Changes in sputum cell counts after exposure to occupational agents: what do they mean?

Identification of true chemical respiratory allergens: Current status, limitations and recommendations

Asthma in the workplace is an important occupational health issue. It comprises various subtypes: occupational asthma (OA; both allergic asthma and irritant-induced asthma) and work-exacerbated asthma (WEA). Current regulatory paradigms for the management of OA are not fit for purpose. There is therefore an important unmet need, for the purposes of both effective human health protection and appropriate and proportionate regulation, that sub-types of work-related asthma can be accurately identified and classified, and that chemical respiratory allergens that drive allergic asthma can be differentiated according to potency. In this article presently available strategies for the diagnosis and characterisation of asthma in the workplace are described and critically evaluated. These include human health studies, clinical investigations and experimental approaches (structure-activity relationships, assessments of chemical reactivity, experimental animal studies and in vitro methods). Each of these approaches has limitations with respect to providing a clear discrimination between OA and WEA, and between allergen-induced and irritant-induced asthma. Against this background the needs for improved characterisation of work-related asthma, in the context of more appropriate regulation is discussed.

Inhalation Challenge Tests in Occupational Asthma: Why Are Multiple Tests Needed?

Occupational and environmental lung diseases are on the rise because of the widespread use of various toxic agents in industry. Asthma etiopathogenesis is unclear because of exposure to high and low molecular agents in workplaces. Approximately 15-25% of asthma in adults is reported to be related to occupational exposure. The prevalence of occupational asthma (OA) is predicted to be high. The difficulties in diagnosing OA results in inadequate treatment, permanent airway damage, and medicolegal and social problems. As with other occupational diseases, it is necessary to demonstrate a direct causal relationship between the suspected agent and OA. Spirometry, peak expiratory flow rate, and/or non-specific bronchial hyperresponsiveness are frequently used to show airway hyperresponsiveness at the workplace and away from work. However, there are some controversies about the specificity and sensitivity of these test methods. Furthermore, these tests do not identify the exposure agent, which could be the causative agent. Specific inhalation challenge (SIC) tests that demonstrate the direct causal relationship are currently the gold standard. However, their positive and negative predictive values have not yet been established; therefore, many low molecular weight agents could cause late or atypical reactions. Therefore, a negative SIC test cannot exclude the disease. This review describes the procedures for the SIC test and discusses the importance of using the combined test methods with the SIC test.

Neutrophil activation in occupational asthma

PURPOSE OF REVIEW

The aim of this review is to emphasize the role of neutrophils in patients with occupational asthma. This review facilitates a better understanding, accurate diagnosis, and proper management of asthmatic reactions provoked at the workplace.

RECENT FINDINGS

Increased recruitment and infiltration of neutrophils are found in patients with occupational asthma. Activated neutrophils release several mediators including pro-inflammatory cytokines and extracellular traps, leading to stimulation of airway epithelium and other inflammatory cells.

SUMMARY

New insights into neutrophils in the pathogenesis of occupational asthma may provide a novel approach to the individual patient with occupational asthma.

Clinical and inflammatory characteristics of Asthma-COPD overlap in workers with occupational asthma

INTRODUCTION

Although Asthma-COPD Overlap (ACO) has been described among populations of subjects with COPD or asthma, ACO has never been described among a population of subjects with occupational asthma (OA).

OBJECTIVES

The aims of this study were to: 1. identify ACO in a population of subjects with OA; and 2. compare the clinical characteristics between ACO and OA.

METHODS

This retrospective study included all subjects diagnosed with OA between 2000 and 2017 in an OA referral center. Occupational Asthma-COPD Overlap (OACO) was defined as post-bronchodilator FEV1/FVC < 70% and smoking history ≥ 10 pack-years, along with a diagnosis of OA.

RESULTS

Three hundred and four subjects were included, 262 (86.2%) were classified as OA and 42 (13.8%) as OACO. OA subjects presented higher sputum eosinophil counts after a specific-inhalation challenge than subjects with OACO (median [IQR]: 6.5 [17.0] vs 2.3 [3.5]). After adjusting for confounding factors, subjects with OACO were older (OR: 1.10 [1.05; 1.14]) and were taking higher doses of inhaled corticosteroids than OA subjects (OR, 5.20 [1.77; 16.48]). Subjects with OACO were less often atopic than OA subjects (OR, 0.19 [0.07; 0.62]).

CONCLUSIONS

Subjects with OACO constitute a distinct clinical and inflammatory phenotype from subjects with OA.

Biomarkers in Occupational Asthma

PURPOSE OF REVIEW

Work-related asthma is a common disorder among adult asthma patients, and in the case of occupational asthma, it is induced by workplace exposures.

RECENT FINDINGS

Occupational asthma provides an excellent model and benchmark for identifying and testing different allergy or inflammatory biomarkers associated with its inception or progression. Moreover, specific inhalation challenge with the incriminated agent represents an experimental setting to identify and validate potential systemic or local biomarkers. Some biomarkers are mainly blood-borne, while local airway biomarkers are derived from inflammatory or resident cells. Genetic and gene-environment interaction studies also provide an excellent framework to identify relevant profiles associated with the risk of developing these work-related conditions. Despite significant efforts to identify clinically relevant inflammatory and genomic markers for occupational asthma, apart from the documented utility of airway inflammatory biomarkers, it remains elusive to define specific markers or signatures clearly associated with different endpoints or outcomes in occupational asthma.

Diagnostic Accuracy of Inflammatory Markers for Diagnosing Occupational Asthma

BACKGROUND

The assessment of airway responsiveness and inflammation is key to the investigation of occupational asthma (OA).

OBJECTIVE

We sought to assess and compare the diagnostic accuracies of the blood and sputum eosinophil counts and the methacholine challenge for the diagnosis of OA.

METHODS

We conducted a retrospective study assessing 618 patients who underwent specific inhalation challenges (SICs) for symptoms suggestive of OA between 2000 and 2015. A sputum induction and a methacholine challenge were performed before and after SICs. Blood samples were collected in all subjects before the SICs and in 100 subjects before and after SICs. The diagnostic accuracies of blood and sputum eosinophil counts and methacholine challenge were calculated for diagnosing OA.

RESULTS

The change in blood eosinophil count failed to differentiate workers with positive and negative SICs. The change in sputum eosinophil counts induced by the exposure to the offending agent had the highest diagnostic accuracy (receiver operating characteristic area under the curve: 86% [95% confidence interval: 0.8-0.9, P < .001]) for diagnosing OA compared with changes in concentration of methacholine inducing a 20% fall in forced expiratory volume in 1 second (PC₂₀) and blood eosinophils. Combining a 2-fold or greater decrease in PC₂₀ or a 3% or greater increase in sputum eosinophil count achieved a sensitivity of 84% and a specificity of 74% with a negative predictive value of 91% for the diagnosis of OA.

