May 21, 2024

Researchers Evaluate 3D Printing Hazards in Educational Settings

By Abby Roberts

Postdoctoral researcher Qian Zhang and environmental health scientist Mark Wilson, CIH, presented their evaluation of hazards associated with three-dimensional printing on May 20 at AIHA Connect 2024. 3D printing is a “kind of additive manufacturing that joins materials in consecutive layers to build up a defined structure,” Wilson explained. The technology is widely used to facilitate interactive learning in science, technology, engineering, and mathematics education, although it also has applications in the dental and medical fields.

Each of the seven different 3D printing processes have unique hazards. Many processes have electrical and mechanical hazards, and some may expose users to lasers, ultraviolet (UV) light, or radiation hazards as well. Zhang and Wilson focused on particulate matter (PM) and volatile organic compound (VOC) emission hazards in the two processes they found were most common in college environments, material extrusion and vat photopolymerization.

Zhang described how the team developed a method for researching 3D printing emissions. Printing took place inside a closed exposure chamber, which allowed the researchers to collect air samples. The researchers could also swap out different print materials, printer brands, and filament brands (3D printer filaments are polymers that melt when heated, allowing them to be shaped). Then researchers analyzed the air samples for mass and number concentrations of emissions, types of chemicals emitted, emission rates, and other factors. They then developed a database of 3D printing exposures in different conditions and created a model for emissions in indoor environments.

They found a range of PM emission rates—some materials had higher emission rates than others. In general, materials with a higher recommended printing temperature had higher emission rates than those with lower recommended temperatures. The printers mainly emitted ultrafine particles smaller than 100 nanometers, which are a major health concern. However, users’ exposures are different based on materials and conditions.

The researchers also detected more than 600 VOCs in printer emissions, including over 100 listed as irritants, odorants, toxins, sensitizers, and carcinogens in indoor air quality regulations and guidance documents. Formaldehyde was found in all printing materials. Some personal exposures to VOCs from 3D printing may exceed LEED’s recommended indoor levels.

While material extrusion printing produced more PM emissions, vat polymerization produced higher VOC emissions, up to 5 micrograms per hour. Most of the VOC emissions were associated with the resins used in this process, but emissions carried over into post processing. In vat polymerization, printed materials are often washed in flammable chemicals, such as isopropanol.

Wilson concluded with a set of recommendations for safe 3D printing in educational environments. First, potential 3D printer users should acquire devices and print media certified for lower PM and VOC emissions. They should consider whether 3D printing systems have built-in local exhaust, are closed systems or open to the atmosphere, or can be integrated into existing ventilation systems. 3D printers should be located in rooms with adequate ventilation, which may require use of room air cleaners. Printers should not be placed in high-traffic areas, and students or others in the area should not crowd around the printer while it is in operation.

Zhang and Wilson’s 3D printing emissions data may be viewed on the Chemical Insights website. NIOSH has produced a guide for safe 3D printing.

Abby Roberts is assistant editor for The Synergist.

Read more coverage of AIHA Connect 2024.