Chemical Management Department, Resonac Corporation, Tokyo Shiodome Bldg.,1-9-1, Higashi-Shimbashi, Minato-ku, Tokyo, 105-7325, Japan.
DIMS Institute of Medical Science, Inc., 64 Goura, Nishiazai, Azai-cho, Ichinomiya-shi, Aichi, 491-0113, Japan.
Part Fibre Toxicol. 2023 Sep 28;20(1):37. doi: 10.1186/s12989-023-00547-5.
Carbon fibers are high aspect ratio structures with diameters on the submicron scale. Vapor grown carbon fibers are contained within multi-walled carbon tubes, with VGCF™-H commonly applied as a conductive additive in lithium-ion batteries. However, several multi-walled carbon fibers, including MWNT-7, have been reported to induce lung carcinogenicity in rats. This study investigated the carcinogenic potential of VGCF™-H fibers in F344 rats of both sexes with the vapor grown carbon fibers VGCF™-H and MWNT-7 over 2 years. The carbon fibers were administered to rats by intratracheal instillation at doses of 0, 0.016, 0.08, and 0.4 mg/kg (total doses of 0, 0.128, 0.64, and 3.2 mg/kg) once per week for eight weeks and the rats were observed for up to 2 years after the first instillation.
Histopathological examination showed the induction of malignant mesothelioma on the pleural cavity with dose-dependent increases observed at 0, 0.128, 0.64, and 3.2 mg/kg in rats of both sexes that were exposed to MWNT-7. On the other hand, only two cases of pleural malignant mesothelioma were observed in the VGCF™-H groups; both rats that received 3.2 mg/kg in male. The animals in the MWNT-7 groups either died or became moribund earlier than those in the VGCF™-H groups, which is thought related to the development of malignant mesothelioma. The survival rates were higher in the VGCF™-H group, and more carbon fibers were observed in the pleural lavage fluid (PLF) of the MWNT-7 groups. These results suggest that malignant mesothelioma is related to the transfer of carbon fibers into the pleural cavity.
The intratracheal instillation of MWNT-7 clearly led to carcinogenicity in both male and female rats at all doses. The equivocal evidence for carcinogenic potential that was observed in male rats exposed to VGCF™-H was not seen in the females. The differences in the carcinogenicities of the two types of carbon fibers are thought due to differences in the number of carbon fibers reaching the pleural cavity. The results indicate that the carcinogenic activity of VGCF™-H is lower than that of MWNT-7.
碳纤维是具有亚微米级直径的高纵横比结构。气相生长碳纤维包含在多壁碳管内，VGCF™-H 通常用作锂离子电池的导电添加剂。然而，已经有报道称，包括 MWNT-7 在内的几种多壁碳纤维会导致大鼠肺癌。本研究在 2 年内对雄性和雌性 F344 大鼠进行了气相生长碳纤维 VGCF™-H 和 MWNT-7 的气管内滴注，以研究 VGCF™-H 纤维的致癌潜力。将碳纤维以 0、0.016、0.08 和 0.4mg/kg（总剂量为 0、0.128、0.64 和 3.2mg/kg）的剂量每周一次滴注到大鼠体内，共 8 周，然后在第一次滴注后观察大鼠长达 2 年。
组织病理学检查显示，MWNT-7 暴露的雄性和雌性大鼠的胸腔腔出现恶性间皮瘤，且随着剂量的增加呈依赖性增加，在 0、0.128、0.64 和 3.2mg/kg 剂量组中均观察到。另一方面，仅在 VGCF™-H 组中观察到 2 例胸膜恶性间皮瘤；这两只大鼠均接受了 3.2mg/kg 的剂量。MWNT-7 组的动物比 VGCF™-H 组的动物更早死亡或濒死，这被认为与恶性间皮瘤的发展有关。VGCF™-H 组的存活率更高，MWNT-7 组的胸腔灌洗液（PLF）中观察到更多的碳纤维。这些结果表明，恶性间皮瘤与碳纤维转移到胸腔有关。
MWNT-7 的气管内滴注在所有剂量下均明显导致雄性和雌性大鼠发生致癌性。在雄性大鼠中观察到的 VGCF™-H 致癌潜力的不确定证据在雌性大鼠中并未观察到。两种类型碳纤维的致癌性差异被认为是由于到达胸腔的碳纤维数量不同所致。结果表明，VGCF™-H 的致癌活性低于 MWNT-7。
