Michalke Bernhard, Halbach Stefan, Nischwitz Volker
GSF National Research Center for Environment and Health, Institute of Ecological Chemistry, 85764 Neuherberg, Germany.
J Environ Monit. 2007 Jul;9(7):650-6. doi: 10.1039/b704173j. Epub 2007 Jun 7.
Although manganese is an essential trace element, concerns are rising about the Mn exposure of humans being related to neurotoxic effects. This review summarizes several aspects of this topic to provide updated information on Mn related investigations, including chemical speciation of Mn-compounds. The paper starts with some chemical aspects of Mn and its compounds, enlightening oxidation states in general and in biological matrices. This is followed by considerations on natural sources of human exposure, on occupational sources and on anthropogenically caused environmental sources, for example from the use of methylcyclopentadienyl manganese tricarbonyl (MMT). Next, the paper deals with Mn levels in the human organism, showing normal Mn concentrations in various tissues or body fluids, and continues with the toxicology of Mn, i.e. absorption, distribution and excretion. Of specific concern is the transfer of Mn to the brain which is the relevant neurotoxic target. In this context, parallels and differences between primary and Mn-dependent Parkinsonism are discussed, concluding with a risk assessment and a consideration of susceptible groups. The main part of this review focuses on recent investigations on Mn speciation. Analytical problems and their solutions are also described for correct identification of relevant Mn-compounds in matrices of human origin. Finally, future needs are discussed, such as further investigations on those Mn-species which may overcome neural barrier control, on disease-modulated barrier control, on susceptibility to certain Mn-species, and on the interaction of Mn with Fe-homeostasis in the brain.
尽管锰是一种必需的微量元素，但人们对人类接触锰与神经毒性效应之间的关系日益担忧。本综述总结了该主题的几个方面，以提供有关锰相关研究的最新信息，包括锰化合物的化学形态。本文首先介绍了锰及其化合物的一些化学方面，阐述了一般情况下以及在生物基质中的氧化态。接下来考虑了人类接触锰的天然来源、职业来源以及人为造成的环境来源，例如使用甲基环戊二烯三羰基锰（MMT）。然后，本文探讨了人体中的锰水平，展示了各种组织或体液中的正常锰浓度，并继续介绍锰的毒理学，即吸收、分布和排泄。特别值得关注的是锰向大脑的转移，大脑是相关的神经毒性靶点。在此背景下，讨论了原发性帕金森病和锰依赖性帕金森病之间的异同，最后进行了风险评估并考虑了易感人群。本综述的主要部分聚焦于近期关于锰形态的研究。还描述了分析问题及其解决方案，以便在人类来源的基质中正确识别相关的锰化合物。最后，讨论了未来的需求，例如对可能突破神经屏障控制的锰物种、疾病调节的屏障控制、对某些锰物种的易感性以及锰与大脑中铁稳态相互作用的进一步研究。
