Long-Term Impairment From Irritant-Induced Occupational Asthma.

OBJECTIVE: The aim of the study is to assess the long-term physical condition, health-related quality of life, employment, and work ability of irritant-induced asthma (IIA) patients. METHODS: Forty-three IIA patients completed a follow-up questionnaire a median of eight (interquartile range 4-11) years after asthma diagnosis. We compared their results with those of 43 low-molecular-weight (LMW) sensitizer-induced occupational asthma (OA) patients and those of 206 adult-onset asthmatics in the general population. RESULTS: Of the IIA patients, 40% reported depressive symptoms. Of the <65-year-olds, 56% were employed, of whom 39% assessed their work ability as limited. IIA patients had more difficulty climbing several flights of stairs than LMW-induced OA patients (70% vs 47%, OR = 4.83 95% CI: 1.51-15.47). Most of the IIA patients' outcomes were inferior to those of the adult-onset asthmatics in the general population. CONCLUSIONS: IIA prognosis appeared poor but resembled that of LMW-induced OA.

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 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.

4,4'-Methylene diphenyl diisocyanate exposure induces expression of alternatively activated macrophage-associated markers and chemokines partially through Krüppel-like factor 4 mediated signaling in macrophages.

Occupational exposure to the most widely used monomeric diisocyanate (dNCO), 4,4'-methylene diphenyl diisocyanate (MDI), may lead to the development of occupational asthma (OA). Alveolar macrophages with alternatively activated (M2) phenotype have been implicated in allergic airway responses and the pathogenesis of asthma. Recent in vivo studies demonstrate that M2 macrophage-associated markers and chemokines are induced by MDI-exposure, however, the underlying molecular mechanism(s) by which this proceeds is unclear.Following MDI exposure (in vivo and in vitro) M2 macrophage-associated transcription factors (TFs), markers, and chemokines were determined by RT-qPCR, western blots, and ELISA.Expression of M2 macrophage-associated TFs and markers including Klf4/KLF4, Cd206/CD206, Tgm2/TGM2, Ccl17/CCL17, Ccl22/CCL22, and CCL24 were induced by MDI/MDI-GSH exposure in bronchoalveolar lavage cells (BALCs)/THP-1 macrophages. The expression of CD206, TGM2, CCL17, CCL22, and CCL24 are upregulated by 3.83-, 7.69-, 6.22-, 6.08-, and 1.90-fold in KLF4-overexpressed macrophages, respectively. Endogenous CD206 and TGM2 were downregulated by 1.65-5.17-fold, and 1.15-1.78-fold, whereas CCL17, CCL22, and CCL24 remain unchanged in KLF4-knockdown macrophages. Finally, MDI-glutathione (GSH) conjugate-treated macrophages show increased chemotactic ability to T-cells and eosinophils, which may be attenuated by KLF4 knockdown.Our data suggest that MDI exposure may induce M2 macrophage-associated markers partially through induction of KLF4.

Occupational asthma induced by fish exposure.

Occupational asthma triggered by inhaling fish-derived aerosols is estimated to affect 2-8% of exposed individuals. This primarily affects workers in the fish processing industry. Fishmongers, rarely experience this issue, as recent research found no significant difference in asthma rates compared to a control group. We report the case of a fishmonger who presented with a 1-year history of rhinoconjunctivitis and asthma. The patient attributed these symptoms to his occupational exposure within the fish market environment, which worsened in the cold storage warehouse. Symptoms improved during holidays. Diagnosis involved skin-prick tests, sIgE (ImmunoCAP-specific IgE) measurements, and bronchial challenge tests, confirming occupational asthma from fish bioaerosol exposure. Parvalbumins, common fish proteins, share structural similarities, leading to cross-reactivity in fish allergy sufferers. In this case, sensitivity to rGad c1 (cod parvalbumin) was identified as the primary trigger for the patient's asthma, and responsible for sensitizations observed across various tested fish species.

Total Reactive Isocyanate Group (TRIG) Measurement: A Commentary.

