Subjects with seasonal allergic rhinitis and nonrhinitic subjects react differentially to nasal provocation with chlorine gas

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.

Understanding food allergy through neuroimmune interactions in the gastrointestinal tract

Food allergies are adverse immune reactions to food proteins in the absence of oral tolerance, and the incidence of allergies to food, including peanut, cow's milk, and shellfish, has been increasing globally. Although advancements have been made toward understanding the contributions of the type 2 immune response to allergic sensitization, crosstalk between these immune cells and neurons of the enteric nervous system is an area of emerging interest in the pathophysiology of food allergy, given the close proximity of neuronal cells of the enteric nervous system and type 2 effector cells, including eosinophils and mast cells. At mucosal sites, such as the gastrointestinal tract, neuroimmune interactions contribute to the sensing and response to danger signals from the epithelial barrier. This communication is bidirectional, as immune cells express receptors for neuropeptides and transmitters, and neurons express cytokine receptors, allowing for the detection of and response to inflammatory insults. In addition, it seems that neuromodulation of immune cells including mast cells, eosinophils, and innate lymphoid cells is critical for amplification of the type 2 allergic immune response. As such, neuroimmune interactions may be critical targets for future food allergy therapies. This review evaluates the contributions of local enteric neuroimmune interactions to the underlying immune response in food allergy and discusses considerations for future investigations into targeting neuroimmune pathways for treatment of food allergies.

Trigeminal Sensitivity in Patients With Allergic Rhinitis and Chronic Rhinosinusitis

OBJECTIVE

Allergic rhinitis (AR) and chronic rhinosinusitis with nasal polyps (CRSwNP) are of high importance in otorhinolaryngology. Some of their symptoms are related to changes in the nasal trigeminal sensitivity. The aim of this study was to compare nasal trigeminal sensitivity in patients with AR, CRSwNP, and healthy controls (HC).

METHODS

A total of 75 individuals participated (age 19-78 years; 34 AR, 10 CRSwNP and 31 HC). Olfactory function was determined using the extended Sniffin' Sticks test battery. Trigeminal sensitivity was assessed with CO₂ detection thresholds. Trigeminal negative mucosal potentials (NMP) and EEG-derived event-related potentials (ERP) were recorded in response to selective olfactory (phenylethyl alcohol) and trigeminal (CO₂ ) stimuli using high-precision air-dilution olfactometry.

RESULTS

In comparison to HC, AR patients had lower CO₂ thresholds, also reflected in shorter peak latencies in NMP and trigeminal ERP measurements. CRSwNP patients had a decreased sensitivity for trigeminal stimuli, also reflected in prolonged trigeminal ERP latencies, and reduced olfactory function compared to HC.

CONCLUSION

AR patients seemed to be more sensitive to trigeminal stimuli than CRSwNP patients. Importantly, the differences could be shown on psychophysical and electrophysiological levels. The changes in trigeminal sensitivity appear to be present already at the level of the respiratory epithelium. The differences between the two groups may depend on the specific inflammatory changes accompanying each disorder, the degree of inflammatory activity, or duration of the inflammatory disorder. However, because the sample sizes are relatively small, these results need to be confirmed in the future studies with larger groups.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:654-660, 2023.

New concepts in pediatric rhinitis

Rhinitis-and especially allergic rhinitis (AR)-remains the most frequent hypersensitivity condition, affecting up to a quarter of the population and impacting the quality of life of individual patients and the health economy. Data, especially with respect to underlying pathophysiologic mechanisms, mainly derive from studies on adults and are subsequently extrapolated to the pediatric population. Therapeutic algorithms for children with rhinitis are long based on the same principles as in adults. We explore and describe novel aspects of rhinitis, ranging from mechanisms to disease classification, phenotypes, diagnostic and monitoring tools, and the use of treatments, with a focus on the traits of pediatric age groups.

International expert consensus on the management of allergic rhinitis (AR) aggravated by air pollutants: Impact of air pollution on patients with AR: Current knowledge and future strategies

Allergic rhinitis affects the quality of life of millions of people worldwide. Air pollution not only causes morbidity, but nearly 3 million people per year die from unhealthy indoor air exposure. Furthermore, allergic rhinitis and air pollution interact. This report summarizes the discussion of an International Expert Consensus on the management of allergic rhinitis aggravated by air pollution. The report begins with a review of indoor and outdoor air pollutants followed by epidemiologic evidence showing the impact of air pollution and climate change on the upper airway and allergic rhinitis. Mechanisms, particularly oxidative stress, potentially explaining the interactions between air pollution and allergic rhinitis are discussed. Treatment for the management of allergic rhinitis aggravated by air pollution primarily involves treating allergic rhinitis by guidelines and reducing exposure to pollutants. Fexofenadine a non-sedating oral antihistamine improves AR symptoms aggravated by air pollution. However, more efficacy studies on other pharmacological therapy of coexisting AR and air pollution are currently lacking.

