D2.152 - Clinical and functional characteristics of patients with suspected epoxy resin-related occupational asthma

Epoxy resins are low-molecular-weight agents widely used in industrial resin-hardener systems. Occupational exposure to epoxy resins is a well-known cause of allergic contact dermatitis and, less frequently, of occupational asthma. Diagnosing asthma in exposed workers is challenging, and a specific inhalation challenge (SIC) is often required. The aim of this study was to compare the clinical and functional characteristics of patients with suspected epoxy resin-related occupational asthma according to SIC results.

We conducted a retrospective review of patients occupationally exposed to epoxy compounds who underwent comprehensive respiratory assessment, including baseline spirometry, methacholine bronchial challenge, and fractional exhaled nitric oxide (FeNO). SIC was performed the day following baseline assessment. Patients were exposed to workplace epoxy resins using a gradual protocol in a 7 m³ challenge chamber for a cumulative duration of 30 minutes. At 24 hours post-SIC, spirometry, methacholine testing, and FeNO were repeated. A positive SIC was defined as a ≥15% fall in FEV₁ from baseline and/or a significant change in methacholine PC20. Collected data included demographics, smoking and atopic status, occupational and clinical history, patch testing to epoxy compounds, and respiratory functional parameters.

A total of 39 patients were included (mean age 38 ± 6.5 years; 89.7% male). At the time of SIC, 30 patients were on work leave (mean duration: 8 weeks). Seventeen patients (43.6%) had a positive SIC, while 22 (56.4%) had a negative result. Baseline bronchial hyperresponsiveness was significantly more frequent in SIC-positive patients compared with SIC-negative patients (64.7% vs. 27.3%, p = 0.026). Post-challenge bronchial hyperresponsiveness was also markedly higher in the SIC-positive group (82.4% vs. 13.6%, p < 0.01). No other significant differences were observed between groups.

In this cohort, baseline bronchial hyperresponsiveness and it increase after SIC was the main distinguishing features of patients with a positive SIC. These findings emphasize the role of airway hyperresponsiveness in epoxyresin–related occupational asthma and support its value as a complementary diagnostic marker. Further studies with larger sample sizes are needed to better clarify disease mechanisms and improve diagnostic strategies in exposed workers.