CONCLUSIONS

Blood eosinophil counts do not appear to be an effective aid for diagnosing OA. The performance of both sputum cell count analysis and a methacholine challenge before and after exposure to the offending agent may represent an effective alternative in diagnosing OA when SICs are unavailable.

Specific inhalation challenge: the relationship between response, clinical variables and lung function

INTRODUCTION

The specific inhalation challenge (SIC) is considered the gold standard for the diagnosis of occupational asthma (OA). However, its use is not standardised, and the intensity of exposure is regulated empirically. The aim of this study was to identify clinical variables and/or pulmonary function variables able to predict the scale of patients' response to SIC.

MATERIAL AND METHODS

All patients who underwent SIC at our centre between 2005 and 2013 were studied. Anthropometric characteristics, atopic status, type of causal agent, latency times, pulmonary function tests and SIC results were analysed.

RESULTS

Two hundred and one patients (51% men) were assessed, of whom 86 (43%) had positive SIC. In the patients with positive results, 29 (34%) were exposed to high molecular weight (HMW) agents and 57 (64%) to low molecular weight (LMW) agents. Patients with a positive SIC exposed to HMW agents had a higher fall in FEV₁ after SIC compared with those exposed to LMW agents (p=0.036). The type of asthmatic reaction after SIC also differed between the groups (p=0.020). The logistic regression analysis showed that patients with a higher PC₂₀ before SIC were less likely to have severe decreases in FEV1 after SIC after adjusting for potential confounders (OR=0.771, 95% CI 0.618 to 0.961, p=0.021).

CONCLUSIONS

The scale of the response to SIC is influenced mainly by the degree of bronchial hyper-responsiveness, regardless of whether the causative agent is HMW or LMW, or whether the response is early or late.

Exhaled nitric oxide dynamics in asthmatic reactions induced by diisocyanates

BACKGROUND

Isocyanate-induced asthmatic reactions are associated with delayed increase in fractional exhaled nitric oxide measured at expiratory flow of 50 mL/s (FeNO50), a biomarker of airway inflammation. The time course of FeNO increase is compatible with the activation of NO synthase, but the origin of NO production in the lung is undetermined.

OBJECTIVE

The aim of this study was to define the dynamics of airway and alveolar NO during specific inhalation challenge (SIC) with isocyanates and the role of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase.

METHODS

Spirometry, exhaled NO parameters (FeNO50, bronchial wall NO concentration, NO airway diffusing capacity, NO flux to luminal space, alveolar NO) and ADMA levels in exhaled breath condensate were measured before and at intervals up to 24 h after exposure to isocyanates. The results were compared between 17 SIC-positive and eight SIC-negative subjects.

RESULTS

A significant FeNO50 increase in SIC-positive subjects was detected 24 h after exposure and was associated with the augmented NO flux from airway wall to the lumen, whereas airway NO diffusion and alveolar NO were not affected. The changes in NO dynamics were specific for the subjects who developed an asthmatic reaction, but were independent from the pattern and magnitude of bronchoconstriction. There was no evidence that exhaled NO is modulated by the changes in ADMA concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Because isocyanate-induced increase in FeNO50 was almost exclusively determined by the increase in NO flux, the use of FeNO50 appears adequate to monitor the exhaled NO dynamics during SIC. FeNO50 measurement may provide additional information to spirometry, because bronchoconstriction and airway inflammatory responses are dissociated.

Fractional exhaled nitric oxide in the interpretation of specific inhalational challenge tests for occupational asthma

PURPOSE

Fractional exhaled nitric oxide (FENO) measurements are recommended for the assessment of eosinophilic airway inflammation in asthma. Clinically relevant increases in FENO have been reported 24 h after positive specific inhalational challenge (SIC) tests in occupational asthma. We aimed to determine whether positive SICs could be discriminated from control tests, on the basis of change in FENO.

METHODS

We reviewed all positive SICs to a variety of agents performed at our institution 2008-2012 and gathered data on age, sex, asthmatic response (immediate/dual/late), smoking status, inhaled corticosteroid usage, and FENO pre- and 24-h postcontrol and positive SIC from each worker. Changes in FENO after positive SICs were compared with control SICs from each worker, by using paired Student's t tests.

RESULTS

In 16 workers, negative control challenges were associated with mean changes in FENO of 9 % (95 % CI -1.14 to 19.01) or 1.1 ppb (95 % CI -3.59 to 5.84); 2 of 16 (13 %) workers tested showed increases in FENO that were clinically relevant based on recent guidelines. Subsequent positive SICs were associated with mean changes in FENO of 7 % (95 % CI −15.73 to 29.6) or 2.1 ppb (95 % CI -6.07 to 10.19), which were not significantly different to controls; only 2 of 16 (13 %) workers had FENO changes that were clinically relevant.

CONCLUSIONS

FENO changes above the upper confidence limits of ≥20 % or ≥6 ppb may be considered to be outside the range of normality. However, the majority of workers who had clearly positive SICs to common low molecular weight agents also had no statistically or clinically relevant increase in FENO. Therefore, change in FENO does not predict a positive SIC in this group.

Sputum inflammatory profile before and after specific inhalation challenge in individuals with suspected occupational asthma

BACKGROUND

The aim of this study was to establish the sputum inflammatory profile and changes in levels of leukotriene B₄ (LTB₄) and a panel of Th1/Th2 cytokines in subjects with suspected occupational asthma (OA) following specific inhalation challenge (SIC) to high-molecular-weight (HMW) and low-molecular-weight (LMW) agents.

MATERIAL AND METHODS

Fifty-one consecutive subjects undergoing SIC for suspected OA were enrolled. Sputum induction was performed the day before and 24 h after exposure to the offending agent. Total and differential cell counts were assessed. LTB₄ and a 10 Th1/Th2 cytokines were measured in sputum supernatant.

RESULTS

Thirty-four patients tested positive to SIC and were diagnosed with OA (in 10 due to HMW agents and in 24 to LMW agents). SIC was negative in 17 subjects. As compared to baseline an increase was found in the percentage of sputum eosinophils and neutrophils, and in IL-10 concentration after SIC (p = 0.0078, p = 0.0195, and p = 0.046, respectively), and a decrease was seen in LTB₄ level (p = 0.0078) in patients with OA due to HMW agents. An increase in the percentage of sputum neutrophils after SIC (p = 0.0040) was observed in subjects without OA exposed to LMW agents. IL-8 levels after SIC were higher in patients without OA compared with patients with OA (p = 0.0146).

CONCLUSION

When conducting airway inflammation studies in OA, patients should be divided according to the causal agent (HMW or LMW). In OA patients exposed to HMW agents, an increase in the number of neutrophils can be found in parallel to the increase of eosinophils, although this does not contradict an IgE-mediated mechanism. Exposure to LMW agents can result in increased neutrophilic inflammation in patients with airway diseases unrelated to OA. There is variability in the responses observed in patients with OA exposed to LMW agents.

