Evaluation of the pulmonary inhalation toxicity of diborane

本研究旨在阐明二硼烷(B_2H_6，CAS：19287-45-7)对大鼠的亚急性肺和睾丸毒性。雄性Wistar大鼠暴露于0.11ppmPr 0.96ppm的二硼烷中8周，每天6小时，每周5天。对照组暴露于过滤空气中。进行支气管肺泡灌洗液(BALF)、血液学、生化和组织病理学检查。取附睾进行精子计数和精子形态观察，并对睾丸进行组织病理学检查。BALF检测显示，暴露于0.96ppm的大鼠，中性粒细胞百分率呈剂量依赖性增加，巨噬细胞百分率下降。0.96 ppm染毒大鼠肺泡灌洗液中总磷脂和单个磷脂含量增加。暴露于0.96ppm的大鼠，磷脂酰甘油+鞘磷脂比例降低，磷脂酰乙醇胺和磷脂酰肌醇增加。暴露于0.96ppm的大鼠乳酸脱氢酶升高，碱性磷酸酶呈剂量依赖性升高。在血清中，暴露于0.11或0.96ppm的大鼠血清中α1-抗胰蛋白酶和超氧化物歧化酶(SOD)活性升高。这些变化对二硼烷染毒大鼠肺组织的影响呈剂量依赖关系，提示0.11ppm染毒大鼠肺组织中也可出现II型细胞增殖和/或肥大，但无组织病理学改变。睾丸检查没有发现特别的发现。二硼烷(0.1ppm)的TLV-TWA(ACGIH 1991)似乎很高，可能是不安全的，考虑到对大鼠肺的8周未观察到的作用水平低于0.11ppm。目前ACGIH(1991)建议的0.1ppm TLV-TWA的职业接触限值似乎太过防止二硼烷对可能反复接触二硼烷的工人的影响。有必要仔细管理工作环境，以避免接触二硼烷。

This study aimed to clarify the subacute pulmonary and testicular toxicity of diborane (B_2H_6, CAS : 19287-45-7) in rats. Male Wister rats were exposed for 8 weeks to 0.11 ppm pr 0.96 ppm of diborane for 6 hours/day, 5days/week. The control group wes exposed to filtered air. Bronchoalveolar lavage fluid (BALF), hematological, biochemical and histopathological examinations were conducted. Sperm counts and spermatic morphological changes were examined in epididymides, and histopathological examination was carried out in testes. BALF examinations revealed that the percentage of neutrophils increased in a dose-dependent manner and that of macrophages decreased in rats exposed to 0.96 ppm. Quantities of total and individual phospholipids in BALF increased in rats exposed to 0.96ppm. The proportion of phosphatidylglycerol plus sphingomyelin decreased, and phosphatidylethanolamine and phosphatidylinositol increased in rats exposed to 0.96 ppm. LDH increased in rats exposed to 0.96 ppm, and ALP showed a dose-dependent increase. In serum, alpha _1-antitrypsin and superoxide dismutase (SOD) activities increased in rats exposed to 0.11 or 0.96 ppm. These changes showed dose-dependent effects on the lung in rats exposed to diborane, possbly indicating that the hyperenergia of type II cells with proliferation and/or hypertrophy without histopathological changes occurred even in rats exposed to 0.11 ppm. Testicular examinations revealed no particular findings. The TLV-TWA of diborane (0.1ppm)(ACGIH 1991) seems to be high and possibly unsafe, considering that the no-observed-effect level over 8 weeks for rat lung was under 0.11 ppm. The current occupational exposure limit of 0.1 ppm TLV-TWA recommended by ACGIH (1991) seems to be too prevent the effects of diborane on workers who may be repeatedly exposed to diborane. It is necessary to manage the working environment carefully in order to avoid exposure to diborane.