Translocation of ultrafine insoluble iridium particles from lung epithelium to extrapulmonary organs is size dependent but very low

Hydrogen sulfide attenuates particulate matter-induced human lung endothelial barrier disruption via combined reactive oxygen species scavenging and Akt activation

Exposure to particulate air pollution is associated with increased cardiopulmonary morbidity and mortality, although the pathogenic mechanisms are poorly understood. We previously demonstrated that particulate matter (PM) exposure triggers massive oxidative stress in vascular endothelial cells (ECs), resulting in the loss of EC integrity and lung vascular hyperpermeability. We investigated the protective role of hydrogen sulfide (H(2)S), an endogenous gaseous molecule present in the circulation, on PM-induced human lung EC barrier disruption and pulmonary inflammation. Alterations in EC monolayer permeability, as reflected by transendothelial electrical resistance (TER), the generation of reactive oxygen species (ROS), and murine pulmonary inflammatory responses, were studied after exposures to PM and NaSH, an H(2)S donor. Similar to N-acetyl cysteine (5 mM), NaSH (10 μM) significantly scavenged PM-induced EC ROS and inhibited the oxidative activation of p38 mitogen-activated protein kinase. Concurrent with these events, NaSH (10 μM) activated Akt, which helps maintain endothelial integrity. Both of these pathways contribute to the protective effect of H(2)S against PM-induced endothelial barrier dysfunction. Furthermore, NaSH (20 mg/kg) reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in bronchoalveolar lavage fluids in a murine model of PM-induced lung inflammation. These data suggest a potentially protective role for H(2)S in PM-induced inflammatory lung injury and vascular hyperpermeability.

DEP induction of ROS in capillary-like endothelial tubes leads to VEGF-A expression

Inhalation of diesel exhaust particles (DEPs) is associated with pulmonary and cardiovascular disease. One contributor to pathogenesis is inhaled particles reaching and injuring the lung capillary endothelial cells, and possibly gaining access to the blood stream. Using in vitro capillary tubes as a simplified vascular model system for this process, it was previously shown that DEPs induce the redistribution of vascular endothelial cell-cadherin (VE-Cad) away from the plasma membrane to intracellular locations. This allowed DEPs into the cell cytoplasm and tube lumen, suggesting the tubes may have become permeable (Chao et al., 2011). Here some of the mechanisms responsible for endothelial tube changes after DEP exposure were examined. The results demonstrate that endothelial tube cells mounted an oxidative stress response to DEP exposure. Hydrogen peroxide and oxidized proteins were detected after 24h of exposure to DEPs. Particles induced relocalization of Nrf2 from the cytoplasm to the nucleus, upregulating the expression of the enzyme heme oxygenase-1 (HO-1). Surprisingly, vascular endothelial cell growth factor-A (VEGF-A), initially termed "vascular permeability factor" (VPF), was found to be up-regulated in response to the HO-1 expression induced by DEPs. Similar to DEPs, applied VEGF-A induced relocalization of VE-Cadherin from the cell membrane surface to an intracellular location, and relocalization of VE-cadherin was associated with permeability. These data suggest that the DEPs may induce or contribute to the permeability of capillary-like endothelial tube cells via induction of HO-1 and VEGF-A.

Diesel exhaust particulate induces pulmonary and systemic inflammation in rats without impairing endothelial function ex vivo or in vivo

Background

Inhalation of diesel exhaust impairs vascular function in man, by a mechanism that has yet to be fully established. We hypothesised that pulmonary exposure to diesel exhaust particles (DEP) would cause endothelial dysfunction in rats as a consequence of pulmonary and systemic inflammation.

