The lung-skin connection in allergy to workplace chemicals
Published: May 25, 2022
Contact with sensitizing agents during work may lead to allergic skin disease (urticaria and contact dermatitis) and to allergic airways disease (asthma and rhinitis), depending on the type of exposure and the type of substance. In the case of airway disease caused by substances of high molecular weight (HMW) – proteins from biologic origin – the connection with the skin is well established, as shown by the use of skin prick testing to identify and demonstrate the causal allergen (e.g., wheat proteins in baker’s asthma). However, the connection, if any, with the skin is much less clear in the case of sensitizers of low molecular weight (LMW) – “chemicals”, such as isocyanates or metals – which generally do not involve IgE antibodies.
The latter issue was the focus of a retrospective study published by Tsui and coworkers in The Journal of Allergy and Clinical Immunology: In Practice. The authors scrutinized the clinical records of 209 patients diagnosed with occupational asthma between 2009 and 2019 in an outpatient clinic dedicated to diagnosing occupational and environmental disease in a tertiary referral hospital in Leuven, Belgium.
Occupational asthma was considered to have been caused by HMW agents in 66 patients and by LMW agents in 143 patients. The evidence for occupational asthma was defined as definite (96 cases), probable (42 cases) or possible (71 cases) based on clinical and occupational history in combination, as available, with specific inhalation challenges (positive in 20/26 patients), self-registered serial peak flow records (positive in 80/119 subjects), specific serum IgEs, skin prick testing, or patch testing (for delayed skin reactions). Compared with patients having occupational asthma caused by HMW agents, those with chemical-induced occupational asthma were three times less likely to also report rhinitis symptoms, but more than four times more likely to have (had) contact dermatitis. This was especially well documented (by patch testing) for workers involved in construction and hairdressing.
The findings from this real-world study strongly argue to inquire carefully about the occurrence of past and current skin symptoms compatible with contact dermatitis in patients with (suspected) occupational asthma (and vice versa to ask about work-related respiratory symptoms in patients with allergic contact dermatitis). Moreover, documented sensitization to a relevant chemical by patch testing may be useful to identify the cause of chemical-induced occupational asthma.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.
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