A cross-sectional study of self-reported chemical-related sensitivity is associated with gene variants of drug-metabolizing enzymes

Metagenomic gut microbiome analysis of Japanese patients with multiple chemical sensitivity/idiopathic environmental intolerance

BACKGROUND

Although the pathology of multiple chemical sensitivity (MCS) is unknown, the central nervous system is reportedly involved. The gut microbiota is important in modifying central nervous system diseases. However, the relationship　between the gut microbiota and MCS remains unclear. This study aimed to identify gut microbiota variations associated with MCS using shotgun metagenomic sequencing of fecal samples.

METHODS

We prospectively recruited 30 consecutive Japanese female patients with MCS and analyzed their gut microbiomes using shotgun metagenomic sequencing. The data were compared with metagenomic data obtained from 24 age- and sex-matched Japanese healthy controls (HC).

RESULTS

We observed no significant difference in alpha and beta diversity of the gut microbiota between the MCS patients and HC. Focusing on the important changes in the literatures, at the genus level, Streptococcus, Veillonella, and Akkermansia were significantly more abundant in MCS patients than in HC (p < 0.01, p < 0.01, p = 0.01, respectively, fold change = 4.03, 1.53, 2.86, respectively). At the species level, Akkermansia muciniphila was significantly more abundant (p = 0.02, fold change = 3.3) and Faecalibacterium prausnitzii significantly less abundant in MCS patients than in HC (p = 0.03, fold change = 0.53). Functional analysis revealed that xylene and dioxin degradation pathways were significantly enriched (p < 0.01, p = 0.01, respectively, fold change = 1.54, 1.46, respectively), whereas pathways involved in amino acid metabolism and synthesis were significantly depleted in MCS (p < 0.01, fold change = 0.96). Pathways related to antimicrobial resistance, including the two-component system and cationic antimicrobial peptide resistance, were also significantly enriched in MCS (p < 0.01, p < 0.01, respectively, fold change = 1.1, 1.2, respectively).

CONCLUSIONS

The gut microbiota of patients with MCS shows dysbiosis and alterations in bacterial functions related to exogenous chemicals and amino acid metabolism and synthesis. These findings may contribute to the further development of treatment for MCS.

TRIAL REGISTRATION

This study was registered with the University Hospital Medical Information Clinical Trials Registry as UMIN000031031. The date of first trial registration: 28/01/2018.

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.

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.

Influence of the SOD2 A16V gene polymorphism on alterations of redox markers and erythrocyte membrane fatty acid profiles in patients with multiple chemical sensitivity

Chronically increased oxidative stress has been reported in patients with multiple chemical sensitivity (MCS). Recently, a single nucleotide polymorphism of the gene coding for mitochondrial superoxide dismutase (SOD2), namely the missense substitution A16V (C47>T) resulting in alteration of SOD2 enzyme activity, has been reported to be associated with MCS. However, the influence of SOD2 A16V genetic background on redox status of patients with MCS has not yet been investigated. Here, the results of a retrospective analysis aimed to evaluate the role of the SOD2 A16V polymorphism in the alterations of antioxidant defense markers as well as fatty acid (FA) composition of erythrocyte membranes in 67 patients with MCS matched with 55 healthy controls is reported. The mutated SOD2 V16 variant was observed more frequently in the MCS group compared with the control group, and this difference was statistically significant. The most common genotype in both groups was the heterozygous SOD2 AV16 variant, whereas the mutated SOD2 VV16 variant was more frequently observed in the MCS group, although the difference was not significant. The MCS cohort showed significantly depleted levels of plasma total antioxidant activity, ubiquinol, erythrocyte reduced glutathione and membrane polyunsaturated FA levels, coupled with significant increases in glutathione peroxidase activity, likely accounting for sustained detoxification from lipoperoxides. Notably, the highest levels of oxidative stress were found in patients with MCS bearing the genotype SOD2 AA16, whereas intermediate levels were found in patients bearing the heterozygous AV16 genotype. Healthy subjects bearing the SOD2 AA16 genotype also showed increased oxidative stress compared with carriers of other SOD2 genotypes. Despite the need for further confirmations in larger cohorts, due to MCS population genetic heterogeneity, these preliminary findings suggest that SOD2 defective activity makes certain patients with MCS more susceptible to developing oxidative stress following a chronic daily exposure to pro-oxidant insults.

