Occupational exposure to gaseous and particulate contaminants originating from additive manufacturing of liquid, powdered, and filament plastic materials and related post-processes

Abstract

The aim of this study was to measure the concentrations of gaseous and particulate contaminants originated from additive manufacturing operations and post-processes in an occupational setting when A c c e p t e d M a n u s c r i p t plastics were used as feedstock materials. Secondary aims were to evaluate the concentration levels based on proposed exposure limits and target values and to propose means to reduce exposure to contaminants released in additive manufacturing processes. Volatile organic compounds were sampled with Tenax® TA adsorption tubes and analyzed with thermo desorption gas chromatography-mass spectrometry instrument. Carbonyl compounds were sampled with DNPH-Silica cartridges and analyzed with high-performance liquid chromatography device. Particles were measured with P-Trak instrument and indoor air quality was sampled with IAQ-Calc instrument. Dust mass concentrations were measured simultaneously with DustTrak DRX instrument and IOM-samplers. Particle concentrations were at highest (2070-81 890 #/cm 3 mean) during manufacturing with methods where plastics were thermally processed. Total volatile organic compounds concentrations, in contrast, were low (113-317 µg/m 3 mean) during manufacturing with such methods, and vat photopolymerization method. However, total volatile organic compounds concentrations of material jetting and multi jet fusion methods were higher (1114-2496 µg/m 3 mean), perhaps because of material and binder spraying, where part of the spray can become aerosolized. Chemical treatment of manufactured objects was found to be a severe volatile organic compounds source as well. Formaldehyde was detected in low concentrations (3-40 µg/m 3) in all methods except for material jetting method, in addition to several other carbonyl compounds. Notable dust concentrations (1.4-9.1 mg/m 3) were detected only during post-processing of powder bed fusion and multi jet fusion manufactured objects. Indoor air quality parameters were not found to be notably impacted by manufacturing operations. Only low concentrations (below 2 ppm) of CO were detected during several manufacturing processes. All studied additive manufacturing operations emitted potentially harmful contaminants into their environments, which should be considered in occupational additive manufacturing and workplace design. According to the measured contaminant levels it is possible that adverse additive manufacturing related health effects may occur amongst exposed workers.

State of the art in additive manufacturing and its possible chemical and particle hazards—review

“…Despite many different 3D printing technologies, material extrusion (represented by FDM ® ) is the best recognized at the moment, as evidenced by the number of publications on the possible emission of gaseous thermal by‐products harmful to the human body released during the operation of the printer. Some of the studies described in the literature concerned emission measurements carried out during the operation of printing machines in the test chambers, 102,106,121 some in the air of specific workplaces or indoors 122,123 …”

Material characterization of polyamide 12 and related agents used in the multi-jet fusion process: complementary application of high-resolution mass spectrometry and other advanced instrumental techniques

“…Väisänen et al [19] investigated the multi-jet fusion process regarding gaseous and particulate contaminants. In their studies pyrrolidin-2-one (2-pyrrolidone) (549-564 µg m −3 ) Fig.…”

“…1 Scheme of the multi-jet fusion process. a applied layer of polymer powder, b application of the agents (black: fusing agent, light blue: detailing agent), c energy delivery by IR radiation, and d fused layer [6] (color figure online) and 2-[2-(2-hydroxyethoxy)ethoxy]ethanol (triethylene glycol) (201-211 µg m −3 ) were found besides acetone, formaldehyde, and butan-2-one which were detected in concentrations ranging from 14 µg m −3 up to 41 µg m −3 [19].…”

The Effects of Virgin and Recycled PA12 Powders in SLS Processes on Occupational Exposures

“…Toxicological studies [12]- [14] confirmed that the operators of SLS AM machines are exposed to particulate matter and ultrafine particles from powder handling, where the particles enter their lungs and bloodstream through respiration. According to Vä isä nen et al [15], PBF technologies increase the risk of health hazards, especially during handling of materials and objects. Graff et al [16] evaluated the occupational exposure to virgin and recycled metal powders during SLS AM process.…”

“…To date, only a few studies [15], [16] have been conducted to investigate the association between occupational exposure the use of virgin and recycled powders in SLS processes. Hence, the objective of this study was to assess the occupational exposure (in terms of the total particulate concentration and respirable particulate concentration) during the pre-processing and post-processing activities of the SLS process, all of which involve powder handling.…”