title: Pulmonary responses in rat lungs after intratracheal instillation of 4 crystal forms of titanium dioxide nanoparticles.
abstract: OBJECTIVE
  Titanium dioxide nanoparticles are widely used as UV filters in cosmetics and as a photocatalyst. We evaluated pulmonary responses to different crystal forms of TiO2nanoparticles.
  
  
  METHODS
  We used 4 different TiO2samples with similar specific surface areas (anatase, rutile, amorphous, and P25). Each sample was suspended in distilled water and intratracheally instilled to male Wister rats at the dose of 1 mg per rat. Five rats per group were sacrificed at 3 days, 1 month, and 6 months after instillation, and bronchoalveolar lavage fluid was collected from the right lung to determine the total cell count and polymorphonuclear cell (PMN) counts. The left lung tissues were stained with hematoxylin and eosin for the evaluation of inflammation and with elastica van Gieson for the evaluation of collagen deposition.
  
  
  RESULTS
  The total cell counts and PMN counts of the amorphous and P25 of four samples showed a significant increase compared with the control group at 3 days after instillation. The inflammation rate of P25 also showed a significant increase compared with controls at 3 days. The collagen deposition rate in the alveolar duct of P25 increased significantly compared with controls from 3 days to 6 months. The other samples showed a mild response after instillation.
  
  
  CONCLUSIONS
  Although the TiO2nanoparticles used in this study had similar specific surface areas, there were different inflammatory responses in the rat lungs. Other factors, such as different production processes or the surface activities of particles, may have been responsible for the different responses.
authors.affiliation: Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health.
authors.forename: Takami
authors.initials: T
authors.lastname: Okada
authors.forename: Akira
authors.initials: A
authors.lastname: Ogami
authors.forename: Byeong Woo
authors.initials: BW
authors.lastname: Lee
authors.forename: Chikara
authors.initials: C
authors.lastname: Kadoya
authors.forename: Takako
authors.initials: T
authors.lastname: Oyabu
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Myojo
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D003094:Collagen / Q000032:analysis; D004396:Coloring Agents / Q000008:administration & dosage / Q000009:adverse effects*; D007958:Leukocyte Count; D008168:Lung / Q000737:chemistry / Q000187:drug effects*; D008297:Male; D053758:Nanoparticles / Q000008:administration & dosage / Q000009:adverse effects* / Q000737:chemistry; D009504:Neutrophils; D051381:Rats; D017208:Rats, Wistar; D014025:Titanium / Q000008:administration & dosage / Q000009:adverse effects*; D014132:Trachea
chemical_list: D004396:Coloring Agents; C009495:titanium dioxide; D003094:Collagen; D014025:Titanium