Causes and Phenotypes of Work-Related Asthma

Multivariate analysis and data mining help predict asthma exacerbations

BACKGROUND

Work-related asthma has become a highly prevalent occupational lung disorder.

OBJECTIVE

Our study aims to evaluate occupational exposure as a predictor for asthma exacerbation.

METHOD

We performed a retrospective evaluation of 584 consecutive patients diagnosed and treated for asthma between October 2017 and December 2019 in four clinics from Western Romania. We evaluated the enrolled patients for their asthma control level by employing the Asthma Control Test (ACT < 20 represents uncontrolled asthma), the medical record of asthma exacerbations, occupational exposure, and lung function (i.e. spirometry). Then, we used statistical and data mining methods to explore the most important predictors for asthma exacerbations.

RESULTS

We identified essential predictors by calculating the odds ratios (OR) for the exacerbation in a logistic regression model. The average age was 45.42 ± 11.74 years (19-85 years), and 422 (72.26%) participants were females. 42.97% of participants had exacerbations in the past year, and 31.16% had a history of occupational exposure. In a multivariate model analysis adjusted for age and gender, the most important predictors for exacerbation were uncontrolled asthma (OR 4.79, p < .001), occupational exposure (OR 4.65, p < .001), and lung function impairment (FEV1 < 80%) (OR 1.15, p = .011). The ensemble machine learning experiments on combined patient features harnessed by our data mining approach reveal that the best predictor is professional exposure, followed by ACT.

CONCLUSIONS

Machine learning ensemble methods and statistical analysis concordantly indicate that occupational exposure and ACT < 20 are strong predictors for asthma exacerbation.

Chronic occupational exposures to irritants and asthma in the CONSTANCES cohort

OBJECTIVES

The impact of chronic occupational exposures to irritants on asthma remains discussed. We studied the associations between occupational exposures and asthma, with specific interest for chronic exposure to irritants, including disinfectants and cleaning products (DCPs) and solvents.

METHODS

Cross-sectional analyses included 115 540 adults (55% women, mean age 43 years, 10% current asthma) working at inclusion in the French population-based CONSTANCES cohort (2012-2020). Current asthma was defined by ever asthma with symptoms, medication or asthma attacks (past 12 months), and the asthma symptom score by the sum of 5 respiratory symptoms (past 12 months). Both lifetime and current occupational exposures were assessed by the Occupational Asthma-specific Job-Exposure Matrix. Associations were evaluated by gender using logistic and binomial negative regressions adjusted for age, smoking status and body mass index.

RESULTS

In women, associations were observed between current asthma and lifetime exposure to irritants (OR 1.05, 95% CI 1.00 to 1.11), DCPs (1.06, 95% CI 1.00 to 1.12) and solvents (1.06, 95% CI 0.98 to 1.14). In men, only lifetime exposure to DCPs (1.10, 95% CI 1.01 to 1.20) was associated with current asthma. Lifetime exposure to irritants was associated with higher asthma symptom score both in women (mean score ratio: 1.08, 95% CI 1.05 to 1.11) and men (1.11, 95% CI 1.07 to 1.15), especially for DCPs (women: 1.09, 95% CI 1.06 to 1.13, men: 1.21, 95% CI 1.15 to 1.27) and solvents (women 1.14, 95% CI 1.10 to 1.19, men: 1.10, 95% CI 1.05 to 1.15). For current exposures, no consistent associations were observed with current asthma and asthma symptom score.

CONCLUSIONS

Lifetime occupational exposures to irritants were associated with current asthma and higher asthma symptom score. These exposures should be carefully considered in asthma management.

