National Prevalence and Effects of Multiple Chemical Sensitivities

Effects of the COVID-19 pandemic on individuals with chemical intolerance

OBJECTIVE

The purpose of this study was to determine if the COVID-19 pandemic had differential effects on individuals with chemical intolerances (CI). CI is characterised by multisystem symptoms initiated by a one-time high dose or persistent low-dose exposure to environmental toxins including chemicals, foods and drugs. With an estimated 20% US prevalence, symptoms include fatigue, headache, weakness, rash, mood changes, musculoskeletal pain, gastrointestinal issues, difficulties with memory, concentration and respiratory problems, which are similar to COVID-19 and its sequelae.

DESIGN

A US population-based survey involving 7500 respondents was asked if they ever had COVID-19, what the severity was, and if they had long COVID-19. CI was assessed using the Quick Environmental Exposure and Sensitivity Inventory.

SETTING

The Center for Disease Control estimates that over 24 million have been infected with COVID-19 in the USA with over 6 700 000 being hospitalised and over 1 174 000 deaths. Other industrialised countries show similar numbers.

RESULTS

Those in the High CI class reported a greater COVID-19 prevalence, symptom severity and long COVID-19 than in the medium and low CI groups (p<0.0001). These associations were independent of race, ethnicity, income, age and sex. However, there were significantly increased odds of COVID-19 severity among women and those over 45 years old. Asian individuals were least likely to have severe symptoms compared with white individuals (OR=0.53; 95% CI 0.35 to 0.79). Black/African American individuals reported a lower prevalence of COVID-19 than non-Hispanic whites. However, one interaction between CI and race was significant, African Americans with high CI reported greater odds (OR=2.2; 95% CI 1.15 to 3.16) of reporting COVID-19 prevalence. Furthermore, African American individuals had significantly greater odds of increased symptom severity.

CONCLUSION

Prior studies show higher risk for COVID-19 among older age groups, male sex, those with pre-existing comorbidities (eg, challenged immunities) and those from minoritised racial/ethnic groups. The results of this study suggest that those with CI be included in a high-risk group. Various risk subsets may exist and future investigations could identify different risk subsets. Understanding these subgroups would be helpful in mounting targeted prevention efforts.

Multiple Chemical Sensitivity: A Clinical Perspective

OBJECTIVE

The etiology of multiple chemical sensitivity (MCS) is still debated, which is an obstacle to assessing treatment options. An analysis of the scientific literature combined with the clinical experience can suggest some avenues.

METHODS

The etiology of MCS and its underlying mechanisms were reviewed from the scientific literature to identify the main factors contributing to its development. The results of the studies involving biomarkers and cerebral imaging techniques on MCS subjects were compared with those performed on subjects having the comorbidities of MCS. From the scientific literature and the experience in a clinical setting in occupational and environmental medicine, distinct types of MCS were looked for, with the application of the underlying mechanisms. The potential effectiveness of available treatments was also reviewed.

RESULTS

Among many factors, unresolved emotional traumas causing chronic and acute stress reactions play an important role in the development of MCS and can be the basis for effective treatment. We identified three types of clinical presentations, called the accidental type, following a toxic exposure causing an associated emotional trauma, the associative type, following a repeated innocuous exposure in a threatening context, and the developmental type, following a traumatic childhood/adolescence causing hypervigilance and chronic stress/trauma-related disorders. We presented real cases to illustrate these types and the mechanisms behind their development, as well as effective resolution.

CONCLUSIONS

MCS and its comorbidities could be treated effectively when the underlying emotional trauma(s) are targeted using trauma-focused psychotherapy and other therapies. Diagnostic criteria, principles of treatment and prevention, and avenues for research were derived from this analysis.

Environmental house calls can reduce symptoms of chemical intolerance: a demonstration of personalized exposure medicine

AIM

The goals of this investigation were to 1) identify and measure exposures inside homes of individuals with chemical intolerance (CI), 2) provide guidance for reducing these exposures, and 3) determine whether our environmental house calls (EHCs) intervention could reduce both symptoms and measured levels of indoor air contaminants.

BACKGROUND

CI is an international public health and clinical concern, but few resources are available to address patients' often disabling symptoms. Numerous studies show that levels of indoor air pollutants can be two to five (or more) times higher than outdoor levels. Fragranced consumer products, including cleaning supplies, air fresheners, and personal care products, are symptom triggers commonly reported by susceptible individuals.

METHODS

A team of professionals trained and led by a physician/industrial hygienist and a certified indoor air quality specialist conducted a series of 5 structured EHCs in 37 homes of patients reporting CI.

RESULTS

We report three case studies demonstrating that an appropriately structured home intervention can teach occupants how to reduce indoor air exposures and associated symptoms. Symptom improvement, documented using the Quick Environmental Exposure and Sensitivity Inventory Symptom Star, corresponded with the reduction of indoor air volatile organic compounds, most notably fragrances. These results provide a deeper dive into 3 of the 37 cases described previously in Perales et al. (2022).