The SNP rs2298383 Reduces ADORA2A Gene Transcription and Positively Associates with Cytokine Production by Peripheral Blood Mononuclear Cells in Patients with Multiple Chemical Sensitivity

Systemic inflammation and immune activation are striking features of multiple chemical sensitivity (MCS). The rs2298383 SNP of ADORA2A gene, coding for adenosine receptor type 2A (A2AR), has been involved in aberrant immune activation. Here we aimed to assess the prevalence of this SNP in 279 MCS patients and 238 healthy subjects, and its influence on ADORA2A, IFNG and IL4 transcript amounts in peripheral blood mononuclear cells of randomly selected patients (n = 70) and controls (n = 66) having different ADORA2A genotypes. The ADORA2A rs2298383 TT mutated genotype, significantly more frequent in MCS patients than in controls, was associated with a three-fold increased risk for MCS (O.R. = 2.86; C.I. 95% 1.99–4.12, p < 0.0001), while the CT genotype, highly prevalent among controls, resulted to be protective (O.R. = 0.33; C.I. 95% 0.224–0.475, p < 0.0001). Notably, ADORA2A mRNA levels were significantly lower, while IFNG, but not IL4, mRNA levels were significantly higher in TT MCS patients compared with controls. A significant negative correlation was found between ADORA2A and both IFNG and IL4, while a significant positive correlation was found between IFNG and IL4. These findings suggest that A2AR defective signaling may play a relevant role in PBMC shift towards a pro-inflammatory phenotype in MCS patients.

A case report of idiopathic environmental intolerance: A controversial and current issue

In this case of idiopathic environmental intolerance, a little known disease characterized by many symptoms of irritation due to exposure to several toxic compounds, genetic analysis could be helpful in case of differential diagnosis issue.

Olfactory-Related Quality of Life in Multiple Chemical Sensitivity: A Genetic-Acquired Factors Model

Genetic polymorphisms as well as environmental exposures to chemical compounds, iatrogenic, psychological, and physical trauma may play a pathophysiological role in multiple chemical sensitivity (MCS) olfactory complaints, given that xenobiotic metabolism is influenced by sequence variations in genes of metabolizing enzymes. Thus, the aim of the present study was to depict-by means of multiple regression analysis-how different genetic conditions, grouped according to their function as well as clinical background and environmental exposure may interfere with those olfactory complaints referred by MCS patients. Therefore, MCS patients after gene polymorphism sequencing, the olfactory-related quality of life score-calculated by means of the Questionnaire of Olfactory Disorder in forty-six MCS patients-have been found to significantly rely on the phase I and II enzymes score and exposure to previous compounds and surgical treatments. The present work-implementing for the first time a genetic-acquired factors model on a regression analysis-further reinforces those theories, positing MCS as a complex, multifactorial, disease in which the genetic risk related to phase I and II enzymes involved in xenobiotic detoxification, olfactory, and neurodegenerative diseases play a necessary, but probably not sufficient role, along the pathophysiological route of the disease.

One Single Question Is not Sufficient to Identify Individuals With Electromagnetic Hypersensitivity

Idiopathic Environmental Intolerance attributed to Electromagnetic Fields (IEI-EMF) is a self-reported condition where non-specific symptoms are attributed to weak non-ionizing electromagnetic fields. Despite its expanding prevalence, there is no generally accepted diagnostic procedure or definition to identify patients with this condition, thus studies usually apply only one question as inclusion criterion. The aim of our study was to demonstrate the heterogeneity of a self-reported IEI-EMF group and to identify further self-report questions that could be applied as inclusion criteria.

