A work group report on ultrafine particles (American Academy of Allergy, Asthma & Immunology): Why ambient ultrafine and engineered nanoparticles should receive special attention for possible adverse health outcomes in human subjects

Benzo[a]pyrene is associated with dysregulated myelo-lymphoid hematopoiesis in asthmatic children

BACKGROUND

The extent to which ambient benzo[a]pyrene (B[a]P) contributes to mechanistically distinct de novo asthma remains unknown.

OBJECTIVES

To identify molecular signatures and regulatory networks underlying childhood exposure to ambient B[a]P and asthma, using robust and unbiased systems biology approaches.

METHODS

Clinically confirmed asthmatic (n = 191) vs. control (n = 194) children (aged, 7-15) were enrolled from a polluted urban center and semi-rural region in Czech Republic. Contemporaneous B[a]P concentration, gene expressions, DNA methylation data were analyzed against asthma diagnosis, as well as a modified prognostic index of asthma, using integrative multiscale co-expression network analysis. Sample-wise cell type compositions were inferred by a machine learning approach (i.e. CIBERSORT) with reference gene expressions of purified 38 distinct hematopoietic cell states from umbilical cord (i.e. stem cell/progenitors) or peripheral blood (i.e. lymphocytes).

RESULTS

The median outdoor B[a]P was increased near the homes of the urban children with 'moderate' or 'severe' prognostic markers of asthma, but not in the urban controls. An elevated B[a]P induced epigenetic suppression of NF-κB inflammation, decreased Natural Killer T (NKT) cells and activated anti-inflammatory IL10-secreting CD8+ T effective memory cells. B[a]P was positively correlated with an increased expression of a heme biosynthesis gene, ALAS2, which in turn, appears to promote concurrent increase of neutrophilic metamyelocyte and mature CD71^low erythroid cells. Furthermore, erythroid-specific master transcription regulator gene (GATA1), glutathione transferase genes (GSTM1 and GSTM3) and Eosinophil marker (IL5RA) were simultaneously activated in the urban asthma cases.

CONCLUSIONS

B[a]P might contribute to concurrent suppression of pro-inflammatory (e.g. NF-κB mediated NKT cells), and activation of anti-inflammatory pathways (e.g. IL10-secreting CD8+ T cells) in the urban asthmatic children. In addition, B[a]P appears to elevate heme biosynthesis, which in turn, promotes neutrophilic metamyelocyte expansion and reduction of CD71⁺ erythroids.

The repeated cytogenetic analysis of subjects occupationally exposed to nanoparticles: a pilot study

The application of nanomaterials has been rapidly increasing during recent years. Inhalation exposure to nanoparticles (NP) may result in negative toxic effects but there is a critical lack of human studies, especially those related to possible DNA alterations. We analyzed pre-shift and post-shift a group of nanocomposite researchers with a long-term working background (17.8 ± 10.0 years) and matched controls. The study group consisted of 73.2% males and 26.8% females. Aerosol exposure monitoring during a working shift (involving welding, smelting, machining) to assess the differences in exposure to particulate matter (PM) including nanosized fractions <25–100 nm, and their chemical analysis, was carried out. A micronucleus assay using Human Pan Centromeric probes, was applied to distinguish between the frequency of centromere positive (CEN+) and centromere negative (CEN−) micronuclei (MN) in the binucleated cells. This approach allowed recognition of the types of chromosomal damage: losses and breaks. The monitoring data revealed differences in the exposure to NP related to individual working processes, and in the chemical composition of nanofraction. The cytogenetic results of this pilot study demonstrated a lack of effect of long-term (years) exposure to NP (total frequency of MN, P = 0.743), although this exposure may be responsible for DNA damage pattern changes (12% increase of chromosomal breaks—clastogenic effect). Moreover, short-term (daily shift) exposure could be a reason for the increase of chromosomal breaks in a subgroup of researchers involved in welding and smelting processes (clastogenic effect, P = 0.037). The gender and/or gender ratio of the study participants was also an important factor for the interpretation of the results. As this type of human study is unique, further research is needed to understand the effects of long-term and short-term exposure to NP.

Long-term field comparison of multiple low-cost particulate matter sensors in an outdoor urban environment

Exposure to ambient particulate matter (PM) air pollution is a leading risk factor for morbidity and mortality, associated with up to 8.9 million deaths/year worldwide. Measurement of personal exposure to PM is hindered by poor spatial resolution of monitoring networks. Low-cost PM sensors may improve monitoring resolution in a cost-effective manner but there are doubts regarding data reliability. PM sensor boxes were constructed using four low-cost PM micro-sensor models. Three boxes were deployed at each of two schools in Southampton, UK, for around one year and sensor performance was analysed. Comparison of sensor readings with a nearby background station showed moderate to good correlation (0.61 < r < 0.88, p < 0.0001), but indicated that low-cost sensor performance varies with different PM sources and background concentrations, and to a lesser extent relative humidity and temperature. This may have implications for their potential use in different locations. Data also indicates that these sensors can track short-lived events of pollution, especially in conjunction with wind data. We conclude that, with appropriate consideration of potential confounding factors, low-cost PM sensors may be suitable for PM monitoring where reference-standard equipment is not available or feasible, and that they may be useful in studying spatially localised airborne PM concentrations.

Impact of weather and climate change with indoor and outdoor air quality in asthma: A Work Group Report of the AAAAI Environmental Exposure and Respiratory Health Committee

Weather and climate change are constant and ever-changing processes that affect allergy and asthma. The purpose of this report is to provide information since the last climate change review with a focus on asthmatic disease. PubMed and Internet searches for topics included climate and weather change, air pollution, particulates, greenhouse gasses, traffic, insect habitat, and mitigation in addition to references contributed by the individual authors. Changes in patterns of outdoor aeroallergens caused by increasing temperatures and amounts of carbon dioxide in the atmosphere are major factors linked to increased duration of pollen seasons, increased pollen production, and possibly increased allergenicity of pollen. Indoor air pollution threats anticipated from climate changes include microbial and mold growth secondary to flooding, resulting in displacement of persons and need for respiratory protection of exposed workers. Air pollution from indoor burning of mosquito repellants is a potential anticipatory result of an increase in habitat regions. Air pollution from fossil fuel burning and traffic-related emissions can alter respiratory defense mechanisms and work synergistically with specific allergens to enhance immunogenicity to worsen asthma in susceptible subjects. Community efforts can significantly reduce air pollution, thereby reducing greenhouse gas emission and improving air quality. The allergist's approach to weather pattern changes should be integrated and anticipatory to protect at-risk patients.