DISCUSSION

We address the long-standing dilemma that worldwide reports of fragrance sensitivity have not previously been confirmed by human or animal challenge studies. Our ancient immune systems' 'first responders', mast cells, which evolved 500 million years ago, can be sensitized by synthetic organic chemicals whose production and use have grown exponentially since World War II. We propose that these chemicals, which include now-ubiquitous fragrances, trigger mast cell degranulation and inflammatory mediator release in the olfactory-limbic tract, thus altering cerebral blood flow and impairing mood, memory, and concentration (often referred to as 'brain fog'). The time has come to translate these research findings into clinical and public health practice.

Prevalence and Factors Related to High Risk of Multiple Chemical Sensitivity among Japanese High School Students

Multiple chemical sensitivity (MCS) onset in minors can greatly impact learning and future employment. This study investigated the prevalence of MCS and related factors in high school students to determine whether it was the same as in adults. A comprehensive survey was conducted on 80 high schools in Gunma Prefecture, Japan. The survey incorporated the Quick Environmental Exposure and Sensitivity Inventory, as well as items related to allergies, the living environment, and lifestyle. Of the 4630 students analyzed, according to Hojo's cut-off value, 9.0% were classified as high-risk for MCS and 77.9% reported some allergy-like symptoms. Significant factors associated with elevated MCS risk included female sex, having various allergic conditions, having experienced living in a new home or home renovations or extensions, proximity to environmental stressors (freeways, national highway, factories, rubbish dumps, or sources of offensive odors), insufficient physical activity (exercising less than once a week outside of physical education classes), having cold hands and feet, being fatigued, having a bedtime earlier than 11 p.m., and having moderate-frequent subjective stress. Overall, 9.0% of high school students in Japan are at high risk for MCS. Enhancing awareness of MCS-like symptoms and addressing allergies, living environments, and lifestyle habits may mitigate these symptoms.

Chemical Intolerance and Mast Cell Activation: A Suspicious Synchronicity

Background: Chemical Intolerance (CI) is characterized by intolerances for chemicals, foods, and drugs with multi-system symptoms. As yet, the biomechanism remains unclear. One study reported converging lines of evidence supporting a substantive association between mast cell activation syndrome (MCAS) and CI. The purpose of this study is to (1) confirm a previous report demonstrating that 60% of MCAS patients report CI and (2) examine the parallels between symptoms and intolerances in CI and MCAS. Methods: Five hundred forty-four MCAS patients were assigned a clinical MCAS score using a validated assessment instrument and were assessed for CI using the validated Quick Environmental Exposure Sensitivity Index. Results: Our outcomes confirm the previously published study where the majority of MCAS patients also have CI. There was a clear overlap between various ICD-10 diagnostic categories and CI symptoms, providing further support for a potential shared mechanism. Conclusions: Exposures to pesticides, volatile organic compounds, combustion products, and mold have previously been reported as initiators of CI. However, until recently, little was known about the biological mechanism involved that could explain the multisystem symptoms associated with CI. This paper addresses a newly identified biomechanism for disease, which may underlie a host of "medically unexplained symptoms" triggered by xenobiotics.

Clinical Implications of the Association between Respiratory and Gastrointestinal Disorders in Migraine and Non-Migraine Headache Patients

Headaches, particularly migraine, are associated with gastrointestinal (GI) disorders. In addition to the gut-brain axis, the lung-brain axis is suspected to be involved in the relationship between pulmonary microbes and brain disorders. Therefore, we investigated possible associations of migraine and non-migraine headaches (nMH) with respiratory and GI disorders using the clinical data warehouse over 11 years. We compared data regarding GI and respiratory disorders, including asthma, bronchitis, and COPD, among patients with migraine, patients with nMH, and controls. In total, 22,444 patients with migraine, 117,956 patients with nMH, and 289,785 controls were identified. After adjustment for covariates and propensity score matching, the odds ratios (ORs) for asthma (1.35), gastroesophageal reflux disorder (1.55), gastritis (1.90), functional GI disorder (1.35), and irritable bowel syndrome (1.76) were significantly higher in patients with migraine than in controls (p = 0.000). The ORs for asthma (1.16) and bronchitis (1.33) were also significantly higher in patients with nMH than in controls (p = 0.0002). When the migraine group was compared with the nMH group, only the OR for GI disorders was statistically significant. Our findings suggest that migraine and nMH are associated with increased risks of GI and respiratory disorders.

Multiple Chemical Sensitivity: It's time to catch up to the science

Multiple chemical sensitivity (MCS) is a complex medical condition associated with low dose chemical exposures. MCS is characterized by diverse features and common comorbidities, including fibromyalgia, cough hypersensitivity, asthma, and migraine, and stress/anxiety, with which the syndrome shares numerous neurobiological processes and altered functioning within diverse brain regions. Predictive factors linked to MCS comprise genetic influences, gene-environment interactions, oxidative stress, systemic inflammation, cell dysfunction, and psychosocial influences. The development of MCS may be attributed to the sensitization of transient receptor potential (TRP) receptors, notably TRPV1 and TRPA1. Capsaicin inhalation challenge studies demonstrated that TRPV1 sensitization is manifested in MCS, and functional brain imaging studies revealed that TRPV1 and TRPA1 agonists promote brain-region specific neuronal variations. Unfortunately, MCS has often been inappropriately viewed as stemming exclusively from psychological disturbances, which has fostered patients being stigmatized and ostracized, and often being denied accommodation for their disability. Evidence-based education is essential to provide appropriate support and advocacy. Greater recognition of receptor-mediated biological mechanisms should be incorporated in laws, and regulation of environmental exposures.