Methods

Wistar rats were exposed to DEP (0.5 mg) or saline vehicle by intratracheal instillation and hind-limb blood flow, blood pressure and heart rate were monitored in situ 6 or 24 h after exposure. Vascular function was tested by administration of the endothelium-dependent vasodilator acetylcholine (ACh) and the endothelium-independent vasodilator sodium nitroprusside (SNP) in vivo and ex vivo in isolated rings of thoracic aorta, femoral and mesenteric artery from DEP exposed rats. Bronchoalveolar lavage fluid (BALF) and blood plasma were collected to assess pulmonary (cell differentials, protein levels & interleukin-6 (IL-6)) and systemic (IL-6), tumour necrosis factor alpha (TNFα) and C-reactive protein (CRP)) inflammation, respectively.

Results

DEP instillation increased cell counts, total protein and IL-6 in BALF 6 h after exposure, while levels of IL-6 and TNFα were only raised in blood 24 h after DEP exposure. DEP had no effect on the increased hind-limb blood flow induced by ACh in vivo at 6 or 24 h. However, responses to SNP were impaired at both time points. In contrast, ex vivo responses to ACh and SNP were unaltered in arteries isolated from rats exposed to DEP.

Conclusions

Exposure of rats to DEP induces both pulmonary and systemic inflammation, but does not modify endothelium-dependent vasodilatation. Other mechanisms in vivo limit dilator responses to SNP and these require further investigation.

Assessment of exposure to airborne ultrafine particles in the urban environment of Lisbon, Portugal

The aim of this study was the assessment of exposure to ultrafine in the urban environment ofLisbon, Portugal, due to automobile traffic, and consisted of the determination of deposited alveolar surface area in an avenue leading to the town center during late spring. This study revealed differentiated patterns for weekdays and weekends, which could be related with the fluxes of automobile traffic. During a typical week, ultrafine particles alveolar deposited surface area varied between 35.0 and 89.2 microm2/cm3, which is comparable with levels reported for other towns such in Germany and the United States. These measurements were also complemented by measuring the electrical mobility diameter (varying from 18.3 to 128.3 nm) and number of particles that showed higher values than those previously reported for Madrid and Brisbane. Also, electron microscopy showed that the collected particles were composed of carbonaceous agglomerates, typical of particles emitted by the exhaustion of diesel vehicles.

Tissue distribution of inhaled micro- and nano-sized cerium oxide particles in rats: results from a 28-day exposure study

In order to obtain more insight into the tissue distribution, accumulation, and elimination of cerium oxide nanoparticles after inhalation exposure, blood and tissue kinetics were investigated during and after a 28-day inhalation study in rats with micro- and nanocerium oxide particles (nominal primary particle size: < 5000, 40, and 5-10 nm). Powder aerosolization resulted in comparable mass median aerodynamic diameter (1.40, 1.17, and 1.02 μm). After single exposure, approximately 10% of the inhaled dose was measured in lung tissue, as was also estimated by a multiple path particle dosimetry model (MPPD). Though small differences in pulmonary deposition efficiencies of cerium oxide were observed, no consistent differences in pulmonary deposition between the micro- and nanoparticles were observed. Each cerium oxide sample was also distributed to tissues other than lung after a single 6-h exposure, such as liver, kidney, and spleen and also brain, testis, and epididymis. No clear particle size-dependent effect on extrapulmonary tissue distribution was observed. Repeated exposure to cerium oxide resulted in significant accumulation of the particles in the (extra)pulmonary tissues. In addition, tissue clearance was shown to be slow, and, overall, insignificant amounts of cerium oxide were eliminated from the body at 48- to 72-h post-exposure. In conclusion, no clear effect of the primary particle size or surface area on pulmonary deposition and extrapulmonary tissue distribution could be demonstrated. This is most likely explained by similar aerodynamic diameter of the cerium oxide particles in air because of the formation of aggregates and irrespective possible differences in surface characteristics. The implications of the accumulation of cerium oxide particles for systemic toxicological effects after repeated chronic exposure via ambient air are significant and require further exploration.

