Chemosensory function and psychological profile in patients with multiple chemical sensitivity: comparison with odor-sensitive and asymptomatic controls

Exposure limits for indoor volatile substances concerning the general population: The role of population-based differences in sensory irritation of the eyes and airways for assessment factors

Assessment factors (AFs) are essential in the derivation of occupational exposure limits (OELs) and indoor air quality guidelines. The factors shall accommodate differences in sensitivity between subgroups, i.e., workers, healthy and sick people, and occupational exposure versus life-long exposure for the general population. Derivation of AFs itself is based on empirical knowledge from human and animal exposure studies with immanent uncertainty in the empirical evidence due to knowledge gaps and experimental reliability. Sensory irritation in the eyes and airways constitute about 30-40% of OELs and is an abundant symptom in non-industrial buildings characterizing the indoor air quality and general health. Intraspecies differences between subgroups of the general population should be quantified for the proposal of more 'empirical' based AFs. In this review, we focus on sensitivity differences in sensory irritation about gender, age, health status, and vulnerability in people, based solely on human exposure studies. Females are more sensitive to sensory irritation than males for few volatile substances. Older people appear less sensitive than younger ones. However, impaired defense mechanisms may increase vulnerability in the long term. Empirical evidence of sensory irritation in children is rare and limited to children down to the age of six years. Studies of the nervous system in children compared to adults suggest a higher sensitivity in children; however, some defense mechanisms are more efficient in children than in adults. Usually, exposure studies are performed with healthy subjects. Exposure studies with sick people are not representative due to the deselection of subjects with moderate or severe eye or airway diseases, which likely underestimates the sensitivity of the group of people with diseases. Psychological characterization like personality factors shows that concentrations of volatile substances far below their sensory irritation thresholds may influence the sensitivity, in part biased by odor perception. Thus, the protection of people with extreme personality traits is not feasible by an AF and other mitigation strategies are required. The available empirical evidence comprising age, lifestyle, and health supports an AF of not greater than up to 2 for sensory irritation. Further, general AFs are discouraged for derivation, rather substance-specific derivation of AFs is recommended based on the risk assessment of empirical data, deposition in the airways depending on the substance's water solubility and compensating for knowledge and experimental gaps. Modeling of sensory irritation would be a better 'empirical' starting point for derivation of AFs for children, older, and sick people, as human exposure studies are not possible (due to ethical reasons) or not generalizable (due to self-selection). Dedicated AFs may be derived for environments where dry air, high room temperature, and visually demanding tasks aggravate the eyes or airways than for places in which the workload is balanced, while indoor playgrounds might need other AFs due to physical workload and affected groups of the general population.

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.

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.

Patient-reported drug and latex allergies negatively affect outcomes after total and reverse shoulder arthroplasty

BACKGROUND

Patient-reported allergies (PRAs) have been identified as a risk factor for worse outcomes and less satisfaction in patients undergoing knee and hip arthroplasty. Similar associations have not been elucidated in shoulder arthroplasty patients; however, previous research is sparse. The purpose of this study was to assess the outcomes following shoulder arthroplasty surgery with respect to patient-reported drug allergies. It was hypothesized that a higher number of allergies would be associated with worse patient-reported outcomes (PROs) following shoulder arthroplasty surgery.

METHODS

Consecutive patients aged 18-89 years at the time of surgery who underwent primary shoulder arthroplasty between October 2005 and March 2018 performed by a single surgeon and had a minimum follow-up period of 1 year were reviewed. PRO scores, including the American Shoulder and Elbow Surgeons score, Single Assessment Numerical Evaluation score, QuickDASH (short version of Disabilities of the Arm, Shoulder and Hand questionnaire) score, and 12-Item Short Form Health Survey Physical Component Summary and Mental Component Summary scores, as well as patient satisfaction, were collected preoperatively and postoperatively. Early clinical failures were reported. Subjects were categorized into a 3-level factor based on the number of PRAs (0, 1, or ≥2), and bivariate comparisons of mean postoperative PRO scores were performed using Kruskal-Wallis analyses. Additionally, multivariate regression was performed to assess the effect of PRAs on PROs while controlling for age, sex, arthroplasty type, baseline PRO scores, and Charlson Comorbidity Index.

RESULTS

Overall, 411 shoulders were included in the final study population (367 patients, 44 of whom were treated bilaterally). The population was predominately male patients (n = 265, 64.5%), and the median age at the time of surgery was 66.5 years (first quartile-third quartile, 61.3-71.4 years). Of the patients, 253 (61.6%) underwent total shoulder arthroplasty (TSA) whereas 158 (38.4%) underwent reverse TSA. Five patients (2 TSA and 3 reverse TSA patients) experienced early clinical failure and required revision surgery. Minimum 1-year PROs were obtained for 345 of 406 patients (85.0%) with a mean follow-up period of 1.9 ± 1.2 years. Nearly all postoperative PROs reflected a trend of worse outcomes with more preoperative PRAs; however, the QuickDASH score was the only score showing a significant difference between allergy groups (P = .004). Pair-wise comparison using Nemenyi post hoc testing showed that the QuickDASH score was significantly higher (worse outcomes) for the group with ≥2 allergies compared with the group with 0 allergies. PRA was found to be a statistically significant predictor of higher postoperative QuickDASH scores (P = .043) and was more influential than the Charlson Comorbidity Index and sex. Additionally, PRA was the only statistically significant predictor of patient satisfaction (P = .016).

