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Stefaniak AB, Johnson AR, du Preez S, Hammond DR, Wells JR, Ham JE, LeBouf RF, Menchaca KW, Martin SB, Duling MG, Bowers LN, Knepp AK, Su FC, de Beer DJ, du Plessis JL. Evaluation of emissions and exposures at workplaces using desktop 3-dimensional printer. J Chem Health Saf 2019; 26:19-30. [PMID: 31798757 PMCID: PMC6889885 DOI: 10.1016/j.jchas.2018.11.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
There is a paucity of data on additive manufacturing process emissions and personal exposures in real-world workplaces. Hence, we evaluated atmospheres in four workplaces utilizing desktop "3-dimensional" (3-d) printers [fused filament fabrication (FFF) and sheer] for production, prototyping, or research. Airborne particle diameter and number concentration and total volatile organic compound concentrations were measured using real-time instruments. Airborne particles and volatile organic compounds were collected using time-integrated sampling techniques for off-line analysis. Personal exposures for metals and volatile organic compounds were measured in the breathing zone of operators. All 3-d printers that were monitored released ultrafine and fine particles and organic vapors into workplace air. Particle number-based emission rates (#/min) ranged from 9.4 × 109 to 4.4 × 1011 (n = 9samples) for FFF3-d printers and from 1.9 to 3.8 × 109 (n = 2 samples) for a sheer 3-d printer. The large variability in emission rate values reflected variability from the printers as well as differences in printer design, operating conditions, and feedstock materials among printers. A custom-built ventilated enclosure evaluated at one facility was capable of reducing particle number and total organic chemical concentrations by 99.7% and 53.2%, respectively. Carbonyl compounds were detected in room air; however, none were specifically attributed to the 3-d printing process. Personal exposure to metals (aluminum, iron) and 12 different organic chemicals were all below applicable NIOSH Recommended Exposure Limit values, but results are not reflective of all possible exposure scenarios. More research is needed to understand 3-d printer emissions, exposures, and efficacy of engineering controls in occupational settings.
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Affiliation(s)
- A B Stefaniak
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - A R Johnson
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - S du Preez
- North-West University, Occupational Hygiene and Health Research Initiative, Private Bag X6001, Potchefst-room, 2520, South Africa
| | - D R Hammond
- National Institute for Occupational Safety and Health, Cincinnati, OH, USA
| | - J R Wells
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - J E Ham
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - R F LeBouf
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - K W Menchaca
- National Institute for Occupational Safety and Health, Cincinnati, OH, USA
| | - S B Martin
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - M G Duling
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - L N Bowers
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - A K Knepp
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - F C Su
- National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - D J de Beer
- North-West University, Technology Transfer and Innovation Support Office, Private BagX6001, Potchefstroom, 2520, South Africa
| | - J L du Plessis
- NorthWest University, Occupational Hygiene and Health Research Initiative, Private Bag X6001, Potchefstroom, 2520, South Africa
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Abstract
Arterial thrombus formation is directly related to the mechanical shear experienced by platelets within flow. High shear strain rates (SSRs) and large shear gradients cause platelet activation, aggregation and production of thrombus. This study, for the first time, investigates the influence of pulsatile flow on local haemodynamics within sutured microarterial anastomoses. We measured physiological arterial waveform velocities experimentally using Doppler ultrasound velocimetry, and a representative example was applied to a realistic sutured microarterial geometry. Computational geometries were created using measurements taken from sutured chicken femoral arteries. Arterial SSRs were predicted using computational fluid dynamics (CFD) software, to indicate the potential for platelet activation, deposition and thrombus formation. Predictions of steady and sinusoidal inputs were compared to analyse whether the addition of physiological pulse characteristics affects local intravascular flow characteristics. Simulations were designed to evaluate flow in pristine and hand-sutured microarterial anastomoses, each with a steady-state and sinusoidal pulse component. The presence of sutures increased SSRmax in the anastomotic region by factors of 2.1 and 2.3 in steady-state and pulsatile flows respectively, when compared to a pristine vessel. SSR values seen in these simulations are analogous to the presence of moderate arterial stenosis. Steady-state simulations, driven by a constant inflow velocity equal to the peak systolic velocity (PSV) of the measured pulsatile flow, underestimated SSRs by ∼ 9% in pristine, and ∼ 19% in sutured vessels compared with a realistic pulse. Sinusoidal flows, with equivalent frequency and amplitude to a measured arterial waveform, represent a slight improvement on steady-state simulations, but still SSRs are underestimated by 1-2%. We recommend using a measured arterial waveform, of the form presented here, for simulating pulsatile flows in vessels of this nature. Under realistic pulsatile flow, shear gradients across microvascular sutures are high, of the order ∼ 7.9 × 106 m-1 s-1, which may also be associated with activation of platelets and formation of aggregates.
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Affiliation(s)
- R A J Wain
- School of Mathematics, University of Birmingham, B15 2TT, UK; Institute of Translational Medicine, University of Birmingham, B15 2TT, UK; School of Medicine and Dentistry, University of Central Lancashire, Preston PR1 2HE, UK; Computational Mechanics Research Group, School of Engineering, University of Central Lancashire, Preston PR1 2HE, UK.
| | - D J Smith
- School of Mathematics, University of Birmingham, B15 2TT, UK; Institute for Metabolism and Systems Research, University of Birmingham, B15 2TT, UK
| | - D R Hammond
- School of Medicine and Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
| | - J P M Whitty
- Computational Mechanics Research Group, School of Engineering, University of Central Lancashire, Preston PR1 2HE, UK
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