Diagnostic approach in cases with suspected work-related asthma

BACKGROUND

Work-related asthma (WRA) is a major cause of respiratory disease in modern societies. The diagnosis and consequently an opportunity for prevention are often missed in practice.

METHODS

Based on recent studies and systematic reviews of the literature methods for detection of WRA and identification of specific causes of allergic WRA are discussed.

RESULTS AND CONCLUSIONS

All workers should be asked whether symptoms improve on days away from work or on holidays. Positive answers should lead to further investigation. Spirometry and non-specific bronchial responsiveness should be measured, but carefully performed and validly analysed serial peak expiratory flow or forced expiratory volume in one second (FEV1) measurements are more specific and confirm occupational asthma in about 82% of those still exposed to the causative agent. Skin prick testing or specific immunoglobulin E assays are useful to document allergy to high molecular weight allergens. Specific inhalational challenge tests come closest to a gold standard test, but lack standardisation, availability and sensitivity. Supervised workplace challenges can be used when specific challenges are unavailable or the results non-diagnostic, but methodology lacks standardisation. Finally, if the diagnosis remains unclear a follow-up with serial measurements of FEV1 and non-specific bronchial hyperresponsiveness should detect those likely to develop permanent impairment from their occupational exposures.

Diagnosis of occupational asthma: an update

Work-related asthma (WRA) includes patients with sensitizer- and/or irritant-induced asthma in the workplace, as well as patients with preexisting asthma that is worsened by work factors. WRA is underdiagnosed; thus, the diagnosis is critical to prevent disease progression and its potential for morbidity and mortality. The interview is the first diagnostic tool to be used by physicians, and the question, "Does asthma improve away from work?" is of the highest sensitivity. However, history can show numerous false positives, and the relationships between asthma worsening and work should be confirmed by objective methods such as peak expiratory flow (PEF) at and away from work. PEF sensitivity and specificity can be enhanced in combination with nonspecific bronchial hyperresponsiveness to histamine/methacholine (NSBP) before and after 2 weeks at work and a similar period off work. Immunologic testing, especially skin prick test (SPT) or specific IgE, is useful for high molecular weight allergens and some low molecular weight agents. Other immunologic tests, as well as induced sputum, measurement of exhaled nitric oxide, exhaled breath condensate, and specific inhalation challenge (SIC) are methods that contribute to the diagnosis and are typically performed at specialized facilities. A diagnosis of occupational asthma (OA) should no longer be based on a compatible history only but should be confirmed by means of objective testing. SIC is the diagnostic gold standard. When SIC is not available, the combination of PEF measurement, NSBP test , a specific SPT, or specific IgE may be an appropriate alternative in diagnosing OA.

Work-exacerbated asthma and occupational asthma: do they really differ?

BACKGROUND

Although work-exacerbated asthma (WEA) is a prevalent condition likely to have an important societal burden, there are limited data on this condition.

OBJECTIVES

The aims of this study were (1) to compare the clinical, functional, and inflammatory characteristics of workers with WEA and occupational asthma (OA) and (2) compare health care use and related costs between workers with WEA and OA, as well as between workers with work-related asthma (WRA; ie, WEA plus OA) and those with non-work-related asthma (NWRA) in a prospective study.

METHODS

We performed a prospective observational study of workers with and without WRA with a 2-year follow-up. The diagnosis of OA and WEA was based on the positivity and negativity of results on specific inhalation challenges, respectively.

RESULTS

One hundred fifty-four subjects were enrolled: 53 with WEA, 68 with OA, and 33 control asthmatic subjects (NWRA). WEA was associated with more frequent prescriptions of inhaled corticosteroids (odds ratio [OR], 4.4; 95% CI, 1.4-13.6; P = .009), a noneosinophilic phenotype (OR, 0.3; 95% CI, 0.1-0.9; P = .04), a trend toward a lower FEV1 (OR, 0.9; 95% CI, 0.9-1.0; P = .06), and a higher proportion of smokers (OR, 2.5; 95% CI, 0.96-9.7; P = .06) than the diagnosis of OA. The health care use of WRA and related costs were 10-fold higher than those of NWRA.

CONCLUSION

Workers with WEA appeared to have features of greater asthma severity than workers with OA. In contrast with OA, WEA was associated with a noneosinophilic phenotype. Both OA and WEA were associated with greater health care use and 10-fold higher direct costs than NWRA.

Utility of exhaled breath condensate pH for diagnosing occupational asthma

INTRODUCTION

The current reference standard method for diagnosing occupational asthma (OA) is specific inhalation challenge (SIC) with the suspected agent. The alternative method is serial peak expiratory flow (PEF) monitoring. Nevertheless, PEF does not have optimal sensitivity and specificity for this purpose. The aim of this study was to evaluate the utility of exhaled breath condensate (EBC) pH for the diagnosis of OA.

MATERIAL AND METHODS

A prospective study was performed in 37 subjects with suspected OA. Serial PEF monitoring was carried out for 2 weeks at work and for 2 weeks off work. At the end of each period, the EBC pH and the methacholine concentration resulting in a 20% FEV(1) decrease (PC20) were measured. SIC was subsequently performed. PEF graphs were interpreted visually by 3 experienced independent readers.

RESULTS

Seventeen patients tested positive with SIC. Receiver-operating characteristic curves showed that a decrease in EBC pH greater than 0.4 units during the period at work compared to the off-work period achieved the most satisfactory sensitivity (40%, CI 19.4-66.5) and specificity (90%, CI 66.9-98.2) for diagnosing OA. When EBC pH findings were added to PEF results, the diagnostic yield of PEF generally increased. Other test combinations (e.g. EBC pH plus PC20 or EBC pH plus PC20 plus PEF) did not improve diagnostic performance.

CONCLUSIONS

Acidification of EBC pH at work and adding the EBC pH measurement to PEF monitoring during periods at work and off work may be useful for improving the diagnosis of OA.

EAACI consensus statement for investigation of work-related asthma in non-specialized centres

Work-related asthma (WRA) is a relevant problem in several countries, is cause of disability and socioeconomic consequences for both the patient and the society and is probably still underdiagnosed. A correct diagnosis is extremely important to reduce or limit the consequences of the disease. This consensus document was prepared by a EAACI Task Force consisting of an expert panel of allergologists, pneumologists and occupational physicians from different European countries. This document is not intended to address in detail the full diagnostic work-up of WRA, nor to be a formal evidence-based guideline. It is written to provide an operative protocol to allergologists and physicians dealing with asthma useful for identifying the subjects suspected of having WRA to address them to in-depth investigations in a specialized centre. No evidence-based system could be used because of the low grade of evidence of published studies in this area, and instead, 'key messages' or 'suggestions' are provided based on consensus of the expert panel members.