Cross-sectional on-line survey study was carried out with 473 participants (76.3% women; age: 35.03 ± 13.24 yrs). Self-diagnosed IEI-EMF (as assessed with a yes-or-no question), frequency of EMF-related symptom and severity of the condition were assessed, as well as somatic symptom distress (Patient Health Questionnaire Somatic Symptom Severity Scale, PHQ-15).

72 (15.2%) individuals labelled themselves as IEI-EMF, however only 61% of them remained in the IEI-EMF group after the use of three inclusion criteria instead of one. 21% of the individuals labelling themselves as IEI-EMF reported neither symptoms nor any negative impact on their daily life.

A minimum of two questions appear to be necessary as inclusion criteria for IEI-EMF in empirical research. Instead of the widely used yes-or-no question on accepting the IEI-EMF label, occurrence of symptoms attributed to EMF on a regular basis and at least a slight negative impact on daily life are required.

Electromagnetic hypersensitivity (IEI-EMF) is often assessed by one yes-or-no self-report question.

This practice is inappropriate from a conceptual and methodological point of view.

At least two questions, assessing frequency of symptoms and their impact, are needed.

Assessment of CYP2C9, CYP2C19, and CYP2D6 Polymorphisms in Allergic Patients with Chemical Sensitivity

BACKGROUND

Self-reported chemical sensitivity (SCS) is characterized by adverse effects due to exposure to low levels of chemical substances. The clinical manifestations of SCS are similar to the allergy, and a high percentage of individuals with both diseases have been found. Various genes, especially genes of importance to the metabolism of xenobiotic compounds, have been associated with SCS.

OBJECTIVES

The purpose of this study was to investigate whether allergic individuals with chemical sensitivity differed from allergic patients without chemical sensitivity with regard to the distribution of genotype and phenotype of CYP2C9, CYP2C19, and CYP2D6 polymorphisms.

METHODS

A total of 180 patients were enrolled for this study. A questionnaire was employed to collect information on individual chemical sensitivity, while the Skin prick test and the PATCH test were used to verify the presence of an allergic condition against inhalants or contact allergens, respectively. For the evaluation of the CYP2C9, CYP2C19, and CYP2D6 polymorphisms, we used a strategy based on the amplification of the entire gene coupled to direct genomic DNA sequencing analysis.

RESULTS

Overall, a total of 15 different CYP2C9, CYP2C19, and CYP2D6 haplotypes were identified in our population. If the 5 CYP2C9 and the 2 CYP2C19 identified alleles correspond to the previously described ones, 4 of the 8 CYP2D6 haplotypes, detected in the study group, present new SNPs combinations. These new suballeles were categorized as CYP2D6*2M Sa-lento Variant 1, CYP2D6*35B Salento Variant 2, CYP2D6*41 Salento Variant 3, and CYP2D6*4P Salento Variant 4 due to the presence of the key SNPs 2,850 C>T, 31G>A, 2,988 G>A, and 1,846 G>A, respectively. When the allergic individuals are divided into 2 groups according to their SCS score, we observed that the distribution of the CYP2D6 phenotypes was significantly different between the 2 groups.

CONCLUSIONS

Our idea is that the application of the questionnaire that we have adopted has enabled us to diagnose a degree of chemical sensitivity, which results as comorbid of the allergic disease and in which a condition of poor or intermediate metabolizes for the detrimental CYP2D6 alleles, could represent a discriminant between the chemical sensitivity and the health state.

Epidemiological association between multiple chemical sensitivity and birth by caesarean section: a nationwide case-control study

INTRODUCTION

Multiple chemical sensitivity (MCS) is characterized by recurrent nonspecific symptoms that are attributed to exposure to trace levels of environmental agents. Although the clinical symptoms of MCS have been described in several studies, the risk factors for this condition remain unclear. Our aim was to clarify the risk factors for MCS and the association between MCS and birth by caesarean section.

METHODS

We conducted a nationwide case-control study of Japanese individuals (aged 20-65 years) with physician-diagnosed MCS (183 cases) and without MCS (345 controls). The study participants were selected from among 150,000 people in a web-based research panel with approximately 1,000,000 registrants. They completed an online survey including questions on their sociodemographic characteristics, birth history (i.e., birth by caesarean section), and other potential risk factors for MCS. Multivariate logistic regression analysis was employed to determine the association between sociodemographic characteristics and the risk of MCS.