Influence of Urbanization on Epiphytic Bacterial Communities of the Platanus × hispanica Tree Leaves in a Biennial Study

The aerial surfaces of plants harbor diverse communities of microorganisms. The rising awareness concerning the potential roles of these phyllosphere microbiota for airborne pollutant remediation and plant growth promotion, advocates for a better understanding of their community structure and dynamics in urban ecosystems. Here, we characterized the epiphytic microbial communities on leaves of Platanus × hispanica trees in the city centre of Hasselt (Belgium), and the nearby forest area of Bokrijk, Genk (Belgium). We compared the influences of season, site, and air pollutants concentration variations on the tree’s phyllosphere microbiome by determining the intra- and inter-individual variation in leaf bacterial communities. High-throughput amplicon sequencing of the 16S rRNA gene revealed large variation in the bacterial community structure and diversity throughout the years but also allowed to discriminate an environment effect on community assembly. Partial drivers for this environment effect on composition can be correlated with the huge differences in ultrafine particulate matter (UFP) and black carbon on the leaves. A change in bacterial community composition was noted for trees growing in the city center compared to the natural site, and also more human-associated genera were found colonizing the leaves from the city center. These integrated results offer an original and first insight in the Platanus phyllomicrobiota, which can offer new opportunities to use phyllosphere microorganisms to enhance air pollution degradation.

Exposure to Atmospheric Ultrafine Particles Induces Severe Lung Inflammatory Response and Tissue Remodeling in Mice

Exposure to particulate matter (PM) is leading to various respiratory health outcomes. Compared to coarse and fine particles, less is known about the effects of chronic exposure to ultrafine particles, despite their higher number and reactivity. In the present study, we performed a time-course experiment in mice to better analyze the lung impact of atmospheric ultrafine particles, with regard to the effects induced by fine particles collected on the same site. Trace element and PAH analysis demonstrated the almost similar chemical composition of both particle fractions. Mice were exposed intranasally to FF or UFP according to acute (10, 50 or 100 µg of PM) and repeated (10 µg of PM 3 times a week during 1 or 3 months) exposure protocols. More particle-laden macrophages and even greater chronic inflammation were observed in the UFP-exposed mice lungs. Histological analyses revealed that about 50% of lung tissues were damaged in mice exposed to UFP for three months versus only 35% in FF-exposed mice. These injuries were characterized by alveolar wall thickening, macrophage infiltrations, and cystic lesions. Taken together, these results strongly motivate the update of current regulations regarding ambient PM concentrations to include UFP and limit their emission.

Ambient air pollution and overweight and obesity in school-aged children in Barcelona, Spain

BACKGROUND

Ambient air pollution may increase the risk of overweight and obesity in children. However, available evidence is still scarce and has mainly focused on ambient air pollution exposure occurring at home without considering the school environment. The aim of this study is to assess whether exposure to ambient air pollution at home and school is associated with overweight and obesity in primary school children.

METHODS

We studied 2660 children aged 7-10 years during 2012 in Barcelona. Child weight and height were measured and age- and sex-specific z-scores for body mass index (zBMI) were calculated using the WHO growth reference 2007. Overweight and obesity were defined using the same reference. Land use regression models were used to estimate levels of nitrogen dioxide (NO₂), particulate matter <2.5 μm (PM_2.5), <10 μm (PM₁₀) and coarse (PM_coarse) at home. Outdoor levels of NO₂, PM_2.5, elemental carbon (EC), and ultrafine particles (UFP) were measured in the schoolyard. Multilevel mixed linear and ordered logistic models were used to assess the association between ambient air pollution (continuous per interquartile range (IQR) increase and categorical with tertile cutoffs) and zBMI (continuous and ordinal: normal, overweight, obese), after adjusting for socio-demographic characteristics.

RESULTS

An IQR increase in PM₁₀-home (5.6 μg/m³) was associated with a 10% increase in the odds of being overweight or obese (odds ratio (OR) = 1.10; 95% CI = 1.00, 1.22). Children exposed to the highest tertile of UFP-school (>27,346 particles/cm³) had a 30% higher odds of being overweight or obese (OR = 1.30; 95%CI = 1.03, 1.64) compared to the lowest tertile of UFP exposure. We also observed that exposure to NO₂, PM_2.5 or EC at schools was associated with higher odds of overweight or obese at medium compared to low levels of exposure. Home and school exposures did not show any significant associations with zBMI (except PM_2.5-school comparing tertile 2 vs tertile 1) but were similar in direction.

CONCLUSIONS

This study suggests that exposure to ambient air pollution, especially at school, is associated with childhood risk for overweight and obesity. A cautious interpretation is warranted because associations were not always linear and because school and home air pollution measurements were not directly comparable.

Oxidative and Toxicological Evolution of Engineered Nanoparticles with Atmospherically Relevant Coatings

The health impacts associated with engineered nanoparticles (ENPs) released into the atmosphere have not been adequately assessed. Such impacts could potentially arise from the toxicity associated with condensable atmospheric secondary organic material (SOM), or changes in the SOM composition induced by ENPs. Here, these possibilities are evaluated by investigating the oxidative and toxicological evolution of TiO₂ and SiO₂ nanoparticles which have been coated with SOM from the O₃ or OH initiated oxidation of α-pinene. It was found that pristine SiO₂ particles were significantly more cytotoxic compared to pristine TiO₂ particles. TiO₂ in the dark or under UV irradiation catalytically reacted with the SOM, increasing its O/C by up to 55% over photochemically inert SiO₂ while having negligible effects on the overall cytotoxicity. Conversely, the cytotoxicity associated with SiO₂ coated with SOM was markedly suppressed (by a factor of 9, at the highest exposure dose) with both increased SOM coating thickness and increased photochemical aging. These suppressing effects (organic coating and photo-oxidation of organics) were attributed to a physical hindrance of SiO₂-cell interactions by the SOM and enhanced SOM viscosity and hydrophilicity with continued photo-oxidation, respectively. These findings highlight the importance of atmospheric processes in altering the cytotoxicity of ENPs.

Exposure to Secondhand Tobacco Smoke at Airport Terminals

Background

Airports may represent significant sources of secondhand smoke (SHS) exposure for both travelers and employees. While previously common smoking rooms have largely disappeared from US airports, smoking continues to occur outdoors at terminal entrances. SHS may be especially high at arrival areas, since they oftentimes are partially enclosed by overhead departures, creating stagnant microenvironments. This study assessed particulate matter <2.5 microns in diameter (PM2.5), a common surrogate for SHS, at airport terminal locations to evaluate both outdoor exposure risk and possible indoor drift of SHS from outdoor sources.