Identification of toxicity-induced biomarkers in human non-immune airway cells exposed to respiratory sensitizers: A mechanistic approach

Occupational asthma covers a group of work-related diseases whose clinical manifestations include airway hyperresponsiveness and airflow limitation. Although the chemical respiratory allergy (CRA) induced by Low Molecular Weight (LMW) sensitizers is a major concern, especially in terms of the regulatory framework, to date there are no methods available for preclinically addressing this toxicological outcome, as its mechanistic background is not fully understood at molecular or cellular levels. This paper proposes a mechanistic study applying New Approach Methodologies (NAM) of the pro-inflammatory and functional effects triggered by LMW respiratory allergens in different respiratory tract cell lines, including bronchial epithelial (BEAS-2B), lung fibroblast (MRC-5), and endothelial cells (EA.hy926), and an analysis of the capacity of such chemicals to interact with the mucin protein, to address certain toxicodynamic aspects of such compounds. The results showed that some of the sensitizers evaluated interact with mucin, the main protein mucus component, but the toxicant-mucin complex formation does not seem to be a common feature of different chemical classes of allergens. At a cellular level, sensitizers promoted an increase in IL-8, IL-6, and IL-1β production in the evaluated cell types. It also impaired the MUC1 expression by bronchial cells and activated endothelial cells, thereby increasing the ICAM-I surface expression. Taken together, our results showed that these aforementioned cell types participate in the CRA Adverse Outcome Pathway and must be considered when developing preclinical testing strategies, particularly investigating danger signal production after exposure to LMW sensitizers in different tissue compartments.

Characterization and applicability of a novel physiologically relevant 3D-tetraculture bronchial model for in vitro assessment of respiratory sensitization

Chemical Respiratory Allergy (CRA) is triggered after exposure to Low Molecular Weight (LMW) sensitizers and manifests clinically as asthma and rhinitis. From a risk/toxicity assessment point of view, there are few methods, none of them validated, for evaluating the respiratory sensitization potential of chemicals once the in vivo-based models usually employed for inhalation toxicity addressment do not comprise allergenicity endpoints specifically. Based on that, we developed, characterized, and evaluated the applicability of a 3D-tetraculture airway model reconstructed with bronchial epithelial, fibroblasts, endothelial and monocytic cell lines. Moreover, we exposed the tissue to maleic anhydride (MA) aerosols to challenge the model and subsequently assessed inflammatory and functional aspects of the tissue. The reconstructed tissue presented phenotypic biomarkers compatible with human bronchial epithelium, and MA aerosol exposure triggered an increased IL-8 and IL-6 production, reactive oxygen species (ROS) formation, and apoptosis of epithelial cells. Besides, augmented IL-8 production by monocytic cells was also found, correlating with dendritic cell activation within the co-culture model after MA exposure. Our results demonstrated that the 3D-tetraculture bronchial model presents hallmarks related to human airways' structure and function. Additionally, exposure to a respiratory sensitizer induced inflammatory and functional alterations in the reconstructed tissue, rendering it a valuable tool for exploring the mechanistic framework of chemically induced respiratory sensitization.

Global patterns of asthma burden related to environmental risk factors during 1990-2019: an age-period-cohort analysis for global burden of disease study 2019

BACKGROUND

Change in asthma burden attributed to specific environmental risk factor has not been evaluated.

OBJECTIVE

We aimed to explore the age, period, and cohort effects on asthma burden attributable to smoking and occupational asthmagens in different socio-demographic index (SDI) regions and the region and sex disparities.

METHODS

Risk factor-specific asthma deaths and disability-adjusted life years (DALYs) rates were extracted from Global Burden of Disease study 2019, estimated by standard Combined Cause of Death Model and DisMod-MR 2.1 modeling tool. Age-period-cohort analysis was conducted to decompose age, period, and cohort effects on asthma burden.