RESULTS

The proportions of case and control subjects who were born by caesarean section were 39.9 and 7.0%, respectively. The association between birth by caesarean section and MCS was significant even after adjusting for potential confounders (adjusted odds ratio: 6.15; 95% confidence interval: 3.13-12.1). A history of agricultural work, mouth breathing, ≥11 vaccinations in the past 10 years, and residing in a new home (< 1 year-old) ≥3 times were also significantly associated with MCS.

CONCLUSION

Our data indicate an epidemiological link between MCS and birth by caesarean section. Moreover, we show that factors other than chemical exposure may be associated with the development of MCS.

[Multiple Chemical Sensitivity (MCS): History, Epidemiology and Mechanism]

Multiple chemical sensitivity (MCS), also known as idiopathic environmental intolerance, has been described as a chronic acquired disorder characterized by nonspecific symptoms in multiple organ systems and is associated with exposure to low-level chemicals. The name was established by Cullen, in 1987, although the name and diagnostic criteria are still under debate even now. A number of hypotheses concering the etiology and pathogenesis of MCS have been proposed, including impairmens of neurological, immunological and psychological systems. However, research on the possible mechanisms underlying MCS is far from complete. The name and diagnostic criteria of its history as well as theoretical and experimental mechanisms underlying MCS are reviewed here.

Spatial variation in risk for physician diagnosed environmental sensitivity

Multiple chemical sensitivity (MCS) is a chronic condition characterized by recurring and severe symptoms triggered by exposures to low levels of toxicants or anthropogenic pollution. This study investigated the spatial structure of MCS incidence and estimated the contribution of socio-economic deprivation to variations in rates of MCS at the community level in Nova Scotia, Canada. Patient data were used to calculate cumulative incidence rate ratios for treated multiple chemical sensitivities. Poisson regression with a spatially autoregressive random effect was employed to assess spatial variation in MCS. Odds of MSC incidence are greatest among patients from the highest socioeconomic category using the most socioeconomically deprived category as reference (OR: 1.94, CI [2.5-95%] 1.45-2.56). No discernable spatial pattern for MCS risk was evident after controlling for known risk factors. This is the first study to investigate spatial variations in cumulative incidence of multiple chemical sensitivities. The socioeconomic status of the community in which patients live has a significant influence on the geographic patterns of MCS. Future research will include a smartphone application to assess positional and temporal information on environmental exposures to further explain MCS prevalence.

Noise sensitivity and hyperacusis in patients affected by multiple chemical sensitivity

PURPOSE

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.

METHODS

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.

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.

CONCLUSIONS

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.

Lack of contralateral suppression in transient-evoked otoacoustic emissions in multiple chemical sensitivity: a clinical correlation study

Multiple chemical sensitivity (MCS) is a chronic disorder characterized by a variety of symptoms associated with the exposure to chemicals at a concentration below the toxic level. Previous studies have demonstrated peculiar responses in brain activity in these patients with respect to sensory stimuli while the association between chemical sensitivity and other environmental intolerances such as noise sensitivity has been questioned by researchers. In this study, a cohort of 18 MCS patients underwent transient-evoked otoacoustic emission (TEOAE) testing with and without contralateral suppression to evaluate the functionality of the medial olivocochlear (MOC) reflex involved in speech-in-noise sensitivity. Results were compared with an age- and gender-matched control group (n = 20) and correlation analysis with disease onset and quick environmental exposure sensitivity inventory (qEESI) symptom severity scale was performed. Subjects affected by MCS showed statistically significant impairment of MOC reflex, and the onset of the disease and several symptom subscales showed to be correlated to such reduction in some of the frequencies tested. These data suggest that alterations of MOC reflex could be part of the complex features of this disease although more studies are needed to further explore auditory perception disorders in environmental intolerances.

