Multiple chemical sensitivity: a 1999 consensus

Physiologic and symptomatic responses to low-level substances in individuals with and without chemical sensitivities: a randomized controlled blinded pilot booth study

We conducted a pilot study using a randomized, single-blind, placebo-controlled exposure among 10 individuals with and 7 without reported chemical sensitivities in a dedicated testing chamber. Objectives of the study were to explore the length of the adaptation period to obtain stable readings, evaluate responses to different substances, and measure the level and type of symptomatic and physiologic reactions to low-level exposures. Reported and observed symptoms, electrodermal response, heart rate, skin temperature, surface electromyogram, respiratory rate, contrast sensitivity, and the Brown-Peterson cognitive test were used and compared between cases and controls and between test substances (glue, body wash solution, dryer sheet) and control substances (unscented shampoo and clean air). Subjects with chemical sensitivities (cases) took longer to adapt to baseline protocols than did controls. After adaptation, despite small study numbers, cases displayed statistically significant responses (all measures, p < 0.02) in tonic electrodermal response to test substances compared with controls and compared with the control substance. Symptoms were also higher in cases than in controls for the body wash solution (p = 0.05) and dryer sheets (p = 0.02). Test-retest showed good agreement for both symptoms and tonic electrodermal responses (McNemar's test, p = 0.32 and p = 0.33, respectively). Outside of skin conductance, other measures had no consistent patterns between test and control substances and between cases and controls. This study shows the importance of using an adaptation period in testing individuals with reported chemical sensitivities and, despite small numbers, raises questions about underlying mechanisms and level of reactivity to low-level chemical exposures in sensitive individuals.

Multiple chemical sensitivity syndrome (MCS)--suggestions for an extension of the U.S. MCS-case definition

PURPOSE

To validate and extend the US case definition for the Multiple Chemical Sensitivity Syndrome (MCS) from 1999 by a systematic literature-review.

DATA SOURCE

MEDLINE-research from 1997 to August 2003, research in the Cochrane-Library in August 2003, earlier reviews since 1997.

STUDY SELECTION

Headings and abstracts were screened by one reviewer. All references dealing with multiple chemical sensitivities (MCS) which covered topics of interest such as symptom-profiles, differential diagnostic procedures, etc. were included in the analysis.

DATA EXTRACTION AND SYNTHESIS

Topic-specific data extraction and synthesis was done by one reviewer. Data interpretation was discussed by all other authors.

RESULTS

Out of 1429 references 36 publications proved to be suitable for the review. The results can be summarized as follows: exposure-related symptoms associated with self-reported multiple chemical sensitivities can be divided into non-specific complaints of the central nervous system--CNS (main characteristics) and functional disturbances in other organ systems (optional complaints). There is a significant overlap of MCS, CFS and fibromyalgie. At present no standards for a diagnostic procedure based on the criteria outlined above are existing

CONCLUSIONS

MCS should only be diagnosed in patients who are mainly suffering from exposure-related non-specific complaints of the Central nervous system. The suggested diagnostic procedure follows the guidelines for CFS which are extended by diagnostic clarification of functional disturbances in other organ systems.

Síndrome de fatiga crónica e hipersensibilidad química múltiple tras exposición a insecticidas

BACKGROUND AND OBJECTIVE

Chronic Fatigue Syndrome (CFS) and Multiple Chemical Sensitivity (MCS) are well-defined illnesses that may appear after some toxic exposures.

PATIENTS AND METHOD

We report a consecutive series of 26 patients who developed CFS after exposure to insecticide products. It was associated with MCS in a third of cases.

RESULTS

Toxic exposure was of labour origin after returning to usual work place after a process of fumigation. In 42% of cases there was no fulfilment of fumigation safety rules. The majority of patients were mean-aged women who developed an acute upper airway inflammatory syndrome, without muscarinic or nicotinic manifestations, followed by digestive syndrome, neurocognitive, fibromyalgic and chronic fatigue manifestations. The course of disease was shorter than 1 year in 5 cases (19%), longer than 1 year in 15(58%), and disabling in 6 cases (23%).