RESULTS

Smoking- and occupational asthmagens-related asthma deaths and DALYs rates dropped by > 45% during 1990-2019. In 2019, Africa, South and Southeast Asia had higher asthma burden than other regions. Male had higher asthma burden than female. Among nearly all age groups, low-middle SDI region had the highest smoking-related asthma burden, and low SDI region had the highest occupational asthmagens-related asthma burden. Inverse "V" shaped trend was observed in the above regions with increasing age. For smoking-related asthma deaths and DALYs rates, the most significant improvement of period rate ratio (RR) occurred in high SDI region, decreased from 1.67 (1.61, 1.74) to 0.34 (0.33, 0.36) and 1.61 (1.57, 1.66) to 0.59 (0.57, 0.61), respectively, as well as the cohort effect on smoking-related asthma burden. For occupational asthmagens-related asthma deaths and DALYs rates, the most sharply decrease of period and cohort RR appeared in the high and high-middle SDI regions. Low SDI region showed least progress in period and cohort RR of smoking- and occupational asthmagens-linked asthma burden.

CONCLUSION

Smoking- and occupational asthmagens-related asthma burden sharply decreases, but region and sex disparities exist. Policy makers from low SDI region should reinforce tobacco control and prioritize workplace protection.

Systematic review and meta-analysis of the potential threats to respiratory health from microbial Bioaerosol exposures

Infectious diseases are a part of everyday life, and acute respiratory diseases are the most common. Many agents carrying out respiratory infections are transmitted as bioaerosols through the air, usually, particulate matter containing living organisms. The purpose of the study is to conduct a systematic review and meta-analysis to assess the likelihood that people exposed to bioaerosols may experience severe respiratory diseases. Nine digital databases and bibliographies were assessed for papers conducted between January 1960 and April 2021. A total of 35 health and exposure studies were included from 825 studies for the systematic review, while only 17 contented the meta-inclusion analysis's criteria. This systematic review found higher bacterial bioaerosol concentrations in poultry farms, waste dumpsites, composting plants, and paper industries. The meta-analysis's Standard Mean Difference (SMD) measurement indicates a substantially positive association between bioaerosol exposure and respiratory disease outcomes in targeted populations. The value is 0.955 [95% CI, range 0.673-1.238; p < 0.001]. As per the Risk of Bias (ROB) findings, most of findings (30 out of 35 [85.71%]) were judged to have low ROB. From the random effect probit model, the total relative risk is 1.477 (95% CI, range 0.987-2.211), indicating a higher risk of respiratory diseases from bioaerosol exposure than the control groups. The total risk difference is 0.121 (95% CI, -0.0229 to 0.264), which means intervention groups may have a higher risk of respiratory diseases from continuous bioaerosol exposure than the control groups. The dose-response relationship revealed a strong positive linear coefficient correlation between bacterial & fungal bioaerosol exposure to respiratory health. Based on self-reported outcomes in those studies, The systematic review and meta-analysis stated that bioaerosol exposure had an effect on pulmonary health.

Winds of change a tale of: asthma and microbiome

The role of the microbiome in asthma is highlighted, considering its influence on immune responses and its connection to alterations in asthmatic patients. In this context, we review the variables influencing asthma phenotypes from a microbiome perspective and provide insights into the microbiome's role in asthma pathogenesis. Previous cohort studies in patients with asthma have shown that the presence of genera such as Bifidobacterium, Lactobacillus, Faecalibacterium, and Bacteroides in the gut microbiome has been associated with protection against the disease. While, the presence of other genera such as Haemophilus, Streptococcus, Staphylococcus, and Moraxella in the respiratory microbiome has been implicated in asthma pathogenesis, indicating a potential link between microbial dysbiosis and the development of asthma. Furthermore, respiratory infections have been demonstrated to impact the composition of the upper respiratory tract microbiota, increasing susceptibility to bacterial diseases and potentially triggering asthma exacerbations. By understanding the interplay between the microbiome and asthma, valuable insights into disease mechanisms can be gained, potentially leading to the development of novel therapeutic approaches.

Update on irritant-induced occupational asthma

PURPOSE OF REVIEW

In this narrative review, we aim to highlight novel research findings on both acute/subacute irritant-induced asthma (IIA) and chronic exposure IIA (also called 'low dose' IIA).

