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3D Printers May Be Toxic To Humans

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Several new studies found that 3D printers emit toxic particles that may be harmful to humans.

The studies, presented at the 2020 Society for Risk Analysis virtual Annual Meeting on December 15, showed that the particles released during the printing process can affect indoor air quality and public health.

For the uninitiated, 3D printers typically work by melting plastic filaments or other base materials such as nanoparticles, metals, thermoplastics etc. and then stacking the melted materials layer upon layer to form an object. When the plastic or other base materials are heated to melt they release volatile compounds into the air near the printer and the object.

The chemical by-products and particles that are released into the environment during the printing process can build up the longer the process takes and some are small enough that they can infiltrate the lungs, causing damage.

The studies presented today at the meeting looked at various types of emissions and how great the risk is.

For example, two of the studies from the Environmental Protection Agency (EPA) analyzed the emissions from a 3D printer filament extruder - a device used to create 3D printer filaments - and then used a simulation model to see how many particles were produced, as well as where they were deposited when using a 3D printer in different age groups.  

The studies found that the filament extruder released amounts of small particles and vapors similar to those found in other studies of 3D printers, and the simulation model predicted higher deposition of particle mass per surface area in the lungs for children ages nine and younger. But more research is needed to determine how much the inhaled dose would be. 

Another one of the studies presented, conducted by Yong Qian from the National Institute for Occupational Safety and Health, looked at the potential toxicity of acrylonitrile butadiene styrene (ABS) emissions generated during 3D printing by examining human lung cells and rats exposed via inhalation. It revealed that the emitted particles cause moderate toxicity in human lung cells and minimal toxicity in rats. 

It’s also worth noting that while much of this research presented today is still early stages, it does add to the growing evidence of the potential toxicity of 3D printers.

For example, research published last year found that both ABS and polylactic acid (PLA) particles negatively impacted cell viability, with the latter prompting a more toxic response.

"The toxicity tests showed that PLA particles were more toxic than the ABS particles on a per-particle comparison, but because the printers emitted so much more of the ABS — it's the ABS emissions that end up being more of the concern," said Rodney Weber, a professor in Georgia Tech's School of Earth & Atmospheric Sciences, who led the research. "Taken together, these tests indicate that exposure to these filament particles could over time be as toxic as the air in an urban environment polluted with vehicular or other emissions."

The study also found that the hotter the temperature required to melt the filament, the more emissions were produced and ABS particles emitted from the 3D printers had chemical characteristics that were different than the ABS filament.

"When the filament companies manufacture a certain type of filament, they may add small mass percentages of other compounds to achieve certain characteristics, but they mostly do not disclose what those additives are," Weber said. "Because these additives seem to affect the amount of emissions for ABS, and there can be great variability in the type and amount of additives added to ABS, a consumer may buy a certain ABS filament, and it could produce far more emissions than one from a different vendor."

This is important especially as 3D printers become more commonplace in homes, schools and other places where people spend a significant amount of time.

"To date, the general public has little awareness of possible exposures to 3D printer emissions," said Peter Byrley, one of the lead authors of the EPA studies, in a statement. "A potential societal benefit of this research is to increase public awareness of 3D printer emissions, and of the possibly higher susceptibility of children." 

And 3D printing might not just be harmful to humans, another study conducted by Joana Marie Sipe from Duke University, found that the bi-products from the plastics made by the printer can also be damaging to the environment.

For the study, Sipe developed a machine that can measure how much a plastic product, like a water bottle, can break down through rubbing and sanding during use and in the environment. The plastic particles were then fed to fish to see the effects that the nanoparticles in the plastic had on their organs. 

What she found was that when the plastics breakdown, the nanomaterials that were incorporated become exposed to the environment. The researchers were able to predict the percentage of nanoparticles that came out of the plastic when they were eaten by the fish, providing a Matrix Release Factor (MRF) which could be used to find out the quantity of plastic and nanoparticles that are released when someone chews a product or when it breaks down in the ocean.

"This research can help set regulations on how much nanomaterial fillers can be added to particular consumer products, based on their MRF value," said Sipe in a statement. "The data can help determine how much plastic and/or nano-filled products release contaminants into the environment or the human body." 

So while 3D printing makes numerous products more readily available, and at cheaper costs, as we’ve seen with the manufacturing of Covid-19 face shields, respirators and other personal protective equipment, it’s important to consider the potential risks. And as 3D printing technologies become more widespread, regulators, manufacturers, and users may need to focus their attention on better managing those risks.

For example, some measures that can be taken by operators of 3D printers to lessen their impact on air quality include:

  • Operating 3D printers only in well-ventilated areas
  • Setting the nozzle temperature at the lower end of the suggested temperature range for filament materials
  • Standing away from operating machines
  • Using machines and filaments that have been tested and verified to have low emissions.

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