Multiple Chemical Sensitivity Symptoms Research Articles

Prevalence and correlation of multiple chemical sensitivity and electromagnetic hypersensitivity with age, sex, and depression in the Japanese population: a retrospective study

BackgroundIn Japan, there are currently no definitive conclusions regarding the characteristics of multiple chemical sensitivity (MCS) and electromagnetic hypersensitivity (EHS). This study aimed to determine the prevalence and correlation of MCS and EHS with age, sex, and depression in the Japanese population.MethodsAn anonymous self-report questionnaire was distributed to 2,007 participants. Variables such as MCS, EHS, depression score, and demographic characteristics were individually evaluated using the U-test, chi-squared test, and correlation analyses. Moreover, we performed a covariance structure analysis to build a structural equation model.ResultsOlder individuals and women were more likely to exhibit MCS and EHS symptoms. Moreover, depression was correlated with MCS and EHS.ConclusionsAlthough MCS and EHS are strongly correlated, they exhibit distinct characteristics and symptoms, indicating that they can be regarded as separate conditions.

Multiple Chemical Sensitivity Syndrome: First Symptoms and Evolution of the Clinical Picture: Case-Control Study/Epidemiological Case-Control Study

Multiple chemical sensitivity (MCS) is a chronic condition characterized by the appearance of symptoms caused by exposure to chemical compounds that are tolerable for the general population. It mainly affects middle-aged women. There are very few studies focusing on the most frequent symptoms of MCS considering age groups and gender. The main goal of this study was to find the most frequent symptoms both at the onset of the disease and at the present time describing them by age groups. The QEESI (Quick Environmental Exposure and Sensitivity Inventory) questionnaire, Scale 3 which assesses symptoms and their severity, was used as a diagnostic tool for the disease. A case-control study was conducted with the participation of 210 people. Of the cases, 94.3% were women. The symptoms that most often manifested first were airway and mucous membrane alterations (68.9%). In the development of the disease, we found cognitive alterations (OR = 31.25), heart or chest problems (OR = 22.49), neuromuscular problems (OR = 20.00) and head-related symptomatology (OR = 19.29). Identifying the most frequent pattern of symptoms by age group and sex will allow an early diagnosis of the disease to improve its prognosis and treatment.

Multiple Chemical Sensitivity.

Multiple Chemical Sensitivity (MCS), a condition also known as Chemical Sensitivity (CS), Chemical Intolerance (CI), Idiopathic Environmental Illness (IEI) and Toxicant Induced Loss of Tolerance (TILT), is an acquired multifactorial syndrome characterized by a recurrent set of debilitating symptoms. The symptoms of this controversial disorder are reported to be induced by environmental chemicals at doses far below those usually harmful to most persons. They involve a large spectrum of organ systems and typically disappear when the environmental chemicals are removed. However, no clear link has emerged among self-reported MCS symptoms and widely accepted objective measures of physiological dysfunction, and no clear dose-response relationship between exposure and symptom reactions has been observed. In addition, the underlying etiology and pathogenic processes of the disorder remain unknown and disputed, although biologic and psychologic hypotheses abound. It is currently debated whether MCS should be considered a clinical entity at all. Nevertheless, in the last few decades MCS has received considerable scientific and governmental attention in light of the many persons reporting this illness. In this review, we provide a general overview of the history, definition, demographics, prevalence, and etiologic challenges in defining and understanding MCS.

New criteria for multiple chemical sensitivity based on the Quick Environmental Exposure and Sensitivity Inventory developed in response to rapid changes in ongoing chemical exposures among Japanese.

