Safety Standards Aim to Rein in 3-D Printer Emissions

By depositing molten plastic layer upon layer, threedimensional (3-D) printers can crank out almost anything, from toys to guns to artificial limbs. The surging 3-D printer market has made desktop versions affordable for schools and libraries. But the printers’ growing prevalence has raised concerns about potential negative health effects from inhaling toxic volatile organic compounds (VOCs) and particles given off by the devices. Although the government has set workplace standards for a few of the VOCs released by 3-D printers, these are for healthy, working-age adults in industrial settings such as tire or plastic manufacturing plants: None of the compounds is regulated in homes or libraries where 3-D printers might be used by sensitive populations such as children. Furthermore, researchers don’t know the identity of most of the compounds emitted by printers. “Scientists know that particles and VOCs are bad for health, but they don’t have enough information to create a regulatory standard for 3-D printers,” says Marina E. Vance, an environmental engineer at the University of Colorado, Boulder. What’s more, data from early studies of 3-D printer emissions are difficult to use in developing standards because of variability in the test conditions, says Rodney J. Weber, an aerosol chemist at Georgia Institute of Technology. Two years ago, UL, an independent safety certification company, established an advisory board and began funding research projects to answer basic questions about the amounts and types of compounds in 3-D printer emissions, what levels are safe, and how to minimize exposures, says Marilyn S. Black, a vice president at UL. The company is working to create a consistent testing and evaluation method so that researchers will be able to compare data across different labs. “By this fall we will put out an ANSI (American National Standards Institute) standard for measuring particles and VOCs for everyone to use,” she says. ■ PRINTING PLASTIC A 3-D printer creates an object by feeding coils of plastic filament through a nozzle that melts the plastic at temperatures up to 320 °C and then extrudes it onto a moving baseplate. A computer directs the motion of the baseplate so that layers of material build up until the foreordained 3-D shape emerges. “We know that when you melt plastic at high temperatures, the long chains of organic matter in the plastic partially degrade and release potentially harmful volatile organic compounds and ultrafine particles (UFPs) into the air,” says Brent Stephens, an environmental engineer at Illinois Institute of Technology. He and other researchers have found that the most common filament materials can cause potentially unhealthy emissions when used in 3-D printers. Petroleum-based acrylonitrile butadiene styrene (ABS), a plastic used in Lego blocks, gives off styrene and formaldehydethe first a suspected human carcinogen and the second a known one. Nylon releases caprolactam, a respiratory irritant. Polylactic acid (PLA)a corn-based plastic found in medical implants, drinking cups, and disposable diapersemits methyl methacrylate, a mild skin irritant. And all the filament types spew UFPs, particles with a