TiO₂ nanoparticles induce dysfunction and activation of human endothelial cells

Nanoparticles can reach the blood and cause inflammation, suggesting that nanoparticles-endothelial cells interactions may be pathogenically relevant. We evaluated the effect of titanium dioxide nanoparticles (TiO₂) on proliferation, death, and responses related with inflammatory processes such as monocytic adhesion and expression of adhesion molecules (E- and P-selectins, ICAM-1, VCAM-1, and PECAM-1) and with inflammatory molecules (tissue factor, angiotensin-II, VEGF, and oxidized LDL receptor-1) on human umbilical vein endothelial cells (HUVEC). We also evaluated the production of reactive oxygen species, nitric oxide production, and NF-κB pathway activation. Aggregates of TiO₂ of 300 nm or smaller and individual nanoparticles internalized into HUVEC inhibited proliferation strongly and induced apoptotic and necrotic death starting at 5 μg/cm². Besides, TiO₂ induced activation of HUVEC through an increase in adhesion and in expression of adhesion molecules and other molecules involved with the inflammatory process. These effects were associated with oxidative stress and NF-κB pathway activation. In conclusion, TiO₂ induced HUVEC activation, inhibition of cell proliferation with increased cell death, and oxidative stress.

Nanoparticle delivery in infant lungs

The lung surface is an ideal pathway to the bloodstream for nanoparticle-based drug delivery. Thus far, research has focused on the lungs of adults, and little is known about nanoparticle behavior in the immature lungs of infants. Here, using nonlinear dynamical systems analysis and in vivo experimentation in developing animals, we show that nanoparticle deposition in postnatally developing lungs peaks at the end of bulk alveolation. This finding suggests a unique paradigm, consistent with the emerging theory that as alveoli form through secondary septation, alveolar flow becomes chaotic and chaotic mixing kicks in, significantly enhancing particle deposition. This finding has significant implications for the application of nanoparticle-based inhalation therapeutics in young children with immature lungs from birth to 2 y of age.

Type 1 pulmonary epithelial cells: a new compartment involved in the slow phase of particle clearance from alveoli

Whilst alveolar macrophages normally clear micron-sized particles from the respiratory units, nanoparticles might by-pass this mechanism and interact with alveolar epithelium. This letter discusses the possible role of alveolar epithelial type 1 cells in uptake and retention of nanoparticles within the alveolar septum. Accelerated apoptosis of nanoparticle-laden type 1 cells might trigger pro-inflammatory responses during apoptotic cell removal by macrophages. In the absence of clearance of apoptotic type 1 cells by this route, release of nanoparticles by dead type 1 cells and continued retention within the alveolar septum could lead to a slow process of nanoparticle removel from within the alveolar septum, rather than surface-only clearance. We suggest that this hypothesis warrants further research.

Emergency visits and hospital admissions in aged people living close to a gas-fired power plant

BACKGROUND

Combustion of natural gas for energy generation produces less pollutants than coke/oil. However, little is known about the short-term effect of pollution generated by gas-fired power plants on the health of elderly people.

METHODS

During three months, daily emergency visits/hospital admissions of subjects living within 3 km from a gas-fueled power plant were counted and related to ambient concentrations of nitrogen dioxide (NO(2)) and particulate matter of median aerometric diameter <10 μm (PM10). A generalized additive model served to correlate visits/hospital admissions to pollutants, controlling for meteorological confounders.

RESULTS

Mean air concentrations of PM10 and NO(2) were higher after-than before the start of operation of the plant, with the highest concentrations recorded within 1 km. Although pollutants were below the limits set by the European legislation, in elderly people there was a positive correlation between the number of emergency visits and daily air concentrations of PM10 and NO(2), as measured at 1 and 3 km from the plant. In subjects aged 70 years or more, the number of hospital admissions was positively correlated with PM10 levels measured within 3 km from the power plant, whereas in older subjects (≥80 year) it was also significantly linked with the lowest air concentration of PM10 (measured at 6 km from the plant).

DISCUSSION

Combustion of natural gas for energy generation produces a rise in air concentration of PM10 and NO(2) close to the plant, with a concentration-dependent increment of daily emergency visits and hospital admissions in elderly people, and with an age-dependent susceptibility.

