Chemical sensitivity: symptom, syndrome or mechanism for disease?

The Impact of COVID-19 Health Measures on Adults With Multiple Chemical Sensitivity: Cross-Sectional Study

BACKGROUND

Multiple chemical sensitivity (MCS) develops in response to repeated small-level chemical exposures or a major exposure in a subset of people, who then experience symptoms that can range from mild to debilitating when exposed to chemicals. The arrival of the COVID-19 pandemic and the stringent health measures put in place may have increased the burden for those living with MCS, as it became more challenging to avoid chemicals that trigger their condition.

OBJECTIVE

This study aimed to better understand the lived experience of Canadians living with MCS during the first year of the COVID-19 pandemic.

METHODS

An online questionnaire was created to ask participants to compare daily living during the pandemic to before March 11, 2020. Data were collected in January and February 2021. Three areas were investigated: (1) environmental exposures to chemical triggers from ambient air (pollution from industry, farming, and traffic) and indoor air (the smell of cleaning products, cooking odors, and smoke); (2) access to, and satisfaction with, health care visits; and (3) how people experiencing MCS rated contact with their social network.

RESULTS

In all, 119 Canadians who had lived with MCS for more than a year completed the questionnaire. The participant sample was mostly female (86.6%, n=103) and highly educated, with 57.1% (n=68) having a university degree. Slightly more than half (57.1%, n=68) were older than 55 years. McNemar chi-square and Wilcoxon signed rank tests were used to evaluate if there were statistically significant changes before ("prepandemic period") and after ("postpandemic period") March 11, 2020. Perceived exposure to pollution from a highway or a road was significantly decreased from the prepandemic to postpandemic period (z=-3.347; P<.001). Analysis of industry or power plants also suggested a significant decrease in the perceived exposure from the prepandemic to postpandemic period (z=-2.152; P=.04). Participants reported an increase in exposure to odors from disinfectants or sanitizers that entered their living environment (P<.001). There was a significant decrease between prepandemic and postpandemic levels of satisfaction when attending in-person meetings with a physician (z=-2.048; P=.04), yet there were no significant differences between prepandemic and postpandemic levels of satisfaction for online or telephone meetings with a physician. Although people with MCS experienced increased social isolation (P<.001), they also reported an increase in understanding from family (P=.03) and a decrease in stigma for wearing personal protective equipment (P<.001).

CONCLUSIONS

During the first year of the COVID-19 pandemic, people with MCS were impacted by inaccessibility, loss of social support, and barriers to accessing health care. This study highlights unique challenges and possible benefits associated with the COVID-19 pandemic public health measures for individuals living with MCS. These findings can guide decision makers to improve policies on accessibility through appropriate accommodation measures.

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.

Housing and Health: Here We Go Again

Housing is one of the major determinants of human health and the current COVID-19 pandemic has highlighted its relevance. The authors summarize the main issues, including dimensional standards, indoor air quality, safety, accessibility, neighborhoods, and area characteristics. The authors propose an operating scheme in order to implement actions to improve residential wellbeing on a local, national, and international level.

[New Scientific Evidence-based Public Health Guidelines and Practical Manual for Prevention of Sick House Syndrome]

Recently, we have published a book containing evidence-based public health guidelines and a practical manual for the prevention of sick house syndrome. The manual is available through the homepage of the Ministry of Health, Labour and Welfare (http://www.mhlw.go.jp/file/06-Seisakujouhou-11130500-Shokuhinanzenbu/0000155147.pdf). It is an almost completely revised version of the 2009 version. The coauthors are 13 specialists in environmental epidemiology, exposure sciences, architecture, and risk communication. Since the 1970s, health problems caused by indoor chemicals, biological pollution, poor temperature control, humidity, and others in office buildings have been recognized as sick building syndrome (SBS) in Western countries, but in Japan it was not until the 1990s that people living in new or renovated homes started to describe a variety of nonspecific subjective symptoms such as eye, nose, and throat irritation, headache, and general fatigue. These symptoms resembled SBS and were designated "sick house syndrome (SHS)." To determine the strategy for prevention of SHS, we conducted a nationwide epidemiological study in six cities from 2003-2013 by randomly sampling 5,709 newly built houses. As a result 1,479 residents in 425 households agreed to environmental monitoring for indoor aldehydes and volatile organic compounds (VOCs). After adjustment for possible risk factors, some VOCs and formaldehyde were dose-dependently shown to be significant risk factors. We also studied the dampness of the houses, fungi, allergies, and others. This book is fully based on the scientific evidence collected through these studies and other newly obtained information, especially from the aspect of architectural engineering. In addition to SHS, we included chapters on recent information about "multi-chemical sensitivity."

Factors Contributing to the Self-Reported Prevalence of Multiple Chemical Sensitivity in Public Facility Workers and the General Population of Korea

Multiple chemical sensitivity (MCS), an acquired disorder with multiple recurrent symptoms, has been studied for its association with diverse environmental factors. The present study investigated the factors associated with the self-reported prevalence of MCS in public facility workers and the general population in Korea. The Quick Environmental Exposure Sensitivity Inventory (QEESI) questionnaire was obtained from public facility workers (N=530) and the general population (N=500) to determine the prevalence of MCS and the degree of its risk. Information about demographic characteristics, subjective perceptions of sick building syndrome or sick house syndrome or allergy (SBS/SHS/Allergy), and certain home- or workplace-related events were also obtained. There was not a statistical difference between the public facility workers and the general population in the QEESI scores. The overall prevalence of MCS was 14.4% and there was no statistical difference between the two groups. Regarding the overall degree of risk of MCS, 21.8% of the study subjects were categorized as "very suggestive", and there was no significant difference between the two groups. Gender and the subjective perception of SBS/SHS/Allergy significantly affected the prevalence of MCS and the MCS risk criteria. Considering the absence of diagnostic criteria and/or treatment methods for MCS in Korea, these results can be utilized in establishing future strategies to manage MCS.