Microbiota Composition and the Integration of Exogenous and Endogenous Signals in Reactive Nasal Inflammation

The prevalence of reactive nasal inflammatory conditions, for example, allergic rhinitis and chronic rhinosinusitis, is steadily increasing in parallel with significant environmental changes worldwide. Allergens and as yet undefined environmental agents may trigger these conditions via the involvement of host intrinsic factors, including the innate and adaptive immune system, the nasal epithelium, and the nasal nervous system. The critical role of the nasal microbiota in coordinating these components has emerged in recent studies documenting a significant association between microbial composition and the onset and progression of allergic or nonallergic inflammation. It is now clear that the local microbiota is a major player in the development of the mucosa-associated lymphoid tissue and in the regulation of such adaptive responses as IgA production and the function of effector and regulatory T cells. Microbial components also play a major role in the regulation of epithelial barrier functions, including mucus production and the control of paracellular transport across tight junctions. Bacterial components, including lipopolysaccharide, have also been shown to induce or amplify neuroinflammatory responses by engaging specific nociceptors. Finally, bacterial products may promote tissue remodeling processes, including nasal polyp formation, by interacting with formyl peptide receptors and inducing the expression of angiogenic factors and matrix-degrading enzymes.

Acute respiratory distress syndrome and chemical burns after exposure to chlorine-containing bleach: a case report

Chlorine-containing bleach can cause acute respiratory distress syndrome (ARDS) and chemical burns. However, simultaneous occurrence of the two conditions caused by this agent is very rare. We describe the case of a 74-year-old female who presented with shortness of breath and hemoptysis following accidental exposure to chlorine-containing bleach. She had second- to third-degree chemical burns on both buttocks and thighs, and received mechanical ventilation because of the development of ARDS. Mechanical ventilation was discontinued on day 6 of hospitalization because of the rapid improvement of hypoxemia, and the patient was transferred to another hospital for further management of the chemical burns on day 18.

Nonallergic Rhinitis: Environmental Determinants

"Nonallergic rhinitis" (NAR) is defined by intermittent or persistent nasal symptoms without evidence of immunoglobulin E-mediated sensitization to relevant aeroallergens. The largest subgroup is idiopathic, and is characterized by nasal hyperreactivity to nonspecific environmental triggers, including temperature, humidity, and chemical exposures. As nonspecific nasal hyperreactivity is often found in the absence of mucosal inflammation, some clinicians refer to this condition as "nonallergic rhinopathy." Irritant rhinitis, can arise de novo after high-level and/or prolonged exposure to airborne irritant chemicals. We review the range of environmentally induced nonallergic nasal symptoms and signs, and explore issues of pathophysiology unique to environmental chemical exposures.

Occupational irritant and allergic rhinitis

The upper airway (extending from the nares to larynx) fulfills essential physiologic functions, including sensation, air conditioning, filtration, and communication. As the portal of entry for the respiratory tract, the upper airway's sentinel function is performed by the olfactory and trigeminal nerves. Sensory (eye, nose and throat) irritation figures prominently in symptom reporting in so-called "problem buildings," as well as in industrial exposures to irritant gases, vapors, and smokes. Both irritants and allergens can alter function in the upper airway, leading to loss of air conditioning and filtering due to airflow obstruction and hypersecretion. Increasing evidence points to a "unified airway" model of pathogenesis (in which rhinitis may precede the development of asthma). The spectrum of occupational irritant- and allergen-related upper airway health effects-including sensory irritation, olfactory dysfunction, rhinitis, sinusitis, nasal septal perforation, and sinonasal cancer-is reviewed in this article.