Biokinetics of embedded surrogate radiological dispersal device material

The terrorist use of a radiological dispersal device (RDD) has been described as "not if, but when" (). Exposures from such an event could occur by a number of routes including inhalation, wound contamination, or embedded fragments. Several of the radionuclides thought to be potential RDD components are metals or ceramic material. The use of such material would increase the potential for wounds from embedded fragments of radioactive material. To date, most research in this area has focused on inhalation exposures, while the consequence of embedded fragment exposure has not been investigated. This study modified a previously used rodent model in order to determine the biokinetics of intramuscularly implanted nonradioactive surrogate RDD material. Cobalt, iridium, or strontium titanate was embedded into the gastrocnemius muscle of Sprague Dawley rats. The rats were euthanized at 1, 3, or 6 mo post-implantation. Tissue metal analysis showed that iridium did not solubilize from the implanted pellet, while cobalt and strontium did so rapidly. Cobalt was found in all tissues analyzed, but it was localized mainly to kidney and liver as well as being excreted in the urine. Strontium was found in lung, liver, and spleen, as well as being deposited in bone. However, the greatest strontium concentrations were found in the popliteal lymph nodes, the lymph nodes responsible for draining the area of the gastrocnemius. These results indicate that, depending upon the material, a variety of treatment strategies will be needed when dealing with embedded fragment wounds from a radiological dispersal device event.

Sub-Chronic Oral Exposure to Iridium (III) Chloride Hydrate in Female Wistar Rats: Distribution and Excretion of the Metal

Iridium tissue distribution and excretion in female Wistar rats following oral exposure to iridium (III) chloride hydrate in drinking water (from 1 to 1000 ng/ml) in a sub-chronic oral study were determined. Samples of urine, feces, blood and organs (kidneys, liver, lung, spleen and brain) were collected at the end of exposure. The most prominent fractions of iridium were retained in kidney and spleen; smaller amounts were found in lungs, liver and brain. Iridium brain levels were lower than those observed in other tissues but this finding can support the hypothesis of iridium capability to cross the blood brain barrier. The iridium kidney levels rose significantly with the administered dose. At the highest dose, important amounts of the metal were found in serum, urine and feces. Iridium was predominantly excreted via feces with a significant linear correlation with the ingested dose, which is likely due to low intestinal absorption of the metal. However, at the higher doses iridium was also eliminated through urine. These findings may be useful to help in the understanding of the adverse health effects, particularly on the immune system, of iridium dispersed in the environment as well as in identifying appropriate biological indices of iridium exposure.

Dynamic monitoring of metal oxide nanoparticle toxicity by label free impedance sensing

The increased use of nanoparticles in industrial and medical products is driving the need for accurate, high throughput in vitro testing procedures to screen new particles for potential toxicity. While approaches using standard viability assays have been widely used, there have been increased reports of the interactions of nanoparticles with their soluble labels or optical readouts which raise concerns over the potential generation of false positive results. Here, we describe the use of an impedance spectroscopy approach to provide real-time reagent free detection of toxicity for a panel of metal oxide nanoparticles (ZnO, CuO, and TiO(2)). Using this approach, we show how impedance measurements can be used to track nanoparticle toxicity over time with comparable IC(50) values to those of standard assays (ZnO-55 μg/mL, CuO-28 μg/mL) as well as being used to identify a critical 6 h period following exposure during which the nanoparticles trigger rapid cellular responses. Through targeted analysis during this response period and the use of a novel image analysis approach, we show how the ZnO and CuO nanoparticles trigger the active export of intracellular glutathione via an increase in the activity of the ATP dependent MRP/1 efflux pumps. The loss of glutathione leads to increased production of reactive oxygen species which after 2.5 h triggers the cells to enter apoptosis resulting in a dose dependent cytotoxic response. This targeted testing strategy provides comprehensive information beyond that achieved with standard toxicity assays and indicates the potential for cell-nanoparticle interactions that could occur following in vivo exposure.