RECENT FINDINGS

Novel case series showed that acute and subacute IIA cases had similar causal agents (e.g., acid or base aerosols/fumes, dusts, mixtures) but had occurred in different circumstances (accidents vs. regular work). Acute and subacute IIA cases had similar clinical characteristics but poorer short-term outcomes than sensitizer-induced occupational asthma patients. Novel large epidemiological studies reported associations between chronic occupational exposure to irritants and current adult-onset asthma and poor asthma control, and with a specific asthma endotype characterized by neutrophilic inflammation and oxidative stress. Recent studies reconfirmed the association of the use of disinfectants and cleaning products (especially sprays) with IIA. A role for genetic susceptibility has been suggested.

SUMMARY

Recent literature provided further understanding of both acute/subacute and chronic exposure IIA, in terms of causes, possible mechanisms, and consequences such as poor asthma control. Research is needed to clarify several aspects of IIA, including its frequency (still likely underestimated), modulating factors, and mechanisms. Research aiming at improving irritant exposure assessment, including intensity/duration, and determining relevant exposure windows would be welcome.

Loss to 5-year follow-up in the population-based Telemark Study: risk factors and potential for bias

OBJECTIVES

This study aimed to characterise participants lost to follow-up and identify possible factors associated with non-participation in a prospective population-based study of respiratory health in Norway. We also aimed to analyse the impact of potentially biased risk estimates associated with a high proportion of non-responders.

DESIGN

Prospective 5-year follow-up study.

SETTING

Randomly selected inhabitants from the general population of Telemark County in south-eastern Norway were invited to fill in a postal questionnaire in 2013. Responders in 2013 were followed-up in 2018.

PARTICIPANTS

16 099 participants aged 16-50 years completed the baseline study. 7958 responded at the 5-year follow-up, while 7723 did not.

MAIN OUTCOME MEASURES

χ² test was performed to compare demographic and respiratory health-related characteristics between those who participated in 2018 and those who were lost to follow-up. Adjusted multivariable logistic regression models were used to assess the relationship between loss to follow-up, background variables, respiratory symptoms, occupational exposure and interactions, and to analyse whether loss to follow-up leads to biased risk estimates.

RESULTS

7723 (49%) participants were lost to follow-up. Loss to follow-up was significantly higher for male participants, those in the youngest age group (16-30 years), those in lowest education level category and among current smokers (all p<0.001). In multivariable logistic regression analysis, loss to follow-up was significantly associated with unemployment (OR 1.34, 95% CI 1.22 to 1.46), reduced work ability (1.48, 1.35 to 1.60), asthma (1.22, 1.10 to 1.35), being woken by chest tightness (1.22, 1.11 to 1.34) and chronic obstructive pulmonary disease (1.81, 1.30 to 2.52). Participants with more respiratory symptoms and exposure to vapour, gas, dust and fumes (VGDF) (1.07 to 1.00-1.15), low-molecular weight (LMW) agents (1.19, 1.00 to 1.41) and irritating agents (1.15, 1.05 to 1.26) were more likely to be lost to follow-up. We found no statistically significant association of wheezing and exposure to LMW agents for all participants at baseline (1.11, 0.90 to 1.36), responders in 2018 (1.12, 0.83 to 1.53) and those lost to follow-up (1.07, 0.81 to 1.42).

CONCLUSION

The risk factors for loss to 5-year follow-up were comparable to those reported in other population-based studies and included younger age, male gender, current smoking, lower educational level and higher symptom prevalence and morbidity. We found that exposure to VGDF, irritating and LMW agents can be risk factors associated with loss to follow-up. Results suggest that loss to follow-up did not affect estimates of occupational exposure as a risk factor for respiratory symptoms.

Occupational Exposures to Irritants and Sensitizers, Asthma and Asthma Control in the Nutrinet-Santé Cohort

BACKGROUND

The role of chronic occupational exposures to irritants in asthma remains not well-defined. Few studies have examined their associations with asthma and its control.

OBJECTIVE

To study the associations of occupational exposures with asthma and its control, with specific interest for irritants, including disinfectants and cleaning products (DCPs) and solvents.

