Low exposure levels of respirable particles during the preparation of NexoBrid® bromelain powder

Background: Burns are common injuries that are usually covered with a layer of necrotic tissue called the eschar. Early removal of the eschar is the current standard of care, however, debridement using tangential excision is usually traumatic and may increase wound surface. In recent years a bromelain-based debriding agent called NexoBrid® that can remove the eschar selectively and thus causes less additional trauma was developed. Bromelain is a pineapple-stem derived mix of proteases. In its raw form bromelain is a yellowish powder. Cases are known where frequent inhalation of bromelain dust led to respiratory sensitization and subsequently to severe allergic reactions. In order to activate bromelain for debridement it has to be mixed with a hydrating gel. We aimed to assess the risk of sensitization by measuring the particle concentration in the air during the mixing process in order to determine the safety of the product for patients as well as practitioners. Methods: The mixing process was repeated five times in a row. Samples of the particle concentration in the workers breathing area were taken with an air particle counting device during continuous performance. The worker wore a lab coat and gloves but no face mask. Results: Particle concentrations ranged from 0.010 mg/m to 0.012 mg/m (mean 0.010 mg/m). The particles were chemically termed as “respirable dust”. Conclusions: We measured very low exposure levels of inhalable particles during the mixing process. Because the particle counter could not distinguish the components of the dust, it is possible that also background particles contributed to the results. A review of literature revealed that relatively high exposure levels are necessary for respiratory sensitization, whereas also low exposure levels may exacerbate an allergic reaction. We suggest that preparation of NexoBrid® is safe as long as standard safety precautions are met. Patients with known allergy to pineapple should be treated more carefully to prevent an allergic reaction.