Background & objectivesThe Quick Environmental Exposure and Sensitivity Inventory (QEESI) developed by Miller and Prihoda in the USA is used as a questionnaire for patients with multiple chemical sensitivity (MCS) in >10 countries. We developed a Japanese version of QEESI, assessed its reliability and validity, and defined original cut-off values for screening Japanese patients with MCS in 2003. Our recent study revealed that opportunities for exposure to various chemicals had increased for people in Japan, while subjective symptoms of MCS in patients had increased in severity. In this study, we considered new cut-off values that combined QEESI subscale scores based on the current situation in Japan.MethodsThe questionnaire used was a Japanese version of QEESI. The survey was conducted from 2012 to 2015. Participants were 111 patients with MCS (mean age: 46 ± 20, 81% female) initially diagnosed by physicians, and 444 age- and gender-matched controls not diagnosed with MCS by doctors. The discriminatory validity of QEESI scores of patients and controls were evaluated by logistic regression and receiver operating characteristic analyses when considering interactions of the Masking Index (ongoing chemical exposure). New combined cut-off values were then set.ResultsNew combined cut-off values (meeting conditions of Chemical Intolerances ≥ 30, Symptom Severity ≥ 13, and Life Impacts ≥ 17) showed high sensitivity (82.0%) and specificity (94.4%). Using new criteria when considering ongoing chemical exposure, study participants were categorized as: Very suggestive, Somewhat suggestive, Problematic, and Not suggestive. Participants classified as Very suggestive included 25 (5.6%) controls.ConclusionsWe have set new criteria with combined cut-off values based on current Japanese conditions. Such new criteria can be used for screening and as a diagnostic aid for Japanese patients with MCS and suggest approximately 6% of the Japanese general population may be classified as “Very suggestive people with MCS”.

Vestibular impairment in Multiple Chemical Sensitivity: Component analysis findings

Multiple chemical sensitivity (MCS) is a common clinical diagnosis in western populations and its symptoms are thought to be mainly related to chemical compounds exposure. Although MCS subjects refer to complain from many central nervous system symptoms, including dizziness, no study to now deepened vestibular detriment nor to what extent such an impairment could worsen MCS. Thus, the purpose of present study was to objectively highlight those clinical/subclinical aspects of vestibular impairment that could be related to MCS symptoms cohorts. A principal component analysis within a wide battery of otoneurological test scores was employed in 18 right-handed MCS patients and 20 sex- and age-matched healthy individuals. A deranged dimensionality in near-optimal re-weighting within otoneurological variables was found in MCS as compared with healthy subjects. These data seem to support the idea that MCS physiopathological underpinnings could lead to a peripheral and higher vestibular decay that could be addressed as a further aspect to better follow MCS patients up along natural history of disease in clinical practice.

Association of Odor Thresholds and Responses in Cerebral Blood Flow of the Prefrontal Area during Olfactory Stimulation in Patients with Multiple Chemical Sensitivity.

Multiple chemical sensitivity (MCS) is a disorder characterized by nonspecific and recurrent symptoms from various organ systems associated with exposure to low levels of chemicals. Patients with MCS process odors differently than controls do. Previously, we suggested that this odor processing was associated with increased regional cerebral blood flow (rCBF) in the prefrontal area during olfactory stimulation using near-infrared spectroscopic (NIRS) imaging. The aim of this study was to investigate the association of odor thresholds and changes in rCBF during olfactory stimulation at odor threshold levels in patients with MCS. We investigated changes in the prefrontal area using NIRS imaging and a T&T olfactometer during olfactory stimulation with two different odorants (sweet and fecal) at three concentrations (zero, odor recognition threshold, and normal perceived odor level) in 10 patients with MCS and six controls. The T&T olfactometer threshold test and subjective assessment of irritating and hedonic odors were also performed. The results indicated that the scores for both unpleasant and pungent odors were significantly higher for those for sweet odors at the normal perceived level in patients with MCS than in controls. The brain responses at the recognition threshold (fecal odor) and normal perceived levels (sweet and fecal odors) were stronger in patients with MCS than in controls. However, significant differences in the odor detection and recognition thresholds and odor intensity score between the two groups were not observed. These brain responses may involve cognitive and memory processing systems during past exposure to chemicals. Further research regarding the cognitive features of sensory perception and memory due to past exposure to chemicals and their associations with MCS symptoms is needed.

Noise sensitivity and hyperacusis in patients affected by multiple chemical sensitivity.

