Persistent asthma following accidental exposure to formaldehyde

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.

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.

Exposure to formaldehyde and its potential human health hazards

A widely used chemical, formaldehyde is normally present in both indoor and outdoor air. The rapid growth of formaldehyde-related industries in the past two decades reflects the result of its increased use in building materials and other commercial sectors. Consequently, formaldehyde is encountered almost every day from large segments of society due to its various sources. Many governments and agencies around the world have thus issued a series of standards to regulate its exposure in homes, office buildings, workshops, public places, and food. In light of the deleterious properties of formaldehyde, this article provides an overview of its market, regulation standards, and human health effects.

Adjuvant effects of gaseous formaldehyde on the hyper-responsiveness and inflammation in a mouse asthma model immunized by ovalbumin

Asthma is a complex pulmonary inflammatory disease, which is characterized by airway hyper-responsiveness, airflow obstruction, and airway inflammation. Exposure to a number of chemicals including formaldehyde (FA) can lead to asthma. This study aimed to explore the underlying role of FA exposure in occupational asthma, especially when it is combined with allergen exposure. Balb/c mice were randomly divided into six groups (n = 6/group): (1) saline control; (2) ovalbumin (OVA)-immunized (OVA(imm)) only; (3) 0.5 mg FA/m(3) exposure; (4) OVA(imm) + 0.5 mg FA/m(3); (5) 3.0 mg FA/m(3) FA exposure; and, (6) OVA(imm) + 3.0 mg FA/m(3). These low and high exposure FA levels were adopted from current (0.5 mg/m(3)) and original (3.0 mg/m(3)) Chinese Occupational Threshold Limit Values. Experiments were conducted after 3 week of combined exposure and a 1-week challenge with aerosolized OVA. Airway hyper-responsiveness, pulmonary tissue damage, eosinophil infiltration, and increased interleukin (IL)-4 and IL-6 levels in lung tissues were found in the OVA + 3.0 mg FA/m(3) hosts as compared to values seen in the OVA-immunized only mice. The results here suggest to us that FA exposure can induce and aggravate asthma in Balb/c mice when it is combined with OVA immunization.

Relationships between asthma and work exposures among non-domestic cleaners in Ontario

BACKGROUND

Cleaners have been reported to have increased risk for work-related asthma symptoms but few studies have studied non-domestic cleaners. In this study, we compared work-related asthma symptoms among cleaners and other building workers and determined associations with tasks.

METHODS

School and racetrack workers in Ontario, Canada, completed a questionnaire to identify the prevalence of cleaning tasks, physician-diagnosed asthma, new-onset asthma, respiratory symptoms, and work-related asthma symptoms.

RESULTS

Cleaners and controls had a similar prevalence of most asthma outcomes although female cleaners reported significantly more respiratory symptoms; odds ratio (OR), 2.59 confidence intervals (CI) 1.6-4.3, and work-related asthma symptoms, OR 3.90 (CI 2.1-7.4) compared with female controls with adjustment for age and smoking history. Male cleaners showed a non-significant trend to more physician-diagnosed asthma, adjusted OR 2.10 (CI 0.9-4.8) and work-related asthma symptoms, adjusted OR 1.53 (CI 0.8-3.0). The work-related asthma symptoms among men were significantly associated with waxing floors, OR 2.19 (CI 1.0-4.4); wax-stripping floors, OR 2.54 (1.2-5.2); spot-cleaning carpets, OR 2.20 (1.3-3.8); and cleaning tiles, OR 4.46 (1.0-19.3) and grout, OR 2.12 (1.1-4.0).

CONCLUSIONS

Female cleaners have more asthma symptoms worse at work than controls. Work-related asthma symptoms among male cleaners were associated with a number of specific cleaning tasks. Findings suggest the need for school cleaners to have reduced exposure to cleaning chemicals and need for protective strategies during performance of tasks expected to exacerbate asthma, such as wax stripping.

Evaluation of the health impact of lowering the formaldehyde occupational exposure limit for Quebec workers

This study aimed at assessing the impact on irritating effects of lowering the current occupational exposure limit (OEL) for formaldehyde in occupational settings in the Province of Quebec, Canada, from a 2 ppm ceiling value to 1, 0.75 or 0.3 ppm. This was achieved through (i) a re-assessment of the exposure-response relationship based on a pooled analysis of published controlled human studies on the incidence of the most sensitive effects related to acute formaldehyde exposure (irritation of the eyes, nose and throat) and (ii) application of this relationship to the data on current exposure to formaldehyde in industrial sectors of Quebec. Results show that the exposure-irritating effect relationship compiled by concentration ranges and by degree of severity was best described by quadratic regression. Considering the current distribution of formaldehyde exposure among the 143,491 Quebec workers concerned, eye irritation, the most sensitive effect, could affect 526 workers (0.367%) at a moderate degree and 50 workers (0.035%) at a severe degree. By reducing the OEL to 1, 0.75 and 0.3 ppm, the proportion of these effects estimated to be avoided would be 442/526 (84%), 526/526 (100%) and 526/526 (100%), respectively. Results for nose and throat irritation follow the same trend. The greatest gain would thus be obtained by respecting the current OEL; the additional gain was estimated to be negligible below 0.75 ppm. The level of 0.75 ppm can be considered as a safe level that allows protecting virtually all workers.