CONCLUSION

An increasing number of preoperative PRAs is associated with worse PROs and patient satisfaction following shoulder arthroplasty. The number of PRAs was the most influential predictor of patient satisfaction.

Chemical Intolerance Is Associated With Altered Response Bias, not Greater Sensory Sensitivity

Chemical intolerance is a surprisingly prevalent condition or affliction characterized by adverse reactions to low levels of chemical, often odorous stimulation. Sufferers often assume that their plight is due to an uncommon sensory acuteness, yet studies repeatedly fail to reveal altered detection thresholds. Here, we investigated whether self-reported chemical intolerance is associated with altered sensory sensitivity or response bias. The sensory acuity (sensitivity; A) and sensory decision rule (criterion; B) to n-butanol was assessed using the method of constant stimuli in 82 participants with different degrees of chemical intolerance (low to high). Higher self-reported chemical intolerance was associated with a lower criterion, but not with sensitivity.

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.

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.

Multiple Chemical Sensitivity: Review of the State of the Art in Epidemiology, Diagnosis, and Future Perspectives

OBJECTIVE

Systematic bibliography analysis of about the last 17 years on multiple chemical sensitivity (MCS) was carried out in order to detect new diagnostic and epidemiological evidence. The MCS is a complex syndrome that manifests as a result of exposure to a low level of various common contaminants. The etiology, diagnosis, and treatment are still debated among researchers.

METHOD

Querying PubMed, Web of Science, Scopus, Cochrane library, both using some specific MESH terms combined with MESH subheadings and through free search, even by Google.

RESULTS

The studies were analyzed by verifying 1) the typology of study design; 2) criteria for case definition; 3) presence of attendances in the emergency departments and hospital admissions, and 4) analysis of the risk factors.

OUTLOOK

With this review, we give some general considerations and hypothesis for possible future research.

Perspectives on multisensory perception disruption in idiopathic environmental intolerance: a systematic review

PURPOSE

Multiple chemical sensitivity (MCS) also known as idiopathic environmental intolerance/illness (IEI) encompasses a cohort of subjective symptoms characterized by susceptibility to a wide spectrum of environmental compounds, causing symptoms involving various organs and a decrease in quality of life. The aim of this systematic review is to summarize evidence about MCS, with focus on indexed studies analyzing sensory pathway-related disorders.

METHODS

Medical databases were searched for English language articles related to the topic, published between 1965 and 2017 in academic, peer-reviewed journals. Particular focus was concentrated on articles depicting disturbances involving sensory organs. References of the relevant articles were examined to identify additional significant documents.

RESULTS

Fifty-eight studies were eligible for full text review. Of these, 34 studies met the selection criteria and were included in this analysis. Many variables, such as different diagnostic criteria, lack of homogeneous symptom questionnaires and the general incidence of personality traits in control subjects, biased studies as confounding factors. However, moderate evidences show that sensory pathways are somewhat altered, especially with respect to information processing in the limbic system and related cortical areas. Recent studies suggested the presence, in MCS cohorts, of attention bias, sensitization and limbic kindling, as well as recently revealed subclinical organic alterations along sensory pathways.

CONCLUSIONS

Evidences are consistent with MCS/IEI to be the result of a neural altered processing of sensorial ascending pathways, which combined with peculiar personality traits constitutes the underpinning of a multisensory condition needing multidisciplinary clinical approach.

Psychological and cognitive effects of laser printer emissions: A controlled exposure study

The possible impact of ultrafine particles from laser printers on human health is controversially discussed although there are persons reporting substantial symptoms in relation to these emissions. A randomized, single-blinded, cross-over experimental design with two exposure conditions (high-level and low-level exposure) was conducted with 23 healthy subjects, 14 subjects with mild asthma, and 15 persons reporting symptoms associated with laser printer emissions. To separate physiological and psychological effects, a secondary physiologically based categorization of susceptibility to particle effects was used. In line with results from physiological and biochemical assessments, we found no coherent, differential, or clinically relevant effects of different exposure conditions on subjective complaints and cognitive performance in terms of attention, short-term memory, and psychomotor performance. However, results regarding the psychological characteristics of participants and their situational perception confirm differences between the participants groups: Subjects reporting symptoms associated with laser printer emissions showed a higher psychological susceptibility for adverse reactions in line with previous results on persons with multiple chemical sensitivity or idiopathic environmental intolerance. In conclusion, acute psychological and cognitive effects of laser printer emissions were small and could be attributed only to different participant groups but not to differences in exposure conditions in terms of particle number concentrations.

Survey of the effect of odour impact on communities

In the context of environmental malodour, surveys are valuable as they allow for the relatively detailed analysis of multiple factors pertaining to odour perception and subsequent reaction. However, the causes for an individual to experience odour impact while a neighbour will not are still not understood. The goal of this current survey design was to consolidate varying research paths for surveys within the environmental odour research space. This survey investigated the area of effect for wastewater treatment plants by using stratified random sampling techniques that radiated from the industrial areas. Additionally, this survey provided a "non-alerted" response to environmental malodour that represents a step forward for ecological validity. We found a small number of items relating to odour annoyance and home ownership that can be used in order to predict odour impact for individual community members. However, we also did not find any relationship with odour impact and perceived control. This survey design and analysis reconciles the varied approaches towards community surveys administered in prior literature, as well as providing information to improve future community engagement policies.

