There is little doubt that 3D printing is or will soon become a major disruptive technology. Futurists predict there will be a 3D printer in most homes and businesses, making everything from food to replacement parts. There is, however, cause for concern.
SEE: Research: 3D Printing 2017: Benefits, trends, enterprise applications (Tech Pro Research)
Potential health risks from 3D printing
Over the past several years numerous studies, including one by Underwriters Laboratories (UL), have tried to determine health risks associated with operating 3D printers. All studies agree on one thing: The potential for health risks is real.
"Emissions from 3D printing can be a source of ultrafine particles in the nanoparticle size range as well as a source of particular Volatile Organic Compounds (VOC), some of which are odorants, irritants, and chronic or acute hazards," writes Marilyn Black, UL vice president, senior technical advisor, and author of the lab's final report (PDF). "These exposure levels are generally low and complete risk assessments have not been conducted, but a precautionary approach of providing good building ventilation with outdoor air exchange and local ventilation in areas where 3D printing is occurring would be prudent."
No uniform strategy to reduce these emissions risks... yet
Regarding particulate pollution, this American Chemical Society August 30, 2017 press release expresses the organization's concern, stating, "... no research has been reported on strategies for preventing or reducing pollution from the machines [3D printers]."
Companies are building air handling systems for 3D printers, but there are no set standards or specific regulations as to what is good enough. What's acceptable air quality is something Ohhun Kwon, Chungsik Yoon, Seunghon Ham, Jihoon Park, Jinho Lee, Danbi Yoo, and Yoojin Kim (environmental-science researchers at Seoul National University) decided to determine. The research team published their results in the paper Characterization and Control of Nanoparticle Emission during 3D Printing. From the paper's abstract:
"Experiments for particle characterization were conducted to measure particle number concentrations, emission rates, morphology, and chemical compositions under manufacturer-recommended and consistent-temperature conditions with seven different thermoplastic materials in an exposure chamber."
For their study, the researchers worked with a 3D printer based on fused-deposition modeling (FDM), the most commonly used process among commercially-available models, where a solid filament is forced through a heated extrusion nozzle controlled by a computer. The filament material melts and is deposited in thin layers on a moving base plate. When the material hardens, the nozzle and base plate coordinate position and timing of when to deposit another layer.
The researchers from Seoul National University tested various thermoplastic materials under different temperatures. Of the tested filaments, high-impact polystyrene and nylon had the highest nanoparticle emission rates, with polylactic acid having the lowest. Something of note in the ACS press release: Printing at the manufacturer-recommended temperature resulted in fewer emissions.
Besides operating temperature, the UL study suggests that printer design, additives, colorants, and the composition of the filament all influence the type and amount of emissions. The chart in Figure A details the UL findings when testing various filament materials used in FDM 3D printing.
Testing emissions-reduction systems
The researchers from Seoul National University analyzed eight methods for controlling pollution from the printers using varying combinations of fans, filters, and enclosures. A depiction of the test environment is shown in Figure B. "All of the designs removed at least 70 percent of nanoparticle emissions," according to the press release. "The most efficient approach eliminated 99.95 percent of such pollution, and involved enclosing the printer and installing a high-efficiency particulate air (HEPA) filter."
Barry Ryan, professor of Environmental Health at Emory University and member of the UL study team, was tasked with looking at the health effects from 3D printing particle emissions. Ryan points out, "The results from the modeling exercise suggest that emissions from 3D printers contribute to the total particle concentration in these scenarios, but the contribution is small."
He cautions that future study is required to get an accurate picture of particle emissions. "We expect the impact of particles could change using a toxicity index for the particles themselves," states Ryan. He also suggests that particulate surface area is another variable needing consideration.
The researchers at Seoul National University and at the Underwriters Laboratories believe there is a strong need for particle emissions standards, and now is better than later, as 3D printers are popping up everywhere, even schools. As a start, the UL report states its engineers and scientists have begun developing American National Standards Institute (ANSI) standards for measuring and assessing printer emissions in enclosed spaces.
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