CONCLUSIONS

Due to the possible prevention of this toxic exposure, it is very important to carefully follow measures of environment isolation and ventilation after insecticide use in order to avoid the development of these diseases.

Symptom profile of multiple chemical sensitivity in actual life

OBJECTIVE

This study was conducted to confirm the definition of multiple chemical sensitivity (MCS) in actual life: that multiple symptoms are provoked in multiple organs by exposure to, and ameliorated by avoidance of, multiple chemicals at low levels. We used the Ecological Momentary Assessment to monitor everyday symptoms and the active sampling and passive sampling methods to measure environmental chemical exposure.

METHODS

Eighteen patients with MCS, diagnosed according to the 1999 consensus criteria, and 12 healthy controls participated in this study. Fourteen patients and 12 controls underwent 1-week measurement of physical and psychologic symptoms and of the levels of exposure to various chemicals. Linear mixed models were used to test the hypotheses regarding the symptom profile of MCS patients.

RESULTS

Some causative chemicals were detected in 11 of 14 MCS patients. Two other patients did not report any hypersensitivity episodes, whereas passive sampling showed far less exposure to chemicals than control subjects. Another subject reported episodic symptoms but was excluded from the following analyses because no possible chemical was detected. Eleven of the 17 physical symptoms and all four mood subscales examined were significantly aggravated in the interview based on "patient-initiated symptom prompts." On the other hand, there were no differences in physical symptoms or mood subscales between MCS patients and control subjects in the interview based on "random prompts."

CONCLUSIONS

MCS patients do not have either somatic or psychologic symptoms under chemical-free conditions, and symptoms may be provoked only when exposed to chemicals.

Approaches to testing for food and chemical sensitivities

Testing for food and chemical sensitivities usually becomes necessary as part of the evaluation of otolaryngology patients who have chronic illness. The more complex the patient, and the more recalcitrant the problem is to treatment, the more likely it is that allergies, and especially food or chemical sensitivities, are involved in the pathogenesis of the illness. Failure to consider all major allergen contacts, including foods and chemicals, can lead to inadequate therapy. Similarly, failure to understand total allergic and oxidant load and the effects of chemical toxicity can lead to inappropriate or ineffective treatment. Clinically, food allergies occur in two different types: immediate, anaphylactic, fixed reactions and delayed, chronic, cyclic reactions. Different test methods have been developed for the two types. Fixed food allergies can be safely and efficiently detected by in vitro specific IgE or histamine release tests. Cyclic food allergies are best detected by either oral food challenges or by the IPDFT test. Choosing the best test for a particular patient requires a clear understanding of the two food allergy types and how their clinical presentations differ. Other tests for food allergies are compared and contrasted with these primary tests. Chemical sensitivity also occurs in two different clinical types: allergic, and toxic. True allergy to chemical haptens, either type I, IgE-mediated, or type IV, delayed hypersensitivity, occurs with significant frequency but is often unsuspected. Chemical toxicity can be caused by the aftereffects of an acute exposure or as a result of chronic, low-level exposure, but is even more frequently unsuspected and will not be diagnosed without a high index of suspicion. Both types of chemical sensitivity need to be addressed in any patients who have either a high allergen or chemical exposure load [105]. Either in vitro or in vivo tests can be used for chemical allergy detection; the advantages of each are outlined. Chemical toxicity screening tests are available and useful but do not detect all possible toxicants. Definitive toxic chemical tests usually require specialized laboratory facilities and expert consultation, for which possible sources are specified. The most important point in testing for food or chemical sensitivity is to be aware that food or chemical sensitivity can be contributing to a specific patient's clinical problems. Only then can appropriate investigations be undertaken to understand and then, perhaps, to intervene successfully in that illness.

