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PubMedDate not supplied

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.

Adolescent↗
PubMed1999

'Multiple chemical sensitivity', the relevance of toxic, neurobiological and psychic effect mechanisms.

The review deals mainly with the key question of chemical causation of multiple chemical sensitivity (MCS). There are only few human studies with valid information on chemical exposure and in no study the chemical toxic causation hypothesis is supported. The animal model of olfactory-limbic/neural sensitization is of heuristic value to explain MCS phenomena and includes both chemical and non-chemical stressors. However, in animal studies seldom chemical substances and exposure levels were used which might be of relevance in the formation of MCS. The problem is demonstrated for toluene exposures in human and animal sensitization studies. In accordance with the sensitization hypotheses, human studies prove a generalized vulnerability to environmental stimuli in subjects with self-reported MCS. However, study designs do not allow to deduce whether the strong responsivity is a premorbid or comorbid phenomenon or is related to exposure. Alternative study approaches to evaluate dose-response relationships are proposed.

Animals↗
PubMed2004

The vanilloid receptor as a putative target of diverse chemicals in multiple chemical sensitivity.

The vanilloid receptor (TRPV1 or VR1), widely distributed in the central and peripheral nervous system, is activated by a broad range of chemicals similar to those implicated in Multiple Chemical Sensitivity (MCS) Syndrome. The vanilloid receptor is reportedly hyperresponsive in MCS and can increase nitric oxide levels and stimulate N-methyl-D-aspartate (NMDA) receptor activity, both of which are important features in the previously proposed central role of nitric oxide and NMDA receptors in MCS. Vanilloid receptor activity is markedly altered by multiple mechanisms, possibly providing an explanation for the increased activity in MCS and symptom masking by previous chemical exposure. Activation of this receptor by certain mycotoxins may account for some cases of sick building syndrome, a frequent precursor of MCS. Twelve types of evidence implicate the vanilloid receptor as the major target of chemicals, including volatile organic solvents (but not pesticides) in MCS.

Environmental Exposure↗
PubMedDate not supplied

Evolutionary game theory and multiple chemical sensitivity.

Newlin's [Newlin D.B. Evolutionary game theory of tolerance and sensitization in substance abuse. Paper presented to the Research Society on Alcoholism, Hilton Head, SC, 1998] evolutionary game theory of addictive behavior specifies how evolutionarily stable strategies for survival and reproduction may lead to addiction. The game theory of multiple chemical sensitivity (MCS) assumes that: (1) the MCS patient responds to low-level toxicants as stressors or as direct threats to their survival and reproductive fitness, (2) this activates the cortico-mesolimbic dopamine system, (3) this system is a survival motivation center--not a 'reward center', (4) the subject emits a counter-response that is in the same direction as the naive response to the chemicals, (5) previously neutral stimuli associated with chemicals also trigger conditioned responses that mimic those to the chemicals, (6) these counter-responses further activate the dopaminergic survival motivation system, and (7) this produces a positive feedback loop that leads to strong neural sensitization in these structures and in behavior controlled by this system, despite a small initial response. Psychologically, the MCS patient with a sensitized cortico-mesolimbic dopamine system is behaving as though his/her survival is directly threatened by these chemicals. Non-MCS subjects have counter-responses opposite in direction to those of the chemicals and show tolerance. An autoshaping/sign-tracking model of this game is discussed. This evolutionary game makes several specific, testable predictions about differences between MCS subjects, non-MCS controls, and substance abusers in laboratory experiments, and between sensitized and nonsensitized animals.

Animals↗
PubMed1992

An olfactory-limbic model of multiple chemical sensitivity syndrome: possible relationships to kindling and affective spectrum disorders.

