Negligible clearance of ultrafine particles retained in healthy and affected human lungs

• Published in: The European respiratory journal Vol. 28; no. 2; pp. 286 - 290
• Main Authors: Wiebert, P, Sanchez-Crespo, A, Seitz, J, Falk, R, Philipson, K, Kreyling, W. G, Moller, W, Sommerer, K, Larsson, S, Svartengren, M
• Format: Journal Article
• Language: English
• Published: Leeds Eur Respiratory Soc 01.08.2006; Maney
• Subjects: Administration, Inhalation; Aged; Biological and medical sciences; Carbon - administration & dosage; Female; Humans; Inhalation Exposure; Lung Diseases - etiology; Lung Diseases - physiopathology; Male; Medical sciences; Middle Aged; Particle Size; Pneumology; Respiratory Function Tests - instrumentation; Respiratory Function Tests - methods; Technetium - administration & dosage; Human; Particle; Lung; ultrafine particles; circulation; Air pollution; Clearance
• ISSN: 0903-1936; 1399-3003
• DOI: 10.1183/09031936.06.00103805

Ambient particles are believed to be a specific health hazard, although the underlying mechanisms are not fully understood. There are data in the literature indicating fast and substantial systemic uptake of particles from the lung. The present authors have developed an improved method to produce ultrafine particles with more stable radiolabelling and defined particle size range. Fifteen subjects inhaled technetium 99m ( 99m Tc)-labelled carbonaceous particles of 100 nm in size. Radioactivity over the lung was followed for 70 h. The clearance of these ultrafine particles from the lungs and specifically translocation to the circulation was tested. Lung retention for all subjects at 46 h was mean± sd 99±4.6%. Cumulative leaching of 99m Tc activity from the particles was 2.6±0.96% at 70 h. The 24-h activity leaching in urine was 1.0±0.55%. No evidence of a quantitatively important translocation of 100-nm particles to the systemic circulation from the lungs was found. More research is needed to establish if the ∼1% cleared activity originates from leached activity or insoluble translocated particles, and whether a few per cent of translocated particles is sufficient to cause harmful effects.