Multiple Chemical Sensitivity, Culture and Delegitimization: A Feminist Analysis

The condition referred to as multiple chemical sensitivity (MCS), chemical injury (CI), environmental illness (El), 20th-century disease or toxic encephalopathy has generated controversy because victims' claims of harm from low levels of chemicals in the environment conflict with general mainstream belief in the safety of these substances. Mainstream (western) culture's response to persons with MCSICI has interacted with sexism, served to delegitimize victims thereby reducing their power, reduced the victim's context (because of forced isolation), and jeopardized jobs and relationships. This article will analyze the situation of the chemically injured person and culture's response from a feminist perspective, and discuss cultural delegitimization as a process used by a chemical culture to neutralize the message of the person with MCSICI, i.e., that the environment is unsafe for her/him, and, by extension, for others.

In-situ Real-Time Monitoring of Volatile Organic Compound Exposure and Heart Rate Variability for Patients with Multiple Chemical Sensitivity

In-situ real-time monitoring of volatile organic compound (VOC) exposure and heart rate variability (HRV) were conducted for eight multiple chemical sensitivity (MCS) patients using a VOC monitor, a Holter monitor, and a time-activity questionnaire for 24 h to identify the relationship between VOC exposure, biological effects, and subjective symptoms in actual life. The results revealed no significantly different parameters for averaged values such as VOC concentration, HF (high frequency), and LF (low frequency) to HF ratio compared with previous data from healthy subjects (Int. J. Environ. Res. Public Health2010, 7, 4127–4138). Significant negative correlations for four subjects were observed between HF and amounts of VOC change. These results suggest that some patients show inhibition of parasympathetic activities along with VOC exposure as observed in healthy subjects. Comparing the parameters during subjective symptoms and normal condition, VOC concentration and/or VOC change were high except for one subject. HF values were low for five subjects during subjective symptoms. Examining the time-series data for VOC exposure and HF of each subject showed that the subjective symptoms, VOC exposure, and HF seemed well related in some symptoms. Based on these characteristics, prevention measures of symptoms for each subject may be proposed.

Indoor volatile organic compounds and chemical sensitivity reactions

Studies of unexplained symptoms observed in chemically sensitive subjects have increased the awareness of the relationship between neurological and immunological diseases due to exposure to volatile organic compounds (VOCs). However, there is no direct evidence that links exposure to low doses of VOCs and neurological and immunological dysfunction. We review animal model data to clarify the role of VOCs in neuroimmune interactions and discuss our recent studies that show a relationship between chronic exposure of C3H mice to low levels of formaldehyde and the induction of neural and immune dysfunction. We also consider the possible mechanisms by which VOC exposure can induce the symptoms presenting in patients with a multiple chemical sensitivity.

The intelligent body and its discontents

The traditional view is that mind is intelligent and the body is stupid. Recent research suggests that the whole body, and not just the brain, acts as a complex parallel processing system. If the whole body is intelligent, then intelligent processes normally attributed to psychology may occur in the non-brain body. This article shows how self-organizing learning error in a brain-body system creates the potential for a new type of pathology, network pathology, that is distributed across over the whole body. The intelligent body concept is illustrated with four examples: chemical sensitivity, asthma, chronic fatigue syndrome and obesity. Network pathology develops when normally adaptive self-organizational processes malfunction so that control system parameters are altered in a way that creates suboptimal self-regulation. Subtle therapies are needed, in addition to the conventional robust therapies to correct network pathology.

Chemical intolerance in primary care settings: prevalence, comorbidity, and outcomes

PURPOSE

This study extends previous community-based studies on the prevalence and clinical characteristics of chemical intolerance in a sample of primary care clinic patients. We evaluated comorbid medical and psychiatric disorders, functional status, and rates of health care use.

METHODS

A total of 400 patients were recruited from 2 family medicine clinic waiting rooms in San Antonio, Texas. Patients completed the validated Quick Environmental Exposure and Sensitivity Inventory (QEESI) to assess chemical intolerance; the Primary Care Evaluation of Mental Disorders (PRIME-MD) screen for possible psychiatric disorders; the Dartmouth-Northern New England Primary Care Cooperative Information Project (Dartmouth COOP) charts for functional status; and the Healthcare Utilization Questionnaire.

RESULTS

Overall, 20.3% of the sample met criteria for chemical intolerance. The chemically intolerant group reported significantly higher rates of comorbid allergies and more often met screening criteria for possible major depressive disorder, panic disorder, generalized anxiety disorder, and alcohol abuse disorder, as well as somatization disorder. The total number of possible mental disorders was correlated with chemical intolerance scores (P <.001). Controlling for demographics, patients with chemical intolerance were significantly more likely to have poorer functional status, with trends toward increased medical service use when compared with non-chemically intolerant patients. After controlling for comorbid psychiatric conditions, the groups differed significantly only regarding limitations of social activities.