This paper reviews the clinical and experimental literature on patients with multiple adverse responses to chemicals (Multiple Chemical Sensitivity Syndrome-MCS) and develops a model for MCS based on olfactory-limbic system dysfunction that overlaps in part with Post's kindling model for affective disorders. MCS encompasses a broad range of chronic polysymptomatic conditions and complaints whose triggers are reported to include low levels of common indoor and outdoor environmental chemicals, such as pesticides and solvents. Other investigators have found evidence of increased prevalence of depression, anxiety, and somatization disorders in MCS patients and have concluded that their psychiatric conditions account for the clinical picture. However, none of these studies has presented any data on the effects of chemicals on symptoms or on objective measures of nervous system function. Synthesis of the MCS literature with large bodies of research in neurotoxicology, occupational medicine, and biological psychiatry, suggests that the phenomenology of MCS patients overlaps that of affective spectrum disorders and that both involve dysfunction of the limbic pathways. Animal studies demonstrate that intermittent repeated low level environmental chemical exposures, including pesticides, cause limbic kindling. Kindling (full or partial) is one central nervous system mechanism that could amplify reactivity to low levels of inhaled and ingested chemicals and initiate persistent affective, cognitive, and somatic symptomatology in both occupational and nonoccupational settings. As in animal studies, inescapable and novel stressors could cross-sensitize with chemical exposures in some individuals to generate adverse responses on a neurochemical basis. The olfactory-limbic model raises testable neurobiological hypotheses that could increase understanding of the multifactorial etiology of MCS and of certain overlapping affective spectrum disorders.

Air Pollutants↗
PubMed2004

Case-control study of genotypes in multiple chemical sensitivity: CYP2D6, NAT1, NAT2, PON1, PON2 and MTHFR.

BACKGROUND: Impaired metabolism of toxic chemicals is a postulated mechanism underlying multiple chemical sensitivity (MCS). Because genetic variation alters the rate of chemical metabolism, this study was designed to determine if MCS cases differed from controls for genetic polymorphisms in drug-metabolizing enzymes. METHODS: Female Caucasian participants (203 cases and 162 controls) were drawn from a larger case-control study based on a reproducible and validated case definition. Common polymorphisms for CYP2D6, NAT1, NAT2, PON1, and PON2 were genotyped. RESULTS: Comparing cases and controls, significant differences were found in genotype distributions for CYP2D6 (P = 0.02) and NAT2 (P = 0.03). Compared with the referent homozygous inactive (CYP2D6) or slow (NAT2) metabolizers, the odds for being CYP2D6 homozygous active (OR = 3.36, P = 0.01) and NAT2 rapid (OR = 4.14, P = 0.01) were significantly higher in cases than controls. The odds for being heterozygous for PON1-55 (OR = 2.05, P = 0.04) and PON1-192 (OR = 1.57, P = 0.04) were also significantly higher in cases. CONCLUSIONS: A genetic predisposition for MCS may involve altered biotransformation of environmental chemicals. The CYP2D6 enzyme activates and inactivates toxins; the NAT2 enzyme bioactivates arylamines to protein-binding metabolites. A gene-gene interaction between CYP2D6 and NAT2 suggested that rapid metabolism for both enzymes may confer substantially elevated risk (OR = 18.7, P = 0.002). Our finding parallels others' observation of a link between PON1 heterozygosity and neurological symptoms in Gulf War syndrome. This first demonstration of genetic variation in drug-metabolizing enzymes in association with MCS requires replication. However, it suggests new research directions on genetically variable toxin pathways that might be important in MCS.

Adult↗
PubMed1994

A toxicologic approach for evaluating cases of sick building syndrome or multiple chemical sensitivity.

The nonspecificity of symptoms and exposures commonly reported as "sick building syndrome" is very similar to that reported for the condition termed "multiple chemical sensitivity (MCS)." In many instances health care practitioners are divided on the reality of the latter. As in all scientific cases of possible cause-and-effect relationships, an organized, dispassionate approach should be used to evaluate each claim of MCS. Most obviously, known medical conditions must be ruled out before chemical "sensitivity" is proposed. Also, several questions on the toxicology of the chemical exposure must be addressed. Although temporality may be apparent (toxicity followed exposure), the time frame for the appearance of symptoms must be appropriate to the exposure conditions and chemical(s) involved. The chemical(s) must have known or reasonably inferred properties to cause the claimed effect. The dose(s) received must be adequate to effect a response (dose-response characteristics). Alternate causation must be evaluated thoroughly, that is, are there other more logical explanations for the symptoms? In contrast to single-chemical exposures, exposure to mixtures of chemicals, as commonly found in sick buildings, is very difficult to evaluate. However, a rational, scientific approach to cause-and-effect questions will help avoid erroneous and subjective decision making.

