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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