Resources and Support for Multiple Chemical Sensitivities, Environmental Illness, and Chemical Injuries in Canada

Iris R. Bell, M.D.

Program in Integrative Medicine
University of Arizona
College of Medicine
Tucson, AZ


A Polysomnographic Study of Sleep Disturbance in Community Elderly with Self-Reported Environmental Chemical Odor Intolerance Abstract. Iris R. Bell et all. Biol Psychiatry Vol. 40, No. 2, July 15, 1996:123-133. PMID: 8793044 [PubMed - indexed for MEDLINE] Subjective sleep complaints and food intolerances, especially to milk products, are frequent symptoms of individuals who also report intolerance for low-level odors of various environmental chemicals.

An olfactory-limbic model of multiple chemical sensitivity syndrome: possible relationships to kindling and affective spectrum disorders. Abstract (Review). Bell IR, Miller CS, Schwartz GE. Biol Psychiatry. 1992 Aug 1;32(3):218-42. PMID: 1420641 [PubMed - indexed for MEDLINE] 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.

Clinically relevant EEG studies and psychophysiological findings: possible neural mechanisms for multiple chemical sensitivity Abstract. Toxicology. 1996 Jul 17;111(1-3):101-17. PMID: 8711727 [PubMed - indexed for MEDLINE] This paper addresses the evidence for the face, construct, and criterion-related validity of the olfactory-limbic/neural sensitization model for multiple chemical sensitivity (MCS). MCS is a poorly-understood, controversial condition in which low levels of environmental chemicals are reported to trigger disabling levels of illness in certain individuals. Neural sensitization processes could generate an endogenous amplification of responsivity to exogenous substances, thereby providing a plausible explanation for the apparent lack of a classical toxicological dose-response relationship in MCS.

Committee on Government Reform Subcommittee on National Security, Veterans Affairs, and International Affairs United States House of Representatives Invited Testimony by Iris R. Bell February 2, 2000. "... I have been asked to give my views about the Government's Gulf War research programs and to summarize my own research related to Gulf veterans' illnesses, with a focus on the direction medical science is taking or should be taking, to address the issue. I am currently a VA-funded researcher investigating an area termed neural sensitization as a possible mechanism for development of heightened responsivity to low levels of environmental chemicals in Gulf veterans ..."

Complementary and Alternative Medicine Use Among Veterans Receiving VA Primary Care Iris R. Bell, C.M. Baldwin et al. "Objectives: The reorganization of the VA into managed care/primary care programs, with a focus on consumer satisfaction, patient-centered care, and concern for quality of life outcomes, has created a need for health services-oriented research on complementary and alternative medicine (CAM) use within the VA system. CAM includes such practices as acupuncture, botanical medicines, chiropractic, folk healing, guided imagery, homeopathy, naturopathy, and massage therapy. Several studies have reported the costs and reasons for use of CAM among civilian populations in the United States. However, few studies have addressed these issues relevant to military veterans. We undertook this study to identify factors related to CAM use by military veterans ..."

Differential resting quantitative electroencephalographic alpha patterns in women with environmental chemical intolerance, depressives, and normals Abstract. Bell IR, Schwartz GE, Hardin EE, Baldwin CM, Kline JP. Biol Psychiatry Vol. 43, No. 5, March 1, 1998:376-388. PMID: 9513754 [PubMed - indexed for MEDLINE] Previous research suggests that a subset of individuals with intolerance to low levels of environmental chemicals have increased levels of premorbid and/or comorbid psychiatric disorders such as depression, anxiety, and somatization. The purpose of this study was to evaluate the psychological profiles and quantitative electroencephalographic (qEEG) profiles at baseline of women with and without chemical intolerance (CI).

Differing Patterns of Cognitive Dysfunction and Heart Rate Reactivity in Chemically Intolerant Individuals With and Without Lifestyle Changes Abstract. Bell, I.R. et al. Journal of Chronic Fatigue Syndrome ISSN: 1057-3321. Volume 5 Number 2, 1999. To access click on the link and enter "Differing Patterns of Cognitive Dysfunction" in the search engine (without quotes). The purpose of the present study was to compare specific neuropsychological, psychological and family history patterns, as well as cardiovascular reactivity of three community-recruited groups of nonsmoking, nonalcoholic middle-aged individuals with and without the symptom of intolerance to low levels of environmental chemicals (CI). CI is a common symptom in chronic fatigue syndrome and fibromyalgia."

