Quantitative biokinetics over a 28 day period of freshly generated, pristine, 20 nm titanium dioxide nanoparticle aerosols in healthy adult rats after a single two-hour inhalation exposure

Table 2 Summary of the inhalation parameters and basic results of the biokinetics study

Time point after inhalation	1 h	4 h	24 h	7d	28d
Inhaled aerosol volume (L) ¹	39.37 ± 1.12	42.94 ± 2.04	38.13 ± 0.96	38.97 ± 1.01	42.77 ± 1.66
Inhaled [⁴⁸V]TiO₂-NP activity (kBq) ¹	34.54 ± 0.98	44.76 ± 2.12	27.57 ± 0.7	24.56 ± 0.63	51.84 ± 2.01
Deposited ^[48V]TiO₂-NP activity (kBq) ¹	20.37 ± 2.21	27.94 ± 9.79	15.64 ± 5.69	12.26 ± 2.85	21.55 ± 6.19
Deposited TiO₂-NP mass (μg) ¹	1.64 ± 0.18	1.51 ± 0.53	1.08 ± 0.39	0.8 ± 0.19	1.37 ± 0.39
Deposited fraction per inhaled aerosol ¹	0.59 ± 0.08	0.39 ± 0.12	0.57 ± 0.21	0.50 ± 0.13	0.42 ± 0.13
Deposited alveolar [⁴⁸V]TiO₂-NP fraction per IPLD ¹	0.95 ± 0.03	0.75 ± 0.12	0.72 ± 0.04	0.69 ± 0.02	0.74 ± 0.02
Mucociliary cleared fraction per ILD ¹	0.04 ± 0.03	0.20 ± 0.12	0.21 ± 0.03	0.26 ± 0.04	0.26 ± 0.04
Long-term macrophage- mediated cleared fraction per ILPD				0.15 ± 0.03	0.31 ± 0.04

¹according to Eq. (4 through 14) of the Additional file 1
Parameters of the intratracheal [⁴⁸V]TiO₂-NP aerosol inhalation and deposition are: inhaled aerosol volume and ⁴⁸V activity, deposited ⁴⁸V activity and corresponding [⁴⁸V]TiO₂-NP mass, deposited ⁴⁸V activity as a fraction of the inhaled ⁴⁸V activity and the alveolar deposited fraction relative to the total lung deposit. Additionally, the fast mucociliary [⁴⁸V]TiO₂-NP clearance (MCC) during the first two days and the long-term macrophage-mediated clearance (LT-MC) of [⁴⁸V]TiO₂-NP from day 3–28 after inhalation are presented, calculated based on fecal excretion and retention in the gastro-intestinal-tract (GIT). MCC fractions are normalized to the initial lung dose (ILD) i.e. the sum of all organ and tissue ⁴⁸V radioactivities

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