Do somatic symptom distress and attribution predict symptoms associated with environmental factors?

OBJECTIVE: Not much is known on the development of symptoms associated with environmental factors (SAEF), also known as (idiopathic) environmental intolerances. Findings from qualitative studies suggest that appearance of symptoms might be the first step, followed by the acquisition of a specific attribution. The current study investigated cross-sectional and longitudinal (three years) associations between attribution and symptoms with respect to symptoms associated with chemical substances, certain indoor environments (buildings), sounds, and electromagnetic fields (EMFs). METHODS: We used data from the first two waves of the population-based Västerbotten Environmental Health Study (n = 2336). Participants completed the Patient Health Questionnaire Somatic Symptom Scale (PHQ-15), the Environmental Symptom-Attribution Scale, and answered single questions on the four aforementioned SAEFs. RESULTS: Using binary logistic regression analyses, all four SAEFs showed significant cross-sectional associations with somatic symptom distress and the respective attribution. In the longitudinal analysis, development of SAEF-Sound and SAEF-Chemicals were predicted by both somatic symptom distress and attribution. SAEF-EMFs was predicted only by attribution, whereas neither somatic symptom distress nor attribution forecasted SAEF-Buildings. CONCLUSION: Overall, these findings suggest that attribution (i.e., a specific expectation) plays a substantial role in the development and maintenance of many SAEFs.

Impact of comorbidity on symptomatology in various types of environmental intolerance in a general Swedish and Finnish adult population.

Comorbidity with various health conditions is common in environmental intolerances (EIs), which restricts understanding for what symptoms that are associated with the intolerance per se. The present objectives were to study (i) prevalence of a broad range of specific symptoms in chemical, building-related, electromagnetic field- (EMF) related, and sound EI, irrespective of comorbidity, (ii) prevalence of symptoms in body systems in exclusive EIs, and (iii) increased risk of symptoms in body systems in exclusive EIs that cannot be referred to functional somatic syndromes, inflammatory diseases or mental disorders. Cross-sectional data (n = 4941) were used from two combined population-based surveys, the Västerbotten (Sweden) and Österbotten (Finland) Environmental Health Studies. Categorization of EI cases and controls were based on self-reports. Symptoms were assessed with the Environmental Hypersensitivity Symptom Inventory, and these were converted to 27 symptoms of the International Classification of Primary Care, 2nd edition, in eight chapters of body systems. The results showed, with few exceptions, that all assessed specific symptoms were significantly more prevalent in all four EIs than in referents. Although a large overlap between EIs, characteristic body system symptoms were eye and respiratory symptoms in chemical and building-related intolerance, skin symptoms in EMF-related intolerance, and general and unspecified, digestive, eye, cardiovascular, neurological, and psychological symptoms in sound intolerance. After controlling for various comorbidities, all studied body system symptoms were positively associated with chemical intolerance, fewer with sound intolerance, only one with building-related intolerance, and none with EMF-related EI. In conclusion, a broad range of symptoms are reported in all four EIs implying common mechanisms, but symptoms of certain body systems are more likely to be reported in a certain EI that cannot be explained by comorbidity.

Social economic factors and the risk of multiple chemical sensitivity in a Danish population-based cross-sectional study: Danish Study of Functional Disorders (DanFunD).

OBJECTIVES: Multiple chemical sensitivity (MCS) is a rare multisystem and poly-symptomatic disease characterised by a report of various somatic symptoms attributed to inhalation of volatile chemicals in usually harmless doses. The aim was to explore four selected social factors and the risk of MCS in the general Danish population. DESIGN: A cross-sectional general population-based study. SETTING: The Danish Study of Functional Disorders was conducted from 2011 to 2015 which included 9656 participants. PARTICIPANTS: A total of 8800 participants were included in analyses after observations with missing data on exposure and/or outcome were excluded. A total of 164 cases fulfilled the questionnaire criteria for MCS. Of the 164 MCS cases, 101 reported no comorbid functional somatic disorder (FSD) and were included in a subgroup analysis. A total of 63 MCS cases fulfilled the criteria for at least one additional FSD, this subgroup was not included in further analysis. The remaining study population without MCS or any FSD were regarded as controls. OUTCOME MEASURES: We used adjusted logistic regression to calculate OR and 95% CIs of MCS and MCS without FSD comorbidities for each social variable separately including education, employment, cohabitation and subjective social status. RESULTS: We found an increased risk of MCS among the unemployed (OR: 2.95, 95% CI: 1.75 to 4.97), and a twofold increased risk of MCS among individuals with low subjective social status (OR: 2.00, 95% CI: 1.08 to 3.70). At the same time, 4 years or more of vocational training were protective of MCS. No significant associations were observed among MCS cases with no comorbid FSD. CONCLUSION: Lower socioeconomic status was found to be associated with a higher risk of having MCS but not with MCS without FSD comorbidities. Due to the cross-sectional design of the study, we cannot determine whether social status is a determinant or a consequence of MCS.