Role of polymorphisms of inducible nitric oxide synthase and endothelial nitric oxide synthase in idiopathic environmental intolerances

Oxidative stress and inflammation play a pathogenetic role in idiopathic environmental intolerances (IEI), namely, multiple chemical sensitivity (MCS), fibromyalgia (FM), and chronic fatigue syndrome (CFS). Given the reported association of nitric oxide synthase (NOS) gene polymorphisms with inflammatory disorders, we aimed to investigate the distribution of NOS2A −2.5 kb (CCTTT)_n as well as Ser608Leu and NOS3 −786T>C variants and their correlation with nitrite/nitrate levels, in a study cohort including 170 MCS, 108 suspected MCS (SMCS), 89 FM/CFS, and 196 healthy subjects. Patients and controls had similar distributions of NOS2A Ser608Leu and NOS3 −786T>C polymorphisms. Interestingly, the NOS3 −786TT genotype was associated with increased nitrite/nitrate levels only in IEI patients. We also found that the NOS2A −2.5 kb (CCTTT)₁₁ allele represents a genetic determinant for FM/CFS, and the (CCTTT)₁₆ allele discriminates MCS from SMCS patients. Instead, the (CCTTT)₈ allele reduces by three-, six-, and tenfold, respectively, the risk for MCS, SMCS, and FM/CFS. Moreover, a short number of (CCTTT) repeats is associated with higher concentrations of nitrites/nitrates. Here, we first demonstrate that NOS3 −786T>C variant affects nitrite/nitrate levels in IEI patients and that screening for NOS2A −2.5 kb (CCTTT)_n polymorphism may be useful for differential diagnosis of various IEI.

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 ω 6/ ω 3 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.

Evaluation of genetic polymorphisms in patients with multiple chemical sensitivity

Objective

Multiple chemical sensitivity (MCS) is a chronic medical condition characterized by symptoms that the affect an individual’s response to low-level chemical exposure. In this study, we identified a chemical sensitive population (CSP) and investigated the effect of genetic polymorphisms on their risk of chemical sensitivity.

Methods

A quick environment exposure sensitivity (QEESI) questionnaire was used to survey 324 Japanese male workers whose DNA samples had been collected and stored. The following genes, which encode enzymes affecting the metabolic activation of a large number of xenobiotic compounds, were selected and analyzed in order to determine their influence on genetic predisposition to CSP: cytochrome P450 (CYP) 2E1, N-acetyl transferase (NAT) 2, glutathione S-transferase (GST) M1, GSTT1, GSTP1, low Km aldehyde dehydrogenase (ALDH2), and superoxide dismutase (SOD) 2.

Results

Significant case-control distributed differences were observed in SOD2 polymorphisms and allele frequency distribution in high chemical sensitive subjects. Both the significant adjusted OR of 4.30 (95% CI, 1.23–15.03) and 4.53 (95% CI, 1.52-13.51) were observed in SOD2 Ala/Ala and Val/Ala compared to Val/Val and in SOD2 Ala/Ala compared to Val/Ala compared to Val/Val genetic analysis in the high chemical sensitivity case-control study.

Conclusions

We observed that high chemical sensitive individuals diagnosed by using Japanese criteria as MCS patients were more significantly associated with SOD2 polymorphisms.

Xenobiotic sensor- and metabolism-related gene variants in environmental sensitivity-related illnesses: a survey on the Italian population