METHODS

Analyses included 4,469 adults (3,792 with neither asthma nor respiratory symptoms, 677 with current asthma; 75.9% women, mean age 54 years) of a case-control study (2018) from the French NutriNet-Santé cohort. Current asthma was defined by ever asthma with symptoms, medication or asthma attacks in the past 12 months, adult-onset asthma by age at first asthma attack older than 16 years, and uncontrolled asthma was defined by an Asthma Control Test score less than 20. Ever/current exposures were assessed with the Occupational Asthma-specific Job Exposure Matrix. Associations were evaluated by multinomial logistic regressions adjusted for sex, age, smoking status, and body mass index.

RESULTS

Ever exposures to sensitizers (high molecular weight [HMW]: OR 1.53, 95% CI 1.18-2.00; and low molecular weight [LMW]: OR 1.42; 95% CI 1.09-1.87), irritants (OR 1.32; 95% CI 1.03-1.68), and DCPs (OR 1.43; 95% CI 1.10-1.85) were associated with current adult-onset asthma. Significant associations between ever exposures and uncontrolled adult-onset asthma were observed for high molecular weight (OR 2.69; 95% CI 1.52-4.78) and low molecular weight (OR 2.27; 95% CI 1.24-4.37) sensitizers, irritants (OR 2.32; 95% CI 1.36-3.95), and DCPs (OR 2.59; 95% CI 1.48-4.54). Results were similar for current exposures, with higher ORs. No association was observed with solvents.

CONCLUSIONS

Occupational exposures to both sensitizers and irritants were associated with current adult-onset asthma and uncontrolled asthma. Irritant and sensitizing agents should be carefully considered in asthma management.

Association between asthma and work absence in working adults in the United States

The present study aimed to investigate the association between asthma and work absence in a large sample of US working adults, while controlling for several sociodemographic and health characteristics. This study used data from the 2019 Health and Functional Capacity Survey of the RAND American Life Panel (ALP). Work absence corresponded to the number of days of absence from work for health-related reasons in the past 12 months. Current asthma was self-reported and was included in the analyses as a dichotomous variable. Control variables included sex, age, ethnicity, marital status, education, occupation, annual family income, health insurance, and number of chronic physical or psychiatric conditions. Finally, the association between asthma and work absence was analyzed using logistic regression models. This study included 1,323 adults aged 22-65 years (53.1% males; mean [SD] age 43.1 [11.7] years). Individuals with asthma were more likely to report at least one (81.5% versus 56.8%, p-value <0.001) or three days of absence (56.9% versus 31.3%, p-value =0.003) from work in the past 12 months than those without asthma. These findings were corroborated in the regression analyses, as asthma was positively and significantly associated with work absence after adjusting for all control variables (at least one day of absence: OR =3.24, 95% CI =1.44-7.29; at least three days of absence: OR =2.61, 95% CI =1.26-5.40). This US study of working adults showed that asthma was a risk factor for work absence. Further research is warranted to better understand the factors predisposing to work absence in the asthma population.

Screening tools for work-related asthma and their diagnostic accuracy: a systematic review protocol

INTRODUCTION

Work-related asthma (WRA) refers to asthma caused by exposures at work (occupational asthma) and asthma made worse by work conditions (work-exacerbated asthma). WRA is common among working-age adults with asthma and impacts individual health, work-life and income but is often not detected by healthcare services. Earlier identification can lead to better health and employment outcomes. However, the optimal tool for screening and its effectiveness in practice is not well established. Screening tools may include whole questionnaires, questionnaire items, physiological measurements and/or immunological tests. Since the publication of the most contemporary WRA or occupational asthma-specific guidelines, further studies evaluating tools for identifying WRA have been performed. Our systematic review aims to summarise and compare the performance of screening tools for identifying WRA in both clinical and workplace settings.