Metabolomics analysis of plasma samples of patients with fibromyalgia and electromagnetic sensitivity using GC-MS technique.

Fibromyalgia (FM) is a chronic and systemic condition that causes widespread chronic pain, asthenia, and muscle stiffness, as well as in some cases depression, anxiety, and disorders of the autonomic system. The exact causes that lead to the development of FM are still unknown today. In a percentage of individuals, the symptoms of FM are often triggered and/or exacerbated by proximity to electrical and electromagnetic devices. Plasma metabolomic profile of 54 patients with fibromyalgia and self-reported electromagnetic sensitivity (IEI-EMF) were compared to 23 healthy subjects using gas chromatography-mass spectrometry (GC-MS) coupled with multivariate statistical analysis techniques. Before the GC-MS analysis the plasma samples were extracted with a modified Folch method and then derivatized with methoxamine hydrochloride in pyridine solution and N-trimethylsilyltrifuoroacetamide. The combined analysis allowed to identify a metabolomic profile able of distinguishing IEI-EMF patients and healthy subjects. IEI-EMF patients were therefore characterized by the alteration of 19 metabolites involved in different metabolic pathways such as energy metabolism, muscle, and pathways related to oxidative stress defense and chronic pain. The results obtained in this study complete the metabolomic "picture" previously investigated on the same cohort of IEI-EMF patients with 1H-NMR spectroscopy, placing a further piece for better understanding the pathophysiological mechanisms in patients with IEI-EMF.

Why electrohypersensitivity and related symptoms are caused by non-ionizing man-made electromagnetic fields: An overview and medical assessment.

Much of the controversy over the cause of electrohypersensitivity (EHS) lies in the absence of recognized clinical and biological criteria for a widely accepted diagnosis. However, there are presently sufficient data for EHS to be acknowledged as a distinctly well-defined and objectively characterized neurologic pathological disorder. Because we have shown that 1) EHS is frequently associated with multiple chemical sensitivity (MCS) in EHS patients, and 2) that both individualized disorders share a common pathophysiological mechanism for symptom occurrence; it appears that EHS and MCS can be identified as a unique neurologic syndrome, regardless their causal origin. In this overview we distinguish the etiology of EHS itself from the environmental causes that trigger pathophysiological changes and clinical symptoms after EHS has occurred. Contrary to present scientifically unfounded claims, we indubitably refute the hypothesis of a nocebo effect to explain the genesis of EHS and its presentation. We as well refute the erroneous concept that EHS could be reduced to a vague and unproven "functional impairment". To the contrary, we show here there are objective pathophysiological changes and health effects induced by electromagnetic field (EMF) exposure in EHS patients and most of all in healthy subjects, meaning that excessive non-thermal anthropogenic EMFs are strongly noxious for health. In this overview and medical assessment we focus on the effects of extremely low frequencies, wireless communications radiofrequencies and microwaves EMF. We discuss how to better define and characterize EHS. Taken into consideration the WHO proposed causality criteria, we show that EHS is in fact causally associated with increased exposure to man-made EMF, and in some cases to marketed environmental chemicals. We therefore appeal to all governments and international health institutions, particularly the WHO, to urgently consider the growing EHS-associated pandemic plague, and to acknowledge EHS as a mainly new real EMF causally-related pathology.

Psychological models of development of idiopathic environmental intolerances: Evidence from longitudinal population-based data.