CONCLUSIONS

Chemical intolerance occurs in 1 of 5 primary care patients yet is rarely diagnosed by busy practitioners. Psychiatric comorbidities contribute to functional limitations and increased health care use. Chemical intolerance offers an etiologic explanation. Symptoms may resolve or improve with the avoidance of salient chemical, dietary (including caffeine and alcohol), and drug triggers. Given greater medication intolerances in chemical intolerance, primary care clinicians could use the QEESI to identify patients for appropriate triage to comprehensive nonpharmacologic care.

Sensitivity-related illness: the escalating pandemic of allergy, food intolerance and chemical sensitivity

The prevalence of allergic-related diseases, food intolerance, and chemical sensitivities in both the pediatric and adult population has increased dramatically over the last two decades, with escalating rates of associated morbidity. Conditions of acquired allergy, food intolerance and chemical hypersensitivity are frequently the direct sequelae of a toxicant induced loss of tolerance (TILT) in response to a significant initiating toxic exposure. Following the primary toxicant insult, the individuals become sensitive to low levels of diverse and unrelated triggers in their environment such as commonly encountered chemical, inhalant or food antigens. Among sensitized individuals, exposure to assorted inciting stimuli may precipitate diverse clinical and/or immune sequelae as may be evidenced by clinical symptoms as well as varied lymphocyte, antibody, or cytokine responses in some cases. Recently recognized as a mechanism of disease development, TILT and resultant sensitivity-related illness (SRI) may involve various organ systems and evoke wide-ranging physical or neuropsychological manifestations. With escalating rates of toxicant exposure and bioaccumulation in the population-at-large, an increasing proportion of contemporary illness is the direct result of TILT and ensuing SRI. Avoidance of triggers will preclude symptoms, and desensitization immunotherapy or immune suppression may ameliorate symptomatology in some cases. Resolution of SRI generally occurs on a gradual basis following the elimination of bioaccumulated toxicity and avoidance of further initiating adverse environmental exposures. As has usually been the case throughout medical history whenever new evidence regarding disease mechanisms emerges, resistance to the translation of knowledge abounds.

Sickness-related dysfunction in persons with self-reported multiple chemical sensitivity at four levels of severity

AIM

To examine quality of life outcome for persons who self-report chemical sensitivity, often referred to as multiple chemical sensitivity.

BACKGROUND

Multiple chemical sensitivity is poorly understood with few providers specialising in its treatment. This lack of treatment and the ubiquity of chemicals engender severe life impacts such as job loss, financial loss, social isolation and even homelessness for persons who experience these sensitivities.

DESIGN

Survey.

METHOD

We examined chemical incitants, symptoms and sickness-related behavioural dysfunction as measured by the Sickness Impact Profile in 254 persons self-identified with multiple chemical sensitivity.

RESULTS

Chemicals rated as causing the most symptomatology in respondents were pesticide, formaldehyde, fresh paint, new carpet, diesel exhaust, perfume and air fresheners. The five highest rated symptoms in this sample were tiredness/lethargy, difficulty concentrating, muscle aches, memory difficulties and long-term fatigue. Overall mean Sickness Impact Profile score was 25.25%, showing serious impairment, with the most serious dysfunction in the categories of work (55.36%), alertness behaviour (53.45%) and recreation and pastimes (45.20%).

CONCLUSION

Multiple chemical sensitivity is an important health care issue because it often includes serious dysfunction, is poorly understood by providers and poses extensive financial and treatment obstacles for those who experience it.

RELEVANCE TO CLINICAL PRACTICE

Persons with multiple chemical sensitivity seek medical treatment in a variety of contexts and informed providers can both avoid iatrogenic harm due to medical exposures and provide any possible treatment for the chemical sensitivities. Understanding the impact of the health condition is crucial to communicate with and treat persons who experience the sensitivities.

Health risk assessment of chlorobenzenes in the air of residential houses using probabilistic techniques

A human health risk assessment was performed to evaluate the risks due to chlorobenzenes in the air of residential houses. Chlorobenzenes found in the air in the toilets, rooms, and outdoors of three houses in Brisbane, Australia, were sampled by trapping on Tenax TA and analyzed using an automated thermal desorption (ATD)-gas chromatography/mass spectrometry (GC/MS) method. Concentrations of 1,4-dichlorobenzene (1,4-DCB) in the rooms, toilets, and outdoors were used as the exposure concentrations (E), while those in the toilets (microg/m3) were used as the high-exposure concentrations (HE). The exposure concentrations were transformed into exposure doses (EXD(E) and EXD(HE)). Dose-response data from the literature for a range of adverse effects in animals were obtained and exposure doses were expressed as human equivalent dose (HED). The HED values were higher than the EXD(E) and EXD(HE) values for all adverse effects, and a hazard quotient was calculated that indicated a low level of risk with the high-exposure environment. The lifetime average daily doses (LADDs) for a wide range of adverse effects observed in human case studies were estimated and compared to the doses in the high-exposure (HE) situation. Using the Monte Carlo simulation technique the probabilities of risk quotients higher than unity ranged from 0.02 to 0.26. This evaluation indicated that 1,4-DCB posed low risks to general residents; however, for individuals with susceptible characteristics and exposure to elevated 1,4-DCB, the probability of adverse responses was moderate to high.

