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J Occup Health year 2007 volume 49 number 2 page 88 - 94
Classification Original
Title Effect of Particle Size of Intratracheally Instilled Crystalline Silica on Pulmonary Inflammation
Author Takayoshi KAJIWARA1, Akira OGAMI2, Hiroshi YAMATO1, 3, Takako OYABU1, Yasuo MORIMOTO2 and Isamu TANAKA1
Organization 1Department of Environmental Health Engineering, 2Department of Occupational Pneumology and 3Department of Health Development, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan
Keywords Crystalline silica, Instillation, Particle size, Rat, Inflammation
Correspondence A. Ogami, Department of Occupational Pneumology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, Fukuoka 807-8555, Japan
(e-mail: gamisan@med.uoeh-u.ac.jp)
Abstract Effect of Particle Size of Intratracheally Instilled Crystalline Silica on Pulmonary Inflammation: Takayoshi KAJIWARA, et al. Department of Environmental Health Engineering, University of Occupational and Environmental Health-Crystalline silica, known as a causal substance of silicosis, has been carefully evaluated for its carcinogenicity and fibrogenicity. In this study, we instilled crystalline silica of two different size (S1.8 :1.80 microm (S.D. 2.0), S0.7 :0.74 microm (S.D. 1.5)) into the trachea of rats to evaluate the size effects of the particles on pulmonary inflammation. S1.8 and S0.7 samples were administered to rats by a single intratracheal instillation (2 mg/ 0.4 ml saline). At three days, 1 wk and 1, 3 and 6 months after the instillation, the blood, bronchoalveolar lavage fluid (BALF), and pulmonary tissues were analyzed. Six images per HE-stained section were digitally captured and examined by the point counting method (PCM). Polymorphonuclear leukocyte (PMN)-in-blood specimens and cytospin specimens from BALF were stained immunohistochemically with BrdU. At six months after the instillation, the effects on inflammatory cells in the pulmonary tissues and BALF tended to be more marked in the rats instilled with S1.8 than those instilled with S0.7. Particularly, clear differences were observed in the number of inflammatory cells in BALF. Even if the particles are of the same chemical composition, the results suggest that, their biological effects vary depending on their particle size. Therefore, when such particles are used in workplaces, strict control systems should be established according to the risks present by different sizes of particles.