Inhalation incidents and respiratory health: results from the European Community Respiratory Health Survey

Irritant-Induced Asthma

Irritant-induced asthma (IIA) is a phenotype of asthma caused by the inhalation of irritant agents. Definite, probable, or possible IIA have been described, depending on the concentration of the inhaled irritants and the onset of respiratory symptoms respective to the time of exposure. Definite IIA represents approximately 4% to 14% of all cases of new-onset work-related asthma. Agents responsible for IIA can be encountered as fumes, gases, aerosols, or dusts. The most frequent are chlorine, nitrogen oxides, sulfur dioxide, ammonia, acetic acid, solvents, and cleaning materials. Although the diagnosis of definite IIA is based on a suggestive clinical history along with evidence of reversible airflow limitation and/or nonspecific bronchial hyperresponsiveness, possible IIA cannot be diagnosed with certainty because the relationship between exposure and the onset of symptoms is difficult to establish. This article reviews the epidemiology, pathophysiology, diagnostic approach, and management of IIA.

Post-endotoxin exposure-induced lung inflammation and resolution consequences beneficially impacted by lung-delivered IL-10 therapy

Although lung diseases typically result from long-term exposures, even a robust, one-time exposure can result in long-lasting consequences. Endotoxin is a ubiquitous environmental/occupational inflammatory agent often used to model airway inflammation. Using a murine model, the return to lung homeostasis following high dose inhalant lipopolysaccharide (LPS, 10-100 μg) exposure were delineated over 2 weeks. LPS-induced rapid weight loss, release of proinflammatory mediators, and inflammatory cell influx with prolonged persistence of activated macrophages CD11c⁺CD11b⁺ and recruited/transitioning CD11c^intCD11b⁺ monocyte-macrophages out to 2 weeks. Next, lung-delivered recombinant (r) interleukin (IL)-10 was intratracheally administered for 3 doses initiated 5 h following LPS (10 μg) exposure for 2 days. IL-10 therapy reduced LPS-induced weight loss and increased blood glucose levels. Whereas there was no difference in LPS-induced bronchoalveolar lavage airway fluid cellular influx, total lung cell infiltrates were reduced (37%) with rIL-10 treatment. Post-LPS exposure treatment with rIL-10 strikingly reduced lavage fluid and lung homogenate levels of tumor necrosis factor-α (88% and 93% reduction, respectively), IL-6 (98% and 94% reduction), CXCL1 (66% and 75% reduction), and CXCL2 (47% and 67% reduction). LPS-induced recruited monocyte-macrophages (CD11c^intCD11b⁺) were reduced (68%) with rIL-10. Correspondingly, LPS-induced lung tissue CCR2⁺ inflammatory monocyte-macrophage were reduced with rIL-10. There were also reductions in LPS-induced lung neutrophils, lymphocyte subpopulations, collagen content, and vimentin expression. These findings support the importance of studying resolution processes for the development of treatment after unintended environmental/occupational biohazard exposures. Short-term, lung-delivered rIL-10 favorably hastened inflammatory recovery processes following acute, high dose inhalant LPS exposure.

Occupational inhalational accidents: analysis of cases from the UK SWORD reporting scheme from 1999 to 2018

OBJECTIVE

To estimate the reported UK incidence of occupational inhalation accidents, and to consider changes of incidence and potential causes over time.

METHODS

Cases of occupational inhalation accident reported to Surveillance of Work Related Occupational Respiratory Diseases (SWORD) over 20 years were grouped into four 5-year time periods. Cases were characterised by causative exposure, occupation and industrial sector. Incidence rates were calculated using Office of National Statistics employment data.

RESULTS

The 172 actual cases reported to SWORD equated to an estimated 502 cases after adjusting for reporting frequency. Their mean age was 41.3 years (SD 12.3); 77% were male. The annual incidence fell from 1.7 per million employed in the first 5-year period, to 0.5 in the most recent. The most common occupations, responsible for 35% of all cases, were in descending order (number, % of total cases): Labourers in process and plant operations (8, 4.7), welding trades (8, 4.7), fire service officers (8, 4.7), heavy goods vehicle drivers (7, 4.1), metal working production and maintenance fitters (7, 4.1), civil service administrative officers and assistants (7, 4.1), food, drink and tobacco process operatives (6, 3.5), and three summated categories of elementary and service occupations including cleaners and domestics (10, 5.8).Three of 40 exposure categories were common to all time periods; acids (19.6% of all cases 1999-2004, 2.3% 2005-2009, 6.3% 2010-2013, 6.3% 2014-2018), chlorine/hypochlorites (7.2%, 7.0%, 2.5%, 6.3%, respectively) and solvents (14.4%, 11.6%, 12.5%, 6.3%, respectively).

CONCLUSIONS

The incidence of inhalation accidents appears to have fallen, although certain exposures appear to be persistently linked to cases.

EAACI position paper: irritant-induced asthma

The term irritant-induced (occupational) asthma (IIA) has been used to denote various clinical forms of asthma related to irritant exposure at work. The causal relationship between irritant exposure(s) and the development of asthma can be substantiated by the temporal association between the onset of asthma symptoms and a single or multiple high-level exposure(s) to irritants, whereas this relationship can only be inferred from epidemiological data for workers chronically exposed to moderate levels of irritants. Accordingly, the following clinical phenotypes should be distinguished within the wide spectrum of irritant-related asthma: (i) definite IIA, that is acute-onset IIA characterized by the rapid onset of asthma within a few hours after a single exposure to very high levels of irritant substances; (ii) probable IIA, that is asthma that develops in workers with multiple symptomatic high-level exposures to irritants; and (iii) possible IIA, that is asthma occurring with a delayed-onset after chronic exposure to moderate levels of irritants. This document prepared by a panel of experts summarizes our current knowledge on the diagnostic approach, epidemiology, pathophysiology, and management of the various phenotypes of IIA.