Methods

A convenience sample of nine airport terminal arrival areas in the US state of Florida was surveyed between February and July 2018. PM2.5 levels were assessed outdoors and indoors at terminal entrances and at control areas far into terminal interiors. We also examined the impact of smoking location on SHS exposure by correlating cigarette and passing vehicle counts with PM2.5 levels at terminals with contrasting proximity of designated smoking locations to terminal entrances.

Results

Although outdoor PM2.5 levels (mean 17.9, SD 6.1 µg/m³) were significantly higher than indoors (p < 0.001), there was no difference between indoor areas directly inside terminal entrances and areas much further interior (mean 8.8, SD 2.6 vs mean 8.5, SD 3.0 µg/m³, p=0.49). However, when smoking areas were in close proximity to terminal entrances, the number of lit cigarettes and vehicular traffic per minute predicted 70% of the variance of PM2.5 levels (p < 0.001), which was attributable mostly to the cigarette number (β = 0.83; 95% CI (0.55 to 1.11); p < 0.001). This effect was not observed at smoking areas further away.

Conclusion

PM2.5 data did not suggest indoor drift from outside smoking. Nevertheless, absolute exposure outdoors was high and correlated with the location of designated smoking areas. Further studies are needed to examine the effect of microclimate formation on exposure risk.

Particle emissions from fused deposition modeling 3D printers: Evaluation and meta-analysis

Fused deposition modeling (FDM) 3D printers, the most popular choice among home hobbyists, have been shown to release volatile organic chemicals (VOCs) and billions of airborne particles per minute, indicating the potential for consumer inhalation exposure and consequent health risks. Publications on FDM 3D printer emissions however, contain large heterogeneity of testing methods and analytical procedures making it difficult to reach overall conclusions for particle characteristics or particle number emission rates across the field. In this publication, data were collected over the printing time from 3D printer emission studies including particle count diameters (PCDs) (nanometers), particle number concentrations (PNCs) (particles/cm³), and particle number emission rates (PNERs) (particles min^-1). Despite heterogeneity in methods, the majority of particles released were reported as ultrafine in size (i.e., <100 nm) indicating that using both acrylonitrile butadiene styrene (ABS) and poly-lactic acid (PLA) may present a risk of exposure to respirable particles. Mean PNC emitted in 3D printing tests ranged over several orders of magnitude across publications with overall means of 300,980 particles/cm³ for ABS and 65,482 particles/cm³ for PLA. Although mean PNC data were available from only 7 of the 16 papers reviewed, ABS resulted in greater particle numbers than PLA suggesting increased exposure to ultrafine particles. A linear mixed model was fitted for mean PNCs to further explore the impact of nozzle temperature and filament material. Finally, the PNER calculation method especially regarding losses, varied widely across studies, and directly impacted the PNERs reported. To strengthen direct comparability of results going forward, it is recommended that standard emissions testing protocols be developed for FDM 3D printers and particle influxes and losses be more uniformly calculated.

Air pollution and diabetes-related biomarkers in non-diabetic adults: A pathway to impaired glucose metabolism?

BACKGROUND

While prior studies have linked air pollution (AP) to diabetes prevalence and incidence, few have investigated whether AP exposure is also associated with alterations in diabetes-related biomarkers in metabolically healthy adults.

OBJECTIVE

To evaluate the associations between short-, medium-, and long-term AP and diabetes-related biomarkers (adiponectin, interleukin-1 receptor antagonist [IL-1RA], high sensitivity C-reactive protein [hsCRP], fibrinogen) in persons without diabetes.

METHODS

Adiponectin, IL-1RA, hsCRP, and fibrinogen were measured in blood samples collected at the baseline (t₀; 2000-2003) and first follow-up (t₁; 2006-2008) examinations of the prospective Heinz Nixdorf Recall (HNR) cohort study in Germany. Participants' residential mean exposures to PM₁₀, PM_2.5, NO₂, and accumulation mode particle number concentration (PN_AM) were estimated for several time windows (1- to 365-day) prior to examination using a dispersion and chemistry transport model. We fitted covariate-adjusted linear mixed effects models using a random participant intercept and investigated effect modification by obesity status.

RESULTS

We analyzed 6727 observations (n_t0 = 3626, n_t1 = 3101) from 4052 participants of the HNR study (52% women; ages 45-76 years at t₀). For all air pollutants, medium-term exposures (60- to 120-day) were negatively associated with adiponectin (e.g., 91-day PN_AM: -2.51% change [-3.40%, -1.53%] per interquartile [IQR] increase). Several short-, medium-, and long-term AP exposures were positively associated with IL-1RA (e.g., 365-day PM₁₀: 2.64% change [1.25%, 4.22%] per IQR increase). Long-term exposures were positively associated with hsCRP level while no consistent patterns were observed for fibrinogen. Stronger associations for adiponectin were observed among non-obese participants.

CONCLUSION

In persons without diabetes, we observed differing patterns of association between AP and diabetes-related biomarkers across a range of exposure windows, supporting the hypothesis that AP may play a role in the development of diabetes.

Ultrafine particles in airways: a novel marker of COPD exacerbation risk and inflammatory status

Purpose

Ultrafine particles (UFP) are toxic due to their small size and penetration into deeper lung compartments. We aimed to evaluate the exhaled breath condensate (EBC)-UFP content as a reflection of inflammation and oxidative stress status in COPD patients and as an exacerbation risk marker.

Methods

EBC was collected by conventional methods. Particles were analyzed with NanoSight LM20. EBC carbonyl and 8-hydroxydeoxyguanosine (8-OHdG) levels were measured using ELISA kits. Study population (58 COPD patients and 40 healthy smoker and non-smoker controls) underwent spirometry, diffusion capacity, EBC testing, and blood sampling.

Results

Absolute eosinophil count, C-reactive protein (CRP), and lactate dehydrogenase in serum were elevated in the COPD group compared with the controls (224 U/L, 5 mg/L, and 391 U/L vs 154 U/L, 3 mg/L, and 330 U/L, P=0.009, P=0.05, and P=0.004, respectively). COPD patients had lower UFP concentrations in EBC compared with controls (0.24 E8/mL vs 0.51 E8/mL, P≤0.001). A mirror image was detected in serum: COPD patients had higher UFP concentrations compared with controls (9.8 E8/mL vs 6.7 E8/mL, respectively, P=0.03). EBC carbonyl and 8-OHdG levels were higher among COPD patients compared with controls (5.1 per 1 µg/mL protein and 0.036 ng/mL vs 0.41 per 1 µg/mL protein and 0.003 ng/mL, P=0.001 and P≤0.001, respectively). EBC UFP concentrations were negatively correlated with pack years (R=−0.44, P ≤0.001) and positively correlated with FEV₁ and diffusing lung capacity for carbon monoxide (R=0.46, 0.23, P ≤0.001 and P=0.04, respectively). Low EBC UFP concentrations (≤0.18 E8/mL) and CRP levels ≥5 mg/L were independent predictors of the frequent exacerbator phenotype (OR 3.6; 95% CI: 1.06–7.97; P=0.04 and OR 4.4; 95% CI: 1.24–10.2; P=0.02, respectively).