Diagnostic utility of exhaled breath condensate analysis in conjunction with specific inhalation challenge in individuals with suspected work-related asthma

BACKGROUND

Establishing the role of exhaled breath condensate (EBC) analysis in work-related asthma (WRA), and more specifically, in conjunction with specific inhalation challenge (SIC), is difficult.

OBJECTIVE

To measure EBC pH, and nitrite/nitrate concentrations before and after SIC in individuals with suspected WRA exposed to either high-molecular-weight (HMW) or low-molecular-weight (LMW) agents and evaluate whether these changes are useful to distinguish between occupational asthma (OA) and work-exacerbated asthma (WEA).

METHODS

One hundred twenty-five consecutive workers undergoing SIC were enrolled. Exhaled breath condensate was collected at the end of the baseline day and 24 hours after exposure to the offending agent. In all EBC samples, pH was measured, and nitrite and nitrate concentrations were determined.

RESULTS

Specific inhalation challenge was positive in 66 individuals, who were then diagnosed with OA. Work-exacerbated asthma was diagnosed in 14, and in 45 patients establishing a direct relationship between the symptoms and work exposure was not possible. In patients with WEA, EBC pH values after SIC were significantly lower than those before SIC (P = .0047). Using the receiver operating characteristic (ROC) curve, we found that an EBC pH decrease of greater than 0.4 units after SIC achieved the most satisfactory sensitivity 79% (confidence interval [CI]: 49-94) and specificity of 100% (CI: 68-100), considering only patients with asthma and without OA. A decrease in EBC pH of 0.4 or more common in those exposed to HMW agents (8/19, 42%) than in those exposed to LMW agents (7/47, 15%).

CONCLUSIONS

Exhaled breath condensate pH in conjunction with SIC may be useful for diagnosing WEA.

Changes in exhaled nitric oxide levels after bronchial allergen challenge

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is a marker of inflammation of the airways accompanying changes in the clinical condition of asthma. Allergen exposure has been associated with a delayed elevation of FeNO. The aim of this study was to assess airway inflammation with FeNO measurements during bronchial allergen challenge (BAC), and to determine the diagnostic performance of FeNO changes.

METHODS

Thirty-four patients with asthma and sensitization to inhalant allergens were studied. BAC with common or high-molecular-weight occupational aeroallergens was performed. FeNO was measured before and 24 h after BAC. Receiver operating characteristics curve was built to assess the sensitivity and specificity of increase in FeNO levels associated with BAC outcome.

RESULTS

In 21 patients (61.76%) a positive asthmatic reaction (responders) was observed. A significant increase in postchallenge FeNO was observed in this group of patients compared to the group of nonresponders. A median increase (FeNO postchallenge-FeNO prechallenge) of 14.0 ppb was observed in the group of responders, whereas a -1.0 ppb change was attained in the nonresponder group (P < 0.001). The cutoff point providing maximal sensitivity and specificity for %ΔFeNO after BAC was 12%. This change in FeNO levels has a sensitivity of 0.81 and a specificity of 0.92 for predicting a positive outcome in the BAC.

CONCLUSION

FeNO measurements can be used as a surrogate of airway inflammation accompanying the asthmatic reaction induced by BAC. FeNO measurements may be a useful and reliable tool in the monitoring and interpreting specific bronchial challenge test with allergens.

Acute respiratory effects in firefighters

BACKGROUND

Associations between acute respiratory inflammatory responses, changes in bronchial hyperresponsiveness, serum pneumoprotein levels, and exposure to fire smoke were studied.

METHODS

The study comprised 51 firefighters. Blood samples were taken within 24 hr following exposure to fire smoke, and after a week and 3 months. Sputum was induced within 5 days post-exposure and subjects underwent spirometry and methacholine provocation one week post-exposure. Exposure was registered by a questionnaire.

RESULTS

No changes were observed following smoke exposure in bronchial hyperresponsiveness and serum pneumoprotein levels. Nevertheless, in a sizable proportion of the firefighters (44%) elevated sputum neutrophil levels (≥60%) were found. Serum IL-8 concentrations were higher 24 hr post-exposure compared to pre-exposure. Elevated neutrophil levels in sputum were associated with elevated serum IL-8 (β = 0.010, P = 0.004) and TNFα (β = 0.005, P = 0.034) levels within 24 hr post-exposure and IL-8 elevation lasted up to 3 months.

CONCLUSIONS

Acute exposure to fire smoke induces acute neutrophilic airway and long-lasting systemic inflammation in healthy firefighters in the absence of bronchial hyperresponsiveness.

Airway inflammatory responses following exposure to occupational agents

BACKGROUND

Airway inflammatory responses to specific inhalation challenges (SICs) with low-molecular-weight (LMW) and high-molecular-weight (HMW) agents have not been studied thoroughly. We assessed the changes in airway inflammatory cells following SIC in sensitized workers, and looked at the influence of various factors on the pattern of inflammatory responses to SIC.

METHODS

Induced sputum analysis was performed in workers sensitized to LMW (n = 41) or HMW agents (n = 41) after a control day and after a positive SIC. Cell counts were compared with lung function and various clinical parameters.

RESULTS

In the LMW group, eosinophils were increased following late asthmatic responses (median [interquartile range], 0.02 [0.04] × 10(6) cells/g vs 0.30 [0.80] × 10(6) cells/g and 1.0% [3.5] vs 8.9% [8.0], P < .05), as were neutrophil numbers (0.8 [1.3] × 10(6) cells/g vs 2.3 [5.4] × 10(6) cells/g, P = .04). In the HMW group, eosinophil percentages increased both after early (1.0% [2.2] vs 5.5% [14.5], P = .003) and dual asthmatic responses (4.5% [3.7] vs 15.0% [13.7], P = .02). In the LMW group, the increases in neutrophils were higher in current smokers than in ex-smokers or nonsmokers. The length of exposure to the agent, tobacco use, and baseline percentage of eosinophils were independent predictors of the change in eosinophils, whereas age and baseline neutrophil percentage were predictors of the change in neutrophils.

CONCLUSIONS

This study confirms that eosinophils and neutrophils are increased after SIC, whatever the causal agent. The type of agent is not predictive of the inflammatory response to SIC. Smoking is associated with a more neutrophilic response after SIC with an LMW agent.

An official american thoracic society statement: work-exacerbated asthma

RATIONALE

Occupational exposures can contribute to the exacerbation as well as the onset of asthma. However, work-exacerbated asthma (WEA) has received less attention than occupational asthma (OA) that is caused by work.

OBJECTIVES

The purpose of this Statement is to summarize current knowledge about the descriptive epidemiology, clinical characteristics, and management and treatment of WEA; propose a case definition for WEA; and discuss needs for prevention and research.

METHODS

Information about WEA was identified primarily by systematic searches of the medical literature. Statements about prevention and research needs were reached by consensus.

