Inhalation of 3D Printing Exhaust Using Fluorescent ABS Filament Modulates Respiratory Immune Response

Details

• Personal Author:
  Chapman, P. D. ; McKinney, Walter G. ; Friend, Sherri A. ; Waugh, Stacey ; Krajnak, Kristine M.
• Description:
  Background and Purpose: Additive manufacturing (3D printing) using thermally extruded plastics has enabled industries to innovate the process of fabrication to produce consumer products. 3D printers use a variety of plastics, colors, and dyes and has become increasingly popular in workplaces, schools and private residences over the past decade. Recent evidence suggests that fumes from 3D printers can contribute to reproductive, and neurological dysfunction, and that workers using unventilated 3D printing machines are at the greatest risk. Previous research has reported the presence of plastic nanoparticles in the emissions of 3D printers, and these particles may pose a health hazard. Fluorescent acrylonitrile butadiene styrene (fABS) is a recently developed filament for 3D printing that fluoresces in response to UV light and its effect on health is unknown. Methods: We examined the emissions of extruding fABS filament from 5 printer heads, and subsequently exposed mice to the emissions for up to 24 days (4 days/week, 4hrs/day). To directly examine particles produced during the exposure, we collected particulate on filters, and imaged particles using scanning electron microscopy. We fractioned the particle size using a MOUDI Impactor to determine the overall aerodynamic particle size distribution. We collected volatile organic compounds (VOCs) using the C1-C10 canister method to measure levels of potentially toxic volatiles. The day after the last exposure for each group, animals were weighed, euthanized, and lung and brain tissues were collected. To measure levels of gene expression, we used quantitative reverse transcription- polymerase chain reaction (qRT-PCR) to measure changes in the mRNA levels of different immune system & inflammation biomarkers in the lungs. To examine changes in protein levels, we used quantitative western blotting. Results: Mass Median Aerodynamic Diameter (MMAD) particle size was 255 nm, and the mean particle concentration inside the exposure chamber was 41 mg/m³; over 20 times higher than when standard ABS filament was used in the same exposure system. VOC analysis determined that toluene was present in concentrations as high as 32 ppm, a level of extended exposure in which central nervous/behavioral, reproductive/developmental, color vision and ototoxic effects have been documented. Gene expression in lung tissue (qRT-PCR) demonstrated clear reductions in gene transcripts that code for pro-inflammatory cytokines suggestive of an immunoregulatory effect. Notably, TNF-a was significantly lower at 1 & 8 days than 24 days in exposed animals, and Interleukin-12 (IL12) & Interferon-gamma (IFNy) were reduced in exposed animals across all exposure durations. Quantitative western blot experiments also demonstrate significant reductions in interleukin-6 (IL6) expression in the hypothalamus, as well as significant changes in androgen receptor (AR) expression. Conclusions: Based on these results, we suspect that either higher concentrations of particulate generated by fABS or the increased levels of volatile toluene underly these effects. Reductions in IL12 in lung tissues may be responsible for the reduction in the other cytokines reported; IL12 is known to stimulate the production of IFNy, TNF-a, and NK cells. These data are consistent with research demonstrating IFN-y reduction and changes in TNF-a in both microplastic and toluene exposure studies (Fujimaki et. al., 2007, Bishop et. al., 2024). In combination with a growing body of research, this data suggests that workers who are routinely exposed to high levels of 3D printing emissions could potentially be at increased risk of respiratory infections or disease. Description provided by NIOSH
• Subjects:
  • Acrylonitrile
  • Butadienes
  • Occupational Health
  • Printing, Three-Dimensional
  • Safety
  • Styrene
  • Volatile Organic Compounds
• Keywords:
  • Additive manufacturing; Three dimensional printing; 3D printing; Nanoparticles; Printer-emitted particles; Volatile organic compounds; VOCs; Laboratory animals
• Source:
  Toxicologist 2025 Mar; 204(S1):251-252
• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Philadelphia Region OSHA ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  3 pdf pages
• Volume:
  204
• NIOSHTIC Number:
  nn:20071577
• Federal Fiscal Year:
  2025
• Peer Reviewed:
  False
• Download URL:
  https://stacks.cdc.gov/view/cdc/259352/cdc_259352_DS1.pdf
• File Type:
  [PDF - 297.56 KB]
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:86bf6ecbb5752105f14b9c4d2ee41c45bc0a0976c6225f4beeb7da48cf6919ffa5d14410d25f094616afeb579535d3031dad4ef6aed6084493e2fbff0636597c