The origin of idiopathic environmental intolerances (IEIs) is an open question. According to the psychological approaches, various top-down factors play a dominant role in the development of IEIs. The general psychopathology model assumes a propensity towards mental ill-health (negative affectivity) increases the probability of developing IEIs. The attribution model emphasizes the importance of mistaken attribution of experienced somatic symptoms; thus, more symptoms should lead to more IEIs. Finally, the nocebo model highlights the role of expectations in the development of IEIs. In this case, worries about the harmful effects of environmental factors are assumed to evoke IEIs. We estimated cross-lagged panel models with latent variables based on longitudinal data obtained at two time points (six years apart) from a large near-representative community sample to test the hypothesized associations. Indicators of chemical intolerance, electromagnetic hypersensitivity, and sound sensitivity fit well under a common latent factor of IEIs. This factor, in turn, showed considerable temporal stability. However, whereas a positive association was found between IEIs and increased somatic symptoms and modern health worries six years later, the changes therein could not be predicted as hypothesized by the three psychological models. We discuss the implications of these results, as well as methodological aspects in the measurement and prediction of change in IEIs.

High prevalence of neurological sequelae and multiple chemical sensitivity among occupants of a Finnish police station damaged by dampness microbiota.

Objectives: The aim of the study was to estimate the risks of different symptoms after the exposure to indoor air dampness microbiota (DM).Methods: This cross-sectional retrospective cohort-based study compared morbidity risks in DM exposed (n = 116) vs. unexposed cohort (n = 45). Gender-adjusted log-binomial regression models were used to calculate risk ratios (RR). The analysis of indoor dust toxicity was based on the inhibition of the motion of boar spermatozoa in vitro. Conventional microbiological work-up was performed in an accredited laboratory.Results: Compared to the unexposed cohort, the study cohort had statistically significant (p < 0.05) risks to develop symptoms of the central nervous system RR = 2.85 (95% CI 1.19-6.85), fatigue RR = 2.82 (1.55-5.11), Multiple Chemical Sensitivity (MCS) RR = 2.81 (1.06-7.46), cardiac arrhythmia RR = 9.58 (1.33-68.81) and respiratory symptoms RR = 2.66 (1.58-4.48).Conclusions: The results of this study corroborate our earlier findings that toxic indoor air may cause a plethora of neurological symptoms. Higher than in the control group the prevalence of MCS associated with the exposure to DM. Bad indoor air is therefore not only a risk for respiratory problems and asthma but should be viewed broader as a systemic biotoxicosis. Therefore, psychologization of this disorder without mentioning the underlying insulting mechanisms should be discouraged.

The role of sensory and olfactory pathways in multiple chemical sensitivity.

Multiple chemical sensitivity (MCS) is characterised by non-specific and recurring symptoms affecting multiple organs and associated with exposure to chemicals, even at low concentrations, which are, under normal circumstances, harmless to the general population. Symptoms include general discomfort, cardiovascular instability, irritation of the sensory organs, breath disorders, hypersensitivity affecting the skin and epithelial lining of the gut, throat and lungs, anxiety, and learning and memory loss. Chemical intolerance is a key distinguishing feature of MCS, limiting considerably patients' lifestyle with serious social, occupational and economic implications. Since no specific diagnostic markers are currently available for chemical intolerance, the diagnosis relies on clinical symptoms. Despite the formulation of several hypotheses regarding the pathophysiology of MCS, its mechanisms remain undefined. A person-centred care approach, based on multidisciplinary and individualised medical plans, has shown promising results. However, more definite treatment strategies are required. We have reviewed the main experimental studies on MCS pathophysiology, focusing on the brain networks involved, the impact of environmental pollution on the olfactory system and the correlation with other pathologies such as neurodegenerative diseases. Finally, we discuss treatment strategies targeting the olfactory system.

Three questions for identifying chemically intolerant individuals in clinical and epidemiological populations: The Brief Environmental Exposure and Sensitivity Inventory (BREESI).