Communication problems with environment-related health disorders as illustrated by a multiple chemical sensitivity (MCS) chatroom

The problem of communication in treating multiple chemical sensitivity (MCS) was analysed and evaluated using the documentation of an MCS chatroom which was set up in April 2001 following the TV programme Gesundheitsmagazin Praxis (Health Magazine: Practice). Approaches were developed for solving communication problems in the chatroom. A total of 490 cases were evaluated, most of which (355) were directly or indirectly affected, 76 came from self-help groups and 10 were from 4 guest experts invited by ZDF (Zweites Deutsches Fernsehen, Second German TV channel). Of these 4 experts, 2 were environmental medicine specialists, 1 psychosomatics expert and 1 psychiatrist. Fourty-nine of the cases included a petition for chatroom participants to join a class-action law. Aside from exchanging basic information on MCS, frequent topics of discussion on the air were the assessment of physicians, clinics, self-help groups and experts. The participants also expressed their views on problems with society, politics, the economy, science and social security. Another common topic was communication in the chatroom itself, which for the most part consisted of sarcasm and insults, which were cause for conflicts in the chatroom. These communication problems led to the conclusion that a chatroom is not the best medium for discussing MCS. If a chatroom is to be used profitably to this end, it is imperative to have a well-defined organisational framework which allows the exchange of current, scientifically accurate information while keeping discussions from escalating and degenerating into arguments.

No evidence for an impact of selenium supplementation on environment associated health disorders – a systematic review

In addition to vitamin C (and other vitamins/antioxidants), clinical ecologists (functional medicine) recommend selenium supplementation as a fundamental therapeutic remedy for the treatment of environment associated health disorders. This recommendation is based on the postulation that the trace element selenium inhibits oxidative stress generated during endogenous detoxification of xenobiotics (phase 1) by increasing selenium-dependent glutathione peroxidase activity, and that it counteracts heavy metal toxicity by forming inert metal complexes. The objective of this review was to investigate whether there are any valid studies providing reliable evidence of the therapeutic benefits of selenium supplementation in potentially environment associated health disorders. A systematic review was conducted based on the rigorous and well-defined methods developed by the Cochrane Collaboration. To achieve the demanding standards for systematic review set by the Cochrane Collaboration, study selection, quality assessment and data abstraction were performed independently and in duplicate using a standardized protocol. Overall, 1290 studies were identified as being eligible for inclusion. Twelve of these met the inclusion criteria and their quality was evaluated individually. None of the studies included in the analysis provided evidence of the therapeutic benefits of selenium supplementation in environment associated health disorders.

Chemical sensitivity in symptomatic Cambodia veterans

Following their participation in a United Nations peacekeeping operation in Cambodia (1992-1993), Dutch veterans complained of symptoms similar to those reported by Gulf War veterans. The authors conducted a matched case-control study to evaluate 76 symptomatic and 32 matched asymptomatic Cambodia veterans on the basis of data collected by postal questionnaire. The number of symptomatic veterans who reported having used insect repellants that contained N,N,-diethyl-meta-toluamide (DEET) during the mission in Cambodia was significantly higher, compared with asymptomatic veterans. The percentage of veterans who reported feeling ill following brief exposures to chemicals such as paint or pesticides was equal in both groups, but the percentage was low compared with the results of other studies of Multiple Chemical Sensitivity Syndrome. The current study was limited by self-report and time delay (potential recall bias) between deployment to Cambodia and the time of survey. Nevertheless, the study results did not support the hypothesis that symptoms in the total group of Cambodia veterans could be related to Multiple Chemical Sensitivity Syndrome.

Reproducibility of immunological tests used to assess multiple chemical sensitivity syndrome

Whether persons with multiple chemical sensitivity syndrome (MCS) have immunological abnormalities is unknown. To assess the reliability of selected immunological tests that have been hypothesized to be associated with MCS, replicate blood samples from 19 healthy volunteers, 15 persons diagnosed with MCS, and 11 persons diagnosed with autoimmune disease were analyzed in five laboratories for expression of four T-cell surface activation markers (CD25, CD26, CD38, and HLA-DR) and in four laboratories for autoantibodies (to smooth muscle, thyroid antigens, and myelin). For T-cell activation markers, the intralaboratory reproducibility was very good, with 90% of the replicates analyzed in the same laboratory differing by < or = 3%. Interlaboratory differences were statistically significant for all T-cell subsets except CD4+ cells, ranging from minor to eightfold for CD25+ subsets. Within laboratories, the date of analysis was significantly associated with the values for all cellular activation markers. Although reproducibility of autoantibodies could not be precisely assessed due to the rarity of abnormal results, there were inconsistencies across laboratories. The effect of shipping on all measurements, while sometimes statistically significant, was very small. These results support the reliability of fresh and shipped samples for detecting large (but perhaps not small) differences between groups of donors in the T-cell subsets tested. When comparing markers that are not well standardized, it may be important to distribute samples from different study groups evenly over time.