Neurological susceptibility to environmental exposures: pathophysiological mechanisms in neurodegeneration and multiple chemical sensitivity

The World Health Organization lists air pollution as one of the top five risks for developing chronic non-communicable disease, joining tobacco use, harmful use of alcohol, unhealthy diets and physical inactivity. This review focuses on how host defense mechanisms against adverse airborne exposures relate to the probable interacting and overlapping pathophysiological features of neurodegeneration and multiple chemical sensitivity. Significant long-term airborne exposures can contribute to oxidative stress, systemic inflammation, transient receptor subfamily vanilloid 1 (TRPV1) and subfamily ankyrin 1 (TRPA1) upregulation and sensitization, with impacts on olfactory and trigeminal nerve function, and eventual loss of brain mass. The potential for neurologic dysfunction, including decreased cognition, chronic pain and central sensitization related to airborne contaminants, can be magnified by genetic polymorphisms that result in less effective detoxification. Onset of neurodegenerative disorders is subtle, with early loss of brain mass and loss of sense of smell. Onset of MCS may be gradual following long-term low dose airborne exposures, or acute following a recognizable exposure. Upregulation of chemosensitive TRPV1 and TRPA1 polymodal receptors has been observed in patients with neurodegeneration, and chemically sensitive individuals with asthma, migraine and MCS. In people with chemical sensitivity, these receptors are also sensitized, which is defined as a reduction in the threshold and an increase in the magnitude of a response to noxious stimulation. There is likely damage to the olfactory system in neurodegeneration and trigeminal nerve hypersensitivity in MCS, with different effects on olfactory processing. The associations of low vitamin D levels and protein kinase activity seen in neurodegeneration have not been studied in MCS. Table 2 presents a summary of neurodegeneration and MCS, comparing 16 distinctive genetic, pathophysiological and clinical features associated with air pollution exposures. There is significant overlap, suggesting potential comorbidity. Canadian Health Measures Survey data indicates an overlap between neurodegeneration and MCS (p < 0.05) that suggests comorbidity, but the extent of increased susceptibility to the other condition is not established. Nevertheless, the pathways to the development of these conditions likely involve TRPV1 and TRPA1 receptors, and so it is hypothesized that manifestation of neurodegeneration and/or MCS and possibly why there is divergence may be influenced by polymorphisms of these receptors, among other factors.

Return to work considerations in the lingering COVID-19 Era: Long COVID, multiple chemical sensitivity, and universal design

This article discusses how COVID-19 has impacted the American workforce, symptoms of Long COVID syndrome, Multiple Chemical Sensitivity, and ways to avoid triggering its symptoms when sanitizing the workplace and using Universal Design practices to increase accessibility and decrease transmission of COVID-19 among workers. Interface with healthcare providers, rehabilitation professionals, and employers is emphasized.

Symptoms of Idiopathic Environmental Intolerance associated with chemicals (IEI-C) are positively associated with perceptual anomalies

OBJECTIVE

Idiopathic Environmental Intolerance (IEI; i.e. the experience of somatic symptoms attributed to environmental agents) represents a functional somatic syndrome of unclear aetiology. Based on previous findings that suggest an association between IEI and perceptual anomalies, this study aimed to investigate the relationship between symptoms of IEI associated with chemicals (IEI-C) and facets of the schizotypy spectrum.

METHODS

A cross-sectional study design was used with N = 410 (78.3% female) persons responding to an online survey in which chemical odor sensitivity (COS) and modern health worries (MHW) that are associated with IEI-C, as well as schizotypal personality traits (SPQ), hallucination proneness (LSHS) and delusional ideation (PDI) as core components of the schizotypy spectrum were assessed.

RESULTS

Schizotypal traits were found to be significantly positively associated with MHWs (r = 0.20, p = .01), COS (r = 0.23, p = .01), and showed significant positive associations with hallucination proneness. Magical thinking was found to exhibit a significant positive relationship with both MHW (r = 0.17, p = .01) and COS (r = 0.21, p = .01). These small associations between IEI-C and facets of the psychosis spectrum remained significant even after statistically controlling for individual levels of trait anxiety and depression.

CONCLUSION

Schizotypal personality traits, particularly magical thinking, and hallucination proneness, appear positively related to facets of IEI-C. The findings are of relevance for the advancement of theoretical models of IEI.

Potential factors affecting chronic chemical intolerance associated with constitutional predisposition or lifestyle and environment during childhood: From a six-year follow-up study

OBJECTIVE

The Japanese chemical intolerance (JCI) study was conducted in January 2012 with a cohort of 7245 adults from population-based sampling. This study aimed to investigate the childhood constitutional and environmental factors involved in the development of chronic CI from the prospective cohort study.