In the environmental sensitivity-related illnesses (SRIs), multiple chemical sensitivity (MCS), chronic fatigue syndrome (FCS), and fibromyalgia (FM), the search for genetic polymorphisms of phase I/II xenobiotic-metabolizing enzymes as suitable diagnostic biomarkers produced so far inconclusive results, due to patient heterogeneity, geographic/ethnic differences in genetic backgrounds, and different methodological approaches. Here, we compared the frequency of gene polymorphisms of selected cytochrome P450 (CYP) metabolizing enzymes and, for the first time, the frequency of the xenobiotic sensor Aryl hydrocarbon receptor (AHR) in the three cohorts of 156 diagnosed MCS, 94 suspected MCS, and 80 FM/FCS patients versus 113 healthy controls. We found significantly higher frequency of polymorphisms CYP2C9∗2, CYP2C9∗3, CYP2C19∗2, CYP2D6∗4 and CYP2D6∗41 in patients compared with controls. This confirms that these genetic variants represent a genetic risk factor for SRI. Moreover, the compound heterozygosity for CYP2C9∗2 and ∗3 variants was useful to discriminate between either MCS or FM/CFS versus SMCS, while the PM ∗41/∗41 genotype discriminated between MCS and either SMCS or FM/CFS. The compound heterozygosity for CYP2C9 ∗1/∗3 and CYP2D6 ∗1/∗4 differentiated MCS and SMCS cases from FM/CFS ones. Interestingly, despite the distribution of the AHR Arg554Lys variant did not result significantly different between SRI cases and controls, it resulted useful for the discrimination between MCS and SMCS cases when considered within haplotypes in combination with CYP2C19 ∗1/∗2 and CYP2D6 ∗1/∗4. Results allowed us to propose the genotyping for these specific CYP variants, together with the AHR Arg554Lys variant, as reliable, cost-effective genetic parameters to be included in the still undefined biomarkers' panel for laboratory diagnosis of the main types of environmental-borne SRI.

Multiple chemical sensitivity and the workplace: current position and need for an occupational health surveillance protocol

Multiple chemical sensitivity, commonly known as environmental illness, is a chronic disease in which exposure to low levels of chemicals causes correlated symptoms of varying intensity. With the continuous introduction of new substances, people with MCS suffer significant limitations to their living environment and frequently to their workplace. This paper describes the current situation as regards MCS and the critical points in its case definition, which is still not generally agreed upon; this makes it difficult to recognize with certainty, especially, its precise relationship with work. Other problems arise in relation to the occupational physician's role in diagnosing and managing the worker with the disorder, the question of low levels of exposure to chemicals, and the best measures possible to prevent it. A diagnostic “route” is proposed, useful as a reference for the occupational physician who is often called in first to identify cases suspected of having this disease and to manage MCS workers. Work-related problems for people with MCS depend not only on occupational exposure but also on the incompatibility between their illness and their work. More occupational physicians need to be “sensitive” to MCS, so that these workers are recognized promptly, the work is adapted as necessary, and preventive measures are promoted in the workplace.

Non-invasive assessment of exhaled breath pattern in patients with multiple chemical sensibility disorder

Multiple chemical sensitivity (MCS) is a complex disorder initiated by chemical exposure, particularly through the airways. MCS patients report sensitivity or intolerance to low levels of a wide spectrum of chemicals. Symptoms could include asthma-like signs, rhinitis, fatigue, cognitive dysfunction, psycho-physiological alteration, and other specific tissue reactions resembling hypoxic and oxidative stress effects. To recognize physiological signs that would allow the diagnosis of MCS in a non-invasive way we investigated the potential application of a new sensor system. In healthy volunteers, we measured exhaled breath content in the control condition and under exposure to olfactory stressors that mimic hypoxic or pollutant stressors playing a potential role in the generation of the MCS disorder. The recording system used is based on metal oxide semiconductor (MOS) sensor having a sensing range of 450-2,000 ppm CO(2) equivalents, which is able to detect a broad range of compounds playing a potential role in the generation of the MCS disorder, while correlating directly with the CO(2) levels. The results indicate that the recording system employed was suitable for the analysis of exhaled breath content in humans. Interestingly, the system was able to detect and discriminate between the exhaled breath content taken from the control condition and those from conditions under stress that mimicked exposures to pollutant or hypoxia. The results suggest that chronic hypoxia could be involved in the MCS disorder.