Conclusion

UFP content in EBC reflects the inflammatory state of airways. Low UFP concentrations in EBC and high in serum of COPD patients support our hypothesis that increased epithelial permeability could be the mechanism behind those findings.

Environmental exposures and mechanisms in allergy and asthma development

Environmental exposures interplay with human host factors to promote the development and progression of allergic diseases. The worldwide prevalence of allergic disease is rising as a result of complex gene-environment interactions that shape the immune system and host response. Research shows an association between the rise of allergic diseases and increasingly modern Westernized lifestyles, which are characterized by increased urbanization, time spent indoors, and antibiotic usage. These environmental changes result in increased exposure to air and traffic pollution, fungi, infectious agents, tobacco smoke, and other early-life and lifelong risk factors for the development and exacerbation of asthma and allergic diseases. It is increasingly recognized that the timing, load, and route of allergen exposure affect allergic disease phenotypes and development. Still, our ability to prevent allergic diseases is hindered by gaps in understanding of the underlying mechanisms and interaction of environmental, viral, and allergen exposures with immune pathways that impact disease development. This Review highlights epidemiologic and mechanistic evidence linking environmental exposures to the development and exacerbation of allergic airway responses.

Bactericidal and Cytotoxic Properties of Silver Nanoparticles

Silver nanoparticles (AgNPs) can be synthesized from a variety of techniques including physical, chemical and biological routes. They have been widely used as nanomaterials for manufacturing cosmetic and healthcare products, antimicrobial textiles, wound dressings, antitumor drug carriers, etc. due to their excellent antimicrobial properties. Accordingly, AgNPs have gained access into our daily life, and the inevitable human exposure to these nanoparticles has raised concerns about their potential hazards to the environment, health, and safety in recent years. From in vitro cell cultivation tests, AgNPs have been reported to be toxic to several human cell lines including human bronchial epithelial cells, human umbilical vein endothelial cells, red blood cells, human peripheral blood mononuclear cells, immortal human keratinocytes, liver cells, etc. AgNPs induce a dose-, size- and time-dependent cytotoxicity, particularly for those with sizes ≤10 nm. Furthermore, AgNPs can cross the brain blood barrier of mice through the circulation system on the basis of in vivo animal tests. AgNPs tend to accumulate in mice organs such as liver, spleen, kidney and brain following intravenous, intraperitoneal, and intratracheal routes of administration. In this respect, AgNPs are considered a double-edged sword that can eliminate microorganisms but induce cytotoxicity in mammalian cells. This article provides a state-of-the-art review on the synthesis of AgNPs, and their applications in antimicrobial textile fabrics, food packaging films, and wound dressings. Particular attention is paid to the bactericidal activity and cytotoxic effect in mammalian cells.

Engineered nanoparticle exposure and cardiovascular effects: the role of a neuronal-regulated pathway

Human and animal studies have confirmed that inhalation of particles from ambient air or occupational settings not only causes pathophysiological changes in the respiratory system, but causes cardiovascular effects as well. At an equal mass lung burden, nanoparticles are more potent in causing systemic microvascular dysfunction than fine particles of similar composition. Thus, accumulated evidence from animal studies has led to heightened concerns about the potential short- and long-term deleterious effects of inhalation of engineered nanoparticles on the cardiovascular system. This review highlights the new observations from animal studies, which document the adverse effects of pulmonary exposure to engineered nanoparticles on the cardiovascular system and elucidate the potential mechanisms involved in regulation of cardiovascular function, in particular, how the neuronal system plays a role and reacts to pulmonary nanoparticle exposure based on both in vivo and in vitro studies. In addition, this review also discusses the possible influence of altered autonomic nervous activity on preexisting cardiovascular conditions. Whether engineered nanoparticle exposure serves as a risk factor in the development of cardiovascular diseases warrants further investigation.

Recent advances in the field of transition metal dichalcogenides for biomedical applications

Nanosheets of transition metal dichalcogenide (TMDs), the graphene-like two-dimensional (2D) materials, exhibit a unique combination of properties and have attracted enormous research interest for a wide range of applications including catalysis, functional electronics, solid lubrication, photovoltaics, energy materials and most recently in biomedical applications. Their potential for use in biosensors, drug delivery, multimodal imaging, antimicrobial agents and tissue engineering is being actively studied. However, the commercial translation of exfoliated TMDs has been limited due to the low aqueous solubility, non-uniformity, lack of control over the layer thickness, and the long-term colloidal stability of the exfoliated material. There is wide interest in the synthesis and exfoliation of TMDs resulting in the reporting of increasing numbers of new methods and their biomedical applications. The unique physicochemical characteristics of the TMD nanosheets have been exploited to tether them with biological payload to achieve selective localized delivery in vivo. The large surface-to-volume ratio, good cytocompatibility, ease of surface modification, tunable bandgap, strong spin-orbit coupling, and high optical and thermal conversion efficiency of TMD nanosheets make them favorable over traditional nanomaterials for biomedical research. Moreover, the presence of abundant active edge sites on the 2D TMDs makes them suitable for catalytic activities, while the large surface area and the interspace between layers are particularly conducive to ion or small molecule intercalation, making them useful for energy storage applications with rapid redox reaction capabilities. One of the major limitations of the exfoliated TMDs has been their limited colloidal stability in aqueous media. In this review, we summarize the recent advances in the exfoliation and synthesis of single-layered TMDs, their biomedical efficacy in terms of cytotoxicity, combinatorial therapy and diagnostic imaging, as well as antimicrobial activity. We highlight the current challenges in the field and propose strategies for the future.

