Twenty-eight-day repeated inhalation toxicity study of nano-sized lanthanum oxide in male sprague-dawley rats

Although the use of lanthanum has increased in field of high-tech industry worldwide, potential adverse effects to human health and to the environment are largely unknown. The present study aimed to investigate the potential toxicity of nano-sized lanthanum oxide (La2 O) following repeated inhalation exposure in male Sprague-Dawley rats. Male rats were exposed nose-only to nano-sized La2O3 for 28 days (5 days/week) at doses of 0, 0.5, 2.5, and 10 mg/m(3). In the experimental period, the authors evaluated treatment-related changes including clinical signs, body weight, haematology, serum biochemistry, necropsy findings, organ weight, and histopathology findings. In addition, lanthanum distribution in the major organs and in the blood, bronchoalveolar lavage fluids (BALF) was analysed, and oxidative stress in lung tissues. Lanthanum level was highest in lung tissues and showed a dose-dependent relation. Alveolar proteinosis was observed in all treatment groups and was accompanied by an increase in lung weight; moreover, lung inflammation was observed in the 2.5 mg/m(3) and higher dose groups and was accompanied by an increase in white blood cells. In the BALF, total cell counts including macrophages and neutrophils, lactate dehydrogenase, albumin, nitric oxide, and tumour necrosis factor-alpha increased significantly in all treatment groups. Furthermore, these changes tended to deteriorate in the 10 mg/m(3) group at the end of the recovery period. In the present experimental conditions, the authors found that the lowest-observed-adverse-effect level of nano-sized La2 O3 was 0.5 mg/m(3) in male rats, and the target organ was the lung.

Authors: Shin SH, Lim CH, Kim YS, Lee YH, Kim SH, Kim JC. ;Full Source: Environmental Toxicology. 2016 Jul 21. doi: 10.1002/tox.22319. [Epub ahead of print] ;