The aim of this study was to investigate the presence of noise sensitivity and hyperacusis in patients suffering from multiple chemical sensitivity (MCS), a chronic condition characterized by several symptoms following low-level chemical exposure. Moreover, distortion product otoacoustic emissions (DPOAE) were performed to further study cochlear function. A questionnaire-based survey was performed. Eighteen MCS patients, selected with strict diagnostic criteria, and 20 healthy age- and gender-matched subjects filled Weinstein's Noise Sensitivity Questionnaire (WNS) and Khalfa's Hyperacusis Questionnaire (HQ). Results were compared with scores from the quick Environmental Exposure Sensitivity Index (qEESI), a routinarily used questionnaire to screen MCS symptoms, and with DPOAE values. An analysis of variance (ANOVA) was performed between MCS and control subjects scores; moreover, Spearman's rank correlation test was performed between questionnaire results. ANOVA testing on DPOAE values showed any significant difference between groups, while WNS, HQ and qEESI scores were significantly higher in MCS group compared to controls. Correlation analysis showed strong positive correlation between WNS, HQ and qEESI in MCS subjects. For the first time, auditory-related perceptual disorders were studied in MCS. A strong association between WNS, HQ results and MCS symptoms severity has been highlighted. These findings suggest that decreased sound tolerance and noise sensitivity could be considered as possible new aspects of this syndrome, contributing to its peculiar phenotype. Furthermore, as DPOAE values did not differ from healthy subjects, present findings might suggest a 'central' source for such disorders in this group of patients.

Reliable disease biomarkers characterizing and identifying electrohypersensitivity and multiple chemical sensitivity as two etiopathogenic aspects of a unique pathological disorder.

Much of the controversy over the causes of electro-hypersensitivity (EHS) and multiple chemical sensitivity (MCS) lies in the absence of both recognized clinical criteria and objective biomarkers for widely accepted diagnosis. Since 2009, we have prospectively investigated, clinically and biologically, 1216 consecutive EHS and/or MCS-self reporting cases, in an attempt to answer both questions. We report here our preliminary data, based on 727 evaluable of 839 enrolled cases: 521 (71.6%) were diagnosed with EHS, 52 (7.2%) with MCS, and 154 (21.2%) with both EHS and MCS. Two out of three patients with EHS and/or MCS were female; mean age (years) was 47. As inflammation appears to be a key process resulting from electromagnetic field (EMF) and/or chemical effects on tissues, and histamine release is potentially a major mediator of inflammation, we systematically measured histamine in the blood of patients. Near 40% had a increase in histaminemia (especially when both conditions were present), indicating a chronic inflammatory response can be detected in these patients. Oxidative stress is part of inflammation and is a key contributor to damage and response. Nitrotyrosin, a marker of both peroxynitrite (ONOO°-) production and opening of the blood-brain barrier (BBB), was increased in 28% the cases. Protein S100B, another marker of BBB opening was increased in 15%. Circulating autoantibodies against O-myelin were detected in 23%, indicating EHS and MCS may be associated with autoimmune response. Confirming animal experiments showing the increase of Hsp27 and/or Hsp70 chaperone proteins under the influence of EMF, we found increased Hsp27 and/or Hsp70 in 33% of the patients. As most patients reported chronic insomnia and fatigue, we determined the 24 h urine 6-hydroxymelatonin sulfate (6-OHMS)/creatinin ratio and found it was decreased (<0.8) in all investigated cases. Finally, considering the self-reported symptoms of EHS and MCS, we serially measured the brain blood flow (BBF) in the temporal lobes of each case with pulsed cerebral ultrasound computed tomosphygmography. Both disorders were associated with hypoperfusion in the capsulothalamic area, suggesting that the inflammatory process involve the limbic system and the thalamus. Our data strongly suggest that EHS and MCS can be objectively characterized and routinely diagnosed by commercially available simple tests. Both disorders appear to involve inflammation-related hyper-histaminemia, oxidative stress, autoimmune response, capsulothalamic hypoperfusion and BBB opening, and a deficit in melatonin metabolic availability; suggesting a risk of chronic neurodegenerative disease. Finally the common co-occurrence of EHS and MCS strongly suggests a common pathological mechanism.

Metabolic and genetic screening of electromagnetic hypersensitive subjects as a feasible tool for diagnostics and intervention.

Growing numbers of “electromagnetic hypersensitive” (EHS) people worldwide self-report severely disabling, multiorgan, non-specific symptoms when exposed to low-dose electromagnetic radiations, often associated with symptoms of multiple chemical sensitivity (MCS) and/or other environmental “sensitivity-related illnesses” (SRI). This cluster of chronic inflammatory disorders still lacks validated pathogenetic mechanism, diagnostic biomarkers, and management guidelines. We hypothesized that SRI, not being merely psychogenic, may share organic determinants of impaired detoxification of common physic-chemical stressors. Based on our previous MCS studies, we tested a panel of 12 metabolic blood redox-related parameters and of selected drug-metabolizing-enzyme gene polymorphisms, on 153 EHS, 147 MCS, and 132 control Italians, confirming MCS altered (P < 0.05–0.0001) glutathione-(GSH), GSH-peroxidase/S-transferase, and catalase erythrocyte activities. We first described comparable—though milder—metabolic pro-oxidant/proinflammatory alterations in EHS with distinctively increased plasma coenzyme-Q10 oxidation ratio. Severe depletion of erythrocyte membrane polyunsaturated fatty acids with increased ω6/ω3 ratio was confirmed in MCS, but not in EHS. We also identified significantly (P = 0.003) altered distribution-versus-control of the CYP2C19∗1/∗2 SNP variants in EHS, and a 9.7-fold increased risk (OR: 95% C.I. = 1.3–74.5) of developing EHS for the haplotype (null)GSTT1 + (null)GSTM1 variants. Altogether, results on MCS and EHS strengthen our proposal to adopt this blood metabolic/genetic biomarkers' panel as suitable diagnostic tool for SRI.

Transcranial pulsed electromagnetic fields for multiple chemical sensitivity: study protocol for a randomized, double-blind, placebo-controlled trial

BackgroundMultiple chemical sensitivity (MCS) is a chronic condition of unknown etiology. MCS is characterized by recurrent nonspecific symptoms from multiple organ systems in response to chemical exposures in concentrations that are normally tolerated by the majority of the population. The symptoms may have severe impact on patients’ lives, but an evidence-based treatment for the condition is nonexisting. The pathophysiology is unclarified, but several indicators point towards abnormal processing of sensory signals in the central nervous system. Pulsed electromagnetic fields (PEMF) offer a promising new treatment for refractory depression and can be targeted at the brain, thereby activating biochemical cell processes.Methods/DesignIn a parallel, randomized, double-blind, placebo-controlled trial conducted at the Danish Research Centre for Chemical Sensitivities, the effects of PEMF in MCS patients will be assessed using the Re5 Independent System. Based on sample size estimation, 40 participants will be randomized to either PEMF therapy or placebo. The allocation sequence will be generated by computer. All involved parties (that is, participants, investigators, the research nurse, and the statistician) will be blinded to group allocation. The participants will receive PEMF therapy or placebo applied transcranially 30 minutes twice a day for 7 days a week over 6 consecutive weeks. Outcomes will be measured at baseline, once weekly during treatment, post treatment, and at 2.5-month and 4.5-month follow-up according to a predefined timetable. The primary outcome will be a measurement of the impact of MCS on everyday life. The secondary outcomes will be measurements of MCS symptoms, psychological distress (stress, anxiety or depressive symptoms), capsaicin-induced secondary punctate hyperalgesia, immunological markers in serum, and quality of life.DiscussionThis trial will assess the effects of PEMF therapy for MCS. Currently, there is no treatment with a documented effect on MCS, and in terms of healthcare there is very little to offer these patients. There is thus a great need for well-conducted randomized trials aimed at assessing possible treatment effects. A positive outcome will pave the way for improved healthcare and understanding of this very disabling and overlooked condition.Trial registrationClinicalTrials.gov, NCT01834781

Long-term Health Effects of Hebei Spirit Oil Spill on Cleanup Workers

S-30C8-2 Background/Aims: Our objective was to examine and evaluate the health effect of the residents who participated in cleanup works in the area near Hebei-Spirit oil spill site and to overview some factors associated with the results 2 years after the accident. Methods: A survey was conducted from February 2009 to August 2009. The number of participants was 9242 adults and 457 students of the elementary school in contaminated coastal area. The symptom of allergic disease and multiple chemical sensitivity (MCS) as well as the information of demographic characteristics, smoking habit, alcohol consumption, number of clean-up working days were investigated using a constructed questionnaire and the oxidative stress markers, eg, 8-hydroxydeoxyguanosine and malondialdehyde were measured. The environmental exposure direct assessment was used by simulation and direct measurement of residual contaminants in water, food, soil, and air was performed and the indirect assessment used by the days of clean-up working and residential area. Results: The prevalence of asthma among children attending school in high contaminated area was 27.2% by the questionnaire and 16.8% by metacholine provocation test, which were higher compared with those among children with similar ages in similar areas but not contaminated (16.0%, 6.4%). In adults, the odds ratio of the various symptoms of the allergic disease and MCS were increased according to increasing cleanup working days and decreasing distance to coastline contaminated by oil spill. We found the dose-response relationship between clean-up work days and 8-hydroxydeoxyguanosine and malondialdehyde. Conclusion: Residents and children in oil spill area showed increasing symptoms of allergic disease, MCS, and higher level of oxidative stress biomarkers according to increasing indices of oil spill exposure, while there were hardly found the residual oil contaminants in various environmental media.