METHODS

In the cohort, 4683 persons were identified after six years. Self-reported questionnaires were administered to the subjects to obtain information on CI status; medical history; constitution, lifestyle, and housing environment during childhood; and recent psychosomatic states. We assessed the differences between individuals with persisting CI status during the follow-up (defined as chronic CI) and controls not having CI status during the follow-up.

RESULTS

A total of 2500 individuals responded. Multiple logistic regression analyses revealed significant associations between chronic CI and motion sickness to car or bus and allergic conjunctivitis during childhood. Significant associations between a possible increased risk of CI and the existence of high-voltage power lines close to housing, the use of vinyl covering in wall material, the use of strong perfume by a family member, and the experience of stinky odor of paint or wax at elementary school were observed. However, the use of carpet in floor material and plaster coating in wall material was associated with a possible decreased risk of CI.

CONCLUSIONS

Some potential constitutional predisposition from childhood, including inherent susceptibility in the autonomic nervous system may be involved in the development of CI.

Multiple Chemical Sensitivity in Patients Exposed to Moisture Damage at Work and in General Working-Age Population-The SAMDAW Study

A considerable proportion of patients having respiratory tract or voice symptoms associated with workplace moisture damage (MD) could have multiple chemical sensitivity (MCS). MCS is characterized by symptoms of different organ systems in association with low-level chemical exposure. The objective of this study was to assess the prevalence of MCS among patients referred to secondary health care because of respiratory or voice symptoms associated with workplace MD compared to the general working-age population. Using three subscales of the QEESI© questionnaire, we assessed MCS in the study patients and 1500 controls in the same district randomly selected from the Finnish Population Information System. Study patients had significantly more often high scores in chemical intolerance (39% vs. 23%, p = 0.001), symptom severity (60% vs. 27%, p < 0.001), and life impact subscales (53% vs. 20%, p < 0.001). Asthma, chronic rhinosinusitis, laryngeal problems, and atopy were not associated with the presence of MCS. MCS is common among patients referred to secondary health care with respiratory tract and/or voice symptoms associated with workplace MD, and it considerably affects their everyday life. MCS should be considered as a possible explanatory factor for MD-associated symptoms.

Small Fiber Neuropathy in Patients with Chronic Pain and a Previous Diagnosis of Multiple Chemical Sensitivity Syndrome

Small fiber neuropathy (SFN) is characterized by the involvement of Aδ and C fibers leading to sensory, mainly pain, and/or autonomic symptoms. Multiple chemical sensitivity syndrome (MCS) is an incompletely defined condition characterized by the onset of various symptoms in patients after exposure to several chemical substances. Pain is a common symptom in these patients. In this study, we report the histological and clinical data of a cohort of 21 patients who had been diagnosed as having MCS and who were referred to us with the suspicion of SFN because of chronic pain. All patients underwent neurological clinical examination, (including scales for pain and autonomic disorders), and a skin biopsy. Age-matched healthy subjects were used as controls for the skin biopsies. Nerve conduction studies and serum screening to exclude possible causes of peripheral neuropathy were also performed. Skin biopsies disclosed a somatic SFN in all patients. Although the majority (18 out of 21) of patients also had autonomic symptoms. we found sparing of autonomic innervation in the biopsies. These observations suggest that chronic pain in MCS could be secondary to the presence of somatic SFN, although more data are needed to confirm these observations.

Validation of a Brief Screening Instrument for Chemical Intolerance in a Large U.S. National Sample

Background: Chemical intolerance (CI) is characterized by multisystem symptoms triggered by low levels of exposure to xenobiotics including chemicals, foods/food additives, and drugs/medications. Prior prevalence estimates vary from 8–33% worldwide. Clinicians and researchers need a brief, practical screening tool for identifying possible chemical intolerance. This large, population-based study describes the validation of a three-item screening questionnaire, the Brief Environmental Exposure and Sensitivity Inventory (BREESI), against the international reference standard used for assessing chemical intolerance, the Quick Environmental Exposure and Sensitivity Inventory (QEESI). Methods: More than 10,000 people in the U.S. responded to the BREESI and the QEESI in a population-based survey. We calculated the overall prevalence of CI in this sample, as well as by gender, age, and income. Common statistical metrics were used to evaluate the BREESI as a screener for CI against the QEESI. Results: The prevalence estimate for QEESI-defined chemical intolerance in the U.S. was 20.39% (95% CI 19.63–21.15%). The BREESI had 91.26% sensitivity (95% CI: 89.20–93.04%) and 92.89% specificity (95% CI: 91.77–93.90%). The positive likelihood ratio was 12.83 (95% CI: 11.07–14.88), and the negative likelihood ratio was 0.09 (95% CI: 0.08–0.12). Logistic regression demonstrates that the predicted probability of CI increased sharply with each increase in the number of BREESI items endorsed (Odds Ratio: 5.3, 95% CI: 4.90–5.75). Conclusions: Chemical intolerance may affect one in five people in the U.S. The BREESI is a new, practical instrument for researchers, clinicians, and epidemiologists. As a screening tool, the BREESI offers a high degree of confidence in case ascertainment. We recommend: screen with the BREESI, confirm with the QEESI.