METHODS AND ANALYSIS

We will conduct a systematic review of observational and experimental studies (1975-2021) using MEDLINE, EMBASE, CINAHL Plus, Web of Science, CDSR, DARE, HTA, CISDOC databases and grey literature. Two independent reviewers will screen the studies using predetermined criteria, extract data according to a schedule and assess study quality using the Quality Assessment of Diagnostic Test Accuracy 2 tool. Screening tools and test accuracy measures will be summarised. Paired forest plots and summary receiver operating characteristic curves of sensitivities and specificities will be evaluated for heterogeneity between studies, using subgroup analyses, where possible. If the studies are sufficiently homogenous, we will use a bivariate random effect model for meta-analysis. A narrative summary and interpretation will be provided if meta-analysis is not appropriate.

ETHICS AND DISSEMINATION

As this is a systematic review and does not involve primary data collection, formal ethical review is not required. We will disseminate our findings through open access peer-reviewed publication as well as through other academic and social media.

PROSPERO REGISTRATION NUMBER

CRD42021246031.

Methyl methacrylate and respiratory sensitisation: a comprehensive review

Methyl methacrylate (MMA) is classified under GHS as a weak skin sensitiser and a skin and respiratory irritant. It has recently been proposed that MMA be classified as a respiratory sensitiser (a designation that in a regulatory context embraces both true respiratory allergens, as well as chemicals that cause asthma through non-immunological mechanisms). This proposal was based primarily upon the interpretation of human data. This review, and a detailed weight of evidence analysis, has led to another interpretation of these data. The conclusion drawn is that persuasive evidence consistent with the designation of MMA as a respiratory sensitiser is lacking. It is suggested that one reason for different interpretations of these data is that occupational asthma poses several challenges with respect to establishing causation. Among these is that it is difficult to distinguish between allergic asthma, non-allergic asthma, and work-related exacerbation of pre-existing asthma. Moreover, there is a lack of methods for the identification of true chemical respiratory allergens. The characterisation and causation of occupational asthma is consequently largely dependent upon interpretation of human data of various types. Recommendations are made that are designed to improve the utility and interpretation of human data for establishing causation in occupational asthma.

Respiratory symptoms and use of dust-control measures in New Zealand construction workers – A cross-sectional study

Dust-exposed construction workers have an increased risk of respiratory symptoms, but the efficacy of dust-control measures remains unclear. This study compared respiratory symptoms, using a modified European Community Respiratory Health Survey questionnaire, between construction workers (n = 208) and a reference group of bus drivers and retail workers (n = 142). Within the construction workers, we assessed the effect of collective (on-tool vacuum/’wet-cut’ systems) and personal (respirators) exposure controls on symptom prevalence. Logistic regression assessed differences between groups, adjusted for age, ethnicity, and smoking status. Construction workers were more likely to cough with phlegm at least once a week (OR 2.4, 95% CI 1.2–4.7) and cough with phlegm ≥3 months/year for ≥2 years (OR 2.8, CI 1.2–7.0), but they had similar or fewer asthma symptoms. Construction workers who had worked for 11–20 years reported more cough/phlegm symptoms (OR 5.1, 1.7–15.0 for cough with phlegm ≥3 months/year for ≥2 years) than those who had worked <10 years (OR 1.9, 0.6–5.8), when compared to the reference group. Those who used ‘wet-cut’ methods reported less cough with phlegm, although the evidence for this association was weak (OR 0.4, CI 0.2–1.1 for cough with phlegm at least once a week); use of on-tool extraction showed a similar trend. No associations between respiratory protective equipment-use and symptoms were found. In conclusion, construction workers reported more symptoms suggestive of bronchitis, particularly those employed in the industry for >10 years. Use of collective dust exposure controls might protect against these symptoms, but this requires confirmation in a larger study.