Chronic diffuse musculoskeletal pain, fibromyalgia and co-morbid unexplained clinical conditions

This chapter reviews our current knowledge on the presence of overlapping syndromes in one form of chronic diffuse pain, fibromyalgia. Patients with fibromyalgia often present with signs and symptoms of other unexplained clinical conditions, including chronic fatigue syndrome, irritable bowel syndrome, temporomandibular disorders, and multiple chemical sensitivities. The high prevalence, impact on function and opportunities for treatment underscore the need for clinicians and researchers to screen routinely for co-morbid unexplained clinical conditions among persons with fibromyalgia. We, therefore, describe a simple approach to screening for such conditions in accordance with published criteria. Interventions should directly address both fibromyalgia symptoms and co-morbid unexplained clinical conditions, as well as the multiple factors that propagate pain, fatigue and limitations in function.

Dietary adequacy of the rotary diversified diet as a treatment for "Environmental Illness"

The rotary diversified diet, used in the management of environmental illness, consists of eliminating prohibited foods from the diet and rotating remaining non-prohibited foods and their "food families" within a regular cycle. We assessed the adequacy of nutrient intakes in 22 women prescribed the diet, described the nature of supplement use, and assessed the relationship between adherence and nutrient intake levels. Except for calcium and folacin intakes, mean nutrient intakes met or exceeded recommended levels. No subjects had calcium intakes above the adequate intake for calcium; 72.7% had folate intakes below the estimated average requirement. Intakes of other nutrients, except thiamin and magnesium, were below the estimated average requirement in less than 25% of the sample; 31.8% and 45.5% of subjects, respectively, had thiamin and magnesium intakes at this level. Those who adhered more closely to the rotary diversified diet had higher intakes of vitamin C, vitamin B6, folate, and fibre than did those who followed the diet less closely. Supplements conferred some nutritional benefits; however, supplemental niacin and magnesium intakes exceeded tolerable upper intake levels. Those prescribed the rotary diversified diet require nutrition counselling from dietitians to cope with the complexity and restrictiveness of the diet.

Multiple chemical sensitivity and idiopathic environmental intolerance (part one)

Multiple chemical sensitivity/idiopathic environmental intolerance (MCS/IEI) is a commonly used diagnostic term for a group of symptoms. These symptoms have been described and commented on for more than 15 years in the USA. Recently, it has also been observed in Japan. The main features of this syndrome are multiple symptoms involving in multiple organ systems that are precipitated by a variety of chemical substances with relapses and exacerbation under certain conditions when exposed to very low levels which do not affect the population at large. There are no laboratory markers or specific investigative findings. Although traditional medical organizations have not agreed on a definition for this syndrome due to the lack of obvious evidence to demonstrate the existence of these symptoms, it is being increasingly recognized. It constitutes an increasing percentage of the caseload at occupational/environmental medical clinics.Part one of this review article discusses pathophysiological theories, substances which cause symptoms, prevalence in the general and specific populations, past history and family history, and clinical symptoms of MCS/IEI patients.

Multiple chemical sensitivity and idiopathic environmental intolerance (part two)

Multiple chemical sensitivity/idiopathic environmental intolerance (MCS/IEI) is a commonly used diagnostic term for a group of symptoms without apparent organic basis. The symptoms are characteristic of dysfunction in multiple organ systems. They wax and wane fluctuate according to exposure to low levels of chemical agents in the patient's environment, and sometimes begin after a distinct environmental change or injury such an industrial accident or chemical introduced after remodeling. Although traditional medical organizations have not agreed on a definition for this syndrome, it is being increasingly recognized and makes up an increasing percentage of the caseload at occupational/environmental medical clinics.Part two of this review article discusses diagnosis, clinical examination, long-term follow up of MCS/IEI, and the role of physicians, research on odor and treatment, diseases with similar symptoms, and further research regarding MCS/IEI patients.

