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

Table 1 Main characteristics of TiO₂ P25, Printex-90, and MWNT-7 aerosols produced for inhalation studies

Material	Target concentration (mg/m³)	Actual concentration (mg/m³)	Number concentration^c (particle×10⁴/cm³)	MMAD^d (μm)	CMoAD^e (μm)	GSD^e	Aerosol effective density (g/cm³)^f
P25	15 15 (2-week) 5^a 5^a (2-week) 1.5^a 1.5^a (2-week)	15.3 ± 3.98 15.3 ± 3.54 5.02 ± 0.39 5.04 ± 1.30 1.59 ± 0.45 2.20 ± 0.64	5.1 ± 1.7	1.56	0.31	1.72	1.70
P25	5^b	5.09 ± 0.65	27 ± 2	0.40	0.17	1.82	0.90
Printex-90	50 15^a 5^a	50.1 ± 3.89 15.0 ± 1.24 4.89 ± 0.39	35 ± 14	0.94	0.03 & 0.20	1.97 & 2.11	0.35
MWNT-7	1.5 0.5^a 0.15^a	1.69 ± 0.49 0.47 ± 0.15 0.13 ± 0.02	0.14 ± 0.05	1.78	0.40	1.69	0.45

^a6 h-equivalent concentration created by modulating the time for which animals were exposed to the aerosols produced from a dry powder generator
^baerosol produced from a nebulized suspension
^cMeasured by CPC particle diameter d_p < 3 μm
^dDetermined from cascade impactor (DPLI+) sampling, subsequent gravimetric analysis and further data inversion to account for particle deposition probabilities [50]
^eDetermined from a log-normal fitting of the number size distribution provided either by SMPS or APS measurements
^fAerosol effective densities were estimated by merging SMPS and APS number size distributions and assuming spherical particles [51]. These data shall be considered as indicative values

ISSN: 1743-8977