Re-evaluation of pulmonary titanium dioxide nanoparticle distribution using the

Table 2 Analysis of TiO₂-nanoparticle distribution 24 h after exposure.

Compartment	N_O	P	N_E	RDI	Χ²	Fraction of total Χ²
Air	348	2052	363	0.96	0.59	0.039
Epi/Endo	17	131	23	0.73	1.63	0.109
CT	11	54	10	1.15	0.22	0.015
Caplum	49	168	30	1.65	12.56	0.837
Total	425	2405	425		15.01

Note. The calculation of the data is described in the Methods section and an illustrating example is provided in the note to table 1. With three degrees of freedom (2-1 groups × 4-1 compartments) and a total chi-squared value of 15.01, the null-hypothesis of random distribution has to be rejected (p < 0.01). The capillary lumen has an RDI of 1.65 and a partial chi-squared value that contributes about 84% of the total chi-squared. It is the only compartment that meets both criteria for a preferential deposition. Abbreviations: Air: Air space; Epi/Endo: Epithelial/endothelial cells; CT: Connective tissue; Caplum: Capillary lumen. Χ²: Chi-squared test values. N_O: Observed number of particles. N_E: Expected number of particles. RDI: Relative deposition index.

ISSN: 1743-8977