Symptoms from masked acrolein exposure suggest altered trigeminal reactivity in chemical intolerance

BACKGROUND

Chemical intolerance (CI) is a widespread occupational and public health problem characterized by symptoms that reportedly result from low-levels of chemical exposure. The mechanisms behind CI are unknown, however modifications of the chemical senses (rather than toxic processes) have been suggested as key components. The aim of this study was to investigate whether individuals with self-reported CI report more sensory irritation during masked acrolein exposure compared to controls without CI.

METHODS

Individuals with CI (n=18) and controls without CI (n=19) were exposed in an exposure chamber. Each participant took part in two exposure conditions - one with heptane (the masking compound), and one with heptane and acrolein at a dose below previously reported sensory irritation thresholds. The exposures lasted for 60min. Symptoms and confidence ratings were measured continuously throughout the exposure as were measurements of electrodermal activity and self-reported tear-film break-up time. Participants were blind to exposure condition.

RESULTS

Individuals with CI, compared with controls reported greater sensory irritation in the eyes, nose and throat when exposed to acrolein masked with heptane. There was no difference during exposure to heptane.

CONCLUSIONS

Masked exposure to acrolein at a concentration below the previously reported detection threshold is perceived as more irritating by individuals with CI compared with controls. The results indicate that there is altered trigeminal reactivity in those with CI compared to controls.

Differences in psychological and somatic symptom cluster score profiles between subjects with Idiopathic environmental intolerance, major depression and schizophrenia

Idiopathic Environmental Intolerance (IEI) has been associated with psychogenic factors and an increased number of comorbid psychiatric disorders such as depression and anxiety disorder. The purpose of the current study was to examine a possible overlap of psychological and somatic symptoms between subjects with IEI and patients with major depression and schizophrenia as well as to specify characteristic differences. The different symptom clusters included symptoms of chemical intolerance, neurotoxicity and psychological distress as well as measurements of mental health such as anxiety, depression, somatoform symptoms, and schizophrenia-specific disturbances in cognitive domains. IEI patients reported higher overall levels in physical symptoms such as chemical intolerance, neurotoxicity and somatic symptoms not attributable to an organic cause. Schizophrenia patients showed higher overall levels in self-experienced disturbances in several schizophrenia-specific cognitive domains, whereas general psychological distress, anxiety and depression were rated highest by patients with major depression. Importantly, the groups markedly differed in the shapes of profiles of various symptom clusters. Our results provide evidence that IEI patients can be distinguished on the phenomenological level from patients with major depression or schizophrenia, and that distinct domains of psychological and somatic symptoms are particularly problematic in specific diagnostic groups.

Patient-Reported Allergies Are Associated With Poorer Patient Satisfaction and Outcomes After Lower Extremity Arthroplasty: A Retrospective Cohort Study

Anecdotal evidence suggests that patient-reported allergies (PRAs) may exhibit prognostic value for patient-reported outcomes after lower extremity arthroplasty. This study's purpose was to investigate associations between PRAs, patient satisfaction and outcomes after total hip arthroplasty (THA) and total knee arthroplasty (TKA). PRAs in 274 patients undergoing primary THA and 257 patients receiving primary TKA were reviewed retrospectively. Satisfaction scores, baseline Western Ontario and McMaster Universities Arthritis Index (WOMAC), 2-year postoperative WOMAC and length-of-stay (LOS) were analyzed with PRAs. Increasing number of PRAs was significantly associated with worse satisfaction scores and worse WOMAC scores for TKA and THA, and it was significantly associated with increased LOS for TKA. These results may have implications for patient counseling and risk-adjusted outcome models.

Negative affect is associated with development and persistence of chemical intolerance: a prospective population-based study

OBJECTIVE

Chemical intolerance (CI) is characterised by negative health effects attributed to a heightened responsiveness to common airborne chemicals. This longitudinal study explored the hypothesised role of negative affect in the development and persistence of CI in a general population.

METHODS

A general population sample aged 19 to 72 years was examined in 2006-2008 and again in 2011-2012. Longitudinal data on CI were analysed with the purpose of examining baseline negative affect as a risk factor for having developed CI at 5-year follow-up and for reporting persistent CI. Participants were classified as reporting no signs of CI, having symptoms of CI and as being a likely CI case based on self-reported reactions to 11 common chemical exposures, symptoms related to chemical exposures and daily life adjustments attributed to reactions when exposed to chemicals.

RESULTS

A total of 69.4% of the participants who had reported CI at baseline also reported CI at follow-up. In participants with no baseline CI, 15.5% reported CI at follow-up and 18.1% reported symptoms related to chemicals but no daily life adjustments. Baseline negative affect was positively and statistically significantly associated with both development and persistence of CI.

CONCLUSIONS

Initial reports of CI were found to be persistent over time, and a considerable proportion of the participants with no CI at baseline reported having developed CI after 5 years. The positive association between negative affect and CI at the 5-year follow-up supports negative affect as a possible risk factor for CI.

Chemosensory perception, symptoms and autonomic responses during chemical exposure in multiple chemical sensitivity

PURPOSE

Multiple chemical sensitivity (MCS) is a prevalent medically unexplained symptom characterized by symptom reactions to everyday chemical exposure below hygienic thresholds. The aim of this study was to investigate the expressions of hyper-reactivity in MCS during whole-body exposure to low concentrations of the odorant n-butanol.

