Feb 1, 2016 | By Alec

Is 3D printing bad for your health? As the hobby is increasingly in popularity, it is becoming more important to think about what all those molten plastics can do to your body, especially as they are known to emit particles into the air. A limited study back in 2013 by researchers from the Illinois Institute of Technology and The University of Texas at Austin suggested that ABS and PLA filaments do release some unhealthy particles into the air during 3D printing, but those same researchers are now back with a more comprehensive study. And the results are not very good – when 3D printing certain filaments in confined spaces, high levels of possibly carcinogenic (cancer-causing) particles can be measured in the air.

This has become apparent from a study entitled Emissions of Ultrafine Particles and Volatile Organic Compounds from Commercially Available Desktop Three-Dimensional Printers with Multiple Filaments, which has just appeared in the journal Environmental Science & Technology. The paper was authored by Parham Azimi, Dan Zhao, Claire Pouzet, Neil E. Crain, and Brent Stephens. As they argued, the thermal processing of plastics definitely release both gases and particles. “However, little is known about the types and magnitudes of emissions from desktop FFF 3D printers and how they vary according to filament material or printer characteristics,” they explain. While they did run tests with ABS and PLA filaments back in 2013, too few 3D printer models and filaments have been tested to say anything definitively. But they did, however, argue that exposure to emissions from “thermal decomposition of thermoplastics has been shown to have toxic effects in animals, and exposure to UFPs from other sources has been linked to a variety of adverse human health effects.”

To get more conclusive results, they have therefore set up a new study involving 16 combinations of popular 3D printers and filaments, including a FlashForge Creator dual extruder 3D printer, a Dremel 3D Idea, an XYZprinting da Vinci 1.0, a MakerBot Replicator, and a LulzBot Mini 3D printer. “The LulzBot printer was tested with nine different filaments that are commonly used, including ABS, PLA, high-impact polystyrene (HIPS), semitransparent nylon, laybrick, laywood, transparent polycarbonate, a semitransparent nylon-based plasticized copolyamide thermoplastic elastomer, and a transparent polyester resin filament called TGlase,” they say, while the other 3D printers were also tested with a few filaments.

To test these materials and machines, the research team measured two emissions: ultrafine particles (UFPs) and volatile organic compounds (VOCs). These were measured in a test environment of a 3.6 m3 stainless steel chamber with a small stainless steel mixing fan, that was filtered extensively before every test. “The 3D printer beds were prepared for printing before sealing the chamber by wiping with isopropyl alcohol, or, in some cases, depending on the printer and filament combination, by applying small amounts of adhesive from glue sticks following manufacturer recommendations. The printer was then powered on and began printing a small object. For all tests but one, we printed a 10 × 10 × 1 cm standardized sample,” they say. The emissions were then measured through an exhaust port of the chamber using a particle counter.

So what are the results? Firstly, the UFP concentrations were especially measurable during the first ten to twenty minutes of 3D printing, but remained present throughout the process. “However, the magnitude and shape of dynamic UFP concentrations varied widely depending on the printer, filament, shape of printed object, and nozzle and bed temperatures,” they said. These particles can, in large quantities, cause respiratory problems.

UFP emissions.

Conforming to previous suspicions, ABS filaments had the highest emission rates, while PLA showed results even lower than expected. “Interestingly, the presence of an enclosure only moderately reduced UFP emission rates from the MakerBot− ABS combination, with a ∼35% reduction in the median emission rate (although this variation is within the estimate of uncertainty),” they say. “Most of the printer/filament combinations with the highest bed temperatures had the highest UFP emission rates, while most of the printer/filament combinations with the lowest bed temperatures had the lowest UFP emission rates.”

More importantly, they found that quite a few dangerous VOCs were emitted into the air during 3D printing, though again differences were caused by model and material choices. “The primary individual VOC emitted from all six ABS filament and printer combinations and the only HIPS filament tested was styrene,” they say, though some 3D printers emitted more than others. “Interestingly, both the lowest and highest styrene emission rates were measured for printers with a partial enclosure (XYZprinting and MakerBot),” they say. Nylon, PCTPE, laybrick, and laywood filaments, all 3D printed on the LulzBot 3D printer, emitted quite high levels of caprolactam, with nylon being the worst offender. TGlase emitted quite low levels of that material, while PLA emitted very low levels of lactide.

In general, ABS, PCTPE, and HIPS filaments thus had high emission rates of both UFPs and VOCs, while PLA emitted quite low levels of both. Incidentally, laywood and laybrick filaments, had high VOC levels and low UFP levels. But the real question is: are these emissions dangerous? While high levels of UFPs should always be avoided, some of these VOCs can potentially be dangerous. Styrene (from ABS) is classified as a possible cancer-causing substance by the International Agency for Research on Cancer, while high-levels of caprolactam (from nylon, PCTPE, laybrick, and laywood) is just listed as “probably not carcinogenic to humans”. They can, however, cause irritation to the eyes and respiratory system (and even the central nervous system). Importantly, the lactide from PLA is not known to be toxic.

So what does this mean? The researchers argue that these results suggest that caution should be used when operating a 3D printer in small office spaces and hazardous filaments might be better avoided. “We continue to suggest that caution should be used when operating many printer and filament combinations in enclosed or poorly ventilated spaces or without the aid of gas and particle filtration systems. This is particularly true for both styrene- and nylon-based filaments, based on data from the relatively large sample of printers and filament combinations evaluated here,” they argue, also calling for the development of better enclosed 3D printing spaces. Perhaps sticking to PLA is not such a bad idea.

 

 

Posted in 3D Printing Technology

 

 

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