The Quick Environmental Exposure and Sensitivity Inventory (QEESI) is a validated questionnaire used worldwide to assess intolerances to chemicals, foods, and drugs, and has emerged as the gold standard for assessing chemical intolerance (CI). Despite a reported prevalence of 8-33%, epidemiological studies and routine primary care clinics rarely assess CI. To help address this gap, we developed the Brief Environmental Exposure and Sensitivity Inventory (BREESI)-a 3-item CI screening tool. We tested the BREESI's potential to predict whether an individual is likely to be classified as chemically intolerant if administered the 50-item QEESI. We recruited 293 participants from a university-based primary care clinic and through online participation. The statistical sensitivity, specificity, and positive and negative predictive values of the BREESI were calculated against the validated QEESI. Ninety percent (90%) of participants answering "yes" to all three items on the BREESI fit the QEESI criteria for being very suggestive of CI based upon their chemical intolerance and symptom scores (positive predictive value = 90%). For participants endorsing two items, 93% were classified as either very suggestive (39%) or suggestive (54%) of CI (positive predictive value = 87%). Of those endorsing only one item, 13% were classified as very suggestive of CI, and 70% as suggestive. Of those answering "No" to all of the BREESI items, 95% were classified as not suggestive of CI (i.e., negative predictive value = 95%). The BREESI is a versatile screening tool for assessing potential CI useful for clinical and epidemiological applications, based upon individuals' past adverse responses in a variety of settings. Just as health care professionals routinely inquire about latex allergy to prevent adverse reactions, the BREESI provides an essential screen for CI. Together, the BREESI and QEESI provide new diagnostic tools that may help predict and prevent future adverse reactions to chemicals, foods, and drugs.

Prospective study of nocebo effects related to symptoms of idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF).

The exact causes of Idiopathic Environmental Intolerance Attributed to Electromagnetic Fields (IEI-EMF, i.e., experience of somatic symptoms attributed to low-level electromagnetic fields) are still unknown. Psychological causation such as nocebo effects seem plausible. This study aimed to experimentally induce a nocebo effect for somatic symptom perception and examined whether it was reproducible after one week. We also examined whether these effects were associated with increased sympathetic activity and whether interoceptive accuracy (IAcc) moderated these relationships. Participants were recruited from the general population and instructed that electromagnetic exposure can enhance somatosensory perception. They participated twice in a cued exposure experiment with tactile stimulation and sham WiFi exposure in 50% of trials. The two sessions were scheduled one week apart (session 1: N = 65, session 2: N = 63). Before session 1, participants watched either a 6-min film on adverse health effects of EMF or a neutral film on trade of mobile phones. IAcc was assessed with the heartbeat detection paradigm. Electrodermal activity served as a measure of sympathetic activation. Evidence for a nocebo effect (i.e., increased self-reported intensity and aversiveness and electrodermal activity) during sham WiFi exposure was observed in both sessions. IAcc moderated the nocebo effect, depending on stimulus intensity. Contrary to previous findings, no difference emerged between the health-related EMF and the neutral films. Based on negative instructions, somatic perception and physiological responding can be altered. This is consistent with the assumption that IEI-EMF could be due to nocebo effects, suggesting an important role for psychological interventions.

Study of the Correlation Between Multiple Chemical Sensitivity and Personality Using the Quick Environmental Exposure Sensitivity Inventory Questionnaire and the Temperament and Character Inventory.

OBJECTIVE: We conducted an analysis using the Quick Environmental Exposure Sensitivity Inventory to examine the correlation between multiple chemical sensitivity (MCS) and personality traits by using temperament and character inventory, and environmental exposures. METHODS: An anonymous questionnaire was distributed to 667 employees working at an IT manufacturing plant in Japan. Variables including chemically sensitive population (CSP), personality, and environmental chemical exposure were individually evaluated using U-test, chi-squared test, and correlation analyses. We also did covariance structure analysis to build a structural equation model. RESULTS: There was little direct impact of temperament on the CSP, while there was a significant impact of character on the CSP. Women were more likely to exhibit symptoms of CSP. CONCLUSION: MCS is correlated with personality, impacted more by character acquired later in life than innate temperament. There were sex differences in the incidence of MCS.

Co-Designed Exposure Protocol in the Study of Idiopathic Environmental Intolerance Attributed to Electromagnetic Fields.