METHODS

We exposed 18 participants with MCS and 18 non-ill controls to a low concentration of the odorant n-butanol using an exposure chamber. The first 10 min constituted blank exposure, after which the n-butanol concentration increased and reached a plateau at 11.5 mg/m(3).

RESULTS

MCS participants, compared with controls, reported greater perceived odor intensities, more unpleasantness to the exposure and increasing symptoms over time. MCS participants also expressed higher pulse rate and lower pulse rate variability than controls did. No group differences were found for breathing rate or tonic electrodermal activity responses.

CONCLUSIONS

We conclude that MCS sufferers differ from healthy controls in terms of autonomic responses, symptoms and chemosensory perception during chemical exposure.

The impact of malodour on communities: a review of assessment techniques

Malodours remain the biggest source of complaints regarding environmental issues. This factor is likely to increase, as the urban development steadily encroaches into areas that have malodourous emitting industries (such as wastewater and waste management operations and intensive livestock practices), and has the potential to be both time and fiscally expensive. Despite the enormous amount of research involved in odour detection and abatement, as well as the creation of several distinct methodologies, there has yet been no definitive procedure to evaluate odour impact on communities, as well as community response. This paper is a review of the current methods that explore this problem, as well as a précis of this research field's goals and challenges. The first aim of this review is to illustrate the dichotomy between regulatory-established procedures, such as panellist testing, and methods that are centred around producing a more comprehensive explanation of factors that influence an odour's impact on a community or individual. In that regard, we have addressed several predominant paradigms of inquiry for this field: analytical methods, panellist testing, qualitative research, and survey methods, with associated variants. Secondly, the challenges of measuring and monitoring community impact are discussed. While the quantification of odorants is crucial to appreciating impact, individual-based modifiers of perception have an enormous scope for which to shape the effect of those odours. Perceptual differences are also likely the most dominant variables that influence the elicited behaviour of individuals who have experienced malodour exposure.

Brain responses to olfactory and trigeminal exposure in idiopathic environmental illness (IEI) attributed to smells -- an fMRI study

OBJECTIVE

Idiopathic environmental intolerance (IEI) to smells is a prevalent medically unexplained illness. Sufferers attribute severe symptoms to low doses of non-toxic chemicals. Despite the label, IEI is not characterized by acute chemical senses. Theoretical models suggest that sensitized responses in the limbic system of the brain constitute an important mechanism behind the symptoms. The aim was to investigate whether and how brain reactions to low-levels of olfactory and trigeminal stimuli differ in individuals with and without IEI.

METHODS

Brain responses to intranasally delivered isoamyl acetate and carbon dioxide were assessed in 25 women with IEI and 26 non-ill controls using functional magnetic resonance imaging.

RESULTS

The IEI group had higher blood-oxygenated-level-dependent (BOLD) signal than controls in the thalamus and a number of, mainly, parietal areas, and lower BOLD signal in the superior frontal gyrus. The IEI group did not rate the exposures as more intense than the control group did, and there were no BOLD signal differences between groups in the piriform cortex or olfactory regions of the orbitofrontal cortex.

CONCLUSIONS

The IEI reactions were not characterized by hyper-responsiveness in sensory areas. The results can be interpreted as a limbic hyperreactivity and speculatively as an inability to inhibit salient external stimuli.

Intranasal Administration of Hyaluronan as a Further Resource in Olfactory Performance in Multiple Chemical Sensitivity Syndrome

Multiple chemical sensitivity (MCS) is a relatively common clinical diagnosis in western populations and its symptoms (i.e. dysosmia) are mainly triggered by chemical compounds, such as common odorants. The aim of this study was to test the effect of intranasal administration of hyaluronic acid (HA) on odour threshold and related quality of life in MCS syndrome. Two randomized groups of MCS patients received 30 days' administration of either a nasal spray (Ialumar®) containing HA [HA group (HAG); n=29] or only physiological solution [PS group (PG); n=30]. Both groups were investigated using the “Sniffin' Sticks” test (SST) battery, Questionnaire of Olfactory Disorder (QOD) and Zung Anxiety Scale (SAS) before randomization and after treatment. Paired t-test analysis found a statistically significant reduction in odour threshold (OT) and an improvement in QOD and SAS between pre- and post-treatment results only in the HAG. Furthermore, positive correlations were found between the OT reduction, SAS and QOD improvement. Thus, intranasal administration of HA could be suggested as a further well-tolerated resource in alleviating MCS olfactory discomfort.

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.

The feasibility of aromatherapy massage to reduce symptoms of Idiopathic Environmental Intolerance: a pilot study

OBJECTIVES

Idiopathic Environmental Intolerance (IEI) is an acquired disorder with multiple recurrent symptoms, which is associated with diverse environmental factors that are tolerated by the majority of people. IEI is an illness of uncertain aetiology, making it difficult to treat using conventional medicine. Therefore, there is a need for novel therapies to control the symptoms of IEI. The objective of this study was to evaluate the feasibility and impact of aromatherapy massage for individuals with IEI.

DESIGN

Non-blinded crossover trial.

SETTING

IEI patients who attended a clinic in Sapporo city were recruited, and sixteen patients were enrolled. Participants were clinically examined by an experienced medical doctor and met the criteria included in the working definition of IEI disorder.

INTERVENTIONS

During the active period, participants received four one-hour aromatherapy massage sessions every two weeks. During the control period, the participants did not receive any massages.

