Quantitative biokinetics over a 28 day period of freshly generated, pristine, 20 nm silver nanoparticle aerosols in healthy adult rats after a single 1½-hour inhalation exposure

Table 3 Summary of the averages (± SD) of parameters and basic results of the biokinetics study after ^[105Ag]AgNP inhalation

Time-point after inhalation	0.75 h(1st)	0.75 h(2nd)	4 h	24 h(1st)	24 h(2nd)	7d	28d
Inhaled aerosol volume (L)¹	37 ± 27	36 ± 27	36 ± 27	35 ± 26	37 ± 28	40 ± 30	40 ± 30
Inhaled [¹⁰⁵Ag]AgNP activity (kBq)¹	124.7 ± 3.3	101 ± 3.1	135.3 ± 7.8	118.3 ± 2	97.9 ± 5.7	112.7 ± 4.8	88.7 ± 3.5
Deposited^[105Ag]AgNP activity (kBq)¹	31.4 ± 9.6	29.6 ± 8.4	37.8 ± 7.1	38.7 ± 4.91	36.1 ± 8.86	34.2 ± 13.9	37.9 ± 13.6
Deposited AgNP mass (μg)¹	12.1 ± 3.7	11.4 ± 3.2	14.6 ± 2.7	14.9 ± 1.9	13.9 ± 3.4	13.2 ± 5.3	14.6 ± 5.3
Deposited number of AgNP (# •10¹¹)	5.78 ± 1.77	6.63 ± 1.89	5.59 ± 1.04	7.13 ± 0.91	8.45 ± 2.08	11.32 ± 4.59	10.82 ± 3.91
Deposited fraction (inhaled)¹	0.25 ± 0.08	0.29 ± 0.09	0.28 ± 0.06	0.33 ± 0.04	0.37 ± 0.09	0.30 ± 0.11	0.43 ± 0.16
Retained alveolar [¹⁰⁵Ag]AgNP fraction (/ILD) at dissection¹	0.90 ± 0.02	0.88 ± 0.05	0.69 ± 0.01	0.55 ± 0.03	0.62 ± 0.05	0.14 ± 0.09	0.041 ± 0.02
Fast early cleared fraction (/ILD)¹	0.07 ± 0.01	0.09 ± 0.04	0.27 ± 0.01	0.36 ± 0.03	0.30 ± 0.02	0.60 ± 0.12	0.57 ± 0.04
Slow long-term cleared fraction (/ILD)¹						0.25 ± 0.03	0.35 ± 0.05

¹ according to Eqns. 1–8, 10–16 of Supplementary Information
Parameters of the intratracheal inhaled [¹⁰⁵Ag]AgNP aerosol inhalation and deposition for each group of rats: inhaled aerosol volume and ¹⁰⁵Ag activity, deposited ¹⁰⁵Ag activity and the corresponding deposited [¹⁰⁵Ag]AgNP mass and NP number, deposited ¹⁰⁵Ag activity as a fraction of the inhaled ¹⁰⁵Ag activity. Additionally, the retained alveolar fraction at the time of dissection, the early clearance during the first two days p.e. and the integral long-term clearance of [¹⁰⁵Ag]AgNP including their secondary products from day 3–28 after inhalation is given; the latter is calculated based on fecal excretion and retention in the gastro-intestinal-tract (GIT). All fractional data are normalized to the Initial Lung Dose (ILD), i.e. the sum of ¹⁰⁵Ag radioactivities of all organs and tissues including excretion

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