The hypothesis of an electromagnetic origin of idiopathic environmental intolerance (IEI) attributed to electromagnetic fields (EMF) has been widely investigated by provocation studies, which consist of deliberately exposing people with IEI-EMF in laboratory settings to particular EMF to observe volunteers' reactions. In the majority of these studies, reactions have been found to be independent of exposure. However, most of these studies suffer from design and methodological limitations that might bias their findings or reduce their precision. As provocation studies are best suited for isolating the effects of EMF, innovative protocols should be applied. In the ExpoComm project (PNREST Anses, EST/2017/2 RF/19), several innovations have been introduced: the involvement of people with IEI-EMF in the development of the protocol, the attenuation of the anxiogenic nature of the tests, the individualization of the protocol, the validation of the neutral or normal reactivity state before the test, and the use of a cocktail of real, rather than artificially generated, sources. The objective of involving people with IEI-EMF was to increase the relevance and acceptability of the protocol, while respecting technical constraints and scientific quality requirements. This paper describes the protocol resulting from the collaborative process. Bioelectromagnetics. 2020;41:425-437. © 2020 Bioelectromagnetics Society.

Dietary factors and endocrine consequences of multiple chemical sensitivity / Factores dietéticos y consecuencias endocrinas de la sensibilidad química múltiple

No disponible

A Proposal for Clinical Biomarkers in Multiple Chemical Sensitivity.

Multiple chemical sensitivity (MCS) is increasingly widespread disease, characterized by non-specific and recurring symptoms from various organs associated with exposure to common chemicals, even if inhaled at low concentrations, usually harmless for normal people. MCS is not yet well recognized from common point of view and for this reason affected patients risk marginalization and their symptoms are often trivialized. It is actually a devastating chronic disease that affects not only the patients in the daily routine but partly conditions their survival. Despite more than 50 years of research, the action mechanisms of MCS is still undefined. In this study we examine the theories about the etiopathogenesis of multiple chemical sensitivity that include genetic susceptibility factors, immunological factors, neurological factors and psychiatric factors. Since no specific diagnostic markers are currently available for the MCS, the diagnosis can only be supposed on the basis symptomatic criteria and patient's medical history. However new biochemical markers and diagnostic imaging techniques have emerged, useful to postulate at least the clinical-diagnostic hypothesis of MCS and in this paper we discuss a list of biomarkers studied for the diagnosis of MCS, based on the available scientific literature. At last but not least, we propose four-levels MCS tests that could help the clinician in the diagnosis of the pathology both through the use of quantifiable serological parameters, both through diagnostic tools, genetic testing and through clinical observation of symptoms.

Mechanisms underlying nontoxic indoor air health problems: A review.

Indoor air health problems of the type non-specific building-related symptoms (NBRS; formally called "sick-building syndrome") and chemical intolerance (CI; e.g. multiple chemical sensitivity) can in severe cases lead to significant disability and poor quality of life. Apart from suffering of the afflicted individuals, the productivity loss ascribed to environmental intolerances of this kind is very costly for society. Preventive measures and appropriate treatment call for understanding of the mechanism underlying NBRS and CI. Considerable similarities between NBRS and CI suggest that the two conditions at large share mechanisms. Since typical cases of these conditions cannot be explained by toxic exposure, the present objective is to describe underlying mechanisms of psychobiological nature for which there is well-developed theoretical ground and empirical support. Focus lies on the mechanisms neurogenic inflammation and neural sensitization. Apart from describing its basic mechanisms, neurogenic inflammation is reviewed in relation to NBRS and CI regarding neurogenic switching, activation of the autonomic nervous system and axon reflex as well as interaction effects between chemical irritants, allergens, and psychosocial stressors. In addition to describing various types of sensitization, empirical support for their role in NBRS and CI is reviewed. The mechanism classical conditioning, symptom misattribution and somatosensory amplification, and nocebo are also addressed. The review rounds off with a discussion on why only a subset of individuals exposed to these indoor environments develop NBRS and CI, and a discussion on integration of the presented mechanisms, accompanied by proposed hypotheses for future research.

Multiple chemical sensitivity: pursuit of a scientific consensus, need for a public health response. Commentary.

