The impact of environmental metals in young urbanites’ brains

Abstract

Air pollution exposures are linked to cognitive and olfaction deficits, oxidative stress, neuroinflammation and neurodegeneration including frontal hyperphosphorilated tau and diffuse amyloid plaques in Mexico City children and young adults. Mexico City residents are chronically exposed to fine particulate matter (PM2.5) concentrations (containing toxic combustion and industrial metals) above the annual standard (15 μg/m3) and to contaminated water and soil. Here, we sought to address the brain-region-specific effects of metals and key neuroinflammatory and DNA repair responses in two air pollution targets: frontal lobe and olfactory bulb from 12 controls v 47 Mexico City children and young adults average age 33.06 ± 4.8 SE years. Inductively coupled plasma mass spectrometry (metal analysis) and real time PCR (for COX2, IL1β and DNA repair genes) in target tissues. Mexico City residents had higher concentrations of metals associated with PM: manganese (p=0.003), nickel and chromium (p=0.02) along with higher frontal COX2 mRNA (p=0.008) and IL1β (p=0.0002) and COX2 (p=0.005) olfactory bulb indicating neuroinflammation. Frontal metals correlated with olfactory bulb DNA repair genes and with frontal and hippocampal inflammatory genes. Frontal manganese, cobalt and selenium increased with age in exposed subjects. Together, these findings suggest PM-metal neurotoxicity causes brain damage in young urbanites, the olfactory bulb is a target of air pollution and participates in the neuroinflammatory response and since metal concentrations vary significantly in Mexico City urban sub-areas, place of residency has to be integrated with the risk for CNS detrimental effects particularly in children.

Magnetite pollution nanoparticles in the human brain

“…Those particles of nanoscale dimensions, requiring analysis by transmission rather than scanning electron microscopy, have, until recently, received less attention than the larger, often more heterogenous spherules. Magnetite nanospheres up to ≾ 200 nm can have a direct entry route to the brain through the axons of the olfactory nerve, as suggested by experimental studies on carbon (29) and TiO 2 nanoparticles (30), and the reported presence of NPs in the olfactory bulb of some Mexico City cases (14,(31)(32)(33).…”

“…Increased metals content and AD neuropathological hallmarks have been found in young human brains exposed to high airborne PM 2.5 concentrations in Mexico City (14,33). However, it was not previously known if the presence of metals in AD brains was due to transport to the brain of nanoparticles themselves or of their solubilized compounds.…”

Effect of Indoor Airpollution on Postural Balance Controlamong School Students

“…63 PM exposures are linked to cognitive deficits, oxidative stress, neuroinflammation and neurodegeneration. 64 Several individual metals including aluminum, arsenic, cadmium, lead, manganese, and mercury have been demonstrated to affect the neurological system 65 , and general accumulation of metal ions in the brain contributes to heightened oxidative stress and neuronal damage. 66 Several studies [67][68] reported that low level lead exposure during early childhood is associated with neuromotor dysfunction such as unsteadiness, clumsiness and fine motor deficits.…”

Gene expression changes in rat brain after short and long exposures to particulate matter in Los Angeles basin air: Comparison with human brain tumors

“…They also found the same alterations as well as Alzheimer's-like pathology, and disruption of the blood-brain barrier (BBB) in Mexico City children and young adults exposed to heavy urban pollution (Calderón-Garcidueñas et al, 2004, 2008a,b, 2012a. Tissue from the brains of pollution-exposed Mexico City residents showed signs of damage that could result from PM-induced formation of reactive oxygen species (ROS), effects of particulate-matter-associated lipopolysaccharides (PM-LPS), and/or effects of metallic components of inhaled PM (Calderón-Garcidueñas et al, 2012b;Block and Calderón-Garcidueñas, 2009). …”