EEG Beta 1 Oscillation And Sucrose Sensitization In Fibromyalgia With Chemical Intolerance Abstract. Iris R. Bell, Carol M. Baldwin et al. Int J Neurosci 2001 May;108(1-2):31-42. Patients with fibromyalgia (FM) have diffuse musculoskeletal pain; half report concomitant intolerance for low levels of environmental chemicals (CI). Previous investigators have hypothesized that the chronic pain and chemical intolerance reflect sensitization of different central nervous system limbic and/or mesolimbic reward pathways.

EEG responses to low-level chemicals in normals and cacosmics. Abstract. Toxicol Ind Health. 1994 Jul-Oct;10(4-5):633-43. PMID: 7778120 [PubMed - indexed for MEDLINE] Recent studies from the University of Arizona indicate that normal subjects, both college students and the elderly, can register the presence of low-intensity odors in the electroencephalogram (EEG) in the absence of conscious awareness of the odors.

EEG sensitization during chemical exposure in women with and without chemical sensitivity of unknown etiology. Abstract. Iris R. Bell, Mercedes Fernandez & Gary E.R. Schwartz Toxicol Ind Health. 1999 Apr-Jun;15(3-4):305-12. PMID: 10416282 [PubMed - indexed for MEDLINE]. This study tested the sensitization model proposed by Bell et al ... to study chemical sensitivity. The sensitization model indicates that a pharmacological stimulus or a traumatic event which elicits a strong response can sensitize limbic and/or mesolimbic pathways; and subsequent less intense trauma or stimuli, in the same or different modality, can elicit an amplified response ... these findings indicate that psychological factors as assessed in this study do not explain electrophysiological differences between chemically and non-chemically-sensitive women."

Illness from Low Levels of Environmental Chemicals: Relevance to Chronic Fatigue Syndrome and Fibromyalgia Am J Med 1998 Sep 28;105(3A):74S-82S. PMID: 9790486 [PubMed - indexed for MEDLINE] This article summarizes (1) epidemiologic and clinical data on the symptoms of maladies in association with low-level chemicals in the environment, i.e., environmental chemical intolerance (CI), as it may relate to chronic fatigue syndrome (CFS) and fibromyalgia; and (2) the olfactory-limbic neural sensitization model for CI, a neurobehavioral synthesis of basic and clinical research. Severe CI is a characteristic of 20-47% of individuals with apparent CFS and/or fibromyalgia, all patients with multiple chemical sensitivity (MCS), and approximately 4-6% of the general population. In the general population, 15-30% report at least minor problems with CI. The levels of chemicals reported to trigger CI would normally be considered nontoxic or subtoxic.

Individual Differences in Neural Sensitization and the Role of Context in Illness from Low-level Environmental Chemical Exposure Iris R. Bell et al. Experimental Approaches to Chemical Sensitivity EHP Supplement Volume 105 Supplement 2, March 1997. Abstract This paper summarizes the clinical phenomenology of multiple chemical sensitivity (MCS), outlines the concepts and evidence for the olfactory-limbic, neural sensitization model for MCS, and discusses experimental design implications of the model for exposure-related research. Neural sensitization is the progressive amplification of responsivity by the passage of time between repeated, intermittent exposures. Initiation of sensitization may require single toxic or multiple subtoxic exposures, but subsequent elicitation of sensitized responses can involve low or nontoxic levels. Thus, neural sensitization could account for the ability of low levels of environmental chemicals to elicit clinically severe, adverse reactions in MCS.

Nutritional Factors In Geriatric Depression Psychopharmacology In Environmental Illness Abstract. Iris R. Bell, M.D., Ph.D. The Seventh Annual International Symposium on Man & His Environment in Health and Disease 1989. This paper reviews relevant clinical literature and the author's recent research findings on B complex vitamins, zinc and other laboratory measures of nutritional status in geriatric psychiatry inpatients with major depression. Although some investigators have found over 50% of new admissions with B vitamin deficiencies in general inpatient psychiatric populations, this writer observed much lower frequencies of B1, B2, B6, folate, and B12 blood level deficiencies in our sample of geropsychiatric inpatients. However, serum zinc levels are abnormally low in the majority of such patients.