PON1 polymorphisms can predict generalized anxiety and depressed mood in patients with multiple chemical sensitivity

Background: Multiple chemical sensitivity (MCS) is a chronic condition with somatic, cognitive and affective symptoms that follow contact with chemical agents at usually non toxic concentrations. We aimed to assess the role of genetic polymorphisms involved in oxidative stress on anxiety and depression in MCS. Materials & methods: Our study investigated the CAT rs1001179, MPO rs2333227, PON1 rs662 and PON1 rs705379 polymorphisms in MCS. Results: The AG genotype of the PON1 rs662 and the TT and CT genotypes of the PON1 rs705379 were involved in anxiety and depression. Discussion: These results are in line with existing evidence of PON1 involvement in MCS and suggest a further role of this gene in the exhibition of anxiety and depression in this disease.

Multiple chemical sensitivity described in the Danish general population: Cohort characteristics and the importance of screening for functional somatic syndrome comorbidity-The DanFunD study

Background

Multiple chemical sensitivity (MCS) is characterized by widespread symptoms attributed to exposure to airborne chemicals. MCS is categorized as a functional somatic syndrome (FSS), and MCS cases often meet the criteria for other types of FSS, e.g. fibromyalgia. The primary aim was to characterize MCS regarding symptom triggers, symptoms, lifestyle and describe demographics, socioeconomics and lifestyle factors associated with MCS. A secondary aim was to examine the implication of FSS comorbidity.

Methods

Data were derived from a random sample of the Danish adult population enrolled in the Danish Study of Functional Disorders (DanFunD; n = 9,656). Questionnaire data comprised information used to delimit MCS and four additional types of FSS, as well as data on demographics, socioeconomics and lifestyle. MCS cases (n = 188) was stratified into subgroups; MCS only (n = 109) and MCS with comorbid FSS (n = 73). Information regarding FSS comorbidities were missing for six MCS cases. MCS subgroups and controls without FSS comorbidities (n = 7,791) were compared by means of logistic regression analyses, adjusted for age and sex.

Results

MCS was associated with female sex, not being in occupation and low social status, but not with age or education. MCS cases reported normal dietary intake and smoking habits and lower alcohol consumption. Additional associations were found between MCS and low rate of cohabitation, sedentarism, daily physically limitations, and poor quality of sleep. However, subgroup analysis revealed that these findings were primarily associated with MCS with comorbid FSS.

Conclusions

MCS was associated with lower socioeconomic status, physically inactivity and poor quality of sleep. Subgroup analysis revealed that several associations was explained by FSS comorbidity, i.e. MCS cases with no comorbid FSS showed normal rate of cohabitation and did not report physical limitations or difficulties sleeping. Overall, our findings emphasise the importance of screening MCS cases for FSS comorbidity both in epidemiological and clinical settings.

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.

Multiple Chemical Sensitivity Syndrome: A Principal Component Analysis of Symptoms

Multiple Chemical Sensitivity (MCS) is a chronic and/or recurrent condition with somatic, cognitive, and affective symptoms following a contact with chemical agents whose concentrations do not correlate with toxicity in the general population. Its prevalence is not well defined; it mainly affects women between 40 and 50 years, without variations in ethnicity, education and economic status. We aimed to assess the core symptoms of this illness in a sample of Italian patients. Two physicians investigated different symptoms with a checklist compilation in 129 patients with MCS (117 women). We conducted a categorical Principal Component Analysis (CATPCA) with Varimax rotation on the checklist dataset. A typical triad was documented: hyperosmia, asthenia, and dyspnoea were the most common symptoms. Patients also frequently showed cough and headache. The CATPCA showed seven main factors: 1, neurocognitive symptoms; 2, physical (objective) symptoms; 3, gastrointestinal symptoms; 4, dermatological symptoms; 5, anxiety-depressive symptoms; 6, respiratory symptoms; 7, hyperosmia and asthenia. Patients showed higher mean prevalence of factors 7 (89.9%), 6 (71.7%), and 1 (62.13%). In conclusion, MCS patients frequently manifest hyperosmia, asthenia, and dyspnoea, which are often concomitant with other respiratory and neurocognitive symptoms. Considering the clinical association that is often made with anxiety, more studies are necessary on the psychosomatic aspects of this syndrome. Further analytical epidemiological studies are needed to support the formulation of aetiological hypotheses of MCS.

Hypnosis as Sole Anesthesia for Dental Removal in a Patient with Multiple Chemical Sensitivity

Despite a number of studies on hypnosis as analgesia and anesthesia in several medical conditions, case studies on patients with multiple chemical sensitivity (MCS) are still relatively few. This case study is about a female patient with MCS who underwent dental removal using hypnosis as the sole anesthesia. The paradigm in which we work is psychosocial genomics of clinical hypnosis. We used the mind-body transformations therapy, one of the clinical methods of the psychosocial genomics paradigm. In order to induce not only effective analgesia and anesthesia but also a condition of well-being, problem-solving, effective coping and self-empowerment in our patient, 3 different hypnotic protocols were used in a multidimensional approach. Although further research is needed, our work might open up new scenarios for the application of hypnosis as sole anesthesia in conditions such as MCS.