MEASUREMENTS AND MAIN RESULTS

WEA is defined as the worsening of asthma due to conditions at work. WEA is common, with a median prevalence of 21.5% among adults with asthma. Different types of agents or conditions at work may exacerbate asthma. WEA cases with persistent work-related symptoms can have clinical characteristics (level of severity, medication needs) and adverse socioeconomic outcomes (unemployment, reduction in income) similar to those of OA cases. Compared with adults with asthma unrelated to work, WEA cases report more days with symptoms, seek more medical care, and have a lower quality of life. WEA should be considered in any patient with asthma that is getting worse or who has work-related symptoms. Management of WEA should focus on reducing work exposures and optimizing standard medical management, with a change in jobs only if these measures are not successful.

CONCLUSIONS

WEA is a common and underrecognized adverse outcome resulting from conditions at work. Additional research is needed to improve the understanding of the risk factors for, and mechanisms and outcomes of, WEA, and to inform and evaluate preventive interventions.

Occupational asthma: review of assessment, treatment, and compensation

Occupational asthma refers to asthma induced by exposure in the working environment to airborne dusts, vapors, or fumes, with or without preexisting asthma. Potential triggers of occupational asthma are diverse and involve a variety of postulated mechanisms. After confirming the presence of asthma, diagnosis hinges on obtaining a detailed and accurate occupational and environmental history and documenting a temporal association of symptoms or signs with workplace exposure. Management of occupational asthma centers on prescribing standard asthma therapies in conjunction with instituting preventive strategies, such as appropriate avoidance of environmental triggers, providing work restrictions, and using environmental controls and/or personal respiratory protection. If a worker is determined to be ill or injured, there are a variety of compensation systems that are designed to protect workers financially from disability related to respiratory impairments; however, the administrative process is frequently difficult to navigate for patients and their providers. Focusing on obtaining a detailed occupational and environmental history, establishing clear objective data to substantiate illness, and estimating or apportioning workplace contribution to the condition is important for the diagnosis and treatment of this relatively common form of asthma.

Occupational and work-exacerbated asthma: similarities and differences

Over the years, there have been tremendous efforts to improve the understanding of occupational asthma (OA), whereas work-exacerbated asthma (WEA) has been somewhat overlooked. The aim of this work is to review the literature, comparing the prevalence of OA and WEA, their clinical and inflammatory characteristics, as well as the work environment of those suffering from OA and WEA. We performed a PubMed search up to September 2006 using the keywords: work-related asthma, WEA, work-aggravated asthma and OA. Only studies in English were included for consideration. We found that OA and WEA are prevalent conditions. The characteristics of subjects with OA and WEA vary according to the type of studies undertaken to describe these conditions. Many sensitizing agents have been reported to cause OA, whereas exposures to irritant agents seem to be associated with the occurrence of WEA. The inflammatory profile may differ between these two conditions, but the data are too limited and sometimes too contradictory to allow a firm conclusion to be drawn. The socioeconomic outcome of these conditions seems similar. Therefore, further studies investigating the prevalence of WEA, as well as its clinical, functional and inflammatory characteristics, are needed to improve the management of the workers with WEA.

Occupational asthma: risk factors, diagnosis and preventive measures

In adulthood, new or recurrent asthma is caused by work in approximately 10% of cases. The term occupational asthma is reserved for those cases arising from respiratory hypersensitivity to a specific workplace agent; in others (work-exacerbated asthma) the mechanism is of nonspecific airway irritation on a background of bronchial hyper-reactivity. Some 300 workplace agents are capable of inducing asthma de novo; fortunately, most cases are attributed to a much smaller number to which exposure occurs in a few high-risk occupations. Exposure level is the most important remediable risk factor; the factors governing individual susceptibility are poorly understood. Diagnosis is generally straightforward. Management is rarely pharmacologic and often difficult since the diagnosis incurs important employment and other social consequences.

Noninvasive methods for assessment of airway inflammation in occupational settings

The present document is a consensus statement reached by a panel of experts on noninvasive methods for assessment of airway inflammation in the investigation of occupational respiratory diseases, such as occupational rhinitis, occupational asthma, and nonasthmatic eosinophilic bronchitis. Both the upper and the lower airway inflammation have been reviewed and appraised reinforcing the concept of 'united airway disease' in the occupational settings. The most widely used noninvasive methods to assess bronchial inflammation are covered: induced sputum, fractional exhaled nitric oxide (FeNO) concentration, and exhaled breath condensate. Nasal inflammation may be assessed by noninvasive approaches such as nasal cytology and nasal lavage, which provide information on different aspects of inflammatory processes (cellular vs mediators). Key messages and suggestions on the use of noninvasive methods for assessment of airway inflammation in the investigation and diagnosis of occupational airway diseases are issued.

Investigation of occupational asthma: sputum cell counts or exhaled nitric oxide?

BACKGROUND

The measure of sputum eosinophil counts is a useful tool in the investigation of occupational asthma (OA), but processing sputum is time consuming. Measuring the fractional concentration of exhaled nitric oxide (FENO) may be an alternative in clinical practice. The aim of this study was to assess the respective changes of sputum eosinophil counts and FENO following exposure to occupational agents in the routine practice of two tertiary centers in North America and Europe.

METHODS

Workers undergoing specific inhalation challenges (SICs) for possible OA in tertiary clinics in both Canada and Belgium were enrolled. Sputum cell counts and FENO were collected at the end of the control day and at 7 and 24 h after exposure to the offending agent.

RESULTS

Forty-one subjects had a negative SIC; 26 subjects had OA proven by a positive SIC. In subjects with positive SIC, there was a significant increase in sputum eosinophils at 7 h (9.0 [9.9]%) and 24 h (11.9 [14.9]%) after exposure compared with the baseline (2.8 [4.2]%), whereas there was a significant increase in FENO only 24 h after exposure (26.0 [30.5] ppb) compared with the baseline (16.6 [18.5] ppb). A 2.2% change in sputum eosinophil counts achieved a much higher sensitivity and positive predictive value than a 10-ppb change in FENO with similar specificity and negative predictive value for predicting a 20% decrease in FEV(1) during SICs.

CONCLUSIONS

Sputum eosinophil counts constitute a more reliable tool than FENO to discriminate positive and negative SICs.

Occupational and environmental lung disease: occupational asthma

Occupational exposures cause 10-15% of new-onset asthma in adults, and that represents a considerable health and economic burden. Exposure to many causative agents is now well controlled but workplace practices are constantly evolving and new hazards being introduced. Overall, there is no good evidence that the incidence of occupational asthma is decreasing. Evidence-based guidelines such as those published by the British Occupational Health research Foundation and Standards of Care documents should help raise awareness of the problem and improve management. Key targets include the control of occupational exposures, a high index of suspicion in any adult with new onset asthma, and early detailed investigation.