Exposure to airborne isocyanates has, for decades, been a leading cause of occupational asthma. As respiratory sensitizers, isocyanates can induce allergic respiratory diseases with symptoms persisting even without further exposure. As this cause of occupational asthma is recognized it should be almost entirely preventable. In several countries isocyanates are assigned occupational exposure limits based on the total of reactive isocyanate groups (TRIG). The measurement of TRIG has some significant advantages over the measurement of individual isocyanate compounds. This exposure metric is explicit, simplifying calculations, and comparisons across published data. It reduces the risk of underestimating exposure by 'missing' important isocyanate compounds that may be present but are not the target analytes. It allows for quantification of exposure to complex mixtures of isocyanates, di-isocyanates monomers, prepolymers, polyisocyanates, oligomers, and/or intermediate forms. This is becoming increasingly important as more complex isocyanate products are being used in the workplace. There are many methods and techniques for measuring air concentrations/potential exposure to isocyanates. Several established methods have been standardized and published as International Organization for Standardization (ISO) methods. While some may be applied directly for determination of TRIG, others (developed for determination of individual isocyanates), require modification. This commentary aims to highlight the relative merits and limitations of those methods capable of determining TRIG and also considers potential future developments.

[Allergy and immunotoxicology in preventive and clinical medicine from theory to practice: Occupational allergy and isocyanate-induced asthma].

Genetic and environmental factors and their interactions cause diseases and deteriorate health (Genetic and Environmental Interaction). Exposure to environmental factors plays a major role in the deterioration of health in the workplace.Occupational asthma (OA) is a common disorder in the workplace. Approaches to OA are well described and discussed in "Japanese Guideline for Diagnosis and Management of Occupational Allergic Diseases" by the Japanese Society of Occupational and Environmental Allergy. According to the guideline, OA and work-aggravated asthma comprise work-related asthma, and OA can be further divided into two disease entities: sensitizer-induced OA and irritant-induced OA. The guidelines also describe diagnostic and therapeutic strategies for OA. Since a definitive diagnosis of OA requires a comprehensive decision based on a detailed interview on clinical symptoms related to employment status and clinical tests, including inhalation tests of suspected substances as needed, the possibility of OA should be considered as the first step toward diagnosis of the patient. Otherwise, OA may not be diagnosed. Therapeutic strategies include exposure avoidance, environmental arrangements in the workplace, utilization of social resources for workers, and conventional pharmacotherapy for asthma.Artificially synthesized small compounds are used in various industries and can cause allergies. For example, isocyanates are small compounds in the -NCO group, which have been toxicologically studied. It was later shown that isocyanate could cause various nontoxic adverse health effects, including allergic reactions. Since small agents with low molecular weights bind to proteins, detecting their specific immunoglobulin E (IgE) antibodies targeting small compounds is generally difficult. In contrast, isocyanate-specific IgE antibodies are detectable in individuals with isocyanate allergies.Suspecting OA is essential in cases exposed to newly synthesized compounds, or to those that are already known but applied to new uses, which can be better understood and predicted by studying the health effects of isocyanates.Academic interest in various issues related to allergies, immunology, and toxicology in the workplace includes clinical medicine, epidemiology, and epigenetics related to environmental exposure. Further advanced research in these areas is necessary and promising.

New Method to Biomonitor Workers Exposed to 1,6-Hexamethylene Diisocyanate.