Carbon nanodots: Opportunities and limitations to study their biodistribution at the human lung epithelial tissue barrier

Inhalation of combustion-derived ultrafine particles (≤0.1 μm) has been found to be associated with pulmonary and cardiovascular diseases. However, correlation of the physicochemical properties of carbon-based particles such as surface charge and agglomeration state with adverse health effects has not yet been established, mainly due to limitations related to the detection of carbon particles in biological environments. The authors have therefore applied model particles as mimics of simplified particles derived from incomplete combustion, namely, carbon nanodots (CNDs) with different surface modifications and fluorescent properties. Their possible adverse cellular effects and their biodistribution pattern were assessed in a three-dimensional (3D) lung epithelial tissue model. Three different CNDs, namely, nitrogen, sulfur codoped CNDs ( N,S-CNDs) and nitrogen doped CNDs ( N-CNDs-1 and N-CNDs-2), were prepared by microwave-assisted hydrothermal carbonization using different precursors or different microwave systems. These CNDs were found to possess different chemical and photophysical properties. The surfaces of nanodots N-CNDs-1 and N-CNDs-2 were positively charged or neutral, respectively, arguably due to the presence of amine and amide groups, while the surfaces of N,S-CNDs were negatively charged, as they bear carboxylic groups in addition to amine and amide groups. Photophysical measurements showed that these three types of CNDs displayed strong photon absorption in the UV range. Both N-CNDs-1 and N,S-CNDs showed weak fluorescence emission, whereas N-CNDs-2 showed intense emission. A 3D human lung model composed of alveolar epithelial cells (A549 cell line) and two primary immune cells, i.e., macrophages and dendritic cells, was exposed to CNDs via a pseudo-air-liquid interface at a concentration of 100 μg/ml. Exposure to these particles for 24 h induced no harmful effect on the cells as assessed by cytotoxicity, cell layer integrity, cell morphology, oxidative stress, and proinflammatory cytokines release. The distribution of the CNDs in the lung model was estimated by measuring the fluorescence intensity in three different fractions, e.g., apical, intracellular, and basal, after 1, 4, and 24 h of incubation, whereby reliable results were only obtained for N-CNDs-2. It was shown that N-CNDs-2 translocate rapidly, i.e., >40% in the basal fraction within 1 h and almost 100% after 4 h, while ca. 80% of the N-CNDs-1 and N,S-CNDs were still located on the apical surface of the lung cells after 1 h. This could be attributed to the agglomeration behavior of N-CNDs-1 or N,S-CNDs. The surface properties of the N-CNDs bearing amino and amide groups likely induce greater uptake as N-CNDs could be detected intracellularly. This was less evident for N,S-CNDs, which bear carboxylic acid groups on their surface. In conclusion, CNDs have been designed as model systems for carbon-based particles; however, their small size and agglomeration behavior made their quantification by fluorescence measurement challenging. Nevertheless, it was demonstrated that the surface properties and agglomeration affected the biodistribution of the particles at the lung epithelial barrier in vitro.

Genotoxicity of fine and coarse fraction ambient particulate matter in immortalised normal (TT1) and cancer-derived (A549) alveolar epithelial cells

Human exposure to airborne particulate matter (PM) is associated with adverse cardiopulmonary health effects, including lung cancer. Ambient PM represents a heterogeneous mixture of chemical classes including transition metals, polycyclic aromatic hydrocarbons (PAHs) and their derivatives such as nitro-PAHs, many of which are classified as putative carcinogens. As the primary site of human exposure to PM is the lungs, we investigated the response of two alveolar epithelial cell lines, the tumour-derived A549 and newly described TT1 cells, to fine and coarse PM collected from background and roadside locations. We show that coarse PM elicits a genotoxic response in the TT1 cells, with the strongest signal associated with the background sample. This response could be recapitulated using the organic extract derived from this sample. No responses were observed in PM-challenged A549 cells. Fine PM failed to elicit a genotoxic response in either cell line despite the higher PAH concentrations within this fraction. Consistent with the lack of a simplistic association between PM PAH content and the observed genotoxic response, TT1 cells treated with benzo[a]pyrene (BaP) demonstrated no increase in the selected markers. In contrast, a pattern of response was observed in TT1 cells challenged with 3-nitrobenzanthrone (3-NBA) similar to that with coarse PM. Together, these data illustrated the suitability of the TT1 cell line for assessing PM-induced genotoxicity and challenge the contention that fine roadside PM poses the higher cancer risk. Furthermore, the response to 3-NBA and not BaP suggests a major contribution of nitro-PAHs to the overall toxicity of PM. Environ. Mol. Mutagen. 59:290-301, 2018. © 2018 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.

A Jagged 1-Notch 4 molecular switch mediates airway inflammation induced by ultrafine particles

BACKGROUND

Exposure to traffic-related particulate matter promotes asthma and allergic diseases. However, the precise cellular and molecular mechanisms by which particulate matter exposure acts to mediate these effects remain unclear.

OBJECTIVE

We sought to elucidate the cellular targets and signaling pathways critical for augmentation of allergic airway inflammation induced by ambient ultrafine particles (UFP).

METHODS

We used in vitro cell-culture assays with lung-derived antigen-presenting cells and allergen-specific T cells and in vivo mouse models of allergic airway inflammation with myeloid lineage-specific gene deletions, cellular reconstitution approaches, and antibody inhibition studies.

RESULTS

We identified lung alveolar macrophages (AM) as the key cellular target of UFP in promoting airway inflammation. Aryl hydrocarbon receptor-dependent induction of Jagged 1 (Jag1) expression in AM was necessary and sufficient for augmentation of allergic airway inflammation by UFP. UFP promoted T_H2 and T_H17 cell differentiation of allergen-specific T cells in a Jag1- and Notch 4-dependent manner. Treatment of mice with an anti-Notch 4 antibody abrogated exacerbation of allergic airway inflammation induced by UFP.

CONCLUSION

UFP exacerbate allergic airway inflammation by promoting a Jag1-Notch 4-dependent interaction between AM and allergen-specific T cells, leading to augmented T_H cell differentiation.

Air Pollution and Glucose Metabolism: An Analysis in Non-Diabetic Participants of the Heinz Nixdorf Recall Study

BACKGROUND

Despite the importance of understanding the connection between air pollution exposure and diabetes, studies investigating links between air pollution and glucose metabolism in nondiabetic adults are limited.

OBJECTIVE

We aimed to estimate the association of medium-term air pollution exposures with blood glucose and glycated hemoglobin A1c (HbA1c) among nondiabetics.

METHODS

This study included observations from nondiabetic participants (n_obs=7,108) of the population-based Heinz Nixdorf Recall study at baseline (2000–2003) and follow-up examination (2006–2008). Daily fine particulate matter (aerodynamic diameter≤2.5 μm, PM_2.5; aerodynamic diameter≤10 μm, PM₁₀), accumulation mode particle number (PN_AM), and nitrogen dioxide (NO₂) exposures were estimated at participants’ residences using the spatiotemporal European Air Pollution Dispersion (EURAD) chemistry transport model. We evaluated the associations between medium-term air pollution exposures (28- and 91-d means) and glucose metabolism measures using mixed linear regression and adjusting for season, meteorology, and personal characteristics. A range of other exposure windows (1-, 2-, 3-, 7-, 14-, 45-, 60-, 75-, 105-, 120-, and 182-d means) were also evaluated to identify potentially relevant biological windows.