MAIN OUTCOME MEASUREMENTS

Scores on the IEI-scales trigger checklist, symptoms, life impact, and the State Anxiety Inventory were assessed before and after each period. Short-term mood enhancement was evaluated using the Profiles of Mood Status (POMS) before and after sessions.

RESULTS

Due to period effects, evaluation of the results had to be restricted to the first period, and the result showed no effect of intervention. All six sub-scales of the POMS improved after each session (mean score differences: 4.89-1.33, P<0.05).

CONCLUSIONS

Aromatherapy was well tolerated by subjects with IEI; however, aromatherapy, as applied in this study, did not suggest any specific effects on IEI condition.

Double-blind non-controlled chemical challenge with environmental toxicological assessment in a Multiple Chemical Sensitivity case

The report of a Multiple Chemical Sensitivity case highlights two original points. First, even if non-controlled, the reappearance of MCS symptoms after an accidental re-exposure to one scentless semi-volatile chemical (permethrin) of the initial toxic cocktail exposure can be considered as a double blind re-exposure study in situ. Second, environmental toxicology investigations were warrant for a correct treatment and prevention measures.

The association between idiopathic environmental intolerance and psychological distress, and the influence of social support and recent major life events

OBJECTIVES

Idiopathic environmental intolerance (IEI) is a disorder characterized by non-specific symptoms attributed to common airborne chemicals. Increasing evidence points to an association between IEI and symptoms of psychological distress. However, whether other risk factors influence this association has not been clarified. The objective of this study was to examine the association between psychological distress and IEI and to determine whether the association is confounded by social support and major life events.

METHODS

Data were collected by postal questionnaires; other results from the study have been published previously in this journal. The study included participants from a general population-based study who had reported symptoms of chemical sensitivities (n = 787) and two patient groups. The first patient group (n = 101) included individuals who had contacted the Danish Research Centre for Chemical Sensitivities, and the second included individuals who had been diagnosed with environmental intolerance (n = 136). Multiple, hierarchical linear regression analyses were conducted with four IEI-related domains, i.e., mucosal and CNS symptoms, chemical intolerances and social consequences, as the dependent variables, and psychological distress, social support and major life events as the independent variables.

RESULTS

Our study confirmed positive and statistically significant associations between psychological distress and IEI. The associations remained statistically significant after adjusting for major life events and social support.

CONCLUSIONS

The results suggest that the association between IEI and psychological distress cannot be explained by known risk factors. More studies, including longitudinal studies, are needed to determine the role of psychological distress in the development and course of IEI.

Psychobehavioral predictors of somatoform disorders in patients with suspected allergies

OBJECTIVE

To explore a combination of health-related psychobehavioral features as potential positive criteria for somatoform disorders (SFD). Currently, SFD can only be diagnosed in the absence of sufficient organic symptom explanation, resulting in low criterion validity and delay of appropriate therapy.

METHODS

Cross sectionally, we studied various psychobehavioral characteristics of 197 inpatients with suspected allergies. At the beginning of the medical work-up, patients were interviewed and completed a set of self-rating questionnaires (Illness Perception Questionnaire-Revised, Whiteley Index-7, Cognitions About Body And Health Questionnaire, Scale for the Assessment of Illness Questionnaire, Health Attitude Survey, Reassurance Questionnaire, and Patient Health Questionnaire). Organic explicability of the presenting symptoms was assessed by allergists at the end of the work-up. Forty-eight patients with SFD were compared with 149 patients without SFD, and predictive models were set up. To control for effects of the work-up situation, we also investigated 47 patients with an established diagnosis of hymenoptera venom allergy.

RESULTS

In the work-up group, various self-reported psychobehavioral features discriminated patients with SFD from patients without SFD. In logistic regression analysis, self-reported dissatisfaction with medical care, disease conviction, reduced symptom controllability, and reduced body scanning independently predicted SFD. A predictive model based on these psychobehavioral characteristics had high sensitivity and specificity (area under the curve = 0.86, 95% Confidence Interval = 0.79-0.93; p < .001), which was comparable to the Patient Health Questionnaire-15, an established SFD screening tool assessing somatization.

CONCLUSIONS

Psychobehavioral characteristics in patients with SFD cannot solely be attributed to the uncertainty of a work-up situation. Their predictive value is comparable to that of the traditional measuring of symptom number and severity; hence, they should be considered as SFD positive criteria in Diagnostic and Statistic Manual of Mental Disorders, 5th Edition.

Attention bias and sensitization in chemical sensitivity

OBJECTIVE

We investigated whether persons with self-reported chemical sensitivity (CS) have an attention bias and enhanced sensitization to chemical exposure.

METHODS

Chemosomatosensory, olfactory, and auditory event-related potentials (ERPs) were recorded from 21 CS subjects and 17 controls in attend and ignore conditions. Reaction times (RTs) and magnitude estimations of perceived intensity were collected in the attend condition. ERPs were averaged over attention conditions and during the first/second part of the testing.

RESULTS

ERP patterns indicated that CS subjects did not habituate to the same extent as the controls and had difficulties ignoring the chemical exposure. CS subjects had faster overall RT, and the perceived intensities for the chemosomatosensory stimuli did not decrease with time in the CS group, which was the case for the controls.

CONCLUSIONS

These results indicating attention bias and enhanced sensitization in CS suggest alterations in central, cognitive responses to chemical exposure.

