TY - JOUR

T1 - Magnetite pollution nanoparticles in the human brain

AU - Maher, Barbara Ann

AU - Ahmed, Imad

AU - Karloukovski, Vassil Vassilev

AU - MacLaren, Donald

AU - Foulds, Penelope

AU - Allsop, David

AU - Mann, David

AU - Torres-Jardon, Ricardo

AU - Calderon-Garciduenas, Lilian

PY - 2016/9/27

Y1 - 2016/9/27

N2 - Biologically-formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 20 years ago (Kirschvink, J.L., Kobayashi-Kirschvink, A. & Woodford, B.J., 1992, Magnetite Biomineralization in the Human Brain. P 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 behaviour. 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 (PM) pollution. They arise as combustion- derived, iron-rich particles, often associated with other transition metal particles, which condense and/or oxidise 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.

AB - Biologically-formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 20 years ago (Kirschvink, J.L., Kobayashi-Kirschvink, A. & Woodford, B.J., 1992, Magnetite Biomineralization in the Human Brain. P 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 behaviour. 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 (PM) pollution. They arise as combustion- derived, iron-rich particles, often associated with other transition metal particles, which condense and/or oxidise 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.

U2 - 10.1073/pnas.1605941113

DO - 10.1073/pnas.1605941113

M3 - Journal article

VL - 113

SP - 10797

EP - 10801

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 39

ER -