The definition and diagnosis of asthma

The diagnosis of asthma depends on what we mean by the word. Its definition continues to be controversial because there is no single genetic or environmental cause. Addressed from a descriptive point of view, the disease components include airway inflammation, symptoms, variable airflow limitation and chronic airflow limitation. The essentialist definition conveys the message that asthma is a separate disease entity, fails to identify a primary defining characteristic which separates it from other diseases and is long winded. These disadvantages are overcome by the nominalist definition of asthma in which the word 'asthma'refers to an abnormality of airway function, specifically to wide variations in airflow limitation over short periods of time. In patients with asthma the other components of airway disease need to be considered. These have separate nominalist definitions and especially include different types of bronchitis for airway inflammation and chronic obstructive pulmonary disease for chronic airflow limitation. What is present will vary between and within patients. The accurate diagnosis of asthma and of other components of disease all require objective measurements. Currently spirometry and airway responsiveness should be available to the general practitioner, who sees milder disease, and additional quantitative sputum cell counts in specialist practice, where moderate to severe disease is more prevalent. Such measurements characterize the patient, identify heterogeneity and allow treatment to be personalized.

Tissue transglutaminase can be involved in airway inflammation of toluene diisocyanate-induced occupational asthma

BACKGROUND

This study was conducted to evaluate whether tissue transglutaminase (tTG) may be involved in airway inflammation of toluene diisocyanate-induced occupational asthma (TDI-OA).

METHODS

We enrolled 93 patients with TDI-OA, 177 asymptomatic exposed subjects, 43 patients with allergic asthma, and 70 unexposed normal controls. The prevalence of serum immunoglobulin G (IgG) to tTG in the TDI-OA group (20.2%) was significantly higher than that in the three other groups (P < 0.001).

RESULTS

TDI-OA patients with serum IgG to tTG had significantly lower methacholine PC(20) values (P < 0.02) and significantly higher prevalence of specific immunoglobulin E to vapor type TDI-human serum albumin conjugate (P < 0.01; r(2) = 0.411, P < 0.05). TDI exposure could increase tTG activity via reactive oxygen species (ROS) production, which was found to cross-link with cytokeratin 19 on immunoblot analysis.

CONCLUSION

Therefore, TDI exposure may activate tTG via ROS-mediated mechanism in the airway epithelium leading to persistent airway inflammation in TDI-OA patients.

Changes in sputum eicosanoids and inflammatory markers after inhalation challenges with occupational agents

BACKGROUND

An increase in cysteinyl-leukotrienes (LTs) after specific inhalation challenge (SIC) with common allergens in patients with atopic asthma has been shown previously, but there are scarce data with occupational agents. We sought to determine whether there are differences in lower airway inflammatory markers and the production of cytokines and eicosanoids between patients with a positive or negative SIC response to occupational agents.

METHODS

Twenty-six patients with suspected occupational asthma and 13 healthy control subjects were studied. Spirometry, methacholine challenge, and sputum induction were performed at baseline and 24 h after SIC with occupational agents. Several cytokines and inflammatory mediators, including eicosanoids, were measured in sputum.

RESULTS

Twenty-six SICs were carried out with high-molecular-weight or low-molecular-weight agents, and the responses were positive in 18 patients. SIC elicited nine early asthmatic responses, two dual asthmatic responses, and seven isolated late asthmatic responses. Significant increments in sputum eosinophil counts were found only in patients with positive SIC responses compared with baseline values. Interleukin-10 levels were decreased in patients with positive and negative SIC responses compared to those in healthy control subjects. A significant increase (p < 0.05) in the LTC(4)/prostaglandin E(2) (PGE(2)) ratio was observed in patients after positive SIC responses compared to those with negative SIC responses.

CONCLUSIONS

Overexpression of LTC(4), relative underproduction of PGE(2), and greater airway eosinophilia were observed in patients with positive SIC responses.

Sputum eosinophilia: an early marker of bronchial response to occupational agents

BACKGROUND

False-negative responses to specific inhalation challenge (SIC) with occupational agents may occur. We explored whether assessing changes in sputum cell counts would help improve the identification of bronchial reactivity to occupational agents during SICs.

METHODS

The predictive value of the changes in sputum cell counts after a negative FEV(1) response to a first challenge exposure to an occupational agent was determined using the changes in airway calibre observed during repeated challenges as the 'gold standard'. The study included 68 subjects investigated for work-related asthma in a tertiary centre. After a control day, the subjects were challenged with the suspected occupational agent(s) for up to 2 h. All subjects who did not show an asthmatic reaction were re-challenged on the following day. Additional challenges were proposed to those who demonstrated a > or = 2% increase in sputum eosinophils or an increase in nonspecific bronchial hyperresponsiveness to histamine after the second challenge day.

RESULTS

Six of the 35 subjects without changes in FEV(1) on the first challenge developed an asthmatic reaction on subsequent challenges. ROC analysis revealed that a >3% increase in sputum eosinophils at the end of the first challenge day was the most accurate parameter for predicting the development of an asthmatic response on subsequent challenges with a sensitivity of 67% and a specificity of 97%.

CONCLUSIONS

An increase in sputum eosinophils is an early marker of specific bronchial reactivity to occupational agents, which may help to identify subjects who will develop an asthmatic reaction only after repeated exposure.

Occupational asthma: current concepts in pathogenesis, diagnosis, and management

Occupational asthma (OA) may account for 25% or more of de novo adult asthma. The nomenclature has now better defined categories of OA caused by sensitizing agents and irritants, the latter best typified by the reactive airways dysfunction syndrome. Selecting the most appropriate diagnostic testing and management is driven by assessing whether a sensitizer is involved, and if so, identifying whether the sensitizing agent is a high-molecular-weight agent such as a protein or a low-molecular-weight reactive chemical such as an isocyanate. Increased understanding of the pathogenesis of OA from reactive chemical sensitizers is leading to development of better diagnostic testing and also an understanding of why testing for sensitization to such agents can be problematic. Risk factors for OA including possible genetic factors are being delineated better. Recently published guidelines for the diagnosis and management of occupational asthma are summarized; these reflect an increasingly robust evidence basis for recommendations. The utility of diagnostic tests for OA is being better defined by evidence, including sputum analysis performed in relation to work exposure with suspected sensitizers. Preventive and management approaches are reviewed. Longitudinal studies of patients with OA continue to show that timely removal from exposure leads to the best prognosis.

Diagnosis and management of work-related asthma: American College Of Chest Physicians Consensus Statement

BACKGROUND

A previous American College of Chest Physicians Consensus Statement on asthma in the workplace was published in 1995. The current Consensus Statement updates the previous one based on additional research that has been published since then, including findings relevant to preventive measures and work-exacerbated asthma (WEA).

METHODS

A panel of experts, including allergists, pulmonologists, and occupational medicine physicians, was convened to develop this Consensus Document on the diagnosis and management of work-related asthma (WRA), based in part on a systematic review, that was performed by the University of Alberta/Capital Health Evidence-Based Practice and was supplemented by additional published studies to 2007.

