Comparative Pulmonary Responses Caused by Exposure to Standard Cobalt and Ultrafine Cobalt

Comparative Pulmonary Responses Caused by Exposure to Standard Cobalt and Ultrafine Cobalt: Qunwei Zhang, et al. Department of Environmental Health, School of Medicine, Fukui Medical University—The aim of this study was to compare the pulmonary toxicity after exposure to standard cobalt (Std‐Co) and ultrafine cobalt (Uf‐Co). Rats were intratracheally instilled with 1 mg of Std‐Co and Uf‐Co, and wet lung weight and bronchoalveolar lavage fluid (BALF) profiles were analysed 1,3,7,15 and 30 d later. The effects of Std‐Co and Uf‐Co on indices that can be presumed to reflect epithelial injury and permeability (lactate dehydrogenase (LDH) and total protein (TP)), and release of proinflammatory cytokine (tumor necrosis factor‐alpha (TNF‐alpha)) were increased throughout the 30 d post‐exposure period. The results showed that the effects of Std‐Co and Uf‐Co on these indices were significantly higher than those of control. The results also showed that the effects of Uf‐Co on indices were significantly higher than those of Std‐Co from 1 to 15 d after instillation. Moreover, the number of neutrophils and LDH activity in BALF in rats after exposure to Uf‐Co were significantly greater than those of Std‐Co‐exposed rats up to 30 d after instillation. Our findings suggest that Uf‐Co has a much more toxic effect on the lungs than Std‐Co, but the mechanism remains to be elucidated.