Discriminating between organic and psychological determinants of multiple chemical sensitivity: A case study

Multiple chemical sensitivity (MCS) is a controversial disorder characterized by a diverse set of debilitating symptoms purportedly induced by environmental chemicals. Many cases of putative MCS are believed to have a strong psychogenic component, making it difficult to differentiate between organic and psychogenic causes. In this case report we describe a procedure that can aid in this differentiation. A patient who met a strict set of criteria for MCS was tested on two test occasions. On the first, the patient was found to have no olfactory dysfunction, as determined from standardized olfactory tests. On the second, odorants, as well as a blank stimulus, were presented to the patient with instructions as to whether they were harmful or harmless. The patient's task was to estimate the intensity of each odorant and report any induced MCS-related symptoms. Potentially harmful odorants presented as harmless were judged significantly less intense, and triggered fewer symptoms, than harmless odorants presented as harmful. When an odorless stimulus was presented as harmful, the patient provided higher intensity evaluations and exhibited more symptoms than when it was presented as harmless. These phenomena were not present in three non-MCS controls. This straight-forward procedure allowed us to determine that the MCS symptoms of this patient were largely psychological and may be of general value for identifying psychogenic cases of MCS.

Sensibilidad química múltiple: análisis de 52 casos

Multiple chemical sensitivity (MCS) is characterized by a loss of tolerance to various environmental chemicals. The objective of this study was to describe patients with MCS seen in our hospital. Patients consecutively seen by the Toxicology and Chronic Fatigue Units who presented symptoms of MCS were included. The diagnosis was clinical. All patients completed the Quick Environmental Exposure and Sensitivity Inventory (QEESI) questionnaire. Fifty-two patients were included. The average age (standard deviation) was 47.2 (7.6) years, and 46 (88%) were females. The origin of the syndrome was related to occupational exposure to various chemical agents in 31 cases (59.6%), including occupational accidents in 14 patients (fumigation of the workplace with insecticides). In 20 patients (38.5%), the syndrome could not be associated with any toxic exposure and was considered a manifestation of chronic fatigue syndrome. The QEESI showed mean scores of 72.9 (18.6) on the chemical inhalant intolerance scale, 45.5 (20.6) on the other intolerances scale, 69.8 (20.6) on the symptom severity scale, 4.4 (1.8) on the masking index and 66.6 (21.7) on the life impact scale. All patients were followed up for a minimum of 12 months, and during this period they remained stable with no deaths. MCS normally affects middle-aged women. It is frequently triggered by exposure to chemical agents, especially insecticides. An association with chronic fatigue syndrome is common. The prognosis is good but the patients' quality of life is seriously affected.

Classification of Patients Complaining of Sick House Syndrome and/or Multiple Chemical Sensitivity

Sick house syndrome (SHS) is a Japanese concept derived from sick building syndrome (SBS), however SHS includes a broader scope of sickness than does SBS. Symptoms of SHS/SBS disappear after leaving the sick house/building, while symptoms of multiple chemical sensitivity (MCS) are elicited by the chance of chemical exposure after leaving the sick house/building. To establish the concept of SHS, we propose to introduce a new classification for SHS. A total of 214 patients complaining of SHS and/or MCS were independently classified using a new classification by clinical ecologists who are experienced physicians with expert knowledge of clinical ecology and general physicians according to disease pathogenesis from clinical records. The classification is as follows: type 1 (symptoms of chemical intoxication), type 2 (symptoms developed possibly due to chemical exposure), type 3 (symptoms developed not because of chemical exposure but rather because of psychological or mental factors), and type 4 (symptoms developed due to allergies or other diseases). The agreements on the classification made by clinical ecologists and general physicians reached 77.1% (Cohen's kappa=0.631), suggesting that this new classification was both apt and accurate. Relations between SHS and allergy/MCS were also studied. The cases classified as SHS type 4 more frequently had allergic past histories than did other types. The proportion of possible MCS cases was higher in the chemical induced SHS group (types 1 and 2) than in other types among male patients. For the universal use in clinical practice, it is necessary to prepare helpful diagnostic criteria of this SHS classification based on pathogenesis and carry our study forward all over the country.

