Effective density of inhaled environmental and engineered nanoparticles and its impact on the lung deposition and dosimetry

Denisa Lizonova; Amogh Nagarkar; Philip Demokritou; Georgios A Kelesidis

doi:10.1186/s12989-024-00567-9

Effective density of inhaled environmental and engineered nanoparticles and its impact on the lung deposition and dosimetry

Part Fibre Toxicol. 2024 Feb 17;21(1):7. doi: 10.1186/s12989-024-00567-9.

Authors

Denisa Lizonova¹, Amogh Nagarkar², Philip Demokritou¹, Georgios A Kelesidis^{3

4}

Affiliations

¹ Nanoscience and Advanced Materials Center (NAMC), Environmental and Occupational Health Science Institute, School of Public Health, Rutgers, The State University of New Jersey, 170 Frelinghuysen Road, Piscataway, NJ, 08854, USA.
² Particle Technology Laboratory, Department of Mechanical and Process Engineering, Institute of Process Engineering, ETH Zürich, Sonneggstrasse 3, 8092, Zurich, Switzerland.
³ Nanoscience and Advanced Materials Center (NAMC), Environmental and Occupational Health Science Institute, School of Public Health, Rutgers, The State University of New Jersey, 170 Frelinghuysen Road, Piscataway, NJ, 08854, USA. georgios.kelesidis@rutgers.edu.
⁴ Particle Technology Laboratory, Department of Mechanical and Process Engineering, Institute of Process Engineering, ETH Zürich, Sonneggstrasse 3, 8092, Zurich, Switzerland. georgios.kelesidis@rutgers.edu.

Abstract

Background: Airborne environmental and engineered nanoparticles (NPs) are inhaled and deposited in the respiratory system. The inhaled dose of such NPs and their deposition location in the lung determines their impact on health. When calculating NP deposition using particle inhalation models, a common approach is to use the bulk material density, ρ_b, rather than the effective density, ρ_eff. This neglects though the porous agglomerate structure of NPs and may result in a significant error of their lung-deposited dose and location.

Results: Here, the deposition of various environmental NPs (aircraft and diesel black carbon, wood smoke) and engineered NPs (silica, zirconia) in the respiratory system of humans and mice is calculated using the Multiple-Path Particle Dosimetry model accounting for their realistic structure and effective density. This is done by measuring the NP ρ_eff which was found to be up to one order of magnitude smaller than ρ_b. Accounting for the realistic ρ_eff of NPs reduces their deposited mass in the pulmonary region of the respiratory system up to a factor of two in both human and mouse models. Neglecting the ρ_eff of NPs does not alter significantly the distribution of the deposited mass fractions in the human or mouse respiratory tract that are obtained by normalizing the mass deposited at the head, tracheobronchial and pulmonary regions by the total deposited mass. Finally, the total deposited mass fraction derived this way is in excellent agreement with those measured in human studies for diesel black carbon.

Conclusions: The doses of inhaled NPs are overestimated by inhalation particle deposition models when the ρ_b is used instead of the real-world effective density which can vary significantly due to the porous agglomerate structure of NPs. So the use of realistic ρ_eff, which can be measured as described here, is essential to determine the lung deposition and dosimetry of inhaled NPs and their impact on public health.

Keywords: Air pollution; Black carbon; Effective density; Engineered nanoparticles; Inhalation; Pulmonary deposition; Wood smoke.

MeSH terms

Animals
Carbon
Humans
Inhalation Exposure* / analysis
Lung
Mice
Nanoparticles* / chemistry
Particle Size
Soot

Substances

Soot
Carbon

Grants and funding

P30 ES005022/ES/NIEHS NIH HHS/United States