Mechanisms underlying the neuronal-based symptoms of allergy

Persons with allergies present with symptoms that often are the result of alterations in the nervous system. Neuronally based symptoms depend on the organ in which the allergic reaction occurs but can include red itchy eyes, sneezing, nasal congestion, rhinorrhea, coughing, bronchoconstriction, airway mucus secretion, dysphagia, altered gastrointestinal motility, and itchy swollen skin. These symptoms occur because mediators released during an allergic reaction can interact with sensory nerves, change processing in the central nervous system, and alter transmission in sympathetic, parasympathetic, and enteric autonomic nerves. In addition, evidence supports the idea that in some subjects this neuromodulation is, for reasons poorly understood, upregulated such that the same degree of nerve stimulus causes a larger effect than seen in healthy subjects. There are distinctions in the mechanisms and nerve types involved in allergen-induced neuromodulation among different organ systems, but general principles have emerged. The products of activated mast cells, other inflammatory cells, and resident cells can overtly stimulate nerve endings, cause long-lasting changes in neuronal excitability, increase synaptic efficacy, and also change gene expression in nerves, resulting in phenotypically altered neurons. A better understanding of these processes might lead to novel therapeutic strategies aimed at limiting the suffering of those with allergies.

Occupational rhinitis and asthma due to EDTA-containing detergents or disinfectants

BACKGROUND

Detergents and disinfectants are an emerging cause of work-related rhinitis and asthma. These products may contain ethylenediamine tetraacetic acid (EDTA). The authors report 10 cases of EDTA-related asthma and/or rhinitis.

METHODS

Review of the medical charts of patients who presented with work-related rhinitis (alone or with asthma), with a history of exposure to aerosols of EDTA-containing products and who underwent a nasal provocation test (NPT) with tetrasodium EDTA (1-4%) in our occupational health unit.

RESULTS

Twenty-eight patients underwent a NPT with EDTA, which was positive in 10 cases. These patients, mostly cleaners or healthcare workers, used spray formulations of cleaning products.

CONCLUSIONS

This case series is the first report of EDTA-related respiratory disease, documented by a specific test. An irritant mechanism is unlikely. Further studies are required to distinguish between an immunoallergic response and a pharmacological mechanism possibly resulting from calcium chelation, as suggested by animal experiments. A ban of spray preparations would be sufficient to prevent respiratory disease induced by EDTA inhalation, regardless of its mechanism.

Sensing pulmonary oxidative stress by lung vagal afferents

Oxidative stress in the bronchopulmonary airways can occur through a variety of inflammatory mechanisms and also following the inhalation of environmental pollutants. Oxidative stress causes cellular dysfunction and thus mammals (including humans) have developed mechanisms for detecting oxidative stress, such that defensive behavior and defensive biological mechanisms can be induced to lessen its potential damage. Vagal sensory nerves innervating the airways play a critical role in the detection of the microenvironment in the airways. Oxidative stress and associated compounds activate unmyelinated bronchopulmonary C-fibers, initiating action potentials in these nerves that conduct centrally to evoke unpleasant sensations (e.g. urge to cough, dyspnea, chest-tightness) and to stimulate/modulate reflexes (e.g. cough, bronchoconstriction, respiratory rate, inspiratory drive). This review will summarize the published evidence regarding the mechanisms by which oxidative stress, reactive oxygen species, environmental pollutants and lipid products of peroxidation activate bronchopulmonary C-fibers. Evidence suggests a key role for transient receptor potential ankyrin 1 (TRPA1), although transient receptor potential vanilloid 1 (TRPV1) and purinergic P2X channels may also play a role. Knowledge of these pathways greatly aids our understanding of the role of oxidative stress in health and disease and represents novel therapeutic targets for diseases of the airways.

Accidental chlorine gas intoxication: evaluation of 39 patients

Background

Chlorine is a known pulmonary irritant gas that may cause acute damage in the respiratory system. In this paper, the socio-demographic and clinical characteristics of 39 accidentally exposed patients to chlorine gas are reported and different emergency treatment modalities are also discussed.

Methods

Two emergency departments applications were retrospectively analyzed for evaluation of accidental chlorine gas exposure for year 2007. Patients were classified into 3 groups according to severity of clinical and laboratory findings based on the literature and duration of land of stay in the emergency department. The first group was slightly exposed (discharged within 6 hours), second group moderately exposed (treated and observed for 24 hours), and third group was severely exposed (hospitalized). Most of the patients were initially treated with a combination of humidified oxygen, corticosteroids, and bronchodilators.

Results

The average age was 17.03 ± 16.01 years (95% CI). Seven (17.9%) of them were female and 29 (74.4%) were children. Twenty-four patients (61.5%) were included in the first, nine (23.1%) were in second and six (15.4%) were in the third group. The presenting symptoms were cough, nausea, and vomiting and conjunctiva hyperemia for the first group, first groups symptoms plus dyspnea for the second group. Second groups symptoms plus palpitation, weakness and chest tightness were for the third group. Cough and dyspnea were seen in 64.1% and 30.8% of the patients respectively. No patients died.