The impact of multiple chemical sensitivity on people's social and occupational functioning; a systematic review of qualitative research studies

OBJECTIVE

Social and occupational functioning are important for psychological health. However, quantitative research has suggested that these areas can be adversely affected by multiple chemical sensitivity (MCS). This systematic review therefore sought to explore what qualitative research has suggested about how people with MCS perceive it to affect their social and occupational functioning.

METHOD

Journal articles were included if they were 1) peer reviewed 2) qualitative or mixed methods 3) published in English 4) reported qualitative findings relevant to the review. Studies were excluded if they were 1) descriptive only 2) primarily concerned with environmental intolerances other than chemicals or 3) focussed on specific populations such as veterans. Quality was assessed using the National Institute for Health and Care Excellence (NICE, 2018) qualitative quality criteria. However, quality was not used to determine eligibility for inclusion. Six databases (CINAHL, Medline, PsychArticles, PsychInfo, Scopus and Web of Science) were searched between the 24th of February 2019 and 2nd of March 2019.

RESULTS

Having removed duplicates, database searches identified 388 potential articles. Thirteen of these articles were eligible for inclusion. Following review, no more articles were included from the reference lists of these studies. Meta-aggregation of the findings identified seven categories. These were synthesised into three themes; 'limited access', 'loss & anxiety' and 'seeking engagement'.

CONCLUSIONS

The findings suggested that MCS limits some people's social and occupational functioning. The results warrant further research, and, the development of prevention and intervention strategies. Studies predominantly recruited United States and Canadian females and had several limitations.

Bidirectional association between asthma and migraines in adults: Two longitudinal follow-up studies

The objective of this study was to evaluate the bidirectional association between asthma and migraines using control subjects matched by demographic factors. The Korean Health Insurance Review and Assessment Service - National Sample Cohort from 2002 to 2013 was used. In study I, 113,059 asthma participants were matched with 113,059 control I participants. In study II, 36,044 migraine participants were matched with 114,176 control II participants. The hazard ratios (HRs) of migraines in the asthma patients (study I) and asthma in the migraine patients (study II) were analyzed using stratified Cox proportional hazard models after adjusting for depression and the Charlson comorbidity index. In study I, 5.3% (6,017/ 113,059) of the asthma group and 3.4% (3,806/ 113,059) of the control I group had migraines (P < 0.001). The asthma group demonstrated an adjusted HR of 1.47 for migraine (95% confidence interval (CI) = 1.41–1.53, P < 0.001). In study II, 15.4% (5,548/36,044) of the migraine group and 10.6% (15,271/144,176) of the control group had asthma (P < 0.001). The migraine group showed an adjusted HR of 1.37 for asthma (95% CI = 1.33–1.41, P value < 0.001). Asthma and migraines are reciprocally associated.

Chemical intolerance: involvement of brain function and networks after exposure to extrinsic stimuli perceived as hazardous

Background

Chemical intolerance (CI) is a chronic condition characterized by recurring and severe symptoms triggered by exposure to low levels of odorous or pungent substances. The etiology of CI has been a controversial subject for a long time. The aim of this review is to summarize findings on the neurological processing of sensory information during and after exposure to low levels of odorous or pungent substances in individuals with CI, focusing on the brain function and networks.

Methods

Scientific studies on CI published between 2000 and 2019 in academic peer-reviewed journals were systematically searched using medical and scientific literature databases. Only peer-reviewed articles reporting original research from experimental human studies directly associated with CI, and involving related neurological responses or brain imaging after exposure to odorous or pungent substances (i.e., in chemical provocation tests), were considered.

Results

Forty-seven studies were found to be eligible for a full-text review. Twenty-three studies met the selection criteria and were included in this review. Evidence indicated that differences between subjects with CI and healthy controls were observed by brain imaging during and after exposure to odorous or pungent substances. Differences in brain imaging were also observed between initial exposure and after exposure to these substances. Neurological processing of sensory information after exposure to extrinsic stimuli in the limbic system and related cortices were altered in subjects with CI. A previous documentable exposure event was likely to be involved in this alteration.

Conclusions

This review documents consistent evidence for the altered neurological processing of sensory information in individuals with CI. Further neurophysiological research exploring the processing of extrinsic stimuli and cognition of sensation through the limbic system and related cortices in CI, and the appearance of symptoms in individuals with CI, are required.

