Three-dimensional (3D) printers, according to those with an eye for technology, will soon revolutionize manufacturing and other industries. New developments in the field of 3D printing beside the new, low-cost desktop versions include the fact that next year, a key laser sintering patent is set to expire. According to the technology magazine Motherboard, it will result in an explosion of new desktop 3D printers. The current generation of 3D printers use a patented process known as fused deposition modeling. Critics say these are primitive compared to what's to come; besides, they are not yet durable enough to create lasting prototypes for mass-production molds or finished goods. Nevertheless, last month Amazon began to sell these 'primitive' 3D printers and accessories. Could anything be a more telling sign that these devices have already begun to gain wide popularity?

Yet, a team of researchers from Illinois Institute of Technology have, by way of an article published in Atmospheric Environment, issued a warning that these printers may not be good for your health.

UFPs

Most 3-D printers use a manufacturing technique known as molten polymer deposition. Essentially, they thread spools of plastic filament onto a heated nozzle that drops the liquid plastic onto a moving baseplate. The material hardens as the baseplate moves to the next layer. Gradually, layer upon layer accumulates and an object is formed. When this process is performed on an industrial level, it has been shown to produce significant aerosol emissions. Until now, no data or at least not a large body of information has yet been aggregated on whether commercially available desktop 3D printers also emit ultrafine particles.

Ultrafine particles, as defined by the Environmental Protection Agency, "are those less than 100nm, so they are nano-sized." Exposure to ultrafine particles (UFP), according to the California Environmental Protection Agency (Cal/EPA), can lead to adverse health effects. "A daily mortality study in Erfürt, Germany, was the first epidemiology study that examined and found significant associations between exposure to ultrafine particulate matter and mortality from respiratory and cardiovascular disease," states a brochure from the state agency. In addition, Cal/EPA warns that UFPs can induce cellular damage, and also suggests that sensitive individuals, such as those with chronic obstructive pulmonary disease, may be at greater risk than healthy individuals when exposed due to an increased dose in the lungs.

According to the research team from Illinois Institute of Technology, studies have shown elevated UFP number concentrations in the air are associated with adverse health effects, including cardio-respiratory mortality, hospital admissions for stroke, and asthma symptoms. Because of these adverse health effects, the researchers believed it was important to measure ultrafine particle concentrations resulting from the operation of two commercially available desktop 3D printers inside a commercial office space.

How potentially harmful might the emissions from these printers be?

Feedstock Issues

For the study, the researchers measured the rates of UFPs emitted from desktop 3D printers inside a small enclosed office space under various conditions. In particular, the authors were interested in the total number of UFPs emitted when different types of feedstock were utilized by the printers. Many of the new desktop 3D printers use either acrylonitrile butadiene styrene (ABS) or polyactic acid (PLA). PLA is a biodegradable, corn-based plastic, whereas ABS is a stronger thermoplastic that typically prints at higher temperatures. Differences in the chemical compositions of the feedstocks have long been known to impact levels of toxicity. For example, previous research in the field provides evidence that ABS emissions are toxic in mice and rats. Contrarily, PLA nanoparticle emissions are known to be safe in humans.

When the printers utilized PLA as the feedstock thermoplastic, the researchers measured UFP emission rates of around 20 billion particles per minute. Comparatively, when the printers used ABS, the researchers measured UFP emission rates of around 200 billion particles per minute. Although the authors discovered emission rates of total UFPs to be higher for 3D printers utilizing the ABS feedstock relative to a PLA feedstock, both can be characterized as "high emitters" of UFPs.

"These results suggests caution should be used when operating some commercially available 3D printers in unvented or inadequately filtered indoor environments," conclude the authors. "More controlled experiments should be conducted to more fundamentally evaluate particle emissions from a wider arrange of desktop 3D printers."

 

Source: Stephens B, Azimi P, El Orch Z, Ramos T. Ultrafine particle emissions from desktop 3D printers. Atmospheric Environment. 2013.