Conclusions

The authors recommend that non symptomatic or slightly exposed patients do not need any specific treatment or symptomatic treatment is sufficient.

Keywords

Accidental; Chlorine exposure; Chlorine gas; Chlorine intoxication; Emergency department

Nasal Physiological Reactivity of Subjects with Nonallergic Rhinitis to Cold Air Provocation: A Pilot Comparison of Subgroups

Background

Noninfectious nonallergic rhinitis (NINAR) is characterized by self-reported hyperreactivity to nonspecific physical or chemical stimuli. The relationship between these two classes of triggers is not well established, however. We compared NINAR subjects with predominantly physical or chemical triggers versus normal controls with respect to subjective (symptomatic) and objective (obstructive) responses to cold, dry air challenge.

Methods

We studied 14 NINAR subjects and 10 normal controls. Exposures consisted of 15 minutes of cold dry air (0°C/5% RH) or warm moist air (25°C/50% RH) on two separate days a week apart. Subjects rated symptoms using visual analog scales and had their nasal airway resistance measured at baseline, immediately after, and at 15-minute intervals for 1 hour postexposure.

Results

The majority of NINAR subjects reported physical triggers as more troublesome than chemical. Immediately postprovocation, the mean net proportional change in nasal airway resistance from baseline was +0.18 in NINAR (physical), +0.05 in NINAR (chemical), and –0.01 in control subjects (NS). However, a pooled linear regression by number of physical triggers (0–5) revealed a 7.5% increase in cold air–induced nasal airway resistance per trigger reported (p < 0.05). Similarly, raising the criterion number of physical triggers from ≥1 to ≥2 also distinguished NINAR subjects from controls in a bivariate analysis.

Conclusion

Either considering self-reported physical triggers as a continuous scale (0–5) or requiring more physical triggers (≥ 2 rather than ≥1) to define NINAR successfully predicts objective nasal reactivity to cold air provocation.

EAACI position paper on occupational rhinitis

The present document is the result of a consensus reached by a panel of experts from European and non-European countries on Occupational Rhinitis (OR), a disease of emerging relevance which has received little attention in comparison to occupational asthma. The document covers the main items of OR including epidemiology, diagnosis, management, socio-economic impact, preventive strategies and medicolegal issues. An operational definition and classification of OR tailored on that of occupational asthma, as well as a diagnostic algorithm based on steps allowing for different levels of diagnostic evidence are proposed. The needs for future research are pointed out. Key messages are issued for each item.

Assessment of Upper Respiratory Tract and Ocular Irritative Effects of Volatile Chemicals in Humans

Accurate assessment of upper respiratory tract and ocular irritation is critical for identifying and remedying problems related to overexposure to volatile chemicals, as well as for establishing parameters of irritation useful for regulatory purposes. This article (a) describes the basic anatomy and physiology of the human upper respiratory tract and ocular mucosae, (b) discusses how airborne chemicals induce irritative sensations, and (c) reviews practical means employed for assessing such phenomena, including psychophysical (e.g., threshold and suprathreshold perceptual measures), physiological (e.g., cardiovascular responses), electrophysiological (e.g., event-related potentials), and imaging (e.g., magnetic resonance imaging) techniques. Although traditionally animal models have been used as the first step in assessing such irritation, they are not addressed here since (a) there are numerous reviews available on this topic and (b) many rodents and rabbits are obligate nose breathers whose nasal passages differ considerably from those of humans, potentially limiting generalization of animal-based data to humans. A major goal of this compendium is to inform the reader of procedures for assessing irritation in humans and to provide information of value in the continued interpretation and development of empirical databases upon which future reasoned regulatory health decisions can be made.

Seasonal Allergic Rhinitic and Normal Subjects Respond Differentially to Nasal Provocation with Acetic Acid Vapor

