Magnetic nanoparticles: An indicator of health risks related to anthropogenic airborne particulate matter

Magnetic iron oxide nanoparticles: An emerging threat for the environment and human health

Magnetic iron oxide nanoparticles (FexOy NPs, mainly Fe3O4 and γ-Fe2O3) are nanomaterials ubiquitously present in aquatic, terrestrial, and atmospheric environments, with a high prevalence and complex sources. Over the past decade, numerous reports have emerged on the presence of exogenous particles in human body, facilitated by the rapid development of separation and detection methods. The health risk associated with magnetic FexOy NP have garnered escalating attention due to their presence in human blood and brain tissues, especially for their potential association with neurodegenerative diseases like Alzheimer's disease. In this paper, we provide a comprehensive overview of sources, analysis methods, environmental impacts, and health risks of magnetic FexOy NP. Currently, most researches are primarily based on engineered FexOy NP, while reports about magnetic FexOy NP existing in real-world environments are still limited, especially for their occurrence levels in various environmental matrices, environmental transformation behavior, and biotoxic effects. Our study reviews this emerging pollutant, providing insights to address current research deficiencies and chart the course for future studies.

Airborne magnetic nanoparticles may contribute to COVID-19 outbreak: Relationships in Greece and Iran

This work attempts to shed light on whether the COVID-19 pandemic rides on airborne pollution. In particular, a two-city study provides evidence that PM_2.5 contributes to the timing and severity of the epidemic, without adjustment for confounders. The publicly available data of deaths between March and October 2020, updated it on May 30, 2021, and the average seasonal concentrations of PM_2.5 pollution over the previous years in Thessaloniki, the second-largest city of Greece, were investigated. It was found that changes in coronavirus-related deaths follow changes in air pollution and that the correlation between the two data sets is maximized at the lag time of one month. Similar data from Tehran were gathered for comparison. The results of this study underscore that it is possible, if not likely, that pollution nanoparticles are related to COVID-19 fatalities (Granger causality, p < 0.05), contributing to the understanding of the environmental impact on pandemics.

The temporal distribution of platinum group elements (PGEs) in PM2.5

In this paper, Changji, Xinjiang, northwest China, was selected as the study area, and platinum group elements (PGEs) in PM_2.5 were quantified by ICP-MS using microwave digestion. The results indicated that the average concentrations (and range) of Rh, Pd, and Pt in PM_2.5 were 0.21 (n.d. -1.41) ng/m³, 8.09 (n.d. -59.50) ng/m³, and 0.12 (n.d. -0.83) ng/m³, respectively_. The concentration of Pd was significantly higher than Rh and Pt. Moreover, the seasonal variations of Rh and Pd were the same: highest in summer and lower in other seasons. However, the seasonal variation of Pt was opposite to that of Rh and Pd: highest in winter and lower in other seasons. Seasonal differences in emission sources of PGEs and the climatic characteristics of arid regions played important roles in the seasonal changes of PGEs. Rh and Pd had a common source and similar diurnal variation. The major influencing factors were traffic volume and meteorological conditions. The diurnal variation regularity of Pt was different from Rh and Pd. The superimposed effect of vehicle exhaust emissions and coal-fired emissions was the main reason why the diurnal variation of Pt was more complicated than those of Rh and Pd. The diurnal concentration of Pt varied with the seasons. It is caused by seasonal coal combustion and meteorological conditions.

Airborne particle accumulation and loss in pollution-tolerant lichens and its magnetic quantification

Pollution-tolerant lichens are recognized ecological indicators of air pollution in cities, which can also collect airborne anthropogenic particles in their tissues. Harmful (sub)micron-sized magnetites are a ubiquitous component of air particle pollution, adversely impacting human health. In this work, in situ magnetic susceptibility κ_is of well-characterized ultrafine magnetite and lichen thalli were measured to quantify the amount of airborne magnetic particles (AMP) after calibration and to assess the lichen's decontamination over time. Up to 2850 magnetic measurements were carried out in twenty-nine transplanted lichens (collected in urban and clean areas) from winter 2020 to winter 2021. Before the transplants, their initial κ_is values were 0.23-9.45 × 10^-5 SI, representing AMP contents of 0.1-4.6 mg in lichen thalli. After lichens were transplanted to a shared site, the magnetic signals evidenced short-term increases and long-term decreases. After three, five and nine months, the AMP loss is more pronounced for transplanted lichens from polluted (e.g., AMP_5-months loss = 0.59 mg) than clean (= 0.08 mg) sites. Rainfall influenced the lichen's decontamination between seasons. In situ measurements and lichens offer a valued and time-saving methodology for biomonitoring harmful airborne particles simply and effectively.

Variation in the concentration and regional distribution of magnetic nanoparticles in human brains, with and without Alzheimer's disease, from the UK

The presence of magnetic nanoparticles (MNPs) in the human brain was attributed until recently to endogenous formation; associated with a putative navigational sense, or with pathological mishandling of brain iron within senile plaques. Conversely, an exogenous, high-temperature source of brain MNPs has been newly identified, based on their variable sizes/concentrations, rounded shapes/surface crystallites, and co-association with non-physiological metals (e.g., platinum, cobalt). Here, we examined the concentration and regional distribution of brain magnetite/maghemite, by magnetic remanence measurements of 147 samples of fresh/frozen tissues, from Alzheimer's disease (AD) and pathologically-unremarkable brains (80-98 years at death) from the Manchester Brain Bank (MBB), UK. The magnetite/maghemite concentrations varied between individual cases, and different brain regions, with no significant difference between the AD and non-AD cases. Similarly, all the elderly MBB brains contain varying concentrations of non-physiological metals (e.g. lead, cerium), suggesting universal incursion of environmentally-sourced particles, likely across the geriatric blood-brain barrier (BBB). Cerebellar Manchester samples contained significantly lower (~ 9×) ferrimagnetic content compared with those from a young (29 years ave.), neurologically-damaged Mexico City cohort. Investigation of younger, variably-exposed cohorts, prior to loss of BBB integrity, seems essential to understand early brain impacts of exposure to exogenous magnetite/maghemite and other metal-rich pollution particles.