On the international scene, Multiple Chemical Sensitivity (MCS) is defined, by several experts, as a multisystem syndrome that develops following chronic exposures to low doses of common chemical contaminants. Its general characteristics are, however, the object of conflicting opinions and a source of debate and research aimed at the appropriate nosological and therapeutic frameworks. In the face of a potentially debilitating trend, both in the occupational and in the economical and social sphere, the scientific community has not so far found an agreement. This problem leads patients and their associations to periodically claim some requests. The syndrome is also taken into consideration at a political level, especially due to the close connection with the problems related to environmental pollution and to decision making in the field of control and prevention. For these reasons we believe that an appropriate widespread surveillance network for MCS should be set up in Italy, capable of intercepting possible cases, analyzing them at a multidisciplinary level, and following their evolution.

Methodological limitations in experimental studies on symptom development in individuals with idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) - a systematic review.

BACKGROUND: Hypersensitivity to electromagnetic fields (EMF) is a controversial condition. While individuals with idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) claim to experience health complaints upon EMF exposure, many experimental studies have found no convincing evidence for a physical relation. The aim of this systematic review was to evaluate methodological limitations in experimental studies on symptom development in IEI-EMF individuals that might have fostered false positive or false negative results. Furthermore, we compared the profiles of these limitations between studies with positive and negative results. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guided the methodological conduct and reporting. Eligible were blinded experimental studies that exposed individuals with IEI-EMF to different EMF exposure levels and queried the development of symptoms during or after each exposure trial. Strengths and limitations in design, conduct and analysis of individual studies were assessed using a customized rating tool. RESULTS: Twenty-eight studies met the eligibility criteria and were included in this review. In many studies, both with positive and negative results, we identified methodological limitations that might have either fostered false or masked real effects of exposure. The most common limitations were related to the selection of study participants, the counterbalancing of the exposure sequence and the effectiveness of blinding. Many studies further lacked statistical power estimates. Methodically sound studies indicated that an effect of exposure is unlikely. CONCLUSION: Overall, the evidence points towards no effect of exposure. If physical effects exist, previous findings suggest that they must be very weak or affect only few individuals with IEI-EMF. Given the evidence that the nocebo effect or medical/mental disorders may explain the symptoms in many individuals with IEI-EMF, additional research is required to identify the various factors that may be important for developing IEI-EMF and for provoking the symptoms. We recommend the identification of subgroups and exploring IEI-EMF in the context of other idiopathic environmental intolerances. If further experimental studies are conducted, they should preferably be performed at the individual level. In particular, to increase the likelihood of detecting hypersensitive individuals, if they exist, we encourage researchers to achieve a high credibility of the results by minimizing sources of risk of bias and imprecision.

Somatosensory amplification absorption contribute to electrosensitivity.

BACKGROUND AND PURPOSE: Two trait-like characteristics, somatosensory amplification and absorption, have been associated with symptom reports and idiopathic environmental intolerances in past research. Purpose - As the two constructs are not connected with each other, their independent contribution to symptom reports and electromagnetic hypersensitivity, as well as their interaction can be expected. METHODS: On-line questionnaire. Patients - 506 college students completed an on-line questionnaire assessing absorption, somatosensory amplification, negative affect, somatic symptoms, and electromagnetic hypersensitivity. RESULTS: Somatosensory amplification (ß = 0.170, p < 0.001) and absorption (ß = 0.128, p < 0.001) independently contributed to somatic symptoms after controlling for gender and negative affect (R2 = 0.347, p < 0.001). Similarly, somatosensory amplification (OR = 1.082, p < 0.05) and absorption (OR = 1.079, p < 0.01) independently contributed to electromagnetic hypersensitivity after controlling for somatic symptoms, gender, and negative affect (Nagelkerke R2 = 0.134, p < 0.001). However, no interaction effects were found. CONCLUSION: Somatosensory amplification and absorption independently contribute to symptom reports and electromagnetic hypersensitivity. Conclusion - The findings suggest that psychological mechanisms underlying symptom reports and electromagnetic hypersensitivity might be heterogeneous.

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 & OBJECTIVES: The 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. METHODS: The 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. RESULTS: New 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. CONCLUSIONS: We 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".