Air Pollution, Indoor↗
PubMed1999

"Eco-syndrome" ("multiple chemical sensitivity"--MCS).

In the physicians's practice in past decades, an increasing number of patients suffering from polysomatic complaints with a subjective feeling of allergy against environmental noxious agents have been seen. Various names for this condition include "Eco-Syndrome" or "Multiple Chemical Sensitivity" (MCS), "Multiorgan Dysesthesia" or "Idiopathic Environmental Intolerances". The uncertainty in the nomenclature reflects the deficiency in the knowledge of the etiopathophysiology and accordingly the diagnostic and therapeutic procedures. Most patients have completed an odyssey of visiting various specialists including psychiatrists and undergone many kinds of so-called alternative or parascientific procedures. We studied such patients since the early 1980s performing intensive interdisciplinary and allergological investigations. In about two third of the patients psychiatric or psychosomatic disturbances were obvious, but in one third of the patients somatic pathophysiological conditions were regarded as predominant cause of the present complaints. Many patients exhibited various pathophysiological patterns including somatic and psychosomatic alterations. Measurements of indoor air pollutants in the dust or in the air showed in some cases increased values of aromatic hydrocarbones, terpenes etc., without, however, explaining the main complaints. We conclude from our experience that patients presenting with hypersensitivity phenomena related to indoor air pollution are a heterogeneous group. There is no evidence, that "MCS" really exists, often it is diagnosed by the patients themselves. The term "eco-syndrome" describes a "working diagnosis" in order to apply careful interdisciplinary investigations for this heterogeneous group of patients. For the practical management of these patients mutual confidence is a prerequisite for success. The role of indoor air pollutants in triggering unspecific complaints beyond the exclusively toxicological field remains to be elucidated by future studies.

Diagnosis, Differential↗
PubMedDate not supplied

Psychiatric symptoms in multiple chemical sensitivity.

Neuropsychiatric symptoms are among the most prominent manifestations of generalized chemical sensitivity. Patients, clinicians, and researchers are in agreement that symptoms such as depression, irritability, and mood instability are prominent among the distressing and disabling symptoms occurring in response to low-level chemical exposure. Beyond that point, however, agreement is difficult. The pathophysiology and clinical management of these symptoms remain quite controversial. This paper will review available data on the prevalence and form of psychiatric symptoms among those suffering from multiple chemical sensitivity. Various models explaining the relationship of psychiatric symptoms to chemical sensitivity will be discussed. Finally, the implications of these models for clinical management and future research will be reviewed.

Humans↗
PubMedDate not supplied

Multiple chemical sensitivities syndrome: toward a working case definition.

A study was conducted to identify clinical diagnostic criteria that experts regarded as major for categorizing patients as having multiple chemical sensitivities (MCS) syndrome. A cross-sectional survey of 148 medical practitioners with an interest in, or familiarity with, the condition was performed scoreable questionnaires were returned by 60.1% of those surveyed. The following five criteria, all based on self-reports, were selected as major for diagnosing the syndrome by more than 50% of the respondents: (1) symptoms are reproducible with exposure; (2) condition is chronic; (3) low levels of exposure result in manifestations of the syndrome; (4) symptoms resolve with removal of incitants; and (5) responses occur to multiple, chemically unrelated substances. It is proposed that the major criteria accepted by the majority of survey respondents be used provisionally as the basis for categorizing cases in investigations of MCS syndrome.

Allergy and Immunology↗
PubMed1998

Missed diagnoses and misdiagnoses of environmental toxicant exposure. The psychiatry of toxic exposure and multiple chemical sensitivity.