RESULTS

We observed positive associations between PM_2.5 and PN_AM exposures and blood glucose levels [e.g., 28-d PM_2.5: 0.91 mg/dL (95% CI: 0.38, 1.44) per 5.7 μg/m³]. PM_2.5, PM₁₀, and PN_AM exposures were positively associated with HbA1c [e.g., 91-d PM_2.5: 0.07 p.p. (95% CI: 0.04, 0.10) per 4.0 μg/m³]. Mean exposures during longer exposure windows (75- to 105-d) were most strongly associated with HbA1c, whereas 7- to 45-d exposures were most strongly associated with blood glucose. NO₂ exposure was not associated with blood glucose or with HbA1c.

CONCLUSIONS

Medium-term PM and PN_AM exposures were positively associated with glucose measures in nondiabetic adults. These findings indicate that reducing ambient air pollution levels may decrease the risk of diabetes. https://doi.org/10.1289/EHP2561.

Genotoxicity, biochemical, and biodistribution studies of magnesium oxide nano and microparticles in albino wistar rats after 28-day repeated oral exposure

Increased utilization and exposure levels of Magnesium oxide (MgO) nanoparticles (NPs) to humans and environment may raise unexpected consequences. The goal of this study was to evaluate the toxicological implications of MgO NPs and MPs after 28 day repeated oral administration in Wistar rats with three different doses (250, 500, and 1000 mg/kg). The MgO particles were characterised systematically in order to get more insights of the toxicological behaviour. MgO NPs induced significant DNA damage and aberrations in chromosomes. Moreover, hepatic enzymes released into the systemic circulation caused significant elevated levels of physiological enzymes in blood. NPs could interfere with proteins and enzymes and alter the redox balance in cell environment. Significant accumulation of Mg in all tissues and clearance via urine and faeces was noted in size dependent kinetics. Oral administration of MgO NPs altered the biochemical and genotoxic parameters in dose dependent and gender independent manner.

Solid Particle Number Emission Factors of Euro VI Heavy-Duty Vehicles on the Road and in the Laboratory

Particulate matter (PM), and in particular ultrafine particles, have a negative impact on human health. The contribution of vehicle PM emissions to air pollution is typically quantified with emission inventories, which need vehicle emission factors as input. Heavy-duty vehicles, although they represent a small percentage of the vehicle population in nearly every major country, contribute the majority of the on-road PM emissions. However, the published data of modern heavy-duty vehicle emissions are scarce, and for the newest Euro VI technologies, almost non-existent. The main objective of this paper is to present Solid Particle Number (SPN) emission factors from Euro VI heavy-duty vehicles using diesel, Compressed Natural Gas (CNG), or Liquefied Natural Gas (LNG). Urban, rural and motorway (highway) emissions were determined on the road at various European cities using SPN Portable Emission Measurement Systems (PEMS). Additional tests on a heavy-duty chassis dynamometer showed that the solid sub-23 nm fraction, which is not covered at the moment in the European regulation, is high, especially for CNG engines. The significant contribution of regeneration events and the effect of ambient temperature and engine cold-start on particle emissions were also discussed.

Cardiopulmonary effects induced by occupational exposure to titanium dioxide nanoparticles

Although some toxicological studies have reported that exposure to titanium dioxide nanoparticles (nano-TiO₂) may elicit adverse cardiopulmonary effects, related data collected from human are currently limited. The purpose of this study is to explore cardiopulmonary effects among workers who were exposed to nano-TiO₂ and to identify biomarkers associated with exposure. A cross-sectional study was conducted in a nano-TiO₂ manufacturing plant in eastern China. Exposure assessment and characterization of TiO₂ particles were performed in a packaging workshop. Physical examination and possible biomarkers for cardiopulmonary effects were examined among 83 exposed workers and 85 controls. In packaging workshop, the total mass concentration of particles was 3.17 mg/m³. The mass concentration of nanoparticles was 1.22 mg/m³ accounting for 39% of the total mass. Lung damage markers (SP-D and pulmonary function), cardiovascular disease markers (VCAM-1, ICAM-1, LDL, and TC), oxidative stress markers (SOD and MDA), and inflammation markers (IL-8, IL-6, IL-1β, TNF-α, and IL-10) were associated with occupational exposure to nano-TiO₂. Among those markers, SP-D showed a time (dose)-response pattern within exposed workers. The data strongly suggest that nano-TiO₂ could contribute, at least in part, to the cardiopulmonary effects observed in workers. The studied markers and pulmonary function tests may be useful in health surveillance for workers exposed to nanomaterials.

In vitro assessment of silver nanoparticles immunotoxicity

This study aimed to characterize unwanted immune effects of nanoparticles (NP) using THP-1 cells, human whole blood and enriched peripheral blood monocytes. Commercially available silver NP (AgNP < 100 nm, also confirmed by Single Particle Extinction and Scattering) were used as prototypical NP. Cells were treated with AgNP alone or in combination with classical immune stimuli (i.e. LPS, PHA, PWM) and cytokine assessed; in addition, CD54 and CD86 expression was evaluated in THP-1 cells. AgNP alone induced dose-related IL-8 production in all models, with higher response observed in THP-1 cells, possibly connected to different protein corona formation in bovine versus human serum. AgNP potentiated LPS-induced IL-8 and TNF-α, but not LPS-induced IL-10. AgNP alone induced slight increase in IL-4, and no change in IFN-γ production. While responses to PHA in term of IL-4 and IFN-γ production were not affected, increased PWM-induced IL-4 and IFN-γ production were observed, suggesting potentiation of humoral response. Reduction in PHA-induced IL-10 was observed. Overall, results indicate immunostimulatory effects. THP-1 cells work as well as primary cells, representing a useful and practical alternative, with the awareness that from a physiological point of view the whole blood assay is the one that comes closest to reality.

Workplace exposure and release of ultrafine particles during atmospheric plasma spraying in the ceramic industry

Atmospheric plasma spraying (APS) is a frequently used technique to produce enhanced-property coatings for different materials in the ceramic industry. This work aimed to characterise and quantify the impact of APS on workplace exposure to airborne particles, with a focus on ultrafine particles (UFPs, <100nm) and nanoparticles (<50nm). Particle number, mass concentrations, alveolar lung deposited surface area concentration, and size distributions, in the range 10nm-20μm were simultaneously monitored at the emission source, in the potential worker breathing zone, and in outdoor air. Different input materials (known as feedstock) were tested: (a) micron-sized powders, and (b) suspensions containing submicron- or nano-sized particles. Results evidenced significantly high UFP concentrations (up to 3.3×10⁶/cm³) inside the spraying chamber, which impacted exposure concentrations in the worker area outside the spraying chamber (up to 8.3×10⁵/cm³). Environmental release of UFPs was also detected (3.9×10⁵/cm³, outside the exhaust tube). Engineered nanoparticle (ENP) release to workplace air was also evidenced by TEM microscopy. UFP emissions were detected during the application of both micron-sized powder and suspensions containing submicron- or nano-sized particles, thus suggesting that emissions were process- (and not material-) dependent. An effective risk prevention protocol was implemented, which resulted in a reduction of UFP exposure in the worker area. These findings demonstrate the potential risk of occupational exposure to UFPs during atmospheric plasma spraying, and raise the need for further research on UFP formation mechanisms in high-energy industrial processes.

