Pulmonary effects and clearance after long-term inhalation of potassium octatitanate whiskers in rats.
The pulmonary effects of long-term inhalation of potassium octatitanate whisker (PT1), one of the durable man-made fibers (MMFs), were examined in rats. Male Wistar rats were exposed to PT1 by inhalation for 6 h/day, 5 days/wk for 1 yr. The daily average exposure concentration of PT1 aerosol was 2.2 +/- 0.7 mg/m3 (111 +/- 34 fiber/ml) during the exposure. Rats were sacrificed at 3 days, 6 mo, and 12 mo after 1 yr of inhalation exposure. The amount of deposited PT1 in rat lungs (lung burden) was 2.4 +/- 0.7 mg and the deposition fraction was 7.2% at 3 days after 1 yr. The clearance of inhaled PT1 after 1-yr inhalation was prolonged so that the biological half-life time (BHT) was difficult to estimate. The histopathological findings showed that mild fibrotic changes were observed around the macrophages that had engulfed the PT1 in the 3-day, 6-mo, and 12-mo rat sacrifice groups. As for pulmonary tumors, no malignant tumors were observed, although 2 adenomas at 6 mo and 1 adenoma and 1 squamous metaplasia at 12 mo after the exposure were found in the rat lungs.
Yamato
Hiroshi
H
Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, 1-1Iseigaoka, Yahatanishi, Kitakyushu, Japan. yamato@med.uoeh-u.ac.jp
Oyabu
Takako
T
Ogami
Akira
A
Morimoto
Yasuo
Y
Higashi
Toshiaki
T
Tanaka
Isamu
I
Ishimatsu
Sumiyo
S
Hori
Hajime
H
Kasai
Takahiko
T
D000236:Adenoma / Q000209:etiology / Q000662:veterinary; D000280:Administration, Inhalation; D000336:Aerosols; D000818:Animals; D000831:Animals, Newborn; D008168:Lung / Q000473:pathology*; D008175:Lung Neoplasms / Q000209:etiology / Q000662:veterinary; D008297:Male; D008420:Manufactured Materials; D019016:Mineral Fibers; D008903:Minerals; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution; D014025:Titanium / Q000493:pharmacokinetics* / Q000633:toxicity*
D000336:Aerosols; D019016:Mineral Fibers; D008903:Minerals; C021028:potassium octatitanate; D014025:Titanium