Comparative toxicity study of three surface-modified titanium dioxide nanoparticles following subacute inhalation.

backgroundThis study aimed to compare the toxic effects of three different titanium dioxide nanoparticles encoded in the European nanomaterial repository as NM-103 (rutile, hydrophobic), NM-104 (rutile, hydrophilic), and NM-105 (anatase/rutile, hydrophilic), suggesting different toxic potentials after uptake in the lungs. Wistar rats were exposed by nose-only inhalation to aerosol concentrations of 3, 12 and 48 mg/m

resultsBronchoalveolar lavage fluid from the groups exposed to low concentrations of NM-103 or NM-104 presented slight inflammation. In the mid- and high-exposure groups, this was also present for the NM-105 group, however, weaker than those of NM-103 and NM-104. Histologically, all three groups presented similar distributions of particles in the respiratory tract. Although marginal differences in the degree of some changes exist, no obvious differences in the degree or characteristics of the induced lesions were observable. In general, compared with the higher exposure groups, all the middle exposure groups presented a greater accumulation and aggregation of macrophages at the terminal bronchi. Using transmission electron microscopy, particles were detected mainly in intraalveolar macrophages, followed by type 1 pneumocytes in the low- and mid-concentration groups and intraalveolar free particles in the high-concentration groups. Compared with the other groups, the NM-103 group presented greater numbers of free particles in the alveoli and fewer in the macrophages. With image analysis, the movement of particles to the bronchus-associated lymphoid tissue and lymph nodes could be detected comparably for the three different particle types.

conclusionsThe no observed adverse effect concentration was 3 mg/m