Occupational Asthma: The Knowledge Needs for a Better Management

The management of occupational asthma (OA) may be influenced by several factors and removal from exposure is the main tertiary prevention approach, but it is not always feasible without personal and socioeconomic consequences. Reducing the delay between the onset of suggestive symptoms of OA and the diagnosis of OA is associated with a better prognosis. Workers' education to increase awareness to trigger agents and a medical surveillance program directed especially at at-risk workers could be helpful in reducing this latency time. An early identification of workers who develop rhinitis and conjunctivitis which often precede the onset of asthma symptoms could be important for an early identification of OA. This is particularly important for cases of asthma caused by high-molecular-weight sensitizers and in the early years of employment. The availability of financial support and compensation measures for workers with OA may influence the latency time before diagnosis and, consequently, may influence the OA outcomes. In conclusion, there is a need for high-quality cohort studies that will increase knowledge about risk factor that may influence the timing of diagnosis of OA. This knowledge will be useful for implementation of future surveillance and screening programs in workplaces.

Occupational chronic obstructive pulmonary disorder: prevalence and prevention

INTRODUCTION

Occupational chronic obstructive pulmonary disorder, i.e. work-related asthma (WRA) and occupational chronic obstructive pulmonary disease (COPD), are the most common occupational lung diseases in the last decades worldwide. As in the case of the other occupational disorders, these diseases may be prevented.

AREAS COVERED

WRA is a heterogeneous entity that includes three subtypes, immunologic occupational asthma (OA), irritant-induced asthma (IIA), and work-exacerbated asthma (WEA), depending on the role of occupational exposures as a causing or aggravating factor of the disease. In addition, there is consistent evidence that a substantial proportion of COPD cases can be explained by exposure to noxious particles and gases other than tobacco smoke, such as workplace dusts, gases, fumes, and vapors. The articles cited in this paper were searched by keywords in several databases in the period up to May-July 2021.

EXPERT OPINION

The development of occupational chronic obstructive disorder is a matter of prevention. WRA and occupational COPD contribute significantly to the overall burden of asthma and COPD. Activities and measures targeted to elimination or reduction of harmful workplace exposures, as well as to early detection and early intervention in the course of the lung damage, can significantly reduce the burden caused by these diseases.

[A definition of work-related asthma and its social and occupational consequences in adults and teenagers]

Work-related asthma (WRA) accounts for 10-25% of all adult asthma. It therefore seems important to raise questions regarding an asthmatic's approach to occupational or job training activities. WRA takes on two forms: work-exacerbated asthma (WEA) and occupational asthma (OA), which encompasses different subtypes of heterogeneous mechanisms. It currently represents a major challenge for occupational medicine in terms of detailed diagnosis, social care, the economic repercussions for workers and employers and, last but not least, social insurance. This review aims to sensitize health care practitioners to the peculiarities of WRA management in routine practice. More specifically, prognosis depends on early diagnosis, medical care and work adjustment measures. WEA and OA are explained in detail in view of identifying causative agents and at-risk occupations and defining adapted medical strategy. Relevant lines of questioning and complementary exams are presented. In addition, the key role of the occupational physician, especially as regards recognition and identification of occupational disease, is underlined, the objective being to facilitate optimal professional and social management. In future studies, the key role of counseling and orientation mechanisms should be highlighted as means of preventing WRA occurrence.

Occupational Exposures to Organic Solvents and Asthma Symptoms in the CONSTANCES Cohort

Solvents are used in many workplaces and may be airway irritants but few studies have examined their association with asthma. We studied this question in CONSTANCES (cohort of ‘CONSulTANts des Centres d’Examens de Santé’), a large French cohort. Current asthma and asthma symptom scores were defined by participant-reported respiratory symptoms, asthma medication or attacks, and the sum of 5 symptoms, in the past 12 months, respectively. Lifetime exposures to 5 organic solvents, paints and inks were assessed by questionnaire and a population-based Job-Exposure Matrix (JEM). Cross-sectional associations between exposures and outcomes were evaluated by gender using logistic and negative binomial regressions adjusted for age, smoking habits and body mass index. Analyses included 115,757 adults (54% women, mean age 47 years, 9% current asthma). Self-reported exposure to ≥1 solvent was significantly associated with current asthma in men and women, whereas using the JEM, a significant association was observed only in women. Significant associations between exposures to ≥1 solvent and asthma symptom score were observed for both self-report (mean score ratio, 95%CI, women: 1.36, 1.31–1.42; men: 1.34, 1.30–1.40) and JEM (women: 1.10, 1.07–1.15; men: 1.14, 1.09–1.18). Exposure to specific solvents was significantly associated with higher asthma symptom score. Occupational exposure to solvents should be systematically sought when caring for asthma.