How do women suffering from multiple chemical sensitivity experience the medical encounter? a qualitative study in Spain

PURPOSE

Multiple Chemical Sensitivity is a condition principally suffered by women. As with fibromyalgia and chronic fatigue syndrome, Multiple Chemical Sensitivity is usually included among the so called "contested illnesses", defined as illnesses whose cause, diagnosis, prevalence and even existence are subject to controversy. This article seeks to explore how women with Multiple Chemical Sensitivity experience this contested illness, through their own descriptions of diagnostic processes, search for treatment and encounters with different health professionals. We aim to observe these experiences in detail and to identify aspects that could improve care for Multiple Chemical Sensitivity sufferers.

METHOD

Qualitative design. We performed personal in-depth interviews, which were recorded and transcribed to conduct a qualitative content analysis supported by Atlas.ti-7.

SUBJECTS/PATIENTS

22 women diagnosed with Multiple Chemical Sensitivity in Spain.

RESULTS

Two main categories were identified in the interviews: (1) unavoidable barriers: patients' exposure to chemicals and the absence of treatment, and (2) Skepticism on the part of care providers and lack of recognition in the process of diagnosis.

CONCLUSION

Training and above all awareness raising strategies are needed to address health professionals' prejudices regarding the existence of contested illnesses such as Multiple Chemical Sensitivity. These prejudices hinder diagnosis and medical follow-up, and add negative emotions to the physical limitations already suffered by patients.IMPLICATIONS FOR REHABILITATION Multiple Chemical SensitivityIt is important to promote a compassionate and empathetic attitude among health providers, in order to avoid rejection and delegitimization of the experiences of women with Multiple Chemical Sensitivity.Multiple Chemical Sensitivity protocols should be developed and implemented to give skills to health professionals to assist patients with Multiple Chemical Sensitivity.These protocols should include avoidance of exposure to chemicals present in healthcare facilities.Training programs for health providers should include not only knowledge, but awareness raising about the characteristics and severity of contested illnesses such as Multiple Chemical Sensitivity.Health providers should avoid stigmatizing patients by psychologizing their symptoms and be aware of the existence of stereotypes regarding women suffering from Multiple Chemical Sensitivity.

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”.

Factors affecting self-reported chemical intolerance: A five-year follow-up study in Japan

OBJECTIVE

Chemical intolerance (CI) has become a strong public health concern in industrialized countries. The Japanese Chemical Intolerance (JCI) study was conducted in January 2012 with a cohort of 7245 adults from population-based sampling as the baseline. The aim of the present study was to investigate the factors involved in the improvement and development of CI from the five-year follow-up study.

METHODS

From the 7245 cohort, 735 persons with CI (case) were identified, and 1750 controls without CI were randomly selected to match gender and age for case and control groups. Self-reported questionnaires were administered to the subjects of the two groups to obtain information on status of CI; medical history; medical, lifestyle, or physical interventions; changes in living situation or occupation; and psychosomatic states.

RESULTS

A total of 909 individuals responded during the follow-up period. After five years, improvement in CI was observed in 67.7% of the case group. Status of CI was reported in 6.7% of the control group. Multiple logistic regression analyses revealed that baseline atopic dermatitis and negative psychosomatic states including irritability, fatigue, anxiety, depressed mood, and somatic symptoms were significantly associated with development of CI in controls. Appropriate physical activity and maintaining a regular lifestyle including diet or sleep during the last three years of the follow-up period were significant factors for improvement of CI in the case group.

CONCLUSIONS

Ensuring appropriate physical activity and regular lifestyle rather than improving physical environment lead to improvement of CI. Stable psychosomatic state is essential for preventing CI.

Onset Patterns and Course of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Background: Epidemiologic studies of myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS) have examined different aspects of this disease separately but few have explored them together. Objective: Describe ME/CFS onset and course in one United States-based cohort. Methods: One hundred and fifty subjects fitting Fukuda 1994 CFS criteria completed a detailed survey concerning the initial and subsequent stages of their illness. Descriptive statistics, graphs, and tables were used to illustrate prevalence and patterns of characteristics. Results: The most common peri-onset events reported by subjects were infection-related episodes (64%), stressful incidents (39%), and exposure to environmental toxins (20%). For 38% of subjects, more than 6 months elapsed from experiencing any initial symptom to developing the set of symptoms comprising their ME/CFS. Over time, the 12 most common symptoms persisted but declined in prevalence, with fatigue, unrefreshing sleep, exertion-related sickness, and flu-like symptoms declining the most (by 20-25%). Conversely, cognitive symptoms changed the least in prevalence, rising in symptom ranking. Pregnancy, menopause, and menstrual cycles exacerbated many women's symptoms. Fatigue-related function was not associated with duration of illness or age; during the worst periods of their illness, 48% of subjects could not engage in any productive activity. At the time of survey, 47% were unable to work and only 4% felt their condition was improving steadily with the majority (59%) describing a fluctuating course. Ninety-seven percent suffered from at least one other illness: anxiety (48%), depression (43%), fibromyalgia (39%), irritable bowel syndrome (38%), and migraine headaches (37%) were the most diagnosed conditions. Thirteen percent came from families where at least one other first-degree relative was also afflicted, rising to 27% when chronic fatigue of unclear etiology was included. Conclusions: This paper offers a broad epidemiologic overview of one ME/CFS cohort in the United States. While most of our findings are consistent with prior studies, we highlight underexamined aspects of this condition (e.g., the evolution of symptoms) and propose new interpretations of findings. Studying these aspects can offer insight and solutions to the diagnosis, etiology, pathophysiology, and treatment of this condition.

