Elsner Robert J F, Spangler John G
Wake Forest University School of Medicine, Department of Family and Community Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1084, USA.
Med Hypotheses. 2005;65(3):607-16. doi: 10.1016/j.mehy.2005.01.043.
Manganese (Mn) is an essential trace element but is neurotoxic at high doses. Showering with Mn-laden water has never been evaluated as a central nervous system (CNS) delivery vector for Mn, even though intranasally administered Mn in laboratory animals circumvents the blood-brain barrier and passes directly into the brain via olfactory pathways.
To review the literature on Mn and attempt to quantify potential human CNS exposure to manganese from showering.
We systematically searched Medline 11/9/02 and again on 3/9/04. The following search terms were used: manganese, water, drinking water, shower, showering, bath, bathing and inhalation, then combined with "water or drinking water or showering or shower or bathing or inhalation."
Animal experimental investigations, human epidemiological studies, and consensus and governmental reports were utilized.
Data were extracted by both authors and extrapolations to humans were calculated by one of us (JGS) controlling for age, length of exposure and known respiratory differences between rats and humans.
During a decade of showering in Mn-contaminated water, models for children and adults show higher doses of aerosolized Mn (3-fold and 112-fold greater, respectively) than doses reported to cause Mn brain deposition in rats.
Long-term shower exposure to Mn-laden water may pose a significant risk for CNS neurotoxicity via olfactory uptake in up to 8.7 million Americans. If our results are confirmed, regulatory agencies must rethink existing Mn drinking water standards.
锰（Mn）是一种必需的微量元素，但高剂量时具有神经毒性。用含锰的水淋浴作为锰进入中枢神经系统（CNS）的一种途径从未被评估过，尽管在实验动物中经鼻给予锰可绕过血脑屏障并通过嗅觉途径直接进入大脑。
回顾关于锰的文献，并尝试量化人类淋浴时中枢神经系统潜在的锰暴露量。
我们于2002年11月9日和2004年3月9日系统检索了Medline。使用了以下检索词：锰、水、饮用水、淋浴、沐浴、洗澡和吸入，然后与“水或饮用水或淋浴或洗澡或沐浴或吸入”组合。
采用动物实验研究、人类流行病学研究以及共识和政府报告。
两位作者均进行数据提取，其中一人（JGS）根据年龄、暴露时长以及大鼠和人类已知的呼吸差异，计算对人类的外推数据。
在受锰污染的水中淋浴十年期间，儿童和成人模型显示，雾化锰的剂量（分别高出3倍和112倍）高于据报道会导致大鼠脑内锰沉积的剂量。
长期淋浴接触含锰的水可能会使多达870万美国人通过嗅觉吸收面临中枢神经系统神经毒性的重大风险。如果我们的结果得到证实，监管机构必须重新审视现有的锰饮用水标准。
