Characterizationof Airborne Emissions and PreliminaryIn Vitro Toxicity Screening of Polyamide 12 Used in Additive Manufacturing

Abstract Polyamide 12 (PA12) is a widely employed feedstock material in industrial additive manufacturing (AM) technologies. Despite this, there is limited epidemiological evidence regarding its health effects, raising particular concern about the potential implications for workers exposed to it. The present study evaluates PA12 in two exposure scenarios: via a laboratory simulation of powder-handling tasks associated with powder bed fusion processes and during active filament-based material extrusion 3D printing. Characterization of particle emissions was carried out through an integrated experimental approach that combined real-time measurements, morphological and elemental analyses, and in vitro cytotoxicity screening of virgin powder. The investigation was performed according to the multimetric tiered approach proposed by the Organization for Economic Cooperation and Development (OECD). Real-time instruments were used to measure particle number concentration, average diameter, and lung deposited surface area, while samples were collected for subsequent off-line analyses. The results reported elevated levels of airborne particles compared to the background in both applications, with emissions characterized as larger micrometric particles (approximately 20 μm) during powder handling and as smaller aggregates of submicrometric components during filament-based extrusion. Preliminary in vitro testing revealed no significant cytotoxic response or alterations in gene expression profiles in human bronchial epithelial cells (HBEC3-KT) when exposed to PA12 virgin powder. Such findings will be useful to develop precautionary hazard measures and appropriate control strategies to ensure the safe use of PA12 3D printing applications in occupational settings.