Isocyanates such as 1,6-hexamethylene diisocyanate (HDI), 4,4'-methylenediphenyl diisocyanate, and toluene diisocyanate are highly reactive compounds that have a variety of commercial applications, including manufacturing polyurethane foam, elastomers, paints, adhesives, coatings, insecticides, and many other products. Their primary route of occupational exposure is through inhalation. Due to their high chemical reactivity, they are toxic and have adverse effects at the cellular and subcellular levels, leading to irritative and immunological reactions associated with lung disease. High concentrations of isocyanates are strong respiratory irritants. Bronchial sensitization and asthma are among the major adverse clinical reactions associated with low-level chronic exposure to isocyanates. Albumin adducts have been linked to the mechanism of occupational asthma caused by isocyanates. Isocyanates react in vivo with albumin, which is recognized by the immune system. Albumin adducts of isocyanates trigger immune responses and are probably the antigenic basis for isocyanate asthma. Sensitization to isocyanates is the main pathway for adverse health effects. Therefore, markers for the biologically effective dose such as albumin adducts of HDI are needed. A new isocyanate adduct of HDI with lysine─Nε-[(6-amino-hexyl-amino)carbonyl]-lysine (HDI-Lys)─was synthesized and characterized by 1H-NMR, 13C-NMR, and mass spectrometry (MS). Appropriate internal standards─HDI-Lys-4,4'-5,5'-d4 (HDI-d4-Lys) and Nε-[(7-amino-heptyl-amino)carbonyl]-lysine (Hep-Lys)─were synthesized to establish a LC-MS/MS method for the analysis of HDI adducts in in vitro modified albumin and in workers. The presence of HDI-Lys was found after pronase digestion of albumin and confirmed by two independent chromatographic approaches: with a C8 reversed-phase column and with a hydrophilic interaction liquid chromatography column. Quantification was performed with positive electrospray ionization (ESI)-MS. The adduct peak found in vivo was confirmed with the less sensitive negative ESI-MS. In summary, these are new compounds and methods to determine isocyanate-specific adducts with albumin in workers exposed to HDI.

Occupational asthma, rhinitis and contact urticaria in a salmon-processing worker.

We report a case of occupational allergy to salmon combining allergic asthma, allergic rhinitis and allergic contact urticaria in a 59-year-old salmon-processing worker. Parvalbumin is the most common allergen, but indeed sensitisation to tropomyosin, preservatives and spices could occur.

The relationship between toluene diisocyanate exposure and respiratory health problems: A meta-analysis of epidemiological studies.

Human epidemiological studies have shown inconclusive results over the effects of diisocyanates on respiratory health problems. A meta-analysis combined evidence on the association between occupational asthma (OA), respiratory function, and toluene diisocyanate (TDI) inhalation exposure. Sixty-one articles on occupational toluene diisocyanate exposure were identified via two databases. Fourteen studies were included in the meta-analysis. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of the studies. Odds ratios (ORasthma) for the association between TDI exposure compared to non-exposure and OA were calculated. The difference in mean differences (MD) of forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC), and the annual mean change differences-in milliliters per year (mL/yr)-in FEV1 and FVC pulmonary function between TDI exposed and non-exposed, were calculated. When applicable, a random effects meta-analysis was performed. The overall summary ORasthma for TDI exposed versus non-exposed was 1.18 (95% CI = 0.78-1.79). The summary of the predicted mean percentage difference (MD%predicted) between exposed versus non-exposed was 2.96% for FEV1 and 3.75% for FVC. A very small decrease of 5 mL/yr for FEV1 and 10 mL/yr for FVC, respectively, was observed between the exposed and the non-exposed groups. There was moderate to low heterogeneity between study results, and most studies were evaluated as high-quality. This meta-analysis found no statistically significant adverse association between TDI occupational exposure and OA. No meaningful differences in lung function were detected between exposed and unexposed groups.

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.

[Isocyanate-induced asthma].

Isocyanates are often found in workplaces in e.g., glue, paint, plastics and foam products. Asthma caused by isocyanates is one of the most common forms of occupational asthma, though it is difficult to diagnose, as described in this review. It is not possible to demonstrate sensitisation with available allergy tests. A certain diagnosis can only be made with the help of specific bronchial provocation, which is performed at three centres in Denmark. A correct diagnosis is important, as it helps provide optimal treatment as well as alerting the employer, that improvements are needed at the workplace.

Association of GSTM1 and GSTT1 Null Genotypes with Toluene Diisocyanate-Induced Asthma.