Multiple chemical sensitivity (MCS) and others: allergological, environmental and psychological investigations in individuals with indoor air related complaints

Clinical observations point to an expanding group of individuals attributing hypersensitivity phenomena to indoor air pollution. It was the aim of this study to characterize such subjects by an interdisciplinary approach. Sixty-five individuals, recruited by a public campaign, were studied by a thorough allergological examination and a structured psychological interview. Measurements of common indoor pollutants in the air and in the dust were performed in rooms of several selected patients. Forty-two patients (65%) revealed a sensitization to common allergens, out of these 32 (49%) to house dust mites. Thirty-eight (58%) patients showed a psychosomatic or psychotic disorder. Increased concentrations of at least one of the measured indoor air pollutants were found in 11 out of 13 investigated houses. According to these results, four groups of patients could be identified: Seventeen patients (26%) had "classic" allergic diseases treated inadequately. In 19 patients (29%) allergic diseases were superimposed by strong psychosomatic interactions. An exclusive psychosomatic or psychotic cause of the complaints was found in 19 (29%). Ten subjects (16%) had "classic" allergic diseases (e.g. allergic rhinoconjunctivitis, urticaria), however, there were additional indications of hypersensitivity reactions to components other than classical allergens. Patients presenting with hypersensitivity phenomena attributed by themselves to indoor air pollution are a heterogeneous group and need a diligent work-up including intense allergological examination. The role of increased concentrations of indoor air pollutants has to be elucidated further.

Mechanisms of multiple chemical sensitivity

Sensitivity to chemicals is a toxicological concept, contained in the dose-response relationship. Sensitivity also includes the concept of hypersensitivity, although controversy surrounds the nature of effects from very low exposures. The term multiple chemical sensitivity has been used to describe individuals with a debilitating, multi-organ sensitivity following chemical exposures. Many aspects of this condition extend the nature of sensitivity to low levels of exposure to chemicals, and is a designation with medical, immunological, neuropsychological and toxicological perspectives. The basis of MCS is still to be identified, although a large number of hypersensitivity, immunological, psychological, neurological and toxicological mechanisms have been suggested, including: allergy; autosuggestion; cacosomia; conditioned response; immunological; impairment of biochemical pathways involved in energy production; impairment of neurochemical pathways; illness belief system; limbic kindling; olfactory threshold sensitivity; panic disorder; psychosomatic condition; malingering; neurogenic inflammation; overload of biotransformation pathways (also linked with free radical production); psychological or psychiatric illness; airway reactivity; sensitisation of the neurological system; time dependent sensitisation, toxicant induced loss of tolerance. Most of these theories tend to break down into concepts involving: (1) disruption in immunological/allergy processes; (2) alteration in nervous system function; (3) changes in biochemical or biotransformation capacity; (4) changes in psychological/neurobehavioural function. Research into the possible mechanisms of MCS is far from complete. However, a number of promising avenues of investigation indicate that the possibility of alteration of the sensitivity of nervous system cells (neurogenic inflammation, limbic kindling, cacosomia, neurogenic switching) are a possible mechanism for MCS.

An interdisciplinary therapeutic approach for dealing with patients attributing chronic fatigue and functional memory disorders to environmental poisoning--a pilot study