MMPI-2 Profiles of Persons with Multiple Chemical Sensitivity

We compared the MMPI-2 profiles of adults with multiple chemical sensitivity (MCS), epileptic seizures (ES), and nonepileptic seizures (NES). Both NES and MCS are medically unexplained conditions. In previous studies profiles associated with NES were elevated on scales Hs and Hy, compared with profiles associated with ES. We predicted that profiles associated with MCS would be elevated on Hs and Hy compared with the ES group. Patients with ES and NES were diagnosed after intensive EEG monitoring using published criteria. MCS was diagnosed if there was a complaint of illness in response to multiple common odors at levels that are not noxious to most people. All the MCS cases had legal claims for injury related to chemical exposures. The results showed that on MMPI-2 scales Hs, D, and Hy the MCS group had means significantly higher than both the ES and NES groups. Fake Bad Scale scores were elevated in 11 MCS cases, and regression-based estimates of Fake Bad Scale scores showed elevation in the MCS group compared with both seizure groups. We conclude that MMPI-2 data, obtained from people seeking financial compensation, indicate that there is a strong psychological component to MCS symptoms.

Symptom patterns, and perceptual and cognitive styles in subjects with multiple chemical sensitivity (MCS)

Multiple chemical sensitivity (MCS) is defined as a syndrome with multiple medically unexplained symptoms attributed to low levels of chemically unrelated substances in the environment. The etiology of this syndrome is still unclear. As MCS may be conceptualized as an atypical type of somatoform disorder, the purpose of the study was to examine whether MCS subjects show symptom patterns, personality traits, and perceptual and cognitive styles as typically found in somatoform patients. Nonsensitive controls ( n = 36 ) were compared to subjects with moderate ( n = 35 ) and high ( n = 35 ) MCS intensity with self-report psychological questionnaires and structured interviews for depression and somatoform disorders. The high MCS group scored significantly higher than the other two groups on self-report scales for somatoform symptoms and depression. Moreover, high MCS was strongly associated with the diagnosis of somatoform disorder, and weaker but still significantly with depression. In a stepwise multiple regression analysis, cognitions about environmental threat, trait anxiety, focus on autonomic sensations, and general environmental sensitivity predicted MCS symptoms in the total sample, explaining 53% of the variance. These results support the hypothesis that trait negativity and mechanisms of symptom perception and symptom amplification contribute to the enhanced symptom reports of MCS individuals.

Identification of responsible volatile chemicals that induce hypersensitive reactions to multiple chemical sensitivity patients.

Multiple chemical sensitivity (MCS) has become a serious problem as a result of airtight techniques in modern construction. The mechanism of the MCS, however, has not been clarified. Responsible chemicals and their exposure levels for patient's hypersensitive reactions need to be identified. We measured the exposure of 15 MCS patients to both carbonyl compounds and volatile organic compounds (VOCs) that may induce hypersensitive reactions. The exposures of those not suffering from MCS (non-MCS individuals) were also measured at the same time. To characterize the chemicals responsible for MCS symptoms, we applied a new sampling strategy for the measurement of carbonyls and VOCs using active and passive sampling methods. The results of our study clearly demonstrated that the chemicals responsible for such hypersensitive reactions varied from patient to patient. Moreover, the concentrations during hypersensitive symptoms, which were apparent in some of the MCS patients, were far below both the WHO and the Japanese indoor guidelines. The average exposure levels of MCS patients within a 7-day period were lower than those of paired non-MCS individuals except for a few patients who were exposed to chemicals in their work places. This result indicates that the MCS patients try to keep away from exposures to the chemical compounds that cause some symptoms.

