there be approval of research protocols or acceptance of investigative results? In order to appropriately address the controversies surrounding this phenomenon we must know where we're going!
REFERENCES
California Medical Association. Clinical Ecology-A Critical Appraisal . Western Journal of Medicine; 144:2,239-49, 1986.
American Academy of Allergy and Immunology. Clinical Ecology. Journal of Allergy and Clinical Immunology 78:2,269-71; 1986.
American College of Physicians. Clinical Ecology. Annals of Internal Medicine 111:2,168-78; 1989.
American College of Occupational Medicine. Multiple Chemical Hypersensitivity Syndrome. Board minutes, April 28, 1991.
