title: Histopathological changes in rat lung following intratracheal instillation of silicon carbide whiskers and potassium octatitanate whiskers.
abstract: We evaluated the pattern of pulmonary inflammation for the assessment of the biological hazards of two man-made mineral fibers. Rats were exposed by intratracheal instillation to a 2 mg dose of each of two kinds of man-made mineral fibers (PT1, potassium octatitanate whisker; and SiCW, silicon carbide whisker), or three kinds of comparable respirable particles (crystalline silica, crocidolite asbestos, and titanium dioxide, TiO(2)). The lung tissue was evaluated at 3 day, 1 wk, and 1, 3 and 6 mo after exposure. Digital images taken of the lung sections were examined by morphometric point counting method (PCM). PT1 and SiCW showed a similar inflammatory pattern, which contains temporal inflammation such as moderate alveolitis within 1 wk after the exposure, and in later phase aggregation foci of instilled fibers. Differences in repair patterns of these two man-made mineral fibers showed that the toxicity of these two fibers is less toxic than for crocidolite or crystalline silica. Although SiCW showed a higher inflammation score than TiO(2) within 1 mo after instillation, the inflammation scores and fibrotic changes of PT1 and SiCW were not significant as TiO(2) at 3 mo and 6 mo in this study. Careful use should be recommended when these materials are used in the workplace.
authors.affiliation: Department of Occupational Pneumology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Yahatanishi-ku, Kitayushu, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Ogami
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Morimoto
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Myojo
authors.forename: Takako
authors.initials: T
authors.lastname: Oyabu
authors.forename: Masahiro
authors.initials: M
authors.lastname: Murakami
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Nishi
authors.forename: Chikara
authors.initials: C
authors.lastname: Kadoya
authors.forename: Isamu
authors.initials: I
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D017554:Carbon Compounds, Inorganic / Q000633:toxicity*; D005355:Fibrosis / Q000139:chemically induced; D008168:Lung / Q000473:pathology*; D008171:Lung Diseases / Q000139:chemically induced* / Q000473:pathology*; D008297:Male; D019016:Mineral Fibers / Q000633:toxicity; D052638:Particulate Matter; D051381:Rats; D017208:Rats, Wistar; D017655:Silicon Compounds / Q000633:toxicity*; D013997:Time Factors; D014025:Titanium / Q000633:toxicity*
chemical_list: D017554:Carbon Compounds, Inorganic; D019016:Mineral Fibers; D052638:Particulate Matter; D017655:Silicon Compounds; C021028:potassium octatitanate; D014025:Titanium; C022088:silicon carbide