Magnetite pollution nanoparticles in the human brain.
Biologically formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 20 y ago [Kirschvink JL, Kobayashi-Kirschvink A, Woodford BJ (1992) Proc Natl Acad Sci USA 89(16):7683-7687]. Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge, and strongly magnetic behavior. We used magnetic analyses and electron microscopy to identify the abundant presence in the brain of magnetite nanoparticles that are consistent with high-temperature formation, suggesting, therefore, an external, not internal, source. Comprising a separate nanoparticle population from the euhedral particles ascribed to endogenous sources, these brain magnetites are often found with other transition metal nanoparticles, and they display rounded crystal morphologies and fused surface textures, reflecting crystallization upon cooling from an initially heated, iron-bearing source material. Such high-temperature magnetite nanospheres are ubiquitous and abundant in airborne particulate matter pollution. They arise as combustion-derived, iron-rich particles, often associated with other transition metal particles, which condense and/or oxidize upon airborne release. Those magnetite pollutant particles which are <∼200 nm in diameter can enter the brain directly via the olfactory bulb. Their presence proves that externally sourced iron-bearing nanoparticles, rather than their soluble compounds, can be transported directly into the brain, where they may pose hazard to human health.
Centre for Environmental Magnetism and Palaeomagnetism, Lancaster Environment Centre, University of Lancaster, Lancaster LA1 4YQ, United Kingdom; b.maher@lancaster.ac.uk.
Barbara A
BA
Maher
Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, United Kingdom;
Imad A M
0000-0003-3868-2919
IA
Ahmed
Centre for Environmental Magnetism and Palaeomagnetism, Lancaster Environment Centre, University of Lancaster, Lancaster LA1 4YQ, United Kingdom;
Vassil
V
Karloukovski
Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom;
Donald A
DA
MacLaren
Division of Biomedical and Life Sciences, Faculty of Health and Medicine, University of Lancaster, Lancaster LA1 4YQ, United Kingdom;
Penelope G
PG
Foulds
Division of Biomedical and Life Sciences, Faculty of Health and Medicine, University of Lancaster, Lancaster LA1 4YQ, United Kingdom;
David
D
Allsop
Division of Neuroscience & Experimental Pyschology, School of Biological Sciences, University of Manchester, Manchester M6 8HD, United Kingdom;
David M A
DM
Mann
Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Mexico City 04310, Mexico;
Ricardo
R
Torres-Jardón
Neurotoxicology Laboratory, The University of Montana, Missoula, MT 59812; Universidad del Valle de México, Mexico City, 04850, Mexico.
Lilian
L
Calderon-Garciduenas
D000397:Air Pollution / Q000032:analysis*; D001921:Brain / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008800:Mexico; D010316:Particle Size; D013052:Spectrometry, X-Ray Emission; D046590:Spectroscopy, Electron Energy-Loss; D006113:United Kingdom
D058185:Magnetite Nanoparticles
Alzheimer's disease; airborne particulate matter; brain magnetite; combustion-derived nanoparticles; magnetite pollution particles