Precision Medicine: The Role of the MSIDS Model in Defining, Diagnosing, and Treating Chronic Lyme Disease/Post Treatment Lyme Disease Syndrome and Other Chronic Illness: Part 2

We present a precision medical perspective to assist in the definition, diagnosis, and management of Post Treatment Lyme Disease Syndrome (PTLDS)/chronic Lyme disease. PTLDS represents a small subset of patients treated for an erythema migrans (EM) rash with persistent or recurrent symptoms and functional decline. The larger population with chronic Lyme disease is less understood and well defined. Multiple Systemic Infectious Disease Syndrome (MSIDS) is a multifactorial model for treating chronic disease(s), which identifies up to 16 overlapping sources of inflammation and their downstream effects. A patient symptom survey and a retrospective chart review of 200 patients was therefore performed on those patients with chronic Lyme disease/PTLDS to identify those variables on the MSIDS model with the greatest potential effect on regaining health. Results indicate that dapsone combination therapy decreased the severity of eight major Lyme symptoms, and multiple sources of inflammation (other infections, immune dysfunction, autoimmunity, food allergies/sensitivities, leaky gut, mineral deficiencies, environmental toxins with detoxification problems, and sleep disorders) along with downstream effects of inflammation may all affect chronic symptomatology. In part two of our observational study and review paper, we postulate that the use of this model can represent an important and needed paradigm shift in the diagnosis and treatment of chronic disease.

Background factors of chemical intolerance and parent-child relationships

Background

Chemical intolerance is a widespread public health problem characterized by symptoms that reportedly result from low-level exposure to chemicals. Although several studies have reported factors related to chemical intolerance in adults, the impact of family members has not been reported. In the present study, we investigated the background factors related to chemical intolerance in family members and parent–child relationships.

Methods

We distributed a self-reported questionnaire to 4325 mothers who were invited to visit the Kishiwada Health Center in Kishiwada City, Osaka, between January 2006 and December 2007 for the regular health checkup of their three-and-a-half-year-old children.

Results

The prevalence of chemical intolerance in the 3-year-old children was almost one eighteenth of that reported by their mothers. Multiple logistic regression analyses revealed that cold sensitivity [odds ratio (OR), 1.89; 95% confidence interval (CI), 1.04–3.44], past bronchial asthma (OR, 2.84; 95% CI, 1.46–5.53), and any past allergies (OR, 2.21; 95% CI, 1.36–3.60) were significantly associated with chemical intolerance in the mother. The presence of indoor cat during childhood (OR, 1.99; 95% CI, 1.08–3.69) was significantly associated with chemical intolerance in the mother; however, the association was weak compared with cold sensitivity and past asthma and allergies. The current chemical intolerance of the mother was significantly associated with allergic rhinitis (OR, 2.32; 95% CI, 1.19–4.53), bronchial asthma (OR, 3.66; 95% CI, 2.00–6.69), and chronic bronchitis (OR, 3.69; 95% CI, 1.04–13.03) in her 3-year-old child.

Conclusions

The results suggest that inherent physical constitution and childhood housing environment are associated with a risk of acquiring chemical intolerance. Children of mothers with chemical intolerance have a possible risk of respiratory hypersensitivity or inflammation. Further investigation is recommended to determine the inherent physical constitution and background environmental factors associated with the risk of acquiring chemical intolerance. The impact of having mothers with chemical intolerance on the health of children also requires further study.

Electronic supplementary material

The online version of this article (10.1186/s12199-018-0743-y) contains supplementary material, which is available to authorized users.

Prevalence and effects of multiple chemical sensitivities in Australia

Multiple chemical sensitivities (MCS) is a medical condition associated with exposure to common chemical pollutants. The aims of this study are to assess the prevalence of MCS, its overlaps with asthma and fragrance sensitivity, and its health and societal effects in Australia. Data were collected in June 2016 using an on-line survey with a representative national sample (N = 1098) of adults (ages 18–65) in Australia. Results found that, across the country, 6.5% report medically diagnosed MCS, 18.9% report chemical sensitivity (being unusually sensitive to everyday chemicals and chemically formulated products), and 19.9% either or both. Among people with MCS, 74.6% also have diagnosed asthma or an asthma-like condition, and 91.5% have fragrance sensitivity, reporting health problems (such as migraine headaches) when exposed to fragranced consumer products (such as air fresheners and cleaning supplies). In addition, among people with MCS, 77.5% are prevented from access to places because of fragranced products, 52.1% lost workdays or a job in the past year due to fragranced product exposure in the workplace, and 55.4% report health effects considered potentially disabling. Results indicate that MCS is a widespread disease, affecting an estimated 1 million adult Australians, with chemical sensitivity affecting another 2 million. Reducing chemical exposure to problematic sources, such as fragranced consumer products, is critical to reduce adverse effects.