Hipersensibilidad química múltiple en el síndrome del edificio enfermo

The sick building syndrome includes irritation of the eyes and the respiratory tract neurotoxicity affectation and skin problems, which can occur in individuals under improperly ventilated buildings. Poor air quality, as shown in CO2 atmospheric levels of more than 1,000 ppm, results in a pathological exposure to biological and chemical products. We present a work-related case of multiple chemical hypersensitivity from a dialysis unit that had no air renewal. This person, who was summitted to continuous exposure despite having taken corrective measures in the ventilation, developed chronic fatigue syndrome. An acoustic voice observation alerted of the case which led to the analysis of the environmental conditions which confirmed the relationship between multiple chemical hypersensitivity and chronic fatigue syndrome. This case stresses the neglected fact that all health service centres pose a high risk of chemical exposure and that there exists a lack of rigoroursness in putting in practice scientific medical knowledge.

Hypothalamo-pituitary-adrenal gland axis in mice inhaling toluene prior to low-level long-term exposure to formaldehyde

We studied the change in the hypothalamo-pituitary-adrenal gland (HPA) axis upon adding prior toluene inhalation to our previous formaldehyde inhalation experiments to determine whether short term exposure to relatively high levels of toluene triggers multiple chemical sensitivity (MCS). Data come from immunocytochemical, morphometrical and RT-PCR measurements. Four groups of adult female mice were exposed to differing concentrations (0, 80, 400, and 2,000 ppb) of formaldehyde for 16 hr/day, 5 days/week for twelve weeks, after the mice were exposed intranasally to 500 ppm toluene per mouse for 6 hr/day, for 3 days. We found that the number of corticotropin releasing hormone (CRH)-immunoreactive (ir) neurons was up-regulated according to the amount of formaldehyde as well as inhalation of formaldehyde alone in our previous experiment. The proportion of adrenocorticotropin hormone (ACTH)-ir cells increased according to the formaldehyde concentration, though there was no significant difference between the 400 and 2,000 groups. The number of ACTH-ir cells was higher in the 400 group than in the other groups (0, 80, and 2,000). Expression of ACTH-mRNA was also up-regulated according to the quantity of formaldehyde. The sinusoid in the anterior pituitary showed more dilatation in the 400 and 2,000 groups than in the control group, especially in the 2,000 group. We propose that exposure to toluene prior to inhalation of formaldehyde has no effect on the HPA axis and as a trigger of MCS, although greater sinusoid dilatation was found in the anterior pituitary gland at higher concentrations of formaldehyde.

Disability-induced identity changes in persons with multiple chemical sensitivity

In this qualitative study, the authors asked respondents with multiple chemical sensitivity (MCS) in an open-ended question how having the condition affected their identities. Authors then examined responses for themes, which they discuss within the framework of critical theory. Emergent themes included loss of a stable, familiar personality, loss of self-positioning, emotional suppression to meet others' expectations, redesigning the planned life, forced growth, struggling with support, discovering the spiritual self, and identity reconsolidation. The authors compare findings with published works on adjustment to chronic illness and other delegitimized illnesses, find them to be fairly congruent, and then discuss problems regarding cultural acceptance of MCS as a condition caused by chemical exposure.

Chemical sensitivity in symptomatic Cambodia veterans

Following their participation in a United Nations peacekeeping operation in Cambodia (1992-1993), Dutch veterans complained of symptoms similar to those reported by Gulf War veterans. The authors conducted a matched case-control study to evaluate 76 symptomatic and 32 matched asymptomatic Cambodia veterans on the basis of data collected by postal questionnaire. The number of symptomatic veterans who reported having used insect repellants that contained N,N,-diethyl-meta-toluamide (DEET) during the mission in Cambodia was significantly higher, compared with asymptomatic veterans. The percentage of veterans who reported feeling ill following brief exposures to chemicals such as paint or pesticides was equal in both groups, but the percentage was low compared with the results of other studies of Multiple Chemical Sensitivity Syndrome. The current study was limited by self-report and time delay (potential recall bias) between deployment to Cambodia and the time of survey. Nevertheless, the study results did not support the hypothesis that symptoms in the total group of Cambodia veterans could be related to Multiple Chemical Sensitivity Syndrome.

Considerações sobre estudos de ambientes industriais e não industriais no Brasil: uma abordagem comparativa

A qualidade do ar em ambientes industriais tem sido palco de estudos desde a segunda metade do século XX. Resultados bem documentados apontaram que a exposição prolongada a poluentes químicos, proveniente do consumo, produção, armazenamento etc., pode causar danos à saúde do trabalhador. Recentemente, estudos direcionados a ambientes não industriais mostraram correlações surpreendentes entre a qualidade do ar e os efeitos causados à saúde. O sistema de ventilação artificial tem sido a principal causa de reclamações e de um alto índice de absenteísmo. Os sintomas relacionados com a qualidade do ar em ambientes não industriais são reconhecidos pela Organização Mundial da Saúde que os identifica como "Síndrome dos Edifícios Doentes". No Brasil, há poucos estudos relacionando qualidade do ar em ambientes fechados e saúde. O presente trabalho pretende mapear as pesquisas já realizadas no País, visando, com isso, incentivar novos estudos nessa área, em virtude de sua importância para a saúde da população.