Nonspecific symptoms and a general feeling of ill health that is difficult to objectify are the commonest health problems with which patients present to an Environmental Medicine Outpatient Department (OPD). Of this group, a great proportion meets the classification criteria for Chronic Fatigue Syndrome (CFS) or Functional Memory Disorders in association with Idiopathic Chronic Fatigue (FMD-ICF). This is a longitudinal study of the OPD of Environmental Medicine, Freiburg University Hospital, Germany, to determine the feasibility and impact of an interdisciplinary therapeutic approach (self-help program, acupuncture, psychosomatic support by group interventions) in 8 patients with CFS, FMD-ICF, or CFS in association with self-reported Multiple Chemical Sensitivities (sr-MCS). The intervention took into consideration the patients' need for treatment of physical aspects of their disease. This is an important step to motivate patients into required psychosomatic support. Although none of the patients was willing to accept psychosomatic support or psychotherapy at study outset, acceptance of psychosomatic group interventions was high during the study course. Additionally five patients started with personal counseling at the Psychosomatic Clinic, and, without feeling stigmatized, 4 patients started with specific psychotherapy. The patients' quality of life showed no increase after four months, but, as shown by the Sum-Score of SF-36, it had improved significantly at the end of the study, which covered eight months' treatment (p = 0.015). Two follow-up investigations showed that this improvement probably persisted in part (mainly in the dimensions mental health, social function, physical role function, and vitality). In conclusion our interdisciplinary therapeutic approach indicates successful treatment of patients attributing CFS, CFS/sr-MCS, and FMD-ICF to environmental poisoning. We now plan to conduct a randomized controlled trial in the future.

'Sensitivity syndromes' related to radiation exposures

The primary health effects of radiation are traditionally believed to result from cellular genetic damage. These effects are believed to result in a statistically detectable increase in the induction of cancer in exposed populations. A significant number of residents of areas affected by the Chernobyl disaster and workers involved in the clean-up ('liquidators') have reported debilitating physical illnesses that cannot be easily explained by a genetic effect. This paper presents results of a literature search that strongly suggests that a previously unrecognized neural pathway may be responsible for the induction of these debilities. In addition, a common link between radiation and chemical sensitivity syndromes may now be identified.

Multiple chemical sensitivity: discriminant validity of case definitions

In this study, the authors used the University of Toronto's Health Survey self-administered questionnaire to determine discriminant validity of multiple chemical sensitivity definitions. The authors distributed a total of 4,126 questionnaires to adults who attended general, allergy, occupational, and environmental health practices. The authors then matched responses to features selected from existing case definitions posited by Thomson et al.; the National Research Council; Cullen; Ashford and Miller; Randolph; Nethercott et al.; and the 1999 Consensus (references 4-7, 2, 9, and 10, respectively, herein). The overall response rate was 61.7%. The prevalence of reported symptoms was lowest in general practices, was intermediate in occupational health and allergy practices, and was highest in environmental health practices. Features from the definitions presented by Nethercott et al. and the 1999 Consensus (references 9 and 10, respectively, herein) correctly identified more than 80% of environmental health practice patients and more than 70% of general practice patients. Combinations of 4 symptoms (i.e., having a stronger sense of smell than others, feeling dull/groggy, feeling "spacey," and having difficulty concentrating) also discriminated successfully. In summary, features from 2 of 7 case definitions assessed by the University of Toronto Health Survey achieved good discrimination and identified patients with an increased likelihood of multiple chemical sensitivity.

A multiple center study of multiple chemical sensitivity syndrome

The lack of widely accepted, standardized, clinical and epidemiologic criteria for Multiple Chemical Sensitivity syndrome has led to confusion about the identification of the condition and has slowed pertinent research. In this article, the authors evaluated the psychometric properties of 2 sets of clinical/epidemiologic criteria for Multiple Chemical Sensitivity syndrome. In this cross-sectional survey of 1,166 patients who visited outpatient occupational, otolaryngology, allergy, and clinical ecological clinics, the authors used the aforementioned sets of criteria to (a) estimate the prevalence of the syndrome in these varied samples and (b) compare the current diagnostic practices of traditional physician specialists with those of clinical ecologists. The authors used a patient-completed questionnaire to assess the medical, psychosocial, and psychological status of patients who reported multiple chemical sensitivities. This approach enabled the formulation of 6 domains, which represented commonly observed characteristics of the syndrome. The authors used a physician-completed questionnaire to collect diagnoses of Multiple Chemical Sensitivity syndrome and other medical conditions. Domains, which were operationalized by the questionnaire and comprised the 2 sets of criteria for identification of the Multiple Chemical Sensitivity syndrome, had test-retest reliabilities that exceeded .75 and estimates of internal consistency that ranged between .59 and .94. Evidence of construct and face validity was considered acceptable. The overall clinic-based prevalences of Multiple Chemical Sensitivity syndrome, based on 6 and 4 domains, were 7% and 23%, respectively. Regardless of the identifying set of criteria used, physicians' diagnoses had relatively low sensitivities (range = 6-50%) and relatively high specificities (range = 82-99%). The study data suggested that the domains operationalized by the questionnaire had reasonable psychometric characteristics. Study data also support the fact that Multiple Chemical Sensitivity syndrome is often overlooked--even by those physicians who treat it most frequently--and that use of both sets of objective criteria for identifying the syndrome would greatly improve the sensitivity of physician diagnoses.