BACKGROUND: Toluene diisocyanate (TDI) causes occupational asthma by generating oxidative stress, leading to tissue injury and inflammation. Glutathione transferases (GSTs) are detoxifying enzymes that eliminate oxidative stress. We examined whether the genotypes of the GSTM1 and GSTT1 genes are associated with TDI-induced occupational asthma (TDI-OA). METHODS: The study population consisted of 26 asthmatics with a positive response to the TDI challenge (TDI-PA) and 27 asthmatics with negative responses (TDI-NA). GSTM1 and GSTT1 null and wild-type genotypes were determined using multiplex PCR. The plasma GSTM1 and GSTT1 protein concentrations were determined using ELISA. RESULTS: The GSTM1 null genotype was more frequent in the TDI-PA than in the TDI-NA (77.8 vs. 50.0%, OR = 3.5, p=0.03), while the frequency of the GSTT1 null genotype tended to be higher in the TDI-PA than in the TDI-NA (59.3 vs. 42.3%, OR = 1.98, p=0.21). When analyzed together, the GSTM1/GSTT1 null genotype was more frequent in the TDI-PA than in the TDI-NA (48.2 vs. 15.3%, OR = 6.5, p=0.04). The decline in the FEV in 1 s after TDI challenge was higher with the GSTM1/GSTT1 null than the GSTM1 wild-type/GSTT1 null genotypes (24.29% vs. 7.47%, p=0.02). The plasma GSTM1 level was lower with the GSTM1 null than with the GSTM1 wild-type genotypes both before (13.7 vs. 16.6 ng/mg, p=0.04) and after (12.9 vs. 17.1 ng/mg, p=0.007) the TDI challenge, while the GSTT1 level was not changed with either the GSTT1 null or wild-type genotype. CONCLUSIONS: The GSTM1 null genotype, but not GSTT1 alone, may confer susceptibility to TDI-OA. However, the genetic effect of the GSTM1 null genotype may be enhanced synergistically by the GSTT1 null genotype. The genetic effect of GSTM1 was validated in the plasma as the GSTM1 protein level. Therefore, the GSTM1 and GSTT1 genotypes may be useful diagnostic markers for TDI-OA.

Prevalence and predictors of occupational asthma among workers in detergent and cleaning products industry and its impact on quality of life in El Asher Men Ramadan, Egypt.

Cleaning products are mixtures of many chemical ingredients that are known to contain sensitizers, disinfectants, and fragrances, as well as strong airway irritants which associated with lower respiratory tract and asthma symptoms. The aim of this study is to assess the prevalence and possible risk factors of occupational asthma and its effect on quality of life among workers in detergent and cleaning products industries in El Asher men Ramadan city. This cross-sectional study was conducted on 780 workers. All participants were personally interviewed at their workplaces and were subjected to a questionnaire regarding sociodemographic, work characteristics and asthma symptoms, clinical examination, chest X-ray, spirometer, and bronchodilator test. The prevalence of occupational asthma among the studied workers was 35.4%. Multivariate logistic regression analysis revealed that female gender [odds ratio 1.397; 95% CI 1.09-1.96], manually working participants [odds ratio 3.067; 95% CI 1.72-5.46], and history of atopy [odds ratio 1.596; 95% CI 1.09-2.33] were risk factors for development of occupational asthma. The total mean score of asthma-specific quality of life was significantly lower in asthmatic (5.10 ± 0.49) than non-asthmatic workers (5.89 ± 0.46) (P < 0.01) indicating impairment of quality of life among asthmatic group. Workers in detergent and cleaning products industry are at higher risk for developing occupational asthma that adversely affects their general health and quality of life.

Severe asthma and death in a worker using methylene diphenyl diisocyanate MDI asthma death.