Review of evidence for a toxicological mechanism of idiopathic environmental intolerance

Idiopathic environmental intolerance (IEI) is a medically unexplained disorder characterised by a wide variety of unspecific symptoms in different organ systems and attributed to nontoxic concentrations of chemicals and other environmental factors that are tolerated by the majority of individuals. Both exposure to chemicals and behavioural conditioning are considered as possible contributors to the development of IEI. However, owing to the heterogeneity of the condition, it is difficult to separate the toxicological, physiological and psychological aspects of IEI. Here, we review the evidence for postulated toxicologically mediated mechanisms for IEI. Available data do not support either a classical receptor-mediated or an idiosyncratic toxicological mechanism. Furthermore, if there were convincing evidence for a psychological cause for many patients with IEI, then this would suggest that the priority for the future is the development of psychological treatments for IEI. Finally, we advocate genome wide screening of IEI patients to elucidate genotypic features of the condition.

Factors in genetic susceptibility in a chemical sensitive population using QEESI

OBJECTIVES

Inherited impairment of xenobiotic metabolism is a postulated mechanism underlying environmentally associated pathogeneses such as multiple chemical sensitivity (MCS). Using the Quick Environmental Exposure and Sensitivity Inventory (QEESI), we defined people who have a strong response to chemical substances as "chemical sensitive populations (CSP)." The aim of this study is to evaluate the condition of subjects sensitive to chemicals and to analyze their genotypes in order to identify susceptibility factors in CSPs in Japanese populations.

METHODS

A total of 1,084 employees of Japanese companies were surveyed using the QEESI, history of MCS, and sick house syndrome. The common genotypes of the participants were analyzed for glutathione S-transferase (GST) M1, GSTT1, aldehyde dehydrogenase2 (ALDH2), and paraoxonase1 (PON1) in order to identify factors in the susceptibility to sensitivity to chemicals.

RESULTS

Four subjects had history of diagnosis of MCS; no subjects had diagnosis of sick house syndrome. The subjects were divided into four levels according to scores of 0, 1-19, 20-39, and 40 or more on three of the QEESI subscales. In addition, we used the MCS criteria by Hojo to differentiate between cases (CSP) and controls. No significant differences in the allelic distribution of genetic polymorphisms in the GSTM1, GSTT1, ALDH2 or PON1 genes were found among the four levels of each subscale, or between cases and controls.

CONCLUSIONS

Our findings suggest that the common genotypes of GSTM1, GSTT1, ALDH2, and PON1 are of little importance to CSP in a Japanese population.

Influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to organophosphate pesticides

Previous studies have revealed that organophosphate pesticides (OPs) are primarily metabolized by xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticides-exposed workers. Present study was designed to determine the influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to OPs. We examined 268 subjects including 134 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using alkaline comet assay and genotyping was done using individual polymerase chain reaction (PCR) or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Acetylcholinesterase and paraoxonase activity were found to be significantly lowered in workers as compared to control subjects which were analyzed as biomarkers of toxicity due to OPs exposure (p<0.001). Workers showed significantly higher DNA tail moment (TM) compared to control subjects (14.32±2.17 vs. 6.24±1.37 tail % DNA, p<0.001). GSTM1 null genotype was found to influence DNA TM in workers (p<0.05). DNA TM was also found to be increased with concomitant presence of NAT2 slow acetylation and CYP2C9*3/*3 or GSTM1 null genotypes (p<0.05). DNA TM was found increased in NAT2 slow acetylators with mild and heavy smoking habits in control subjects and workers, respectively (p<0.05). The results of this study suggest that GSTM1 null genotypes, and an association of NAT2 slow acetylation genotypes with CYP2C9*3/*3 or GSTM1 null genotypes may modulate DNA damage in workers occupationally exposed to OPs.

Role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to organophosphate pesticides

Organophosphate pesticides (OPs) are primarily metabolized by several xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticide-exposed workers. The present study was designed to determine the role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to OPs. We examined 284 subjects including 150 workers occupationally exposed to OPs and 134 normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using PCR-RFLP. The results revealed that the PONase activity toward paraoxonase and AChE activity was found significantly lowered in workers as compared to control subjects (p<0.001). Workers showed significantly higher DNA damage compared to control subjects (14.37±2.15 vs. 6.24±1.37 tail% DNA, p<0.001). Further, the workers with CYP2D6*3PM and PON1 (QQ and MM) genotypes were found to have significantly higher DNA damage when compared to other genotypes (p<0.05). In addition, significant increase in DNA damage was also observed in workers with concomitant presence of certain CYP2D6 and PON1 (Q192R and L55M) genotypes which need further extensive studies. In conclusion, the results indicate that the PON1 and CYP2D6 genotypes can modulate DNA damage elicited by some OPs possibly through gene-environment interactions.