Are syndromes in environmental medicine variants of somatoform disorders?

To date, relatively little is known about the etiology, pathophysiology, diagnosis, therapy, prevention and prognosis of environment-related syndromes like multiple chemical sensitivity (MCS), idiopathic environmental intolerance (IEI), sick building syndrome (SBS), chronic fatigue syndrome (CFS), candida syndrome (CS) and burnout syndrome (BS). Part of the reason is that these syndromes have not been clearly defined and classified in scientific categories distinct from each other, and that they show clinical similarities to classified somatoform disorders. Furthermore, there are at least three possible explanations for the existence of these syndromes: (1) The syndromes may result from the interaction of environmental factors, individual susceptibility and psychological factors (i.e., how they are perceived and seen by the patient); (2) they may reflect socially and culturally accepted methods of expressing distress; and/or (3) they may be iatrogenic. Despite all the uncertainties in evaluation of environmental syndromes, physicians have the duty to take the affected person's problems seriously. A comprehensive systematic classification which better accounts for these complex clinical manifestations is long overdue. Until these syndromes are well defined, the terms used for them should definitely not be applied to connote a specific disease process.

Dietary adequacy of the rotary diversified diet as a treatment for "Environmental Illness"

The rotary diversified diet, used in the management of environmental illness, consists of eliminating prohibited foods from the diet and rotating remaining non-prohibited foods and their "food families" within a regular cycle. We assessed the adequacy of nutrient intakes in 22 women prescribed the diet, described the nature of supplement use, and assessed the relationship between adherence and nutrient intake levels. Except for calcium and folacin intakes, mean nutrient intakes met or exceeded recommended levels. No subjects had calcium intakes above the adequate intake for calcium; 72.7% had folate intakes below the estimated average requirement. Intakes of other nutrients, except thiamin and magnesium, were below the estimated average requirement in less than 25% of the sample; 31.8% and 45.5% of subjects, respectively, had thiamin and magnesium intakes at this level. Those who adhered more closely to the rotary diversified diet had higher intakes of vitamin C, vitamin B6, folate, and fibre than did those who followed the diet less closely. Supplements conferred some nutritional benefits; however, supplemental niacin and magnesium intakes exceeded tolerable upper intake levels. Those prescribed the rotary diversified diet require nutrition counselling from dietitians to cope with the complexity and restrictiveness of the diet.

Latex allergies in the health care worker

A dramatic increase in the incidence of latex allergies in health care workers followed the surge in latex glove use accompanying the rise of human immunodeficiency virus (HIV) in the early 1980s. This increase in latex glove use was driven by the release of Universal Precautions issued by the Centers for Disease Control (CDC) in response to the rise of HIV and other blood-borne pathogens. Efforts to stem allergic responses in the workplace have relied on the substitution of other materials for latex. Unfortunately, there is so much latex in everyday life that avoiding this allergen is exceedingly difficult once one is sensitized. Additionally, there are numerous cross reactants that are present in the environment. The situation is further confounded by the introduction of genetically manipulated foods and agricultural products that contain defense proteins genetically inserted to protect plants from pests and pathogens. Many of these defense proteins are antigens that will cross react with latex. Sensitivity reactions, once developed, may progress to the point at which the health care worker is excluded from working. This report provides an overview of rubber products and cross reactants, allergic reactions, and latex sensitivity for the health care worker.

Capsaicin inhalation test for identification of sensory hyperreactivity

BACKGROUND

Patients with upper and lower airway symptoms and with pronounced sensitivity to chemical odours, such as perfumes, flower scents and tobacco smoke, have been suggested to have sensory hyperreactivity (SHR). The symptoms have been difficult to identify with physiological measurements and the effects of various medications are doubtful. However, these patients have been found to be more sensitive to inhalation of capsaicin than healthy people. The aim of this study was to establish limit values with the capsaicin inhalation test in patients with SHR.

METHODS

Ninety-five consecutive patients with upper and lower airway problems, who were admitted for allergy testing, underwent a capsaicin inhalation test with three different concentrations. The number of coughs was registered during each challenge. Score systems were used for symptoms and influence on social life of sensitivity to odours. In relation to scored symptoms, the patients were grouped as SHR or not, and compared with 73 healthy controls.

RESULTS

All patients and controls coughed on capsaicin in a dose-dependent manner. Symptom score of odour sensitivity in patients was positively correlated to the response of the test. Out of 95 patients, 15 (16%) were scored to SHR. Patients with SHR reacted more to the capsaicin inhalation test than the other patients and the healthy controls. The limit values for a positive capsaicin inhalation test for the SHR were determined to be 10, 35 and 55 coughs at 0.4, 2.0 and 10 microM capsaicin, respectively.

CONCLUSION

The capsaicin inhalation test well reflects the degree of airway sensitivity to chemicals and to what extent the social life is influenced. The cut-off values of the test can distinguish patients with pronounced sensitivity to odours.