Neural sensitization model for multiple chemical sensitivity: overview of theory and empirical evidence Abstract. Toxicol Ind Health. 1999 Apr-Jun;15(3-4):295-304. Review. PMID: 10416281 [PubMed - indexed for Medline] This paper summarizes theory and evidence for a neural sensitization model of hyperresponsivity to low-level chemical exposures in multiple chemical sensitivity (MCS). MCS is a chronic polysymptomatic condition in which patients report illness from low levels of many different, structurally unrelated environmental chemicals (chemical intolerance, CI). Neural sensitization is the progressive host amplification of a response over time from repeated, intermittent exposures to a stimulus. Drugs, chemicals, endogenous mediators, and exogenous stressors can all initiate sensitization and can exhibit cross-sensitization between different classes of stimuli. The properties of sensitization overlap much of the clinical phenomenology of MCS. Animal studies have demonstrated sensitization to toluene, formaldehyde, and certain pesticides, as well as cross-sensitization, e.g., formaldehyde and cocaine.

Neuropsychiatric and Biopsychosocial Mechanisms in Multiple Chemical Sensitivity: An Olfactory-Limbic System Model Multiple Chemical Sensitivities: Addendum to Biologic Markers in Immunotoxicology (1992) Iris R. Bell Pages 89-108. The purpose of this paper is to review the clinical and research psychiatric and psychophysiologic literature on multiple chemical sensitivity patients (MCS) and to develop an integrative neuropsychiatric and biopsychosocial systems model of possible mechanisms. Much of the controversy over MCS has focused on hypotheses that the clinical syndromes must derive exclusively either from physiological or from pyschogenic sources. However, such a dichotomous view of MCS is overly simplistic. A large body of data from both human and animal studies supports a more complex biopsychosocial approach involving an interplay of multiple influences in the expression of all human illness (Engel, 1977; Schwartz, 1982), including the clinical phenomenology of chemical sensitivities (Bell, 1987).

Odor sensitivity and respiratory complaint profiles in a community-based sample with asthma, hay fever, and chemical odor intolerance Abstract. Toxicol Ind Health. 1999 Apr-Jun;15(3-4):403-9. PMID: 10416292 [PubMed - indexed for MEDLINE] This is a community-based study of odor sensitivity and respiratory complaints for persons reporting asthma (n = 14/141), hay fever (n = 72/140), and chemical odor intolerance (CI) (n = 41/181). CI, a symptom of multiple chemical sensitivity (MCS), was determined from self-ratings of feeling 'moderately' to 'severely' ill using the Chemical Odor Intolerance Index (CII). Index odors included perfume, pesticide, drying paint, new carpet odor, and car exhaust. Six additional odors [natural gas, disinfectants, chlorinated water, room deodorizers, and environmental tobacco smoke (ETS)] were also assessed in the health and environment survey.

Patterns of waking EEG spectral power in chemically intolerant individuals during repeated chemical exposures. Abstract. Int J Neurosci. 1999 Mar;97(1-2):41-59. Previous studies indicate that low level chemical intolerance (CI) is a symptom of several different controversial conditions with neuropsychiatric features, e.g., chronic fatigue syndrome, fibromyalgia, multiple chemical sensitivity, and "Persian Gulf Syndrome". Prior studies suggest that limbic and/or mesolimbic sensitization may contribute to development of CI.

Serum neopterin and somatization in women with chemical intolerance, depressives, and normals Iris R. Bell, Roberto Patarca, Nancy G. Klimas, and Elizabeth Hardin. Abstracts of Papers Presented at The Bi-Annual Research Conference of the American Association for Chronic Fatigue Syndrome (AACFS). The symptom of intolerance to low levels of environmental chemicals (CI, chemical intolerance) is a feature of several polysymptomatic conditions that overlap symptomatically with depression and somatization, i.e., chronic fatigue syndrome, fibromyalgia, multiple chemical sensitivity, and Persian Gulf War syndrome. These syndromes can involve many somatic symptoms consistent with possible inflammation. Immunological or neurogenic triggering might account for such inflammation.

Subjective ratings of odorants by women with chemical sensitivity. Fernandez M, Schwartz GE, Bell IR Toxicol Ind Health. 1999 Oct;15(6):577-81. PMID: 10560135 [PubMed - indexed for MEDLINE]. The purpose of the present study was to investigate whether women with chemical sensitivity rated the intensity and pleasantness of three odorants [peppermint, vanilla, and propylene glycol (PG)] and odorless room air differently than women without chemical sensitivity. The ratings of the experimental group (women with self-reported chemical sensitivity and no history of sexual abuse) were compared to those of two control groups who did not report chemical sensitivity [sexually abused (SA) women and healthy women without sexual abuse history].

