ChemRisk, LLC, San Francisco, CA 94105, USA.
Regul Toxicol Pharmacol. 2012 Dec;64(3):491-503. doi: 10.1016/j.yrtph.2012.08.022. Epub 2012 Sep 8.
Cobalt (Co) is an essential element in humans as a component of vitamin B12. However, at high levels Co exposure has been shown to have detrimental effects. This study was designed to identify a chronic oral reference dose (RfD) for Co. Currently available data indicate that non-cancer health effects associated with Co exposure may include hematological, neurological, immunological, reproductive, cardiovascular, and endocrine responses. This analysis employs the standard US EPA risk assessment methodology for establishing a chronic RfD. In this analysis, the Jaimet and Thode (1955) 10-week, multiple dose human study of thyroid effects (decreased iodine uptake) in children was determined to be the most robust and sensitive study for identifying a potential point of departure dose (POD). A dose of 0.9 mgCo/kg-day was chosen as the POD. Consistent with the US EPA's previous derivation of the perchlorate RfD, which is also based on decreased iodine uptake in humans, we considered several uncertainly factors (UFs), and determined that a factor of 10 for human variability was appropriate, as well as a factor of three for database adequacy. Applying an aggregate uncertainty factor of 30 to the POD yields a chronic oral RfD of 0.03 mg/kg-day. We believe this value would be protective of non-cancer health effects in the general population for a lifetime of daily exposure to Co.
钴（Co）是人体维生素 B12 的必需元素。然而，高浓度的 Co 暴露已被证明具有有害影响。本研究旨在确定 Co 的慢性口服参考剂量（RfD）。目前可用的数据表明，Co 暴露相关的非癌症健康影响可能包括血液学、神经学、免疫学、生殖、心血管和内分泌反应。本分析采用了美国环保署标准风险评估方法来建立慢性 RfD。在本分析中，Jaimet 和 Thode（1955）的为期 10 周、多剂量儿童甲状腺效应（碘摄取减少）的人类研究被确定为识别潜在的起始剂量（POD）的最稳健和敏感的研究。选择 0.9mgCo/kg-day 的剂量作为 POD。与基于人类碘摄取减少的美国环保署先前推导的高氯酸盐 RfD 一致，我们考虑了几个不确定性因素（UFs），并确定人类变异性的 10 倍因素是合适的，数据库充分性的 3 倍因素也是合适的。将 POD 的综合不确定性因素乘以 30，得到慢性口服 RfD 为 0.03mg/kg-day。我们相信，对于终生每天接触 Co 的一般人群来说，这个值将对非癌症健康影响具有保护作用。