The search for reliable biomarkers of disease in multiple chemical sensitivity and other environmental intolerances

Whilst facing a worldwide fast increase of food and environmental allergies, the medical community is also confronted with another inhomogeneous group of environment-associated disabling conditions, including multiple chemical sensitivity (MCS), fibromyalgia, chronic fatigue syndrome, electric hypersensitivity, amalgam disease and others. These share the features of poly-symptomatic multi-organ cutaneous and systemic manifestations, with postulated inherited/acquired impaired metabolism of chemical/physical/nutritional xenobiotics, triggering adverse reactions at exposure levels far below toxicologically-relevant values, often in the absence of clear-cut allergologic and/or immunologic involvement. Due to the lack of proven pathogenic mechanisms generating measurable disease biomarkers, these environmental hypersensitivities are generally ignored by sanitary and social systems, as psychogenic or "medically unexplained symptoms". The uncontrolled application of diagnostic and treatment protocols not corresponding to acceptable levels of validation, safety, and clinical efficacy, to a steadily increasing number of patients demanding assistance, occurs in many countries in the absence of evidence-based guidelines. Here we revise available information supporting the organic nature of these clinical conditions. Following intense research on gene polymorphisms of phase I/II detoxification enzyme genes, so far statistically inconclusive, epigenetic and metabolic factors are under investigation, in particular free radical/antioxidant homeostasis disturbances. The finding of relevant alterations of catalase, glutathione-transferase and peroxidase detoxifying activities significantly correlating with clinical manifestations of MCS, has recently registered some progress towards the identification of reliable biomarkers of disease onset, progression, and treatment outcomes.

Functional impairment in chronic fatigue syndrome, fibromyalgia, and multiple chemical sensitivity

OBJECTIVE

To characterize patients diagnosed with multiple chemical sensitivity (MCS), chronic fatigue syndrome (CFS), or fibromyalgia (FM), to compare their level of function with Canadian population average values, and to assess factors associated with function.

DESIGN

Chart review and abstraction of clinical information.

SETTING

The Environmental Health Clinic (EHC) at Women's College Hospital in Toronto, Ont, which is a provincial referral centre for patients with illnesses with suspected environmental links, especially MCS, CFS, and FM.

PARTICIPANTS

A total of 128 consecutive patients diagnosed with 1 or more of MCS, CFS, or FM, seen between January 2005 and March 2006 at the EHC.

MAIN OUTCOME MEASURES

Demographic and socioeconomic characteristics, comorbid diagnoses, duration of illness, health services usage, life stresses, helpful therapeutic strategies, and functional impairment measured by the Short Form-36, compared with Canadian population average values. Factors significantly associated with function in bivariate analyses were included in multiple linear and logistic regression models.

RESULTS

The patient population was predominantly female (86.7%), with a mean age of 44.6 years. Seventy-eight patients had discrete diagnoses of 1 of MCS, CFS, or FM, while the remainder had 2 or 3 overlapping diagnoses. Most (68.8%) had stopped work, and on average this had occurred 3 years after symptom onset. On every Short Form-36 subscale, patients had markedly lower functional scores than population average values, more so when they had 2 or 3 of these diagnoses. Having FM, younger age at onset, and lower socioeconomic status were most consistently associated with poor function.

CONCLUSION

Patients seen at the EHC demonstrated marked functional impairment, consistent with their reported difficulties working and caring for their homes and families during what should be their peak productive years. Early comprehensive assessment, medical management, and social and financial support might avoid the deterioration of function associated with prolonged illness. Education and information resources are required for health care professionals and the public, along with further etiologic and prognostic research.

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.