RESULTS

The Consensus Document defined WRA to include occupational asthma (ie, asthma induced by sensitizer or irritant work exposures) and WEA (ie, preexisting or concurrent asthma worsened by work factors). The Consensus Document focuses on the diagnosis and management of WRA (including diagnostic tests, and work and compensation issues), as well as preventive measures. WRA should be considered in all individuals with new-onset or worsening asthma, and a careful occupational history should be obtained. Diagnostic tests such as serial peak flow recordings, methacholine challenge tests, immunologic tests, and specific inhalation challenge tests (if available), can increase diagnostic certainty. Since the prognosis is better with early diagnosis and appropriate intervention, effective preventive measures for other workers with exposure should be addressed.

CONCLUSIONS

The substantial prevalence of WRA supports consideration of the diagnosis in all who present with new-onset or worsening asthma, followed by appropriate investigations and intervention including consideration of other exposed workers.

Induced sputum and exhaled nitric oxide as noninvasive markers of airway inflammation from work exposures

PURPOSE OF REVIEW

Noninvasive measures of airway inflammation are increasingly used in the investigation and management of asthma. Their role in the investigation of occupational lung diseases, however, is not as clearly established. The present article reviews the use of noninvasive methods - induced sputum and exhaled nitric oxide - in the assessment of airway inflammation during the investigation of occupational asthma and eosinophilic bronchitis, and reviews studies investigating the effect of exposure to various occupational agents on airway inflammation in healthy individuals.

RECENT FINDINGS

A number of studies have confirmed the association between exposure to occupational agents and the presence of eosinophilic airway inflammation after that exposure in individuals with occupational asthma. Individuals with positive specific inhalation challenges to occupational agents seem to show a greater increase in exhaled nitric oxide than those with negative specific inhalation challenges. Exposure to various agents associated with an increase in exhaled nitric oxide mainly induced a neutrophilic inflammation.

SUMMARY

Increasing evidence supports the use of induced sputum as an additional tool in the investigation of occupational asthma. The role of exhaled nitric oxide in the investigation of occupational asthma needs to be clarified due to conflicting evidence reported in the literature.

New insights into occupational asthma

PURPOSE OF REVIEW

To examine recent publications on the types of agents involved in occupational asthma, the mechanisms by which they induce asthma, and how best to evaluate and treat workers suspected of this respiratory condition.

RECENT FINDINGS

High rates of occupational asthma and inhalation accidents were found in workers in crafts and related occupations in the manufacturing industries, and in plant and machine operatives; cleaners and construction workers may also be at risk. Further data support a role for CD4 T cells in low-molecular-weight agent-induced asthma, such as with isocyanates, and neurogenic mechanisms may also be involved. The use of noninvasive measures of airway inflammation in the diagnosis and management of occupational asthma such as sputum eosinophils monitoring is promising, although this is less obvious for exhaled nitric oxide. Finally, the persistence of troublesome asthma even after withdrawal from relevant exposure has been re-emphasized and surveillance programs have been proposed.

SUMMARY

Further data have been gathered on the prevalence of occupational asthma in various working populations, its mechanisms of development, the contribution of noninvasive measures of airway inflammation in the diagnosis and management of this condition, and its management and prevention.

Occupational asthma after withdrawal from the occupational allergen exposure

Occupational asthma is characterised by airway inflammation, variable airflow limitation and airway hyperresponsiveness related causally to work. The aim of the study was to ascertain whether in patients with occupational asthma findings persist after withdrawal from occupational allergen exposure. A group of 37 patients with occupational asthma and a control group of 19 persons were examined. Results in asthmatics obtained during the first visit when occupational asthma was acknowledged, were compared with recent results about 6.5 yr on average after elimination of occupational allergen exposure. Recent findings in occupational asthma patients were compared with the control group. In patients with occupational asthma, no significant differences were found between results obtained at the first and recent visit. Symptoms of asthma persisted in as much as 86.5% of patients. During recent examination there were more positive results in asthmatic patients comparing with the control group in histamine challenge (61.3 vs. 5.3%, p<0.01), eosinophile cationic protein (41.7 vs. 5.3%, p<0.05), prick tests (45.9 vs. 10.5%, p<0.05). Positive results of the present histamine challenge test and elevated eosinophils in sputum were more frequent (p<0.05) in patients with occupational asthma due to high molecular weight allergens than to low molecular weight allergens.

[Use of induced sputum in the investigation of occupational asthma]

The diagnosis of occupational asthma relies mainly on the demonstration of changes in airway calibre and airway responsiveness after exposure to occupational agents in the laboratory or at the workplace. However, spirometry or peak expiratory flow measurements may be open to misinterpretation when they are not performed optimally. As in non-occupational asthma, airway inflammation is one of the main characteristics of occupational asthma. Induced sputum, a non invasive method to assess airway inflammation, has been successfully used in the management of asthma. This article reviews the studies that have investigated and characterized the changes in sputum cell counts occurring in subjects with occupational asthma after exposure to occupational agents in the laboratory or at the workplace in order to assess the place of induced sputum in the investigation of occupational asthma. It also reviews the use of induced sputum during the follow-up of workers with occupational asthma after removal from exposure. This article also describes a new condition identified thanks to the use of induced sputum : occupational eosinophilic bronchitis. In conclusion, induced sputum is a useful tool in the investigation of occupational asthma. Its use on a regular basis in the investigation of occupational asthma also allows for the possibility of diagnosis of overlooked conditions such as occupational eosinophilic bronchitis. Its role in the surveillance of workers at risk to develop occupational asthma remains to be determined.

Diagnosing occupational asthma: insight from induced sputum

The diagnosis of occupational asthma needs to be made objectively using as many criteria as possible. The latter include laboratory exposure tests with occupational agent(s), which are only available in specialized centers. Another approach is to monitor peak expiratory flow (PEF) and (or) methacholine airway responsiveness during periods at work and away from work. However, these measurements are open to misinterpretation when they are not optimally performed. Airway inflammation is one of the main characteristics of asthma. Induced sputum, a non-invasive method to assess airway inflammation, has been successfully used in the management of asthma. However, airway inflammation is seldom assessed during the investigation of occupational asthma. This article reviews the studies that have investigated and characterized the changes in sputum cell counts occurring in subjects with occupational asthma after exposure to occupational agents in the laboratory, or at the workplace to assess to place of induced sputum in the investigation of occupational asthma.

Biomonitoring and biomarkers: exposure assessment will never be the same

Using modern analytical technology, it is now possible to measure almost any chemical present in our bodies. The future role of classical exposure assessment will perhaps be marginalized because biomonitoring programs can directly measure the concentration of chemicals that are present in biologic matrices. Although the concentration of chemicals in the environment will continue to be measured and related to exposure parameters, the prioritization of the national environmental agenda will be dictated by biomonitoring. Recent biomonitoring studies have examined the levels of >200 chemicals. Biomonitoring data, by themselves, are not informative in helping consumers understand their individual health risk. A major challenge facing those who conduct biomonitoring programs is how to best communicate the information to the public. In this article, we review benefits and challenges, along with select results from the Centers for Disease Control and Prevention's 2005 National Report on Human Exposure to Environmental Chemicals. We recommend that these data be carefully interpreted, with the goal of establishing baseline exposure information, rather than creating surrogates for conclusions about human health risk.

