When plastics were first discovered, they were derived from natural substances that contained very little toxicity and were generally considered biochemically inert. However with the Industrial Revolution, Industrial Chemistry was born, and natural plastics that had been used harmlessly for centuries like chicle (natural chewing gum), natural rubber, collagen and gelatin were chemically modified and often had substances added to them that could make them harmful to humans. For the average person during that time, exposure to plastic was pretty rare so there was very little danger. However by the 1940s, with the birth of mass production, hundreds of applications for modified or synthetic plastics had been discovered–and at this point virtually everyone on the planet interacts with plastic materials daily.
These days most plastic materials are tightly regulated and materials that regularly come into contact with people or their food are generally considered quite safe, but that wasn’t always the case. With desktop 3D printers becoming more common and affordable, small businesses, research labs, schools and labs are using printers, and their plastic materials, at rapidly increasing rates. Unfortunately there is very little regulation of 3D printing materials, and as material developers create more and more exotic variations those same businesses, labs, schools and homes may be bringing toxic materials into them without even knowing it.
Last year when Shirin Mesbah Oskui, a researcher at the University of California Riverside, was studying zebrafish embryos she decided to use her research lab’s brand new 3D printer to develop some tools for her project. Unfortunately, when she first started to use her new tools she noticed that the zebrafish embryos quickly died after being exposed to the 3D printed plastic components. Oskui and assistant professor of bioengineering William Grover at the Bourns College of Engineering where she studied decided to test the level of toxicity present in 3D printed parts from the two types of printers regularly used by the lab. Today they published their findings in a paper titled “Assessing and Reducing the Toxicity of 3D-Printed Parts,” online in the Environmental Science and Technology Letters journal.
“These 3D printers are like tiny factories in a box. We regulate factories. We would never bring one into our home. Yet, we are starting to bring these 3D printers into our homes like they are toasters. Many people, including myself, are excited about 3D printing, but, we really need to take a step back and ask how safe are these materials,” explained Grover.
Grover, Oskui and their team of researchers focused their study on two types of 3D printers, a standard FDM 3D printer that uses PLA 3D printing material and a stereolithography (SLR) 3D printer that uses light-cured resin materials. Oskui used each printer to make simple, one-inch diameter disc-shaped objects. The discs were placed inside of petri dishes with zebrafish embryos and she monitored the survival rates, hatch rates and developmental abnormalities. She discovered that parts made by both types of 3D printers were in some way toxic to the zebrafish embryos, and the parts printed by the SLR 3D printer were considerably more toxic than the FDM parts.
The two models of printers used by researchers in their study were a Stratasys Dimension Elite 3D printer and a Formlabs Form 1+ stereolithography 3D printer. The zebrafish embryos exposed to parts from the Dimension Elite had marginally decreased survival rates in comparison to the embryo control group. However the embryos tested with resin parts printed with the Form 1+ printer had dramatically decreased survival rates. More than half of the embryos were dead by the third day of exposure, and by day seven they were all dead. Of the few zebrafish embryos exposed to the resin parts that did hatch, 100 percent of them displayed significant developmental abnormalities.
Here is a video produced by UC Riverside explaining some of their findings:
While this is just preliminary research, the early test results raise clear questions about how 3D printed parts and waste materials should be regulated and disposed of, not to mention regulations of the materials themselves. Just based on this research project 3D printing materials probably should be regulated by the Toxic Substances Control Act, which is governed by the EPA. But most material manufacturers don’t even disclose exactly what their 3D printing materials are specifically made of, so it is hard to classify exactly what potential toxins they contain.
The research team plans to expand their study to try and narrow down exactly what substances makes the materials toxic, and also to determine at what levels they would be toxic to humans. Oskui has developed a post-printing treatment that will reduce the toxicity of parts printed with the SLR 3D printer involving exposure to ultraviolet light. But for now the researchers suggest that the safest way to dispose of any 3D printed parts or waste material is to send them to a hazardous waste center.
Is this a potential downfall to the market? Let us know your thoughts on this study in the Toxic 3D Printing forum thread on 3DPB.com.