Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) throughout their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nanomaterials. Information about safety and potential hazards is urgently needed. Results of older bio-kinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract. The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels. Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species. Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need for basic research on their interactions with subcellular structures. Additional considerations for assessing safety of engineered NSPs include careful selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and also the benefits of possible desirable effects. An interdisciplinary team approach (e.g., toxicology, materials science, medicine, molecular biology, and bioinformatics, to name a few) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment.

/pdf/nanotoxicology-an-emerging-discipline-evolving-from-studies-pb7art8sfp.pdf

Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles

Efforts to understand and mitigate the health effects of particulate matter (PM) air pollution have a rich and interesting history. This review focuses on six substantial lines of research that have been pursued since 1997 that have helped elucidate our understanding about the effects of PM on human health. There has been substantial progress in the evaluation of PM health effects at different time-scales of exposure and in the exploration of the shape of the concentration-response function. There has also been emerging evidence of PM-related cardiovascular health effects and growing knowledge regarding interconnected general pathophysiological pathways that link PM exposure with cardiopulmonary morbidity and mortality. Despite important gaps in scientific knowledge and continued reasons for some skepticism, a comprehensive evaluation of the research findings provides persuasive evidence that exposure to fine particulate air pollution has adverse effects on cardiopulmonary health. Although much of this research has been motivated by environmental public health policy, these results have important scientific, medical, and public health implications that are broader than debates over legally mandated air quality standards.

/pdf/health-effects-of-fine-particulate-air-pollution-lines-that-s831sp8jap.pdf

Health effects of fine particulate air pollution: lines that connect

Polycyclic aromatic compounds (PACs) are known due to their mutagenic activity. Among them, 2-nitrobenzanthrone (2-NBA) and 3-nitrobenzanthrone (3-NBA) are considered as two of the most potent mutagens found in atmospheric particles. In the present study 2-NBA, 3-NBA and selected PAHs and Nitro-PAHs were determined in fine particle samples (PM 2.5) collected in a bus station and an outdoor site. The fuel used by buses was a diesel-biodiesel (96:4) blend and light-duty vehicles run with any ethanol-to-gasoline proportion. The concentrations of 2-NBA and 3-NBA were, on average, under 14.8 µg g−1 and 4.39 µg g−1, respectively. In order to access the main sources and formation routes of these compounds, we performed ternary correlations and multivariate statistical analyses. The main sources for the studied compounds in the bus station were diesel/biodiesel exhaust followed by floor resuspension. In the coastal site, vehicular emission, photochemical formation and wood combustion were the main sources for 2-NBA and 3-NBA as well as the other PACs. Incremental lifetime cancer risk (ILCR) were calculated for both places, which presented low values, showing low cancer risk incidence although the ILCR values for the bus station were around 2.5 times higher than the ILCR from the coastal site.

Occurrence of the potent mutagens 2- nitrobenzanthrone and 3-nitrobenzanthrone in fine airborne particles

In 2004, the first American Heart Association scientific statement on “Air Pollution and Cardiovascular Disease” concluded that exposure to particulate matter (PM) air pollution contributes to card...

https://cdr.lib.unc.edu/downloads/p2676x621

Particulate Matter Air Pollution and Cardiovascular Disease An Update to the Scientific Statement From the American Heart Association

Changes in Atmospheric Constituents and in Radiative Forcing

http://www.cell.com/article/S2405844023000518/pdf

Validation of an optimised microwave-assisted acid digestion method for trace and ultra-trace elements in indoor PM2.5 by ICP-MS analysis