Individuals with seasonal allergic rhinitis (SAR) show a more marked nasal obstructive response (increases in nasal airways resistance or NAR) after provocation with chlorine gas (Cl2) than do nonrhinitic (NR) controls. We were interested in learning whether similar differential responsiveness was apparent after provocation with acetic acid vapor. Sixteen nonsmoking, nonasthmatic subjects, aged 21-63 yr, equally divided by gender and nasal allergy status, were enrolled in a single-blinded crossover study involving exposure to acetic acid (AA) vapor (15 ppm) or air for 15 min on separate days 1 wk apart. NAR was measured in triplicate before, immediately post-, and 15 min postexposure, was normalized to baseline on a given exposure day, and was expressed as Net [NAR/baseline] after acetic acid versus control (air) exposure. After log transformation to achieve normality, the mean loge of Net [NAR/baseline] was 0.22 for SAR subjects and -0.11 for NR subjects immediately postexposure (p<.05); the corresponding values were 0.24 and -0.08, respectively, at 15 min postexposure (p<.05). Inhalation of acetic acid at the (NIOSH-recommended) short-term exposure limit of 15 ppm for 15 min produces differential nasal airflow obstruction among SAR versus NR subjects, with the former showing greater physiologic reactivity to this stimulus. This differential responsiveness is consistent with our previous findings with Cl2, indicating that there may be a generalized susceptibility factor associated with allergic rhinitis. The response occurs with slight subjective nasal irritation.

Occupational rhinitis

The present document is the result of a consensus reached by a panel of experts from European and nonEuropean countries on Occupational Rhinitis (OR), a disease of emerging relevance, which has received little attention in comparison to occupational asthma. The document covers the main items of OR including epidemiology, diagnosis, management, socio-economic impact, preventive strategies and medicolegal issues. An operational definition and classification of OR tailored to that of occupational asthma, as well as a diagnostic algorithm based on steps allowing different levels of diagnostic evidence, are proposed. The needs for future research are pointed out. Key messages are issued for each item.

TRPA1 is a major oxidant sensor in murine airway sensory neurons

Sensory neurons in the airways are finely tuned to respond to reactive chemicals threatening airway function and integrity. Nasal trigeminal nerve endings are particularly sensitive to oxidants formed in polluted air and during oxidative stress as well as to chlorine, which is frequently released in industrial and domestic accidents. Oxidant activation of airway neurons induces respiratory depression, nasal obstruction, sneezing, cough, and pain. While normally protective, chemosensory airway reflexes can provoke severe complications in patients affected by inflammatory airway conditions like rhinitis and asthma. Here, we showed that both hypochlorite, the oxidizing mediator of chlorine, and hydrogen peroxide, a reactive oxygen species, activated Ca(2+) influx and membrane currents in an oxidant-sensitive subpopulation of chemosensory neurons. These responses were absent in neurons from mice lacking TRPA1, an ion channel of the transient receptor potential (TRP) gene family. TRPA1 channels were strongly activated by hypochlorite and hydrogen peroxide in primary sensory neurons and heterologous cells. In tests of respiratory function, Trpa1(-/-) mice displayed profound deficiencies in hypochlorite- and hydrogen peroxide-induced respiratory depression as well as decreased oxidant-induced pain behavior. Our results indicate that TRPA1 is an oxidant sensor in sensory neurons, initiating neuronal excitation and subsequent physiological responses in vitro and in vivo.

Objective monitoring of nasal patency and nasal physiology in rhinitis

Nasal obstruction can be monitored objectively by measurement of nasal airflow, as evaluated by nasal peak flow, or as airways resistance/conductance as evaluated by rhinomanometry. Peak flow can be measured during inspiration or expiration. Of these measurements, nasal inspiratory peak flow is the best validated technique for home monitoring in clinical trials. The equipment is portable, relatively inexpensive, and simple to use. One disadvantage, however, is that nasal inspiratory peak flow is influenced by lower airway as well as upper airway function. Rhinomanometry is a more sensitive technique that is specific for nasal measurements. The equipment, however, requires an operator, is more expensive, and is not portable. Thus, it is applicable only for clinic visit measures in clinical trials. Measurements require patient cooperation and coordination, and not all can achieve repeatable results. Thus, this objective measure is best suited to laboratory challenge studies involving smaller numbers of selected volunteers. A nonphysiological measure of nasal patency is acoustic rhinometry. This sonic echo technique measures internal nasal luminal volume and the minimum cross-sectional area. The derivation of these measures from the reflected sound waves requires complex mathematical transformation and makes several theoretical assumptions. Despite this, however, such measures correlate well with the nasal physiological measures, and the nasal volume measures have been shown to relate well to results obtained by imaging techniques such as computed tomography scanning or magnetic resonance imaging. Like rhinomanometry, acoustic rhinometry is not suitable for home monitoring and can be applied only to clinic visit measures or for laboratory nasal challenge monitoring. It has advantages in being easy to use, in requiring little patient cooperation, and in providing repeatable results. In addition to nasal obstruction, allergic rhinitis is recognized to be associated with impaired mucociliary clearance and altered nasal responsiveness. Measures exist for the monitoring of these aspects of nasal dysfunction. Although measures of mucociliary clearance are simple to perform, they have a poor record of reproducibility. Their incorporation into clinical trials is thus questionable, although positive outcomes from therapeutic intervention have been reported. Measures of nasal responsiveness are at present largely confined to research studies investigating disease mechanisms in allergic and nonallergic rhinitis. The techniques are insufficiently standardized to be applied to multicenter clinical trials but could be used in limited-center studies to gain insight into the regulatory effects of different therapeutic modalities.