Mechanisms of multiple chemical sensitivity

Sensitivity to chemicals is a toxicological concept, contained in the dose-response relationship. Sensitivity also includes the concept of hypersensitivity, although controversy surrounds the nature of effects from very low exposures. The term multiple chemical sensitivity has been used to describe individuals with a debilitating, multi-organ sensitivity following chemical exposures. Many aspects of this condition extend the nature of sensitivity to low levels of exposure to chemicals, and is a designation with medical, immunological, neuropsychological and toxicological perspectives. The basis of MCS is still to be identified, although a large number of hypersensitivity, immunological, psychological, neurological and toxicological mechanisms have been suggested, including: allergy; autosuggestion; cacosomia; conditioned response; immunological; impairment of biochemical pathways involved in energy production; impairment of neurochemical pathways; illness belief system; limbic kindling; olfactory threshold sensitivity; panic disorder; psychosomatic condition; malingering; neurogenic inflammation; overload of biotransformation pathways (also linked with free radical production); psychological or psychiatric illness; airway reactivity; sensitisation of the neurological system; time dependent sensitisation, toxicant induced loss of tolerance. Most of these theories tend to break down into concepts involving: (1) disruption in immunological/allergy processes; (2) alteration in nervous system function; (3) changes in biochemical or biotransformation capacity; (4) changes in psychological/neurobehavioural function. Research into the possible mechanisms of MCS is far from complete. However, a number of promising avenues of investigation indicate that the possibility of alteration of the sensitivity of nervous system cells (neurogenic inflammation, limbic kindling, cacosomia, neurogenic switching) are a possible mechanism for MCS.

Repeated formaldehyde effects in an animal model for multiple chemical sensitivity

Chemical intolerance is a phenomenon observed in multiple chemical sensitivity (MCS) syndrome, an ill-defined disorder in humans attributed to exposure to volatile organic compounds. Amplification of symptoms in individuals with MCS resembles the phenomenon of psychostimulant- and stress-induced sensitization in rodents. We have recently tested in rats the hypothesis that repeated chemical exposure produces sensitization of central nervous system (CNS) circuitry. A rat model of MCS in our laboratory has employed several endpoints of CNS function after repeated formaldehyde (Form) exposure (1 h/day x 5 days/week x 4 weeks). Repeated Form exposure produced behavioral sensitization to later cocaine injection, suggesting altered dopaminergic sensitivity in mesolimbic pathways. Rats given repeated Form also demonstrated increased fear conditioning to odor paired with footshock, implicating amplification of neural circuitry guiding fear responding to a conditioned odor cue. Recent studies examining the effects of repeated Form on locomotor activity during each daily exposure showed a decrease in rearing activity after 12-15 days of Form exposure compared to air-exposed controls. EEG recordings taken 1 week after withdrawal from daily Form revealed altered sleep architecture. Some of the differences in sleep disappeared after subsequent brief (15 min) challenge with Form the next day. Overall, the findings indicate that repeated low-level chemical exposure produces behavioral changes that may be akin to those observed in individuals with MCS, such as greater sensitivity to chemicals manifest as increased anxiety upon chemical exposure and altered sleep and/or fatigue. Study of the underlying CNS changes will provide a basis for mechanistically based animal models for MCS.

The compelling anomaly of chemical intolerance

In science, anomalies expose the limitations of existing paradigms and drive the search for new ones. In the late 1800s, physicians observed that certain illnesses spread from sick, feverish individuals to those contacting them, paving the way for the germ theory of disease. The germ theory served as a crude, but elegant formulation that explained dozens of seemingly unrelated illnesses affecting literally every organ system. Today, we are witnessing another medical anomaly-a unique pattern of illness involving chemically exposed groups in more than a dozen countries, who subsequently report multisystem symptoms and new-onset chemical, food, and drug intolerances. These intolerances may be the hallmark for a new disease process or paradigm, just as fever is a hallmark for infection. The fact that diverse demographic groups, sharing little in common except some initial chemical exposure event, develop these intolerances is a compelling anomaly pointing to a possible new theory of disease, one that has been referred to as "Toxicant-Induced Loss of Tolerance" ("TILT"). TILT has the potential to explain certain cases of asthma, migraine headaches, and depression, as well as chronic fatigue, fibromyalgia, and "Gulf War syndrome". It appears to evolve in two stages: (1) initiation, characterized by a profound breakdown in prior, natural tolerance resulting from either acute or chronic exposure to chemicals (pesticides, solvents, indoor air contaminants, etc.), followed by (2) triggering of symptoms by small quantities of previously tolerated chemicals (traffic exhaust, fragrances, gasoline), foods, drugs, and food/drug combinations (alcohol, caffeine). While the underlying dynamic remains an enigma, observations indicating that affected individuals respond to structurally unrelated drugs and experience cravings and withdrawal-like symptoms, paralleling drug addiction, suggest that multiple neurotransmitter pathways may be involved.

Sensitization studies in chemically intolerant individuals: implications for individual difference research

Chemical intolerance (CI) is an individual difference trait in which persons report feeling ill in multiple physiological systems from low levels of a wide range of chemically unrelated environmental substances. This paper discusses the neural sensitization model for progressive host amplification of polysymptomatic responses elicited by chemical exposures following an initiating event. The sensitization model accommodates hypotheses for initiating and eliciting CI in human populations that involve both environmental chemicals and physical or psychological stressors. Recent studies in this laboratory have demonstrated sensitization in individuals with CI over repeated sessions for dependent variables such as electroencephalographic (EEG) activity and diastolic blood pressure. Psychological distress variables alone do not explain these findings. Individuals with CI and/or vulnerability to sensitization share specific characteristics, for example, female gender, certain genetic background (offspring of alcohol-preferring parents), and personal preference for high sugar/ carbohydrate intake. Overall, the data suggest that the 15-30% of the general population who report heightened CI are highly sensitizable. Sensitizability may serve an adaptive, sentinel function in threatening environments with poor signal-to-noise ratios. However, as sensitization gradually shifts operating set points of physiological systems out of the normal range in response to allostatic load, this process may contribute to the development of chronic, polysymptomatic health conditions such as multiple chemical sensitivity and/or fibromyalgia. Individual response specificity and stereotypy rather than toxicant properties may determine which types of central, autonomic, and/or peripheral nervous system dysfunctions manifest at subclinical and clinical levels.