Work-related asthma

Work-related asthma (WRA) is highly prevalent in the adult population. WRA includes occupational asthma (OA), which is asthma caused by workplace exposures, and work-exacerbated asthma (WEA), also known as work-aggravated asthma, which is preexisting or concurrent asthma worsened by workplace conditions. In adults, the estimated prevalence of OA is 16.0%, whereas that of WEA is 21.5%. An increasing number of chemicals used in industrial production, households, and services are associated with the incidence of adult-onset asthma attributable to exposure to chemicals. This review article summarizes the different types of WRA and describes diagnostic procedures, treatment, prevention, and approaches to patient management. It is not always easy to distinguish between OA and WEA. It is important to establish a diagnosis (of sensitizer-/irritant-induced OA or WEA) in order to prevent worsening of symptoms, as well as to prevent other workers from being exposed, by providing early treatment and counseling on social security and work-related issues.

Endotyping asthma related to three different work exposures

BACKGROUND

Work exposures play a significant role in adult-onset asthma, but mechanisms of work-related asthma are not fully elucidated.

OBJECTIVE

We aimed to reveal the molecular mechanisms of work-related asthma associated with flour (FA), isocyanate (IA) or welding fume (WA) exposures and identify potential biomarkers that distinguish these groups from each other.

METHODS

We used a combination of clinical tests, transcriptomic analysis and associated pathway analyses to investigate underlying disease mechanisms of the blood immune cells and the airway epithelium of 61 men.

RESULTS

Compared to the healthy controls, the WA patients had more differentially expressed genes than the FA and IA patients both in the airway epithelia and in the blood immune cells. In the airway epithelia, active inflammation was detected only in WA patients. In contrast, large number of differentially expressed genes were detected in all asthma groups in blood cells. Disease-related immune functions in blood cells were suppressed in all the asthma groups including leukocyte migration and inflammatory responses and decreased expression of upstream cytokines such as TNF and IFNγ. In transcriptome-phenotype correlations, hyperresponsiveness (R∼|0.6|) had the highest clinical relevance and associated with a set of exposure-group specific genes. Finally, biomarker subsets of only 5 genes specifically distinguished each of the asthma exposure group.

CONCLUSIONS

This study provides novel data on the molecular mechanisms underlying work-related asthma. We identified set of 5 promising biomarkers in asthma related to flour, isocyanate and welding exposure to be tested and clinically validated in future studies.

Classification of chemicals as respiratory allergens based on human data: Requirements and practical considerations

Occupational asthma is an important health problem that can include exacerbation of existing asthma, or induce new asthma either through allergic sensitisation, or non-immunological mechanisms. While allergic sensitisation of the respiratory tract can be acquired to proteins, or to low molecular weight chemicals (chemical respiratory allergens) this article is on the latter exclusively. Chemical respiratory allergy resulting in occupational asthma is associated with high levels of morbidity and there is a need, therefore, that chemicals which can cause sensitisation of the respiratory tract are identified accurately. However, there are available no validated, or even widely accepted, predictive test methods (in vivo, in vitro or in silico) that have achieved regulatory acceptance for identifying respiratory sensitising hazards. For this reason there is an important reliance on human data for the identification of chemical respiratory allergens, and for distinguishing these from chemicals that cause occupational asthma through non-immunological mechanisms. In this article the reasons why it is important that care is taken in designating chemicals as respiratory allergens are reviewed. The value and limitations of human data that can aid the accurate identification of chemical respiratory allergens are explored, including exposure conditions, response characteristics in specific inhalation challenge tests, and immunological investigations.