In a previous blog post—3D Printers: Do emitted chemicals from inexpensive desktop models pose health risks?—we discussed a study on emissions and possible risks associated with small commercial desktop 3D printers. Due to lower cost, this class of printer is becoming more widespread in universities, commercial facilities, and even homes. As a result, they’re increasingly on the radar of workers' compensation and other insurers. The findings of the study addressed by our blog were published in Environmental Science & Technology, a leading scientific journal.
Since then, researchers from West Virginia University Medical School and the National Institute for Occupational Safety and Health (NIOSH) have further investigated emissions and potential health effects associated with desktop 3D printers. Their study, published in the Journal of Toxicology and Environmental Health (JTEH), addresses additional information on practical measures you can use to limit and control exposure to emissions.
3D printer operations generate contaminants through a thermal extrusion process called fused deposition modeling (FDM). In that process, thin filaments of polymer are fed into the machine, heated, and extruded through a nozzle, depositing a layer of plastic onto a base plate. The process is repeated, applying layer upon layer, to build up and “print” the object. Factors such as the type of filament used to print the object, run time, and printer enclosures can affect the type of contaminants and how they’re generated.
In the West Virginia University School of Medicine/NIOSH study, researchers measured emissions from a desktop 3D printer in a test chamber designed to simulate real-world conditions. Tests indicated that high numbers of particles were emitted during printing, especially a few minutes after printing started when emission levels peaked. However, levels of emitted particles didn’t return to normal until about 100 minutes after printing stopped. During one test, the printer malfunctioned. The filament became stuck in the extruder nozzle, leading to higher particle emissions.
The emissions varied by filament type and color. Filaments made from polylactic acid (PLA)—a natural, biodegradable plant-based material—emitted smaller particles than acrylonitrile butadiene styrene (ABS) plastic filaments. Calculations showed that the risk of the smaller PLA particles lodging in the lungs was three times higher compared with the larger ABS plastic particles.
Color also affected particle size. PLA filaments in true red emitted the smallest particles on average, while blue plastic filaments emitted the largest particles. Researchers hypothesize that for filaments made of the same polymer, the additives used to color the filament account for this effect. When comparing filaments made of different polymers, the extrusion temperatures and color additives appeared to affect printer emissions.
Placing the manufacturer-supplied cover on the printer decreased the number of particles by half, but according to the investigators, the level was still relatively high. The printer used in the study had a loose-fitting cover, and the researchers noted that a sealed cover may be more effective in reducing emissions.
To reduce emissions from desktop 3D printers in nonindustrial settings, the researchers recommended the following:
- Always use the manufacturer’s supplied controls (full enclosure appears more effective at controlling emissions than a cover).
- Use the printer in a well-ventilated space and directly ventilate the printer.
- Maintain a distance from the printer to minimize breathing in emitted particles and choose a low-emitting printer and filament when possible.
- Turn off the printer if the nozzle jams and allow it to ventilate before removing the cover.
- Use the hierarchy of controls to minimize or eliminate emissions. For example, engineering/design controls should be implemented first, such as using manufacturer-supplied equipment, proper ventilation, and low-emitting materials. Second, administrative controls, such as limiting worker time near the printers, should be implemented, followed by use of personal protective equipment, such as respirators.
Although not addressed in the JTEH article, preliminary research conducted by NIOSH indicated a potential link between some chemical emissions from desktop 3D printers and asthma. Some of the emissions apparently combine chemically to form contaminants of concern. NIOSH is in the process of submitting a paper on this study to a peer-reviewed publication.
You can access “Emission of particulate matter from a desktop three-dimensional (3D) printer” at JTEH.
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