The work described has focused on a number of inter-related areas, mostly concerned with the chemistry of nitrogen compoundsin the marine atmosphere. Initially, concentrations of various individual nitrogen compounds were determined over the North Sea. The averaging of data from many individual cruises permitted the mapping of average concentrations across the southern bight of the North Sea. These measurements were used to infer chemical transformations of nitrogen compounds, particularly the dissociation of ammonium nitrate aerosol and the reaction of nitric acid with sodium chloride particles and to calculate atmospheric nitrogen inputs to the North Sea. The measurements of gaseous ammonia in the North Sea atmosphere were combined with data from ammonium in seawater made during the same series of cruises to estimate surface exchange of ammonia. The work showed that the North Sea system is rather finally balanced with respect to ammonia, with the majority of net fluxes from air-to-sea, but some periods when the sea becomes a net source of ammonia in air. In a Lagrangian experiment, concentrations of a number of gaseous and particulate nitrogen species were measured on two ships located 200 km apart. The data have been used to evaluate the rate of oxidation of nitrogen dioxide in the North Sea atmosphere and to estimate concentrations of the hydroxyl radical in daytime, and to evaluate the mechanism of the night-time oxidation of NO2. In a variant upon this experiment, neutralisation of aerosol acidity arriving at the English coast in ammonia-depleted North Sea air was followed as the air was adverted in ammonia-rich air over eastern England. A pseudo first rate order rate constant for the loss of aerosol H+ was estimated and found to vary with the degree of neutralisation of the aerosol. In a numerical modelling study collaborative with the Danish National Environmental Research Institute, the North Sea measurement data were compared with the predictions of airborne concentrations from the Danish Eulerian model with non-linear chemistry. After some modifications to the chemical scheme in the model, it was found that model predictions were in extremely good agreement with measured concentrations.

Chemical Transformations in the North Sea Atmosphere

Concentrations of tetra-, tri and di-alkyl-lead compounds in rain have been measured at rural and urban sites in England. The measurements are compared with similar data collected in the early 1980s, prior to a 72% reduction in the emission of lead from combustion of leaded petrol. Whilst concentrations of inorganic lead have fallen broadly in line with emissions of automotive lead, alkyl-lead concentrations in rain have fallen by only 50% or less, and thus the ratio of alkyl-lead to inorganic lead in rain has increased appreciably. The reason for this phenomenon is unclear. The data suggest that lead in rainwater would fall to approximately 2 μg dm−3 if automotive lead emissions fell to zero.

Assessment of Recent Trends in Concentrations of Alkyl-Lead Compounds in Rainwater.

New particle formation (NPF) is a leading source of particulate matter by number and a contributor to particle mass during haze events. Reductions in emissions of air pollutants, many of which are NPF precursors, are expected in the move toward carbon neutrality or net-zero. Expected changes to pollutant emissions are used to investigate future changes to NPF processes, in comparison to a simulation of current conditions. The projected changes to SO2 emissions are key in changing future NPF number, with different scenarios producing either a doubling or near total reduction in sulfuric acid-amine particle formation rates. Particle growth rates are projected to change little in all but the strictest emission control scenarios. These changes will reduce the particle mass arising by NPF substantially, thus showing a further cobenefit of net-zero policies. Major uncertainties remain in future NPF including the volatility of oxygenated organic molecules resulting from changes to NOx and amine emissions.

https://pubs.acs.org/doi/pdf/10.1021/acs.est.2c08348

Estimates of Future New Particle Formation under Different Emission Scenarios in Beijing

In order to better understand the transport and removal of atmospheric trace metals more knowledge in the following basic atmospheric processes is needed: 

(i)

initial size distribution at the source




(ii)

aerosol dynamics




(iii)

atmospheric dispersion




(iv)

chemical reactions




(v)

interaction with the earth’s surface




(vi)

interaction with clouds

Roy M. Harrison

Papers

Validation of an optimised microwave-assisted acid digestion method for trace and ultra-trace elements in indoor PM2.5 by ICP-MS analysis

Chemical Transformations in the North Sea Atmosphere

Assessment of Recent Trends in Concentrations of Alkyl-Lead Compounds in Rainwater.

Estimates of Future New Particle Formation under Different Emission Scenarios in Beijing

Research Needs in Understanding Processes of Transformation, and Dry and Wet Deposition of Atmospheric Metals