Estimates of particulate matter inhalation doses during three-dimensional (3D) printing.

Harmful emissions including particulates, volatile organic compounds, and aldehydes are generated during three-dimensional (3D) printing. Ultrafine particles are particularly important due to their ability to penetrate deep into the lung. We modeled inhalation exposure by particle size during 3D printing. A total of six thermoplastic filaments were used for printing under manufacturer's recommended conditions, and particle emissions in the size range between 10 nm and 10 μm were measured. The inhalation exposure dose including inhaled and deposited doses was estimated using a mathematical model. For all materials, the number of particles between 10 nm and 1 μm accounted for a large proportion among the released particles, withnano-sized particles being the dominant size. More than 1.3×109 nano-sized particles/kgbw/g (95.3±104.0 ng/kgbw/g) could be inhaled, and a considerable amount were deposited in respiratory regions. The total deposited dose in terms of particle number was 3.1×108 particles/kgbw/g (63.6% of the total inhaled dose), and most (41.3%) were deposited in the alveolar region. The total mass of particles deposited was 19.8±16.6 ng/kgbw/g, with 10.1% of the total mass deposited in the alveolar region. Given our findings, the inhalation exposure levelis mainly determined by printing conditions, particularly, the filament type and manufacturer-recommended extruder temperature.