Overview
Key numbers
- Study set: 8 filaments and matched emitted-particle samples; filaments included three pure PLA filaments, two composite PLA filaments, two nylon-based composite filaments, and one stainless-steel-containing metal filament.
- Filament metals: bronze PLA3 was 80% by weight bronze, and measured metals accounted for 79.8% of filament weight; the stainless-steel metal filament had measured total metals equal to 95.9% of filament mass.
- Particle detections: silicon was detected in all 8 emitted-particle samples; boron was detected in 7 of 8; magnesium, calcium, manganese, zinc, arsenic, strontium, tin, and lead were each detected in 5 to 6 of 8 emitted-particle samples.
- Emission yields: silicon had the highest elemental yield, 15.3-248 ng/g for PLA-based filaments and 614-2251 ng/g for nylon and metal-composite filaments.
- Reported yields for toxicologically relevant metals included chromium (Cr) at 5.51 ng/g, Cu at 0.43-1.31 ng/g, total arsenic (tAs) at 0.002-0.76 ng/g, cadmium (Cd) at 0.02 ng/g, Sb at 0.24-1.96 ng/g, and Tl at 0.32 ng/g.
- Metal-composite transfer was limited: in metal-composite filaments where metals made up as much as 95.9% of filament weight, metals made up only about 1-2% of emitted-particle weight, or below 0.1% when silicon was excluded.
- Exposure modelling found residential Mn, Cd, and lead (Pb) exposure concentrations from 3D printing below most comparison residential PM2.5 literature values, while some Zn, arsenic (As), Cu, Cr, Co, Sb, and Se scenarios were comparable to or above selected indoor-comparison cases.
Methods (brief)
The team printed filaments in stainless-steel exposure chambers with one air exchange per hour. Particle number and size distributions were measured with SMPS and OPS instruments, while particle samples and unused filament pieces were microwave-acid-digested and analysed by ICP-MS. The metal yield calculation normalised emitted elemental mass to filament mass consumed; the partition-factor analysis compared element concentrations in emitted particles with raw-filament concentrations. Species were not speciated: arsenic is total arsenic and chromium is total chromium, not hexavalent chromium (Cr-VI).
Related evidence
- Lead
- Arsenic
- Cadmium
- Chromium
- Nickel
- Aluminum
- Tin
- ICP-MS — Inductively coupled plasma mass spectrometry
- Fabric protectants (excluding waterproofing/flame-retardant per GS-48 boundaries)
Update history
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