Mechanistic insight into the impact of nanomaterials on asthma and allergic airway disease

Asthma is a chronic respiratory disease known for its high susceptibility to environmental exposure. Inadvertent inhalation of engineered or incidental nanomaterials is a concern for human health, particularly for those with underlying disease susceptibility. In this review we provide a comprehensive analysis of those studies focussed on safety assessment of different nanomaterials and their unique characteristics on asthma and allergic airway disease. These include in vivo and in vitro approaches as well as human and population studies. The weight of evidence presented supports a modifying role for nanomaterial exposure on established asthma as well as the development of the condition. Due to the variability in modelling approaches, nanomaterial characterisation and endpoints used for assessment in these studies, there is insufficient information for how one may assign relative hazard potential to individual nanoscale properties. New developments including the adoption of standardised models and focussed in vitro and in silico approaches have the potential to more reliably identify properties of concern through comparative analysis across robust and select testing systems. Importantly, key to refinement and choice of the most appropriate testing systems is a more complete understanding of how these materials may influence disease at the cellular and molecular level. Detailed mechanistic insight also brings with it opportunities to build important population and exposure susceptibilities into models. Ultimately, such approaches have the potential to more clearly extrapolate relevant toxicological information, which can be used to improve nanomaterial safety assessment for human disease susceptibility.

Differential Effects of Surface-Functionalized Zirconium Oxide Nanoparticles on Alveolar Macrophages, Rat Lung, and a Mouse Allergy Model

Nanoparticles (NPs) may affect the lung via their chemical composition on the surface. Here, we compared the bioactivity of zirconium oxide (ZrO₂) NPs coated with either aminopropilsilane (APTS), tetraoxidecanoic acid (TODS), polyethyleneglycol (PGA), or acrylic acid (Acryl). Supernatants from NPs-treated cultured alveolar macrophages (NR8383) tested for lactate dehydrogenase, glucuronidase, tumor necrosis factor α, and H₂O₂ formation revealed dose-dependent effects, with only gradual differences among particles whose gravitational settling and cellular uptake were similar. We selected TODS- and Acryl-coated NPs for intratracheal administration into the rat lung. Darkfield and hyperspectral microscopy combined with immunocytochemistry showed that both NPs qualities accumulate mainly within the alveolar macrophage compartment, although minute amounts also occurred in neutrophilic granulocytes. Dose-dependent signs of inflammation were found in the broncho-alveolar lavage fluid on day 3 but no longer on day 21 post-application of ≥1.2 mg per lung; again only minor differences occurred between TODS- and Acryl-coated NPs. In contrast, the response of allergic mice was overall higher compared to control mice and dependent on the surface modification. Increases in eosinophils, lymphocytes and macrophages were highest following ZrO₂-PGA administration, followed by ZrO₂-Acryl, ZrO₂-TODS, and ZrO₂-APTS. We conclude that surface functionalization of ZrO₂ NPs has minor effects on the inflammatory lung response of rats and mice, but is most relevant for an allergic mouse model. Allergic individuals may therefore be more susceptible to exposure to NPs with specific surface modifications.

Ins and Outs in Environmental and Occupational Safety Studies of Asthma and Engineered Nanomaterials

According to the Centers for Disease Control and Prevention, approximately 25 million Americans suffer from asthma. The disease total annual cost is about $56 billion and includes both the direct and indirect costs of medications, hospital stays, missed work, and decreased productivity. Air pollution with xenobiotics, bacterial agents, and industrial nanomaterials, such as carbon nanotubes, contribute to the exacerbation of this condition and are a point of particular attention in environmental toxicology as well as in occupational health and safety research. Mast cell degranulation and activation of Th2 cells triggered either by allergen-specific immunoglobulin E (IgE) or by alternative mechanisms, such as locally produced neurotransmitters, underlie the pathophysiological process of airway constriction during an asthma attack. Other immune and non-immune cell types, including basophils, eosinophils, Th1, Th17, Th9, macrophages, dendritic cells, and smooth muscle cells, are involved in the inflammatory and allergic responses during asthma, which, under chronic conditions, may progress without mast cells, the key trigger of the acute asthma attack. To decipher complex molecular, cellular, and genetic mechanisms, many researchers have attempted to develop in vitro and in vivo models to study asthma. Herein, we summarize the advantages and disadvantages of various models and their applicability to nanoparticle evaluation in asthma research. We further suggest that a framework for both in vitro and in vivo methods should be used to study the impact of engineered nanomaterials on asthma etiology, pathophysiology, and treatment.

Assessing the Risk of Engineered Nanomaterials in the Environment: Development and Application of the nanoFate Model

We developed a dynamic multimedia fate and transport model (nanoFate) to predict the time-dependent accumulation of metallic engineered nanomaterials (ENMs) across environmental media. nanoFate considers a wider range of processes and environmental subcompartments than most previous models and considers ENM releases to compartments (e.g., urban, agriculture) in a manner that reflects their different patterns of use and disposal. As an example, we simulated ten years of release of nano CeO₂, CuO, TiO₂, and ZnO in the San Francisco Bay area. Results show that even soluble metal oxide ENMs may accumulate as nanoparticles in the environment in sufficient concentrations to exceed the minimum toxic threshold in freshwater and some soils, though this is more likely with high-production ENMs such as TiO₂ and ZnO. Fluctuations in weather and release scenario may lead to circumstances where predicted ENM concentrations approach acute toxic concentrations. The fate of these ENMs is to mostly remain either aggregated or dissolved in agricultural lands receiving biosolids and in freshwater or marine sediments. Comparison to previous studies indicates the importance of some key model aspects including climatic and temporal variations, how ENMs may be released into the environment, and the effect of compartment composition on predicted concentrations.

Why the Immune System Should Be Concerned by Nanomaterials?