Multiple Chemical Sensitivity--An Elevation of Enzyme Induction Thresholds

The hypothesis was advanced in previous papers that the symptoms of multiple chemical sensitivity (MCS) are due to the presence of thresholds, or increases in thresholds, in detoxication processes, so that these are not activated by low exposures to xenobiotic chemicals. Here the argument is taken further forward, to propose that thresholds for the induction of the enzymes which mediate the biotransformation of xenobiotics, and the elevation of those thresholds above normal levels, are the basic parameters giving rise to the symptoms of MCS. Some theoretical and experimental evidence is quoted to support the existence of these thresholds, and examples are given of how many of the characteristics of MCS can be expected to follow from the application of these ideas, which do not conflict with orthodox toxicology.

Multiple Chemical Sensitivities: Psychogenic or Toxicodynamic Origins

The multiple chemical sensitivity (MCS) phenomenon can cause significant dysfunction and symptomatology and presents a difficult challenge for patient management. Central to the MCS debate is whether this phenomenon results from a primary emotional response to perceived chemical exposures or from pathological interactions between chemicals and biological systems. Those who believe the latter argue that toxic interactions result in physiological impairment and that subsequent emotional problems derive from such impairment. Distinguishing between psychogenic (emotional) or a toxicodynamic (chemical toxicity) origin is essential to the medical management of an MCS patient. A psychogenic basis requires treatment with appropriate behavioral therapies; in contrast, a belief in a strictly toxicodynamic etiology argues for avoidance and often precludes treatments that address the psychological responses. Current scientific evidence strongly suggests that behavioral or psychogenic explanations predominate for reported MCS symptoms. Acceptance of a purely toxic origination (i.e., pathological abnormalities result from a low level chemical exposure) defies known toxicological and medical principles; whereas psychogenic explanations are consistent with these principles. Because symptoms are the end points of many diseases with many causes, both physical and emotional, modern medicine is charged with and expected to consider both when treating MCS patients. The argument can be made that insufficient information exists about the causal nature of many diseases, and future research may provide support for a strict toxicodynamic cause. However, the practice of medicine must be based upon current knowledge, not future possibilities. Proper care of MCS patients requires identifying the existence of both psychological and organic pathological dysfunction. The rejection of a psychological aspect of the MCS phenomenon and appropriate behavioral treatments is both illogical and detrimental to MCS sufferers.

Sensory irritation and multiple chemical sensitivity.

Many of the symptoms described in Sick Building Syndrome (SBS) and multiple chemical sensitivity (MCS) resemble the symptoms known to be elicited by airborne irritant chemicals. Irritation of the eye, nose, and throat is common to SBS, MCS, and sensory irritation (SI). Difficulty of breathing is often seen with SBS, MCS, and pulmonary irritation (PI). We therefore asked the question: can indoor air pollutants cause SI and/or PI? In laboratory testing in which mice breathed the dilute volatile emissions of air fresheners, fabric softeners, colognes, and mattresses for 1 h, we measured various combinations of SI and PI as well as airflow decreases (analogous to asthma attacks). Air samples taken from sites associated with repeated human complaints of poor air quality also caused SI, PI, and airflow limitation (AFL) in the mice. In previous publications, we have documented numerous behavior changes in mice (which we formally studied with a functional observational battery) after exposure to product emissions or complaint site air; neurological complaints are a prominent part of SBS and MCS. All together, these data suggest that many symptoms of SBS and MCS can be described as SI, PI, AFL, and neurotoxicity. All these problems can be caused by airborne irritant chemicals such as those emitted by common commercial products and found in polluted indoor air. With some chemical mixtures (e.g., emissions of some fabric softeners, disposable diapers, and vinyl mattress covers) but not others (e.g., emissions of a solid air freshener), the SI response became larger (2- to 4-fold) when we administered a series of two or three 1-h exposures over a 24-h period. Since with each exposure the intensity of the stimulus was constant yet the magnitude of the response increased, we concluded that there was a change in the sensitivity of the mice to these chemicals. The response was not a generalized stress response because it occurred with only some mixtures of irritants and not others; it is a specific response to certain mixtures of airborne chemicals. This is one of the few times in MCS research that one can actually measure both the intensity of the stimulus and the magnitude of the response and thus be allowed to discuss sensitivity changes. The changing SI response of the mice might serve as a model of how people develop increasing sensitivity to environmental pollutants. Intensive study of this system should teach us much about how people respond to and change sensitivity to airborne irritant chemicals.