Organic Metal Species as Risk Factor for Neurological Diseases
This chapter will focus on organic metal species of environmental concern that can exercise some influence on neurological disorders. A variety of organic metal species were identified in the last couple of years and their concentrations in the environmen
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Organic Metal Species as Risk Factor for Neurological Diseases Sören Meyer, Till Weber, Robert Haferkorn-Starke, Tanja Schwerdtle, and Julia Bornhorst Abstract This chapter will focus on organic metal species of environmental concern that can exercise some influence on neurological disorders. A variety of organic metal species were identified in the last couple of years and their concentrations in the environment are rising. Moreover cases of overnutrition are increasing and due to the fortification of various organic metallic compounds in our diet there are growing anxieties that food ingredients may inadvertently be contributing to neurological disorders. This chapter provides a summary of organic metal species that have been linked with neurological disorders including its exposure pathways (especially diet), and a possible risk in the context of consumers safety pointing out gaps in the actual research. The list includes agents which have no known biological role in humans as organic species of mercury, tin, lead and arsenic. Besides the classical organometals also aluminium is illuminated. Additionally those, such as iron and manganese which are essential for life but can be toxic when absorbed in excess amounts will be discussed.
Keywords Neurological diseases • Diet • Organic metal species
5.1
Methylmercury
The heavy metal mercury (Hg) is ubiquitously distributed in the environment. Through natural effects including volcanic emissions and anthropogenic effects including waste disposal and mining, elemental mercury (Hg0) and inorganic mercury (iHg: Hg22+, Hg2+) are distributed in the environment. The environmentally most common organic mercury species methylmercury (MeHg) is formed by biomethylation of inorganic mercury in phytoplankton, by both
S. Meyer • T. Weber • R. Haferkorn-Starke • T. Schwerdtle • J. Bornhorst (*) Department of Food Chemistry, Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany e-mail: [email protected] © Springer International Publishing Switzerland 2016 J.M. Pacyna, E.G. Pacyna (eds.), Environmental Determinants of Human Health, Molecular and Integrative Toxicology, DOI 10.1007/978-3-319-43142-0_5
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sulfate- and iron-reducing bacteria, and bioaccumulates in the aquatic food chain (FAO/WHO 2011). Apart from occupational exposure, diet is the main contributor to Hg exposure. While total Hg in non-seafood predominantly consists of iHg, 80–100 % of total Hg in fish and other seafood is represented by MeHg (EFSA 2012). After ingestion the iHg displays a low absorption rate in the gastro intestinal tract. iHg is mainly excreted via faeces and urine with the kidney being the critical target organ for iHg toxicity. MeHg is rapidly intestinally absorbed. Furthermore, it is also well known to transfer across other physiological barriers including the blood brain barrier, the blood liquor barrier and the blood placenta barrier, resulting in neurotoxic and neurodevelopmental effects (FAO/WHO 2
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