Toxins such as carbon monoxide, lead, and mercury that present occasionally with primarily psychiatric symptoms can pose some of the most difficult diagnoses. This article reviews the clues that can allow the diagnostician to identify the role of one of these substances. Equally important, the article discusses the contentious issues that surround the phenomen known as multiple chemical sensitivity. Viewed primarily as a functional illness, often with legal overtones, this putative disorder is critically reviewed to see if it meets the same demanding standard of validity that is found in the psychiatric symptoms associated with other toxic disorders. Although questioning the strict medical origin of medical chemical sensitivity, the article outlines some treatment hints that may helpful in the management of this difficult group of patients.

Adult↗
PubMed1998

[The non-specific environmental syndromes MCS (Multiple Chemical Sensitivity), IEI (Idiopathic Environmental Intolerance) and SBS (Sick Building Syndrome)].

This review starts with a clinical description of the most common unspecific environmental diseases, such as Multiple Chemical Sensitivities (MCS), Idiopathic Environmental Intolerances (IEI) and Sick Building Syndrome (SBS). These syndromes are very controversial discussed between scientific medicine and "clinical ecology". In addition, they have fundamental similarities to Chronic Fatigue Syndrome (CFS) and Fibromyalgia. Finally the spectrum of therapeutic approaches is discussed.

Desensitization, Immunologic↗
PubMed2004

A national population study of the prevalence of multiple chemical sensitivity.

The authors conducted a telephone survey of 1054 randomly selected individuals within the continental United States to determine the prevalence of chemical hypersensitivity and the medical diagnosis of multiple chemical sensitivity (MCS) in the American population. The etiology and symptomatology of MCS also were investigated. Results produced a 95% confidence level and a +/-3% margin of error. The authors found that 11.2% of Americans reported an unusual hypersensitivity to common chemical products such as perfume, fresh paint, pesticides, and other petrochemical-based substances, and 2.5% reported they had been medically diagnosed with MCS. Additionally, 31.1% of those sampled reported adverse reactions to fragranced products, and 17.6% experienced breathing difficulties and other health problems when exposed to air fresheners. Although chemical hypersensitivity was more common in women, it affected individuals in all demographic groups studied.

Adult↗
PubMed2006

[Multiple chemical sensitivity, a well-defined illness?].

Some people react to smells or chemicals at levels far below toxicological thresholds with nonspecific symptoms, fear and social isolation. They may be diagnosed with multiple chemical sensitivity. There is no empirical evidence indicating that this condition is explained by toxicological mechanisms, even though a number of theories have been proposed. The authors of this review conclude that this is a functional condition. These patients need information and treatment in accordance with this fact. Instead of being advised how to avoid exposure to chemicals, they should be properly trained in appropriate confrontation with the chemicals encountered in everyday life.

Humans↗
PubMedDate not supplied

A controlled comparison of symptoms and chemical intolerances reported by Gulf War veterans, implant recipients and persons with multiple chemical sensitivity.

Using the Environmental Exposure and Sensitivity Inventory (EESI), a standardized instrument for measuring chemical sensitivity, we obtained and compared ratings of symptoms, chemical (inhalant) intolerances, other intolerances (e.g., drugs, caffeine, alcohol, skin contactants), lifeimpact, and masking (ongoing exposures) in five populations: multiple chemical sensitivity (MCS) patients who did (n = 96) or did not (n = 90) attribute onset of their illness to a specific exposure event, patients with implanted devices (n = 87), Gulf War veterans (n = 72), and controls (n = 76). For each patient group, mean scores on the first four scales were significantly greater than for controls. MCS patients reported avoiding more chemical exposures (were less masked) than the other groups. Across groups, for a given level of symptoms, as masking increased, mean scores on the Chemical Intolerance Scale decreased. In contrast, mean scores on the Other Intolerance Scale appeared to be less affected by masking. These findings suggest that some patients with antecedent chemical exposures, whether exogenous (chemical spill, pesticide application, indoor air contaminants) or endogenous (implant), develop new chemical, food, and drug intolerances. Reports of new caffeine, alcohol, medication, food, or other intolerances by patients may signal exposure-related illness. Masking may reduce individuals' awareness of chemical intolerances, and, to a lesser degree, other intolerances.

Adult↗