The pulmonary deposition and retention of indium-111 labeled ultrafine carbon particles in healthy individuals

Abstract

Context: Particulate air pollution, for example, from ultrafine (UF) particles, has negative health effects. However, there is still limited knowledge regarding the fate of inhaled particles in the human body.

Objectives: To describe the normal lung deposition and 1 week particle retention of indium-111 labeled UF carbon particles in healthy subjects. Additionally, the possibility to extend the follow-up period to 4 weeks was also investigated for one of the subjects.

Results: The cumulative pulmonary particle clearance 1 week post-administration, corrected for activity leaching and mucocilliary transport of activity deposited in the central airways, was 4.3 ± 8.5% (average ± standard deviation at group level), with marginal translocation of particles from lungs to blood, 0.3%. There was no observable elimination of particles from the body via urine. Seven days after exposure, the cumulated activity leaching was 3% (group level), which indicates a stable bonding between the particles and Indium-111. The volunteer followed for a total of 4 weeks, showed a cumulative decrease of activity retention in the lungs of 10.5%. After correction for activity leaching and clearance from central airway deposition, the estimated particle clearance was about 2%.

Conclusions: No evidence for particle translocation from the lungs could be proven 7 days after exposure. It is possible to follow-up Indium-111 labeled UF carbon particles at least 1 month post-administration without increasing the administered activity.

Keywords::

• Air pollution
• ultrafine particles
• pulmonary deposition and pulmonary retention

Acknowledgments

The authors wish to thank Stina Gustavsson and Anneli Sandberg (Institute of Environmental Medicine, Karolinska Institute) for their excellent technical assistance.

Declaration of interest

Grants from the Swedish Heart-Lung Foundation supported this project. None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript.