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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.

ObjectiveTo determine the agents causing asthmatic reactions during specific inhalation challenges (SICs) in workers with cleaning-related asthma symptoms and to assess the pattern of bronchial responses in order to identify the mechanisms involved in cleaning-related asthma.DesignA retrospective case series analysis.SettingThe study included all participants who completed an SIC procedure with the cleaning/disinfection products suspected of causing work-related asthma over the period 1992–2011 in a tertiary centre, which is the single specialised centre of the French-speaking part of Belgium where all participants with work-related asthma are referred to for SIC.ResultsThe review identified 44 participants who completed an SIC with cleaning/disinfection agents. Challenge exposure to the suspected cleaning agents elicited a ≥20% fall in forced expiratory volume in 1 s (FEV1) in 17 (39%) participants. The cleaning products that induced a positive SIC contained quaternary ammonium compounds (n=10), glutaraldehyde (n=3), both of these agents (n=1) and ethanolamines (n=2). Positive SICs were associated with a significant decrease in the median (IQR) value of the provocative concentration of histamine causing a 20% fall in FEV1 (PC20) from 1.4 (0.2–4.2) mg/mL at baseline to 0.5 (0.4–3.0) mg/mL after the challenge and a significant increase in sputum eosinophils from 1.8 (0.8–7.2)% at baseline to 10.0 (4.1–15.9)% 7 h after the challenge exposure while these parameters did not significantly change in participants with a negative SIC. Overall, 11 of 17 participants with positive SICs showed greater than threefold decrease in postchallenge histamine PC20 value, a >2% increase in sputum eosinophils, or both of these outcomes.ConclusionsThese data indicate that a substantial proportion of workers who experience asthma symptoms related to cleaning materials show a pattern of bronchial reaction consistent with sensitiser-induced occupational asthma. The results also suggest that quaternary ammonium compounds are the principal cause of sensitiser-induced occupational asthma among cleaners.

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Nasal symptoms are highly prevalent in subjects with WEA, although their clinical pattern differs from that found in OA. Further investigations of the health and socio-economic impacts of upper airways symptoms in WEA are required to improve the understanding and management of this common condition.