Particles possess huge specific surface area and therefore nanomaterials exhibit unique characteristics, such as special physical properties and chemical hyper-reactivity, which make them particularly attractive but also raise numerous questions concerning their safety. Interactions of nanomaterials with the immune system can potentially lead to immunosuppression, hypersensitivity (allergy), immunogenicity and autoimmunity, involving both innate and adaptive immune responses. Inherent physical and chemical NP characteristics may influence their immunotoxicity, i.e., the adverse effects that can result from exposure. This review will focus on the possible interaction of nanomaterials including protein aggregates with the innate immune system with specific emphasis on antigen-presenting cells, i.e., dendritic cells, macrophages and monocytes.

Air Pollution and Climate Change Effects on Allergies in the Anthropocene: Abundance, Interaction, and Modification of Allergens and Adjuvants

Air pollution and climate change are potential drivers for the increasing burden of allergic diseases. The molecular mechanisms by which air pollutants and climate parameters may influence allergic diseases, however, are complex and elusive. This article provides an overview of physical, chemical and biological interactions between air pollution, climate change, allergens, adjuvants and the immune system, addressing how these interactions may promote the development of allergies. We reviewed and synthesized key findings from atmospheric, climate, and biomedical research. The current state of knowledge, open questions, and future research perspectives are outlined and discussed. The Anthropocene, as the present era of globally pervasive anthropogenic influence on planet Earth and, thus, on the human environment, is characterized by a strong increase of carbon dioxide, ozone, nitrogen oxides, and combustion- or traffic-related particulate matter in the atmosphere. These environmental factors can enhance the abundance and induce chemical modifications of allergens, increase oxidative stress in the human body, and skew the immune system toward allergic reactions. In particular, air pollutants can act as adjuvants and alter the immunogenicity of allergenic proteins, while climate change affects the atmospheric abundance and human exposure to bioaerosols and aeroallergens. To fully understand and effectively mitigate the adverse effects of air pollution and climate change on allergic diseases, several challenges remain to be resolved. Among these are the identification and quantification of immunochemical reaction pathways involving allergens and adjuvants under relevant environmental and physiological conditions.

Whole Blood Cytokine Response to Local Traffic-Related Particulate Matter in Peruvian Children With and Without Asthma

This study sought to investigate if acute phase immune responses of whole blood from Peruvian children with controlled and uncontrolled asthma differed from children without asthma, following exposure to traffic-related particulate matter (TRPM). TRPM, including particulate matter from diesel combustion, has been shown to stimulate acute airway inflammation in individuals with and without asthma. For this study, a whole blood assay (WBA) was used to test peripheral whole blood samples from 27 children with asthma, and 12 without asthma. Participant blood samples were stimulated, ex vivo, for 24-h with an aqueous extract of TRPM that was collected near study area highways in Lima, Peru. All participant blood samples were tested against the same TRPM extract, in addition to purified bacterial endotoxin and pyrogen-free water, which served as positive and negative WBA controls, respectively. The innate and adaptive cytokine responses were evaluated in cell-free supernatants of the whole blood incubations. Comparatively similar levels were recorded for nine out of the 10 cytokines measured [e.g., – Interleukin (IL)-1β, IL-6, IL-10], regardless of study participant asthma status. However, IL-8 levels in TRPM-stimulated blood from children with uncontrolled asthma were diminished, compared to subjects without asthma (633 pg/ml vs. 1,023 pg/ml, respectively; p < 0.01); IL-8 responses for subjects with controlled asthma were also reduced, but to a lesser degree (799 pg/ml vs. 1,023 pg/ml, respectively; p = 0.10). These relationships were present before, and after, adjusting for age, sex, obesity/overweight status, C-reactive protein levels, and residential proximity to the study area’s major roadway. For tests conducted with endotoxin, there were no discernible differences in cytokine response between groups, for all cytokines measured. The WBA testing conducted for this study highlighted the capacity of the TRPM extract to potently elicit the release of IL-8 from the human whole blood system. Although the small sample size of the study limits the capacity to draw definitive conclusions, the IL-8 responses suggest that that asthma control may be associated with the regulation of a key mediator in neutrophil chemotaxis, at a systemic level, following exposure to PM derived from traffic-related sources.

Nano-Inclusions Applied in Cement-Matrix Composites: A Review

Research on cement-based materials is trying to exploit the synergies that nanomaterials can provide. This paper describes the findings reported in the last decade on the improvement of these materials regarding, on the one hand, their mechanical performance and, on the other hand, the new properties they provide. These features are mainly based on the electrical and chemical characteristics of nanomaterials, thus allowing cement-based elements to acquire "smart" functions. In this paper, we provide a quantitative approach to the reinforcements achieved to date. The fundamental concepts of nanoscience are introduced and the need of both sophisticated devices to identify nanostructures and techniques to disperse nanomaterials in the cement paste are also highlighted. Promising results have been obtained, but, in order to turn these advances into commercial products, technical, social and standardisation barriers should be overcome. From the results collected, it can be deduced that nanomaterials are able to reduce the consumption of cement because of their reinforcing effect, as well as to convert cement-based products into electric/thermal sensors or crack repairing materials. The main obstacle to foster the implementation of such applications worldwide is the high cost of their synthesis and dispersion techniques, especially for carbon nanotubes and graphene oxide.

Smoking and Cerebral Oxidative Stress and Air Pollution: A Dreadful Equation with Particulate Matter Involved and One More Powerful Reason Not to Smoke Anything!

Smoking has serious health effects. Cigarettes, including tobacco, marijuana, and electronic nicotine delivery systems are very effective ways to inhale harmful amounts of fine and ultrafine particulate matter. Does size matter? Yes, indeed! The smaller the particle you inhale, the higher the ability to produce reactive oxygen species and to readily access the brain. In this issue of the Journal of Alzheimer's Disease, Durazzo provides evidence of an association between active cigarette tobacco smoking in cognitively-normal elders and increased cerebral oxidative stress, while in actively smoking Alzheimer's disease (AD) patients, the association was also seen with smaller left and total hippocampal volumes. This paper has highly relevant results of interest across the US and the world because millions of people are active smokers and they have other genetic and environmental risk factors that could play a key role in the development/worsening of brain oxidative stress and neurodegeneration. Smoking basically anything producing aerosols with particulate matter in the fine and ultrafine size range is detrimental to your brain. Marijuana and e-cigarette use has grown steadily among adolescents and young adults. Smoking-related cerebral oxidative stress is a potential mechanism promoting AD pathology and increased risk for AD. Current knowledge also relates fine and ultrafine particles exposures influencing neurodevelopmental processes in utero. The results from Durazzo et al. should be put in a broader context, a context that includes evaluating the oxidative stress of nano-aerosols associated with cigarette emissions and their synergistic effects with air pollution exposures. AD is expected to increase in the US threefold by the year 2050, and some of these future AD patients are smoking and vaping right now. Understanding the impact of everyday exposures to long-term harmful consequences for brain health is imperative.