Fibromyalgia and other unexplained clinical conditions

Several unexplained clinical conditions frequently coexist with fibromyalgia; these include chronic fatigue syndrome, irritable bowel syndrome, temporomandibular disorder, tension and migraine headaches, and others. However, only recently have studies directly compared the physiological parameters of these conditions (eg, fibromyalgia vs irritable bowel syndrome) to elucidate underlying pathogenic mechanisms. This review summarizes data from comparative studies and discusses their implications for future research.

Mediators of inflammation and their interaction with sleep: relevance for chronic fatigue syndrome and related conditions

In humans, activation of the primary host defense system leads to increased or decreased NREM sleep quality, depending on the degree of early immune activation. Modest elevations of certain inflammatory cytokines are found during experimental sleep loss in humans and, in addition, relatively small elevations of cytokines are seen following commencement of pharmacological treatments with clozapine, a CNS active antipsychotic agent, known to have immunomodulatory properties. Cytokines such as TNF-alpha, its soluble receptors, and IL-6, present in the periphery and the CNS, comprise a link between peripheral immune stimulation and CNS-mediated behaviors and experiences such as sleep, sleepiness, and fatigue. The debilitating fatigue experienced in chronic fatigue syndrome and related diseases may also be related to altered cytokine profiles.

The compelling anomaly of chemical intolerance

In science, anomalies expose the limitations of existing paradigms and drive the search for new ones. In the late 1800s, physicians observed that certain illnesses spread from sick, feverish individuals to those contacting them, paving the way for the germ theory of disease. The germ theory served as a crude, but elegant formulation that explained dozens of seemingly unrelated illnesses affecting literally every organ system. Today, we are witnessing another medical anomaly-a unique pattern of illness involving chemically exposed groups in more than a dozen countries, who subsequently report multisystem symptoms and new-onset chemical, food, and drug intolerances. These intolerances may be the hallmark for a new disease process or paradigm, just as fever is a hallmark for infection. The fact that diverse demographic groups, sharing little in common except some initial chemical exposure event, develop these intolerances is a compelling anomaly pointing to a possible new theory of disease, one that has been referred to as "Toxicant-Induced Loss of Tolerance" ("TILT"). TILT has the potential to explain certain cases of asthma, migraine headaches, and depression, as well as chronic fatigue, fibromyalgia, and "Gulf War syndrome". It appears to evolve in two stages: (1) initiation, characterized by a profound breakdown in prior, natural tolerance resulting from either acute or chronic exposure to chemicals (pesticides, solvents, indoor air contaminants, etc.), followed by (2) triggering of symptoms by small quantities of previously tolerated chemicals (traffic exhaust, fragrances, gasoline), foods, drugs, and food/drug combinations (alcohol, caffeine). While the underlying dynamic remains an enigma, observations indicating that affected individuals respond to structurally unrelated drugs and experience cravings and withdrawal-like symptoms, paralleling drug addiction, suggest that multiple neurotransmitter pathways may be involved.