Nasal hyperreactivity in allergic and non-allergic rhinitis: a potential risk factor for non-specific building-related illness

Self-reported non-allergic nasal symptom triggers in non-allergic ('vasomotor') rhinitis overlap with commonly identified environmental exposures in non-specific building-related illness. These include extremes of temperature and humidity, cleaning products, fragrances, and tobacco smoke. Some individuals with allergic rhinitis also report non-allergic triggers. We wished to explore the phenotypic overlap between allergic and non-allergic rhinitis by ascertaining self-reported non-allergic nasal symptom triggers among allergic rhinitics. Sixty subjects without work-related respiratory exposures or symptoms, aged 19-68 years, stratified by age, gender and (skin test-proven) allergic rhinitis status, were queried with regard to self-reported non-allergic nasal symptom triggers (aggregate score 0-8). In this sample, the number of self-reported non-allergic triggers was bimodal, with peaks at 1 and 5. Forty-two percent of seasonal allergic rhinitic subjects reported more than three non-allergic triggers, compared with only 3% of non-allergic non-rhinitics (P < 0.01). Subjects over 35 years were more likely to report one or more non-allergic triggers, particularly tobacco smoke (P < 0.05). Allergic rhinitics reported more non-allergic symptom triggers than did non-allergic, non-rhinitics. As indexed by self-reported reactivity to non-specific physical and chemical triggers, both non-allergic rhinitics and a subset of allergic rhinitics may constitute susceptible populations for non-specific building-related illness.

PRACTICAL IMPLICATIONS

Judging by self-report, a substantial subset of individuals with allergic rhinitis--along with all individuals with nonallergic rhinitis (by definition)--are hyperreactive to non-allergic triggers. There is overlap between these triggers (elicited in the process of obtaining a clinical diagnosis) and environmental characteristics associated with ''problem buildings.'' Since individuals with self-identified rhinitis report an excess of symptoms in most epidemiologic studies of problem buildings (even in the absence of unusual aeroallergen levels), rhintics may be acting as a ''sentinel'' subgroup when indoor air quality is suboptimal. Together, non-allergic rhinitics plus allergic rhinitics with prominent non-allergic triggers, are thought to constitute approximately one-sixth of the US population.

Intranasal trigeminal sensitivity in subjects with allergic rhinitis

Trigeminal nerve endings of the human nasal mucosa are activated by chemical, physical or thermal stimuli. Activation of these A(delta) and C fibers can be quantified through the recording of chemo-somatosensory event-related potentials (ERP). The aim of this study was to investigate whether allergy-related activation of trigeminal nerve endings leads to changes in their responsiveness to intranasal trigeminal stimulation. Gaseous carbon dioxide (CO(2)) stimuli were applied in three sessions (baseline, after NaCl solution and after allergen application) to the nasal mucosa of 13 subjects with allergic rhinitis. Chemo-somatosensory ERP were recorded, and subjects rated the intensity of rhinitis symptoms. Administration of allergen produced a significant shortening of chemo-somatosensory ERP peak latencies P1 and N1. Observed changes of latencies were in line with rhinitis symptoms subjects indicated during the session. In addition, there was a negative relation between the general symptom score and ERP peak latencies, obtained both at baseline and after allergen exposure. In conclusion, it is hypothesized that in patients suffering from allergic rhinitis, nasal itching and sneezing after allergen exposure are, at least in part, clinical correlates of the activation of trigeminal nerve endings due to local inflammatory mechanisms. The correlations between ERP latencies and the patients' symptoms indicate that ERP latencies may possess a predictive value of the subjects' responsiveness to allergens.

Chlorine inhalation produces nasal airflow limitation in allergic rhinitic subjects without evidence of neuropeptide release

BACKGROUND

Seasonal allergic rhinitic (SAR) subjects are more physiologically reactive to airborne irritants than non-rhinitic (NR) subjects; however the mechanism underlying this difference is unclear.

OBJECTIVE

We sought to determine whether irritant-induced nasal airflow limitation involves neuropeptide release into nasal lining fluid, and if so, whether such release occurs differentially by rhinitic status.