Occupational asthma

Substantial epidemiologic and clinical evidence indicates that agents inhaled at work can induce asthma. In industrialized countries, occupational factors have been implicated in 9 to 15% of all cases of adult asthma. Work-related asthma includes (1) immunologic occupational asthma (OA), characterized by a latency period before the onset of symptoms; (2) nonimmunologic OA, which occurs after single or multiple exposures to high concentrations of irritant materials; (3) work-aggravated asthma, which is preexisting or concurrent asthma exacerbated by workplace exposures; and (4) variant syndromes. Assessment of the work environment has improved, making it possible to measure concentrations of several high- and low-molecular-weight agents in the workplace. The identification of host factors, polymorphisms, and candidate genes associated with OA is in progress and may improve our understanding of mechanisms involved in OA. A reliable diagnosis of OA should be confirmed by objective testing early after its onset. Removal of the worker from exposure to the causal agent and treatment with inhaled glucocorticoids lead to a better outcome. Finally, strategies for preventing OA should be implemented and their cost-effectiveness examined.

The use of sputum eosinophils in the evaluation of occupational asthma

PURPOSE OF REVIEW

The diagnosis of occupational asthma needs to be made objectively using as many criteria as possible. These include laboratory exposure tests with occupational agent(s), which are only available in specialized centres. Another approach is to monitor peak expiratory flow or methacholine airway responsiveness during periods at work and away from work. However, these measurements are open to misinterpretation when they are not performed optimally. Airway inflammation is one of the main characteristics of occupational asthma, but is not often assessed during its investigation. The purpose of this work was to review recent studies that have investigated and characterized the changes in sputum cell counts occurring in patients with occupational asthma, in order to evaluate the role of the analysis of sputum cell counts.

RECENT FINDINGS

There is evidence that monitoring sputum eosinophils can help in the management of asthma. In the majority of cases of occupational asthma, the percentage of sputum eosinophils increases after exposure to occupational agents in the laboratory compared with baseline, but an increase in sputum neutrophils has also been observed. The changes in airway inflammation occurring at the workplace have been less investigated, but indicate that there are significant changes in airway inflammation and especially sputum eosinophils when workers are exposed to a sensitizer at their workplace compared with periods away from the workplace.

SUMMARY

Induced sputum has successfully been used to manage patients with mild to moderate asthma. Its use is promising in occupational asthma, and its role in the investigation of occupational asthma needs to be better defined.

Eosinophilic bronchitis in the workplace

PURPOSE OF REVIEW

The purpose of this review is to report that eosinophilic bronchitis without asthma may occur as an occupational airway disease. This condition is characterized by cough that is responsive to corticosteroids and eosinophilia detectable in the sputum, without variable airflow obstruction or airway hyperresponsiveness.

RECENT FINDINGS

Eosinophilic bronchitis can be regarded as an occupational respiratory disorder when it develops as a consequence of work exposures. Recently, exposure to certain occupational allergens or sensitizers, such as natural rubber latex, mushroom spores, acrylates and an epoxy resin hardener, have been reported to cause eosinophilic bronchitis without asthma. Several hypotheses have been put forward trying to explain why patients with eosinophilic bronchitis do not have airway hyperresponsiveness. It is unknown whether eosinophilic bronchitis may progress to typical occupational asthma, or if eosinophilic airway inflammation may persist when asthma symptoms and airway hyperresponsiveness have waned after the cessation of exposure to the occupational agent.

SUMMARY

Eosinophilic bronchitis, like asthma, may arise from occupational exposures. The examination of induced sputum should be added to the objective monitoring of lung function during periods at work and away from work, as well as before and after specific inhalation challenges with occupational agents.

Induced sputum assessment in New York City firefighters exposed to World Trade Center dust

New York City Firefighters (FDNY-FFs) were exposed to particulate matter and combustion/pyrolysis products during and after the World Trade Center (WTC) collapse. Ten months after the collapse, induced sputum (IS) samples were obtained from 39 highly exposed FDNY-FFs (caught in the dust cloud during the collapse on 11 September 2001) and compared to controls to determine whether a unique pattern of inflammation and particulate matter deposition, compatible with WTC dust, was present. Control subjects were 12 Tel-Aviv, Israel, firefighters (TA-FFs) and 8 Israeli healthcare workers who were not exposed to WTC dust. All controls volunteered for this study, had never smoked, and did not have respiratory illness. IS was processed by conventional methods. Retrieved cells were differentially counted, and metalloproteinase-9 (MMP-9), particle size distribution (PSD), and mineral composition were measured. Differential cell counts of FDNY-FF IS differed from those of health care worker controls (p < 0.05) but not from those of TA-FFs. Percentages of neutrophils and eosinophils increased with greater intensity of WTC exposure (< 10 workdays or greater than or equal to 10 workdays; neutrophils p = 0.046; eosinophils p = 0.038). MMP-9 levels positively correlated to neutrophil counts (p = 0.002; r = 0.449). Particles were larger and more irregularly shaped in FDNY-FFs (1-50 microm; zinc, mercury, gold, tin, silver) than in TA-FFs (1-10 microm; silica, clays). PSD was similar to that of WTC dust samples. In conclusion, IS from highly exposed FDNY-FFs demonstrated inflammation, PSD, and particle composition that was different from nonexposed controls and consistent with WTC dust exposure.

Induced-sputum particle size distribution and pulmonary function in foundry workers

The authors studied and determined a correlation between the distribution of particle size in induced sputum and pulmonary function tests among 54 foundry workers, of whom 34 had been exposed to a variety of metals. Sputum was induced with an ultrasonic nebulizer and processed by conventional methods; a particle scanner was used to measure particle size. All participants underwent spirometry to measure their flow rates. There were significant differences between the exposed and nonexposed groups with respect to the proportion of particles with diameters greater than 2 microm and with diameters greater than 5 microm. A positive correlation was found between the proportion of particles greater than 5 microm in diameter and the ratio of forced expiratory volume in 1 sec (FEV1.0) to forced vital capacity (FVC) (i.e., FEV1.0/FVC) for all 54 workers, and there was a significant correlation for non-smokers. Correlations by work categories revealed a significant negative correlation among casting workers between particles with diameters greater than 5 microm and percentage of FVC. These findings indicate the value of measuring particle size in induced-sputum specimens as a tool for differentiating between exposed and nonexposed workers. Also indicated was a tendency toward a restrictive pattern in pulmonary function tests among workers who had exposure to higher percentages of large particles.