Abnormalities in cognitive-emotional information processing in idiopathic environmental intolerance and somatoform disorders

Idiopathic environmental intolerance (IEI) represents a functional somatic syndrome marked by diverse bodily complaints attributed to various substances in the environment. Evidence for abnormalities in affective information processing similar to somatoform disorders (SFD) has recently been found in people with IEI. In order to further investigate these cognitive-emotional abnormalities, we compared people with IEI (n=49), SFD only (n=43), and non-somatoform controls (n=54) with respect to their performance in the extrinsic affective Simon task (EAST). This task allowed us to dissociate indicators of automatic affective associations and emotional intrusion effects of both bodily complaints and IEI-trigger words. Negative association effects toward IEI-trigger words were strongest for IEI participants. Emotional intrusion effects of symptom words were larger both in IEI and SFD than in controls. The results of enhanced negative automatic evaluations of IEI-trigger words and greater attention allocation to symptom words support cognitive models of IEI.

General practitioners' experiences with provision of healthcare to patients with self-reported multiple chemical sensitivity

OBJECTIVE

To describe general practitioners' (GPs') evaluation of and management strategies in relation to patients who seek medical advice because of multiple chemical sensitivity (MCS).

DESIGN

A nationwide cross-sectional postal questionnaire survey. The survey included a sample of 1000 Danish GPs randomly drawn from the membership list of GPs in the Danish Medical Association.

SETTING

Denmark.

RESULTS

Completed questionnaires were obtained from 691 GPs (69%). Within the last 12 months 62.4% (n = 431) of the GPs had been consulted by at least one patient with MCS. Of these, 55.2% of the GPs evaluated the patients' complaints as chronic and 46.2% stated that they were rarely able to meet the patients' expectations for healthcare. The majority, 73.5%, had referred patients to other medical specialties. The cause of MCS was perceived as multi-factorial by 64.3% of the GPs, as somatic/biologic by 27.6%, and as psychological by 7.2%. Partial or complete avoidance of chemical exposures was recommended by 86.3%. Clinical guidelines, diagnostic tools, or more insight in the pathophysiology were requested by 84.5% of the GPs.

CONCLUSION

Despite the lack of formal diagnostic labelling the patient with MCS is well known by GPs. The majority of the GPs believed that MCS primarily has a multi-factorial explanation. However, perceptions of the course of the condition and management strategies differed, and many GPs found it difficult to meet the patients' expectations for healthcare. The majority of the GPs requested more knowledge and clinical guidelines for the management of this group of patients.

On the relation between capsaicin sensitivity and responsiveness to CO2: detection sensitivity and event-related brain potentials

OBJECTIVE

Sensory hyperreactivity (SHR) with predominantly airway symptoms is a subgroup of chemical intolerance to various environmental substances with pungent/odorous properties. The hallmark of SHR is sensitivity to capsaicin inhalation, resulting in extensive coughing likely to be mediated by a C-fiber hyperreactivity of the airway sensory neurons. However, it is not clear whether capsaicin sensitivity implies a greater sensitivity to chemosomatosensory substances in general. Therefore, the present study tested the hypothesis of an association between capsaicin cough sensitivity and sensitivity to CO(2) with respect to detection sensitivity and electrophysiological brain response.

METHODS

A correlational study was employed to investigate the relation between capsaicin cough sensitivity and detection thresholds and chemosomatosensory event-related potentials (ERPs) for CO(2) presented in the nasal cavity in 35 persons varying in capsaicin cough sensitivity.

RESULTS

Number of coughs were found to correlate negatively with CO(2) threshold and tended to correlate negatively also with N1 and P2 latencies of the chemosomatosensory ERP for CO(2). No tendencies of correlations were found between number of coughs and latencies for olfactory and auditory ERPs, recorded for comparison, but, unexpectedly, were found between number of coughs and auditory N1 amplitude.

CONCLUSIONS

The results imply that capsaicin cough sensitivity, such as in SHR, is related to higher detection sensitivity, and tends to be related to faster cortical processing of other chemosomatosensory substances, at least of CO(2).

Moderne Gesundheitssorgen und ihre Beziehung zu umweltbezogenen Beschwerden

Zusammenfassung. Theoretischer Hintergrund: Nach Petrie und Wessely (2002) bedeuten neue Technologien (z.B. Mobiltelefone und gentechnologisch veränderte Nahrungsmittel) neue Gesundheitssorgen und -beschwerden. Diese modernen Gesundheitssorgen können mittels Fragebogen standardisiert erfasst werden. Fragestellung: Es wurden die Faktorenstruktur, Reliabilität und Validität einer deutschen Übersetzung der Modern Health Worries (MHW) Scale sowie deren Beziehung zu einem funktionellen umweltbezogenen Syndrom, der Idiopathischen Umweltintoleranz (IUI), untersucht. Methode: 757 Studenten einer deutschen Universität füllten Fragebögen zur Erfassung von MHW, IUI, Krankheitsangst, Depressivität und multiplen körperlichen Beschwerden aus. Ergebnisse: Die vier Subskalen der MHW-Skala - Umweltgifte, Umweltverschmutzung, belastete Nahrungsmittel und elektrische Strahlung - konnten faktorenanalytisch bestätigt werden. Die interne Konsistenz (Cronbach’s α) der Subkalen erreichte Werte zwischen .77 und .89. MHW, negativer Affekt und Somatisierungsneigung trugen als unabhängige Prädiktoren jeweils signifikant zur Vorhersage des IUI-Beschwerdeniveaus bei. Schlussfolgerungen: Die deutsche Version der MHW-Skala kann als Messinstrument zur Verwendung für wissenschaftliche Zwecke empfohlen werden. Die Implikationen der Befunde für ein psychogenes Modell der IUI werden diskutiert.