METHODS

Eight SAR and 8 NR subjects were exposed to 1.0 ppm chlorine and filtered air in random order during separate visits; exposures were via nasal mask and lasted 15 min. Rhinomanometry was performed before, immediately post-, and 15 min post-exposure. Following a minimum of 2 weeks' time, exposures and symptom reporting were repeated with nasal lavage pre- and post-exposure. Neuropeptides (substance P, cacitonin gene-related protein, vasoactive intestinal peptide, and neuropeptide Y) as well as markers of plasma leakage (albumin and urea) and glandular secretion (lysozyme and 7F10-mucin) were measured using standard methods.

RESULTS

Cl(2) provocation significantly increased nasal airway resistance in SAR but not NR subjects (p<0.05). Neuropeptide levels in nasal lavage fluid, on the other hand, were unaffected, with the exception of a paradoxical increase in vasoactive intestinal peptide in non-rhinitic controls post-Cl(2) provocation.

CONCLUSIONS

Irritant-induced nasal airflow limitation is more pronounced among SAR than NR subjects. We could not, however, demonstrate a role for neuropeptide release in the nasal congestive response of SAR subjects.

Relationship of airway symptoms from chemicals to capsaicin cough sensitivity in atopic subjects

BACKGROUND

It is well known that some patients with allergy complain of airway symptoms from chemicals (ASCs) and strong odours. However, the importance of such information for the treatment of allergic disease is not known. Such symptoms in non-allergic patients have previously been shown to be related to increased sensory nerve reactivity, which is expressed as increased cough sensitivity to inhaled capsaicin.

OBJECTIVE

The aim of this study was to examine ASC in atopic patients and relate it to cough reaction to capsaicin inhalation.

MATERIALS AND METHODS

Fifty-seven consecutively chosen, skin prick-positive patients with symptoms of the upper and/or lower airways completed a questionnaire concerning ASC. The patients were then divided into two groups, those with and those without such symptoms. Both groups were provoked with inhaled capsaicin in three increments and compared with 73 healthy control subjects.

RESULTS

Out of 57 atopic patients, 34 reported ASC agents and 23 did not. The patients with ASC were older (P<0.01) and coughed significantly more on capsaicin provocation (P<0.001), but did not differ from them with respect to the allergic disease or its treatment or to smoking habits. Patients with atopy but without ASC did not differ from healthy controls with regard to sensitivity to capsaicin inhalation. The scored degree of ASC was directly related to the number of coughs during the capsaicin provocation.

CONCLUSION

ASC in atopic patients are related to increased airway sensory nerve reactivity. There is still no explanation for this in certain patients with atopy, but age may be a confounding factor.

Work-attributed symptom clusters (darkroom disease) among radiographers versus physiotherapists: associations between self-reported exposures and psychosocial stressors

BACKGROUND

"Darkroom disease" (DRD) has been used to describe unexplained multiple symptoms attributed by radiographers to their work environment. This study determines the prevalence of symptom clusters similar to other unexplained syndromes among (medical radiation technologists (MRTs) as compared with physiotherapists (PTs), and identifies associated work-related (WR) factors.

METHODS

A mail survey was undertaken of members of the professional associations of MRTs and PTs in Ontario, Canada. Questions were included to determine the prevalence and frequency of symptom clusters including abnormal tiredness as well as WR headaches, and symptoms suggestive of eye, nasal, and throat irritation. For the purpose of this study, these are considered to be DRD symptom clusters. Individuals with doctor-diagnosed asthma were excluded from our analyses.

RESULTS

Overall, 63.9% of MRTs and 63.1% of PTs participated. Criteria for DRD were met by 7.8% of 1,483 MRTs and 1.8% of 1,545 PTs [odds ratio, OR 4.8 (confidence interval, CI 3.1-7.5); (P < 0.0001)]. Both occupations showed significant associations between responses reflecting psychosocial stressors and DRD. Those with this symptom cluster were more likely to report additional symptoms than those without, and MRTs with DRD symptoms reported significantly more workplace chemical exposures.

CONCLUSIONS

Findings suggest excess symptoms consistent with DRD among MRTs versus PTs, and there were associations among those meeting our definition of DRD with self-reported irritant exposures and psychosocial stressors.

Toxicology of nasal irritants

The upper airway, including nasal cavities, naso-, oro-, and hypopharynx, is the portal of entry for air pollutants. Upper airway (as well as eye) irritation figures prominently in symptom reporting in so-called problem buildings and with exposure to environmental tobacco smoke. Large particles and water-soluble gases and vapors are likely to have their initial irritant effects in the mucous membranes of the upper airway and eyes, giving warning to the exposed individual to minimize further exposure. The spectrum of irritant-related upper airway health effects is reviewed in this article.

