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Table 2 Neutrophil influx (normalized relative to total cell count in BALF) and retained NM mass and surface area lung burden observed at various post-exposure times after 4 weeks’ (or as indicated) nose-only inhalation exposure in rats

From: Retained particle surface area dose drives inflammation in rat lungs following acute, subacute, and subchronic inhalation of nanomaterials

Material Target concentration
(mg/m3)
Post-exposure time n = Retained amount measured
(mg / g lung)
Retained surface
(cm2 / g lung)
Neutrophils (%)c
P25 15 D3
W4
W26
6
6
6
3.809 ± 0.641
3.272 ± 1.144
1.328 ± 0.873
2095 ± 327
1800 ± 629
730 ± 480
40.9 ± 7.0
57.7 ± 8.8
19.9 ± 12.7
15 (2-week) D3 10 1.699 ± 0.241 935 ± 123 22.0 ± 8.7
5a D3
W4
W26
6
6
6
1.368 ± 0.177
1.386 ± 0.384
0.756 ± 0.429
752 ± 90
762 ± 211
416 ± 236
13.5 ± 4.9
12.4 ± 7.5
1.7 ± 1.3
5a (2-week) D3 10 0.672 ± 0.127 370 ± 65 5.1 ± 4.0
1.5a D3
W4
W26
6
6
6
0.511 ± 0.125
0.296 ± 0.041
0.097 ± 0.074
281 ± 64
163 ± 23
54 ± 41
2.7 ± 2.9
2.5 ± 0.6
2.2 ± 2.6
1.5a (2-week) D3 10 0.246 ± 0.060 135 ± 31 2.3 ± 2.6
P25 5b D0
D3
W4
W13
W26
6
6
6
6
6
1.372 ± 0.105
1.286 ± 0.152
0.585 ± 0.055
0.258 ± 0.036
0.122 ± 0.008
700 ± 54
656 ± 78
298 ± 28
132 ± 18
62 ± 4
4.4 ± 0.9
8.1 ± 2.4
1.2 ± 0.5
1.0 ± 0.6
1.8 ± 0.7
Printex-90 50 D3
W4
W26
6
6
6
2.467 ± 0.131
2.950 ± 0.492
3.708 ± 0.631
7797 ± 414
9322 ± 1555
11,717 ± 1994
72.9 ± 5.6
52.3 ± 7.4
48.3 ± 6.4
15a D3
W4
W26
6
6
6
1.340 ± 0.269
1.418 ± 0.234
1.080 ± 0.177
4234 ± 850
4481 ± 739
3413 ± 559
55.1 ± 19.0
41.0 ± 10.0
9.5 ± 6.0
5a D3
W4
W26
6
6
6
0.895 ± 0.228
1.428 ± 0.372
0.553 ± 0.161
2827 ± 721
4512 ± 1176
1747 ± 509
18.8 ± 4.2
5.2 ± 1.8
2.2 ± 2.3
MWNT-7 1.5 D3
W4
W26
6
6
6
0.834 ± 0.460
0.310 ± 0.181
< 0.060
192 ± 106
71 ± 42
< 14
44.7 ± 9.9
28.3 ± 8.9
10.1 ± 5.3
0.5a D3
W4
W26
6
6
6
0.397 ± 0.217
< 0.060
< 0.060
91 ± 50
< 14
< 14
30.6 ± 13.5
9.0 ± 4.4
8.3 ± 8.6
0.15a D3
W4
W26
6
6
6
< 0.060
< 0.060
< 0.060
< 14
< 14
< 14
10.2 ± 8.1
4.9 ± 6.5
4.7 ± 5.3
  1. a6 h-equivalent concentration created by modulating the exposure time to the aerosols
  2. baerosol produced from a suspension by nebulization
  3. cFor each experiment, control groups (exposed to filtered air) were monitored in parallel to groups of aerosol-exposed animals. In control animals, levels of % neutrophils never exceeded 3.6% (1.8% on average) regardless of the post-exposure time