Environmental sensitivities: prevalence of major symptoms in a referral center: the Nova Scotia Environmental Sensitivities Research Center Study

Although the phenomenon of environmental sensitivities (ES) has no clear etiology nor well-accepted pathophysiology, affected individuals experience symptoms that cause varying levels of dysfunction. Through a dedicated, government-funded research and treatment center, a detailed questionnaire covering 217 symptoms in 13 systems was mailed in 1997-1998 to 812 individuals referred to the center by physicians. A total of 385 (47%) questionnaires were returned, and data were analyzed on 351 individuals. Participants tended to be women (80%), middle-aged individuals (37% age 40-49 years), and those in higher educational groups (28% completed university), but there was wide variation in demographic variables. General symptoms such as difficulty concentrating, fatigue, forgetfulness, and irritability dominated the overall prevalence of symptoms since the start of their illness. Those related to irritation such as sneezing, itchy or burning eyes, and hoarseness or loss of voice were more common after exposure to environmental irritants. Ranking of symptoms using severity scores was consistent between men and women. Overall scores were higher in women, in participants who were separated or divorced, and in low-income groups. The type and consistency of symptoms experienced after exposure to triggering substances may not fit a purely psychogenic theory.

Chronic fatigue syndrome, fibromyalgia, and multiple chemical sensitivities in a community-based sample of persons with chronic fatigue syndrome-like symptoms

OBJECTIVE

The aim of this study was to determine illness comorbidity rates for individuals with chronic fatigue syndrome (CFS), fibromyalgia (FM), and multiple chemical sensitivities (MCS). An additional objective was to identify characteristics related to the severity of fatigue, disability, and psychiatric comorbidity in each of these illness groups.

METHODS

A random sample of 18,675 residents in Chicago, Illinois, was first interviewed by telephone. A control group and a group of individuals with chronic fatigue accompanied by at least four minor symptoms associated with CFS received medical and psychiatric examinations.

RESULTS

Of the 32 individuals with CFS, 40.6% met criteria for MCS and 15.6% met criteria for FM. Individuals with MCS or more than one diagnosis reported more physical fatigue than those with no diagnosis. Individuals with more than one diagnosis also reported greater mental fatigue and were less likely to be working than those with no diagnosis. Individuals with CFS, MCS, FM, or more than one diagnosis reported greater disability than those with no diagnosis.

CONCLUSIONS

Rates of coexisting disorders were lower than those reported in prior studies. Discrepancies may be in part attributable to differences in sampling procedures. People with CFS, MCS, or FM endure significant disability in terms of physical, occupational, and social functioning, and those with more than one of these diagnoses also report greater severity of physical and mental fatigue. The findings illustrate differences among the illness groups in the range of functional impairment experienced.

Gulf War illnesses: causes and controversies

Numerous studies investigating Gulf War illnesses have documented that, while Gulf War veterans are no more likely to die or be hospitalized, they complain of more symptoms than their non-Gulf War counterparts and are more likely to seek medical treatment and disability retirement. Proposed causes include exposure to chemical and microbiological agents and psychological factors. No definitive evidence has emerged to link chemical exposures to these illnesses, although epidemiological studies and animal research suggest possible synergistic effects to multiple exposures. Microbiological agents are unlikely to be etiologic. Psychological and cultural factors undoubtedly contribute to a number of illnesses, but their exact role requires further study. Based on a review of the scientific and popular literature, it is reasonable to conclude that Gulf War illnesses remain a poorly defined group of symptom clusters. Well-controlled research from independent groups is required to answer the numerous questions that have arisen from this illness outbreak.

Somatic hypotheses of war syndromes

Since the end of the American Civil War, unexplained symptoms in military personnel arising after a war or peace mission have frequently been described. The pattern of symptoms is highly similar for all of the various war syndromes although the conditions of each war or peace mission are widely different. Many somatic hypotheses have been formulated to explain these syndromes; a considerable proportion of them are already outdated. In the last few years much attention has been given to Gulf War Syndrome and to unexplained symptoms of military personnel who were sent to Cambodia, Rwanda, Burundi, Zaire, or the former Yugoslavia. In this review the symptoms of war syndromes will be considered in more detail and the suggested somatic explanations will be discussed. During the last decade the following somatic causes have been suggested as possible explanations for these symptoms: (persistent) infection, abnormal immune response, administration of multiple vaccinations within a short period of time, use of malaria chemoprophylaxis, neurological abnormalities, exposure to toxicological substances and environmental factors. The various investigations performed to study these hypotheses are discussed. The fact that bias regularly occurs in the course of these investigations is pointed out. For the future, a reliable investigation of a war syndrome should be a prospective multidisciplinary study and should distinguish between causative and sustaining factors.