On-Site Deployment of an Air-Liquid-Interphase Device to Assess Health Hazard Potency of Airborne Workplace Contaminants: The Case of 3-D Printers

Lung cell toxicological effects of 3D printer aerosolized filament byproducts

As 3D printing has become more compact and affordable, the use of the technology has become more prevalent across household, classroom, and small business settings. The emissions of fused filament fabrication (FFF) 3D printers consist of volatile organic compounds (VOCs) and aerosolized particulate matter (PM) dependent upon the filament in use. This study investigates the hazards posed by these emissions through aerosol characterization and cell exposure. Seventeen filaments were obtained from five manufacturers, consisting of fourteen plastic filaments (polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), or polycarbonate (PC) polymers) and three filaments with metal filler (copper, bronze, and steel). For 1-h trials, BEAS-2B human bronchial epithelial cells were directly exposed to aerosolized 3D printer emissions at the air-liquid interface (ALI). Particle characterization showed ABS filaments produced more PM and VOC emissions with particles in the ultrafine size range. ABS filaments also elicited a greater biological response, with significant shifts in mitochondrial activity compared to the PLA filaments. Significant changes in amounts of glutathione (GSH) were observed after ABS and PLA emission exposure. Exposure to emissions from the steel filament resulted in the lowest average amount of glutathione, though insignificant, and a significantly lower mitochondrial activity, revealing a unique cause for concern among filaments tested. 3D printer emissions and subsequent cell responses appear filament-dependent, and users should mitigate personal exposure to aerosols.

Real-Time Exposure to 3D-Printing Emissions Elicits Metabolic and Pro-Inflammatory Responses in Human Airway Epithelial Cells

Three-dimensional (3D) printer usage in household and school settings has raised health concerns regarding chemical and particle emission exposures during operation. Although the composition of 3D printer emissions varies depending on printer settings and materials, little is known about the impact that emissions from different filament types may have on respiratory health and underlying cellular mechanisms. In this study, we used an in vitro exposure chamber system to deliver emissions from two popular 3D-printing filament types, acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA), directly to human small airway epithelial cells (SAEC) cultured in an air-liquid interface during 3D printer operation. Using a scanning mobility particle sizer (SMPS) and an optical particle sizer (OPS), we monitored 3D printer particulate matter (PM) emissions in terms of their particle size distribution, concentrations, and calculated deposited doses. Elemental composition of ABS and PLA emissions was assessed using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). Finally, we compared the effects of emission exposure on cell viability, inflammation, and metabolism in SAEC. Our results reveal that, although ABS filaments emitted a higher total concentration of particles and PLA filaments emitted a higher concentration of smaller particles, SAEC were exposed to similar deposited doses of particles for each filament type. Conversely, ABS and PLA emissions had distinct elemental compositions, which were likely responsible for differential effects on SAEC viability, oxidative stress, release of inflammatory mediators, and changes in cellular metabolism. Specifically, while ABS- and PLA-emitted particles both reduced cellular viability and total glutathione levels in SAEC, ABS emissions had a significantly greater effect on glutathione relative to PLA emissions. Additionally, pro-inflammatory cytokines including IL-1β, MMP-9, and RANTES were significantly increased due to ABS emissions exposure. While IL-6 and IL-8 were stimulated in both exposure scenarios, VEGF was exclusively increased due to PLA emissions exposures. Notably, ABS emissions induced metabolic perturbation on amino acids and energy metabolism, as well as redox-regulated pathways including arginine, methionine, cysteine, and vitamin B3 metabolism, whereas PLA emissions exposures caused fatty acid and carnitine dysregulation. Taken together, these results advance our mechanistic understanding of 3D-printer-emissions-induced respiratory toxicity and highlight the role that filament emission properties may play in mediating different respiratory outcomes.