Immunological and in-vivo neurological studies on a benzoic acid-specific T cell-derived antigen-binding molecule from the serum of a toluene-sensitive patient

T-cell-derived antigen-binding molecules (TABMs) specific for benzoic acid were isolated from the serum of a toluene-sensitive patient. The resulting purified TABMs (BA-TABMs) did not contain immunoglobulin G and were associated with the cytokine transforming growth factor-beta (TGF-beta). BA-TABMs bound to benzoic acid conjugated to human serum albumin (BA-HSA), as well as to other chemicals conjugated to human serum albumin-including dinitrophenol and oxazolone. The binding of BA-TABMs to the conjugated chemicals increased the level of detectable TGF-beta, and a similar effect was observed with the unconjugated chemicals, benzoic acid and 2,4-dinitrophenol glycine. The increase in TGF-beta was critically dependent on the ratio between BA-TABMs and the conjugated or unconjugated chemicals; the increase was optimum at intermediate concentrations and absent at low and high concentrations. The authors used an established animal model in vivo and demonstrated that TGF-beta enhanced the inflammatory response induced by the release of neuropeptides from sensory nerves; this enhancement occurred in a dose-dependent manner. The BA-TABMs also enhanced this neurogenic inflammatory response in a dose-dependent manner, and this effect was blocked by anti-TGF-beta antibody. When the authors added either BA-HSA or benzoic acid, the effect of BA-TABMs on neurogenic inflammation was further enhanced at intermediate concentrations of antigen and was unaltered or reduced at higher concentrations. TABMs specific to particular chemicals, as a result of their association with cytokines (e.g., TGF-beta), may be implicated in symptom production in chemically sensitive patients.

Quality of life and capsaicin sensitivity in patients with sensory airway hyperreactivity

BACKGROUND

A group of patients with asthma-like symptoms and sensitivity to chemical irritants has shown an increased cough sensitivity to inhaled capsaicin compared to patients with asthma and to healthy controls. The condition is called sensory hyperreactivity (SHR), and the patients often feel that they are socially handicapped because of the risk of exposure to chemical irritants in daily life.

METHODS

Twenty-six patients with asthma-like symptoms after exposure to nonspecific irritating stimuli, but without IgE-mediated allergy or demonstrable bronchial obstruction, were selected for a study of the response to a capsaicin test and measurement of quality of life by a general health profile (the Nottingham Health Profile [NHP]). We also investigated whether there was a correlation between quality of life and sensitivity to capsaicin.

RESULTS

The patients demonstrated a dose-dependent response to the capsaicin provocation, with coughing and respiratory and other symptoms, that significantly differed from 12 healthy controls. The health profile showed that patients with SHR had a significantly reduced quality of life compared to reference values, and there was a significant correlation between the health profile and sensitivity to capsaicin.

CONCLUSIONS

Patients with asthma-like symptoms verified by the capsaicin inhalation test for sensory hyperreactivity have a poor quality of life. The correlation between quality of life and sensitivity to capsaicin objectively demonstrates the validity of this general health profile study.

Olfaction and symptoms in the multiple chemical sensitivities syndrome

Whereas most idiosyncratic environmental sensitivity complaints do not fit known diagnoses, the multiple chemical sensitivities syndrome (MCS) is an extreme presentation that has defined diagnostic criteria. MCS symptomatics claim that they acquired a sensitized state as the result of a chemical exposure, usually to a solvent or pesticide, but not to a fragrance. Before this exposure, they did not experience symptoms. Following sensitization, symptoms increasing in number and severity with time are attributed by the MCS symptomatic to various exposures that are innocuous to most individuals. Although phenomenological studies have provided no evidence that particular odors elicit MCS symptoms, low levels of fragrances and perfumes are frequently associated with the reporting of MCS symptoms. This evaluation examines proposed mechanisms by which odorants and fragrances might cause either sensitization or elicitation of MCS symptoms, including altered odor sensitivity, primary irritancy or irritancy-induced upper airway reactivity, neurogenic switching of trigeminal irritancy signals, time-dependent sensitization and limbic kindling, CNS toxicity, and various psychiatric conditions. In no case was there persuasive evidence that any olfactory mechanism involving fragrance underlies either induction of a sensitized state or the triggering of MCS symptoms. Fragrances and other odorants could, however, be associated with symptoms as claimed by MCS symptomatics, because they are recognizable stimuli, but fragrance has not been demonstrated to be causal in the usual sense.

Provocations with perfume in the eyes induce airway symptoms in patients with sensory hyperreactivity

BACKGROUND

In earlier studies, we have shown that patients with a history of sensory hyperreactivity develop asthma-like symptoms when exposed to strong scents, even if they cannot smell any scent.