Diisocyanates are well-recognized to cause occupational asthma, yet diisocyanate asthma can be challenging to diagnose and differentiate from asthma induced by other allergens. The present study assesses the potential contribution of methylene diphenyl diisocyanate (MDI) to a workplace fatality. Examination of medical records, tissue, and blood from the deceased worker were undertaken. Formalin-fixed paraffin-embedded lung tissue sections were assessed through histologic and immunochemical stains. Serum MDI-specific IgE and IgG, and total IgE, were measured by enzyme-linked immunosorbent assays and/or Western blot. Information about potential chemical exposures and industrial processes in the workplace were provided by the employer and through interviews with co-workers. Review of the worker's medical records, occupational history, and autopsy findings were consistent with severe asthma as the cause of death, and ruled out cardiac disease, pulmonary embolism, or stroke. Lung pathology revealed hallmarks of asthma including smooth muscle hypertrophy, eosinophilia, basement membrane thickening, and mucus plugging of bronchioles. Immunochemical staining for MDI was positive in the thickened basement membrane of inflamed airways. MDI-specific serum IgE and IgG were significantly elevated and demonstrated specificity for MDI versus other diisocyanates, however, total serum IgE was normal (24 IU/ml). The workplace had recently introduced MDI into the foundry as part of a new process, but MDI air levels had not been measured. Respirators were not required. In summary, post-mortem findings support the diagnosis of diisocyanate asthma and a severe asthma attack at work as the cause of death in a foundry worker.

Association between occupational exposure to irritant agents and a distinct asthma endotype in adults.

AIM: The biological mechanisms of work-related asthma induced by irritants remain unclear. We investigated the associations between occupational exposure to irritants and respiratory endotypes previously identified among never asthmatics (NA) and current asthmatics (CA) integrating clinical characteristics and biomarkers related to oxidative stress and inflammation. METHODS: We used cross-sectional data from 999 adults (mean 45 years old, 46% men) from the case-control and familial Epidemiological study on the Genetics and Environments of Asthma (EGEA) study. Five respiratory endotypes have been identified using a cluster-based approach: NA1 (n=463) asymptomatic, NA2 (n=169) with respiratory symptoms, CA1 (n=50) with active treated adult-onset asthma, poor lung function, high blood neutrophil counts and high fluorescent oxidation products level, CA2 (n=203) with mild middle-age asthma, rhinitis and low immunoglobulin E level, and CA3 (n=114) with inactive/mild untreated allergic childhood-onset asthma. Occupational exposure to irritants during the current or last held job was assessed by the updated occupational asthma-specific job-exposure matrix (levels of exposure: no/medium/high). Associations between irritants and each respiratory endotype (NA1 asymptomatic as reference) were studied using logistic regressions adjusted for age, sex and smoking status. RESULTS: Prevalence of high occupational exposure to irritants was 7% in NA1, 6% in NA2, 16% in CA1, 7% in CA2 and 10% in CA3. High exposure to irritants was associated with CA1 (adjusted OR aOR, (95% CI) 2.7 (1.0 to 7.3)). Exposure to irritants was not significantly associated with other endotypes (aOR range: 0.8 to 1.5). CONCLUSION: Occupational exposure to irritants was associated with a distinct respiratory endotype suggesting oxidative stress and neutrophilic inflammation as potential associated biological mechanisms.

Surveillance of work-related asthma including the emergence of a cannabis-associated case series in Washington State.

OBJECTIVE: We conducted surveillance for work-related asthma (WRA) in Washington State to identify the industry sectors and asthma exposures most commonly affecting injured workers and in need of prevention activities. METHODS: Using workers' compensation data as the primary data source, valid cases were classified as work-aggravated asthma (WAA) or new onset asthma that includes occupational asthma (OA) and reactive airways dysfunction syndrome (RADS). The source of exposure that caused the worker's asthma, their industry and occupation were determined. RESULTS: There were 784 valid work-related asthma cases identified for the period 2009-2016, WAA (n = 529) was most common followed by occupational asthma (n = 127) and RADS (n = 12). The Health Care and Social Assistance industry had the highest number of cases (n = 170) with 82% classified as WAA. The highest overall proportions of new onset asthma are occurring in Agriculture, Forestry, Fishing and Hunting (33% of work related asthma cases), Manufacturing (31%) and Construction (30%). The leading substances associated with new onset asthma across all industries include hop plant dust, wood and cedar dust, mineral and inorganic dust, mold, and cleaning materials. We describe ten cases of cannabis-associated asthma including seven from workers in the legalized cannabis industry, four of whom had OA. CONCLUSION: State-based work-related asthma surveillance is critical in identifying the workers and exposures associated with this occupational disease, including the detection of a case-series in the cannabis industry.