Psychological predictors of short- and medium term outcome in individuals with idiopathic environmental intolerance (IEI) and individuals with somatoform disorders

Idiopathic environmental intolerance (IEI), also known as multiple chemical sensitivity (MCS), is defined as a chronic polysymptomatic condition that cannot be explained by an organic disease. Previous studies suggest that IEI may be a variant of somatoform disorders (SFD), because both disorders overlap with respect to symptoms and psychological features of somatization. However, little is known about the short- and medium-term outcome of IEI and psychological outcome predictors. Two clinical groups (IEI and SFD) and a comparison group (CG) were followed through 32 mo to assess both the outcome, and the extent to which trait anxiety and somatic symptom attribution (assessed at first examination) predict outcome presented 12 and 32 mo later. Outcome measures were the number of self-reported IEI symptoms, IEI triggers, IEI-associated functional impairments, and the number of somatoform symptoms. In addition, the course of the 2 syndromes over the 32-mo follow-up period was investigated with standardized screening scales. The 3 diagnostic groups consisted of 46 subjects with IEI, 38 subjects with SFD but without IEI, and 46 subjects (CG) with neither IEI nor SFD. Syndrome stability was high over the 32-mo follow-up period, and at both follow-ups IEI and non-IEI subjects differed on all IEI outcome measures (symptoms, triggers, functional impairments). Both trait anxiety and somatic attribution (the tendency to attribute common somatic complaints to an illness) predicted outcome. In addition, somatic attribution was found to partially mediate the effect of trait anxiety on outcome in the IEI group. In conclusion, these results suggest that IEI is a chronic and disabling condition and that trait anxiety contributes to the maintenance of the disorder via somatic attributions.

Odor annoyance of environmental chemicals: sensory and cognitive influences

In low concentrations, environment pollutants like volatile organic compounds (VOCs) may be perceived via olfaction. Modulators of odor-mediated health effects include age, gender, or personality traits related to chemical sensitivity. Severe multi-organ symptoms in response to odors also characterize a syndrome referred to as idiopathic environmental intolerance (IEI). One prominent feature of IEI is self-reported odor hypersensitivity that is usually not accompanied by enhanced olfactory functioning. The impact of interindividual differences in olfactory functioning on chemosensory perceptions is sparsely investigated, and therefore this study addressed the influences of different types of modulators, including olfactory functioning. In a psychophysical scaling experiment, an age-stratified sample of 44 males and females was examined. After controlled application of nine concentrations of six chemicals by flow-olfactometry, the participants rated four olfactory and nine trigeminal perceptions. Weak effects were found for gender and age, as well as some modulating effects of self-reported chemical sensitivity and odor discrimination ability. For chemical sensitivity, the results were as expected: Subjects with higher sensitivity reported stronger perceptions. The individual odor threshold (n-butanol) exerted no influence on the subjects' ratings of olfactory and trigeminal perceptions. Surprisingly, above-average odor discrimination ability was associated with lower ratings of odor intensity and nausea. This particular aspect of olfactory functioning might be a reflection of a more objective odor evaluation model buffering emotional responses to environmental odors.

Subgrouping outpatients of an environmental medicine unit using SCL-90-R and cluster analysis

Between 1999 and 2003 all consecutive outpatients of the environmental medicine unit of the Charité hospital in Berlin were invited to participate in a study on environmentally related disorders. One hundred and sixty-nine of the patients completed a psychosocial questionnaire which comprised SCL-90-R and 14 other tests. When compared with clinical controls, SCL-90-R mean scores of the environmental patients (EP) were found to lie in between those of inpatients of a psychosomatic clinic and melanoma aftercare patients; but they were, with exception of the somatisation dimension, much closer to the latter. Application of the TwoStep Cluster component of SPSS resulted in three subgroups with high, moderate and low scores which were significantly different (p<0.001) although separation was incomplete (87% correct identification; cross-validated discriminant analysis). With all subgroups, scores for somatisation, depression and obsessive compulsion were highest and those for phobic anxiety and psychoticism were lowest. SCL-90-R scores correlated well with results of the Freiburg Personality Inventory, Whiteley Index of hypochondriasis, the short form health questionnaire (SF-36), and the Composite International Diagnostic Interview (CIDI). Hierarchical grouping (average linkage between groups), performed with involvement of SCL-90-R data from literature, resulted in a dendrogram with three distinct groups and three outliers. EP with low SCL-90-R scores were assigned to a group which comprised also general populations (USA, Germany), allergy patients, and melanoma controls. Those with moderate SCL-90-R scores were placed in a group together with chronic pain patients, and 26 'environmentally ill' subjects. The third subgroup of EP formed a cluster with our psychosomatic controls, psychosomatic patients from another study, depressed people, and patients undergoing psychotherapy. The three outliers of the dendrogram, however, were SCL-90-R profiles obtained from persons with toxic waste exposure, neurotoxic workplace exposure or with solvent-induced chronic toxic encephalopathy.