METHODS

For study of possible pathophysiologic mechanisms behind sensory hyperreactivity, the patients' airways and eyes were separately exposed to a common inducing factor, perfume. Eleven patients with a history of hyperreactivity to chemical trigger factors, such as perfume, were provoked single-blindly in a placebo-controlled, randomized study. During airway exposure, the eyes were covered and, during the eye exposure, the patients inhaled fresh air. A special face mask or a nose clip was used to avoid any smell.

RESULTS

During the 30-min exposure to perfume, there was a gradual increase in three main symptoms; i.e., eye irritation, cough, and dyspnea, after both the airway and eye exposures. The increases were significant compared with placebo.

CONCLUSIONS

Asthma-like and other symptoms, such as irritation of the eyes, may be induced by exposure of both the airways and the eyes in patients with sensory hyperreactivity. This points to the importance of studying the sensory nervous system, not only in the airways, but also in other organs.

Neural sensitization model for multiple chemical sensitivity: overview of theory and empirical evidence

This paper summarizes theory and evidence for a neural sensitization model of hyperresponsivity to low-level chemical exposures in multiple chemical sensitivity (MCS). MCS is a chronic polysymptomatic condition in which patients report illness from low levels of many different, structurally unrelated environmental chemicals (chemical intolerance, CI). Neural sensitization is the progressive host amplification of a response over time from repeated, intermittent exposures to a stimulus. Drugs, chemicals, endogenous mediators, and exogenous stressors can all initiate sensitization and can exhibit cross-sensitization between different classes of stimuli. The properties of sensitization overlap much of the clinical phenomenology of MCS. Animal studies have demonstrated sensitization to toluene, formaldehyde, and certain pesticides, as well as cross-sensitization, e.g., formaldehyde and cocaine. Controlled human studies in persons with self-reported CI have shown heightened sensitizability in the laboratory to nonspecific experimental factors and to specific chemical exposures. Useful outcome measures include spectral electroencephalography, blood pressure, heart rate, and plasma beta-endorphin. Findings implicate, in part, dopaminergic mesolimbic pathways and limbic structures. A convergence of evidence suggests that persons with MCS or with low-level CI may share some characteristics with individuals genetically vulnerable to substance abuse: (a) elevated family histories of alcohol or drug problems; (b) heightened capacity for sensitization of autonomic variables in the laboratory; (c) increased amounts of electroencephalographic alpha activity at rest and under challenge conditions over time. Sensitization is compatible with other models for MCS as well. The neural sensitization model provides a direction for further systematic human and animal research on the physiological bases of MCS and CI.

Are we on the threshold of a new theory of disease? Toxicant-induced loss of tolerance and its relationship to addiction and abdiction

'Toxicant-induced loss of tolerance' (or TILT) describes a two-step disease process in which (1) certain chemical exposures, e.g., indoor air contaminants, chemical spills, or pesticide applications, cause certain susceptible persons to lose their prior natural tolerance for common chemicals, foods, and drugs (initiation); (2) subsequently, previously tolerated exposures trigger symptoms. Responses may manifest as addictive or abdictive (avoidant) behaviors. In some affected individuals, overlapping responses to common chemical, food, and drug exposures, as well as habituation to recurrent exposures, may hide (mask) responses to particular triggers. Accumulating evidence suggests that this disease process might underlie a broad array of medical illnesses including chronic fatigue, fibromyalgia, migraine headaches, depression, asthma, the unexplained illnesses of Gulf War veterans, multiple chemical sensitivity, and attention deficit disorder.

Sensory hyperreactivity--a possible mechanism underlying cough and asthma-like symptoms

BACKGROUND

Investigations of patients referred for suspected asthma have revealed a little-known group with symptoms suggesting hyperreactive airways in whom provocation with methacholine does not lead to bronchial obstruction. The underlying mechanisms are not known, and no objective diagnostic method has been available.

METHODS

Provocations by inhalation of capsaicin solutions in stepwise increasing concentrations were used. Ten patients with asthma-like symptoms after exposure to nonspecific irritating stimuli, but without IgE-mediated allergy or demonstrable bronchial obstruction, were compared to 10 patients with verified bronchial asthma and 28 healthy controls.

RESULTS

The patients with asthma-like symptoms reacted with cough in a dose-dependent way. The number of coughs was significantly greater than in asthmatic patients and healthy controls. The latter two groups did not differ significantly.

CONCLUSIONS

The capsaicin provocation test may be a valuable method for showing not only a greater cough sensitivity, but also asthma-like symptoms. The pathophysiology underlying the symptoms may be related to increased sensitivity of free, overactive nerve endings in the respiratory mucosa. Therefore, we suggest that this overreaction in the lower airways be called "sensory hyperreactivity".

Putting chemical and environmental sensitivities in perspective

Chemical sensitivity has been recognized for an extended period. Over the last 30 years or more, there has been a growing number of chemicals to which humans are being exposed. Some people have become sensitive to one or more of these chemicals and present this sensitivity in a wide variety of signs or symptoms. Single or multiple organ systems may become involved. This article is intended to give an overview on the existence and recognition of chemical sensitivities and how they may be diagnosed and treated. The important item is to educate physicians to the existence of chemical sensitivity and to consider this in their differential diagnosis when the patient presents with the signs, symptoms, or clinical pattern that is explained.