The rapid expansion of three-dimensional (3D) printing from industrial settings to homes, schools, and small businesses has raised questions about its safety. This additive manufacturing process, which builds objects layer by layer, is now a common technology used by millions. While 3D printing offers utility, the process of heating or curing materials releases airborne contaminants. This leads to public concern about potential long-term health risks, particularly carcinogenicity. This article explores the current scientific understanding of emissions from 3D printers and the resulting risk profile.
Emissions from 3D Printing: Ultrafine Particles and VOCs
The primary health concern involves the release of two categories of airborne contaminants: Ultrafine Particles (UFPs) and Volatile Organic Compounds (VOCs). These emissions occur when printing materials are heated or chemically cured. The quantity and composition of these airborne substances can vary widely depending on the printer technology and the material used.
Ultrafine Particles are microscopic solid particles smaller than 100 nanometers, predominantly associated with filament-based Fused Deposition Modeling (FDM) printers. Because of their minute size, UFPs can bypass the body’s natural respiratory defenses, penetrating deep into the lungs and potentially entering the bloodstream.
Volatile Organic Compounds are gases released from printing materials, concerning both FDM and resin-based printing. These compounds include substances like styrene, formaldehyde, and acrylates, which are known irritants to the eyes, nose, and throat. In poorly ventilated spaces, the concentration of total VOCs can quickly exceed recommended indoor air quality limits.
Material-Specific Risks in FDM and Resin Printing
The specific material and technology employed profoundly influence the nature and quantity of the emitted UFPs and VOCs. Fused Deposition Modeling (FDM) involves melting thermoplastic filaments, and material choice is the largest factor in emission rates. Filaments like Acrylonitrile Butadiene Styrene (ABS) and Nylon are high-emitting materials, releasing significantly higher concentrations of both UFPs and VOCs such as styrene.
Polylactic Acid (PLA) and Polyethylene Terephthalate Glycol (PETG) are generally considered lower-emitting options, though they still produce UFPs and VOCs. Operating FDM printers at higher temperatures tends to increase both particle and VOC emissions. Managing print settings can partially mitigate the release of contaminants.
Resin-based printing, such as Stereolithography (SLA) or Digital Light Processing (DLP), uses liquid photopolymer resins cured by UV light. Resin printing is characterized by high total VOC emissions and relatively low UFP release compared to FDM. The VOCs include methyl acrylate and various methacrylates, which can reach levels exceeding occupational exposure thresholds in unventilated spaces. A unique hazard is the risk of direct dermal exposure to the uncured liquid resin, which contains monomers that are potent skin sensitizers.
Current Scientific Understanding of Carcinogenic Risk
The International Agency for Research on Cancer (IARC) has not classified the general act or process of 3D printing as carcinogenic. However, many individual chemicals released during the printing process are classified as known, probable, or possible human carcinogens.
For instance, styrene, commonly released by ABS, is classified as a probable human carcinogen (IARC Group 2A), and formaldehyde, found in both FDM and resin emissions, is a known human carcinogen (IARC Group 1). The risk is not from the printer itself, but from the cumulative exposure to these hazardous compounds and UFPs in the emitted mixture. Risk assessments suggest that the estimated lifetime cancer risk from UFP exposure in poorly ventilated 3D printing environments can be significantly higher than that from typical urban air pollution.
Currently, large-scale, long-term human epidemiological studies definitively linking exposure to 3D printer emissions with increased cancer incidence are lacking. Toxicological studies show that particulate matter from ABS and PLA can induce changes in cell metabolism and the expression of cancer-related genes. The carcinogenic potential cannot be entirely dismissed, but the risk is highly dependent on the concentration and duration of exposure.
Essential Safety and Ventilation Measures
Given the presence of hazardous emissions, implementing proper safety measures is the most effective way to minimize personal risk. The most important control strategy is the use of local exhaust ventilation (LEV) to capture emissions at the source. This involves venting the air directly outdoors or using a sealed enclosure with a dedicated filtration system.
Filtration systems should be multi-stage, incorporating a High-Efficiency Particulate Air (HEPA) filter to capture UFPs and an activated carbon filter to adsorb VOCs. Placing the printer in a dedicated enclosure helps contain the contaminants and makes the ventilation system more effective. Users should also prioritize lower-emitting materials, such as PLA, over higher-emitting ones like ABS, whenever the application allows.
For resin-based printing, meticulous handling of the liquid material is necessary to prevent skin sensitization. This includes consistently wearing impervious gloves and eye protection when pouring, handling uncured prints, or cleaning the equipment. Practicing good personal hygiene, such as washing hands thoroughly after handling materials and cleaning the printer surfaces, further reduces the potential for exposure.