Trauma experience in individuals with idiopathic environmental intolerance and individuals with somatoform disorders

OBJECTIVE

Results from previous studies suggest that past trauma experience increases the risk for medically unexplained somatic symptoms and somatoform disorders (SFD). This cross-sectional study examined the link between various lifetime traumas, idiopathic environmental intolerance (IEI), and SFD.

METHODS

Two clinical groups of 54 subjects with IEI and 44 subjects with SFD were compared to 54 subjects (comparison group, CG) free from both IEI and SFD regarding self-reported traumas. The subjects were mainly recruited via advertisements in local newspapers. From 970 individuals screened for IEI and multiple somatic symptoms, 152 were included through a two-step selection procedure consisting of screening questionnaires, a medical examination, and structured interviews for IEI and mental disorders.

RESULTS

In all three groups at least one potential traumatic event was reported rather frequently (CG: 70%; IEI: 82%; SFD: 73%). But contrary to our expectation, significant group differences were neither found in regard to the proportion of subjects with any trauma, nor traumas fulfilling DSM-IV criteria (CG: 41%; IEI: 48%; SFD: 59%), nor multiple traumas (CG: 43%, IEI: 56%, SFD: 39%). Only two trauma categories were endorsed more frequently by the two clinical groups than by the CG: the unspecified 'other' category (IEI, SFD>CG) and 'life-threatening illness' (IEI>CG).

CONCLUSION

No clear evidence was found for increased rates of trauma experience in IEI and SFD. However, the results of this exploratory study should be considered as preliminary. Comparing larger IEI and SFD groups with a representative population-based sample may yield different results.

Odor frequency and odor annoyance Part II: dose–response associations and their modification by hedonic tone

OBJECTIVE

Risk-assessment for environmental odors and the development of an appropriate guideline for protection against undue odor annoyance have long been hampered by the difficulties of assessing odor exposure and community annoyance responses. In recent years, however, dose-response associations between frequency of odor events and odor annoyance level in the affected population were established. However, the influence of hedonic tone (pleasantness-unpleasantness) and perceived odor strength (intensity) on the degree of odor annoyance have long been neglected in such studies and accompanying guidelines. In order to close this gap a pertinent field study was conducted in the vicinity of six odor emitting plants, two with pleasant (sweets production, rusk bakery), with neutral (textile production, seed oil production), and with presumably unpleasant odor emissions (fat refinery, cast iron production).

METHODS

A standardized sensory method was developed (described in Part I in the accompanying paper) to quantify intensity and hedonic tone within the assessment of odor exposure by systematic field inspection with trained observers. Additionally, exposure-information, the degree of annoyance, and the frequency of general health complaints and irritation symptoms were collected from the exposed residents through direct interviews. Multiple logistic regression analysis was used to establish dose-response associations between odor frequency, intensity and hedonic tone as independent variables and annoyance or symptom reporting as the dependent variable.

RESULTS

It is shown that exposure-annoyance as well as exposure-symptom associations are strongly influenced by odor hedonic. Whereas pleasant odors induced little to no annoyance, both neutral and unpleasant ones did. Additional inclusion of odor intensity did not improve the prediction of odor annoyance. Frequency of reported symptoms was found to be exclusively mediated by annoyance. The results are discussed in terms of environmental stress emphasizing the WHO-definition of health.

CONCLUSIONS

Based on these findings the existing German guideline against undue odor annoyance was modified.

Dysfunctional cognitions in idiopathic environmental intolerances (IEI)—An integrative psychiatric perspective

Idiopathic environmental intolerances (IEI) - formerly multiple chemical sensitivities (MCS) - are characterized by diffuse symptoms reported after exposure to low doses of everyday chemicals. Previous theories about the origin of IEI have emphasized either biological or psychological factors, neglecting a probable interplay. Many have suggested classifying IEI as a somatoform or an anxiety disorder, irrespective of some incongruities. By focusing on dysfunctional cognitions we discuss obvious parallels of IEI with somatoform disorders, and also indicate overlaps with anxiety and delusional disorders. To propose a hypothetical psycho-neurobiological basis of IEI, recent evidence about cortically represented symptoms in the absence of peripheral stimuli is briefly summarized. We conclude that IEI can serve as an illustrative example for the impact of cognitive, representational processes in symptom generation.

Investigations in subjects with cough following upper respiratory tract infection

The study aimed to investigate subjects with cough following acute upper respiratory tract infection (URTI), and to compare those subjects unable to suppress cough ("non-suppressors") with those who were able to suppress cough ("suppressors"). Forty-three URTI subjects participated, 31 with cough associated with acute URTI and 12 healthy controls; 21 of the coughing subjects were "suppressors", 10 were "non-suppressors". We obtained responses to chemical and mechanical stimulation of the nasal cavity or the pharynx using both psychophysical measures and event-related potentials. The study provided the following results: (1) "non-suppressors" did not exhibit significantly different intensity ratings or event-related potentials in comparison to "suppressors" in terms of responses to intranasal irritant, mechanical, or olfactory stimuli; (2) when pharyngeal mechanical stimuli were investigated "suppressors" rated the stimuli as more intense than "non-suppressors" and controls; (3) latencies of event-related potentials to pharyngeal stimuli were longest in "non-suppressors". Keeping in mind the relatively small sample size, it appears possible to differentiate certain types of cough during uncomplicated URTI. This may help to explain interindividual differences in responsiveness to cough medication.