Occupational upper airway disease

The upper airway plays a critical role in filtering and conditioning air for the lungs. It provides the first line of warning and defense against microbials, allergens, and toxic inhalants. Current evidence suggests that the upper airway is susceptible to many of the pathogenic processes that the agents cause in the lower respiratory tract. Work-related rhinosinusitis or vocal cord dysfunction should prompt physicians and employers to identify the injurious agent(s) and formulate strategies to eliminate or reduce such exposures. Improving the work environment will prevent the development of new cases and the worsening of symptoms in existing cases.

Capsaicin cough sensitivity in allergic asthmatic patients increases during the birch pollen season

BACKGROUND

A change in neural responsiveness may occur as the result of allergic inflammation in the lower airways as well as in the upper airways. In the lower airways, capsaicin cough sensitivity is known to reflect sensory neural reactivity.

OBJECTIVE

The aim of this study was to establish whether allergic inflammation changes airway neural sensory reactivity during prolonged allergen exposure.

METHODS

Ten nonsmoking patients with birch pollen-allergic asthma performed a capsaicin inhalation challenge twice, once in the off-pollen season and once during the pollen season. The number of coughs and symptoms induced by capsaicin were recorded and compared with those of healthy control subjects.

RESULTS

The response to capsaicin, expressed as number of coughs, increased in a dose-dependent manner during both tests. Before the season, the response was similar to that of healthy control subjects, but during the pollen season, the reactivity was significantly increased. Variations in forced expiratory volume in 1 second were not significant before and after each challenge, and values did not change during the pollen season as compared with the winter season.

CONCLUSIONS

Sensory reactivity in allergic asthmatic patients may be increased during prolonged allergen exposure as during the pollen season. This finding suggests that allergic inflammation in the lower and/or upper airways may trigger neurogenic mechanisms of significant clinical importance.

Mechanisms of wood smoke-induced increases in nasal airway resistance and reactivity in rats

We investigated the mechanisms of wood smoke-induced increases in nasal airway resistance (RNA) and airway reactivity in anesthetized rats. Delivery of wood smoke into a functionally isolated nasal airway produced an increase in RNA, which was attenuated by CP-96,345 [a tachykinin NK(1) receptor antagonist; (2S,3S)-cis-2-(diphenylmethyl)-N-((2-methoxyphenyl)-methyl)-1-azabicyclo(2.2.2.)-octan-3-amine] or atropine. Additionally, smoke pre-exposure animals displayed a greater amplitude and a longer duration of RNA responses to capsaicin or histamine provocation, as compared to air controls. This enhanced airway reactivity to capsaicin or histamine was largely alleviated by CP-96,345 or atropine. The nasal secretory responses to capsaicin or histamine in smoke pre-exposure animals were similar to those in air controls. We concluded that (1) reflex cholinergic and tachykininergic mechanisms play important roles in wood smoke-induced increases in nasal airway resistance and airway reactivity, and (2) this nasal airway hyperreactivity might not be due to an exaggerated secretory response, but is presumably due to augmented nasal swelling.

Association between air pollution and daily consultations with general practitioners for allergic rhinitis in London, United Kingdom

Few published studies have looked at the health effects of air pollution in the primary care setting, and most have concentrated on lower rather than upper respiratory diseases. The authors investigated the association of daily consultations with general practitioners for allergic rhinitis with air pollution in London, United Kingdom. Generalized additive models were used to regress time series of daily numbers of patients consulting for allergic rhinitis against 1992--1994 measures of air pollution, after control for possible confounders and adjustment for overdispersion and serial correlation. In children, a 10th--90th percentile increase in sulfur dioxide (SO(2)) levels 4 days prior to consultation (13-31 microg/m(3)) was associated with a 24.5% increase in consultations (95% confidence interval: 14.6, 35.2; p < 0.00001); a 10th--90th percentile increase in averaged ozone (O(3)) concentrations on the day of consultation and the preceding 3 days (6--29 parts per billion) was associated with a 37.6% rise (95% confidence interval: 23.3, 53.5; p < 0.00001). For adults, smaller effect sizes were observed for SO(2) and O(3). The association with SO(2) remained highly significant in the presence of other pollutants. This study suggests that air pollution worsens allergic rhinitis symptoms, leading to substantial increases in consultations. SO(2) and O(3) seem particularly responsible, and both seem to contribute independently.