Testing the Neural Sensitization and Kindling Hypothesis for Illness from Low Levels of Environmental Chemicals Experimental Approaches to Chemical Sensitivity EHP Supplement Volume 105 Supplement 2, March 1997. Sensitization in the neuroscience and pharmacology literatures is defined as progressive increase in the size of a response over repeated presentations of a stimulus. Types of sensitization include stimulant drug-induced time-dependent sensitization (TDS), an animal model related to substance abuse, and limbic kindling, an animal model for temporal lobe epilepsy. Neural sensitization (primarily nonconvulsive or subconvulsive) to the adverse properties of substances has been hypothesized to underlie the initiation and subsequent elicitation of heightened sensitivity to low levels of environmental chemicals. A corollary of the sensitization model is that individuals with illness from low-level chemicals are among the more sensitizable members of the population. The Working Group on Sensitization and Kindling identified two primary goals for a research approach to this problem: to perform controlled experiments to determine whether or not sensitization to low-level chemical exposures occurs in multiple chemical sensitivity (MCS) patients; and to use animal preparations for kindling and TDS as nonhomologous models for the initiation and elicitation of MCS. -- Environ Health Perspect 105(Suppl 2):539-547 (1997).

The Biopersonality of Allergies and Environmental Illness Iris R. Bell. Abstract 1990. The Eighth Annual International Symposium on Man and His Environment in Health and Disease. Special Focus: The Health Effects of Indoor Air Pollution. "Clinical ecologists and allergists often deal with patients whose course of environmental illness (EI) is particularly severe despite appropriate treatment. Previous and recent research on the personality traits of asthmatic patients may offer clues to one subset of individuals "i.e., extremely introverted or shy persons" prone to a worse clinical course.

Time-Dependent Sensitization in Environmental Illness: A Pharmacologic Model Iris R. Bell. Abstract 1993. The Eleventh International Symposium on Man and His Environment in Health and Disease. Special Focus: Human Physiological Effects of Mycotoxins and Environmental Influences on the Autonomic Nervous System. "Time-dependent sensitization (TDS) is a well-documented process in the basic neuroscience research literature with properties that significantly overlap those of environmental illness (EI). TDS is the progressive, persistent amplification of responses within a susceptible individual from repeated, intermittent exposures to an environmental factor, pharmacological or nonpharmacological in nature. A single high dose or numerous low doses of various substances can initiate TDS, with the optimal time for testing sensitization 7-28 days after the original exposure. Multiple chemically-unrelated agents share the ability to initiate TDS; and life stress can cross-sensitize with such chemical substances. TDS has already been demonstrated with organophosphate pesticides and ethanol (a solvent) in animals. Female animals are more vulnerable than are males to TDS; estradiol accelerates the process of sensitization. Moreover, TDS can be bidirectional; the intensity of the initial exposure may determine the subsequent degree of increase or decrease in response. Responses can occur in overall behavior as well as in specific neurotransmitter, neuroendocrine, and/or immune variables.

Time-dependent sensitization of plasma beta-endorphin in community elderly with self-reported environmental chemical odor intolerance. Biol Psychiatry. 1996 Jul 15;40(2):134-43. PMID: 8793045 [PubMed - indexed for MEDLINE]. This study examined plasma beta-endorphin as a marker of the physiological stress response in community elderly who were either high (n = 15) or low (n = 15) in self-rated frequency of illness from environmental chemical odors. Individuals who report nonatopic multiple sensitivities to or intolerances for low levels of environmental chemicals also claim high rates of comorbid food sensitivities or intolerances. Subjects gave 9 AM blood samples for plasma beta-endorphin 90 min after ingesting either 1% fat cow's milk or a soy-based nondairy drink, on six different mornings in the laboratory after all-night sleep recordings.

White Paper: Neuropsychiatric Aspects of Sensitivity to Low-Level Chemicals: A Neural Sensitization Model Abstract. Iris R. Bell, Toxicology and Industrial Health, Vol. 10, NO. 4/5, 1994. PMID: 7778100 [PubMed - indexed for MEDLINE]. "The present paper summarizes the proposed time-dependent sensitization (TDS) and partial limbic kindling model for illness from low-level chemicals; reviews and critiques prior studies on CNS aspects of multiple chemical sensitivity (MCS); and outlines possible experimental approaches to future studies. TDS is the progressive and persistent amplification of behavioral, neurochemical, endocrine, and/or immunological responses to repeated intermittent stimuli over time.

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