The impact of intratracheally instilled carbon black on the cardiovascular system of rats: elevation of blood homocysteine and hyperactivity of platelets

Carbon black (CB) is an industrial chemical with high potential for human exposure. Although the relationship between exposure to particulate matter (PM) and cardiovascular disease is well documented, the risk of adverse cardiovascular effects attributed to CB particles has not been clearly characterized. This study was performed to (1) investigate the effects of CB on cardiovascular system and (2) identify the target tissue or potential biomarkers. Carbon black with a distinct particle size, N330 (ultrafine particle) and N990 (fine particle), was intratracheally instilled into rats at a doses of 1, 3, or 10 mg/kg. Measurements of thrombotic activity and determination of plasma homocysteine levels, cardiac functionality, and inflammatory responses were conducted at 24-h and 1-wk time points. Exposure to N330 accelerated platelet-dependent blood clotting at 10 mg/kg, the highest exposure tested. Unexpectedly, both N330 and N990 led to prolongation of activated partial thromboplastin time (aPTT), whereas these CB particles failed to affect prothrombin time (PT). N990 produced a significant elevation in the level of plasma homocysteine, a well-established etiological factor in cardiovascular diseases. Both N330 and N990 induced apparent inflammation in the lungs; however, both particles failed to initiate systemic inflammation. Neither CB particle produced observable cardiac symptoms as detected by electrocardiography. Taken together, data show CB exposure enhanced the cardiovascular risk by inducing hyperhomocysteinemia and platelet hyperactivity, although these effects may be variable depending on particle size and exposure duration. Homocysteine may be a potential biomarker for cardiovascular toxicity following CB exposure.

Determination of airborne nanoparticles from welding operations

The aim of this study is to assess the levels of airborne ultrafine particles emitted in welding processes (tungsten inert gas [TIG], metal active gas [MAG] of carbon steel, and friction stir welding [FSW] of aluminum) in terms of deposited area in pulmonary alveolar tract using a nanoparticle surface area monitor (NSAM) analyzer. The obtained results showed the dependence of process parameters on emitted ultrafine particles and demonstrated the presence of ultrafine particles compared to background levels. Data indicated that the process that resulted in the lowest levels of alveolar deposited surface area (ADSA) was FSW, followed by TIG and MAG. However, all tested processes resulted in significant concentrations of ultrafine particles being deposited in humans lungs of exposed workers.

Methods for understanding the interaction between nanoparticles and cells

A critical view of the current toxicological methods used in nanotechnology and their related techniques. Hereby, toxicological effects derived from the intracellular accumulation and uptake will be examined. Then advantages/disadvantages of these methods will be discussed. Additional analytical techniques necessary to implement the results will be reviewed.

Size distributions and exposure concentrations of nanoparticles associated with the emissions of oil mists from fastener manufacturing processes

The aims of the present study were set out to measure size distributions and estimate workers' exposure concentrations of oil mist nanoparticles in three selected workplaces of the forming, threading, and heat treating areas in a fastener manufacturing plant by using a modified electrical aerosol detector (MEAD). The results were further compared with those simultaneously obtained from a nanoparticle surface area monitor (NSAM) and a scanning mobility particle sizer (SMPS) for the validation purpose. Results show that oil mist nanoparticles in the three selected process areas were formed mainly through the evaporation and condensation processes. The measured size distributions of nanoparticles were consistently in the form of uni-modal. The estimated fraction of nanoparticles deposited on the alveolar (AV) region was consistently much higher than that on the head airway (HD) and tracheobronchial (TB) regions in both number and surface area concentration bases. However, a significant difference was found in the estimated fraction of nanoparticles deposited on each individual region while different exposure metrics were used. Comparable results were found between results obtained from both NSAM and MEAD. After normalization, no significant difference can be found between the results obtained from SMPS and MEAD. It is concluded that the obtained MEAD results are suitable for assessing oil mist nanoparticle exposures.

Toxicity of nanomaterials

Nanoscience has matured significantly during the last decade as it has transitioned from bench top science to applied technology. Presently, nanomaterials are used in a wide variety of commercial products such as electronic components, sports equipment, sun creams and biomedical applications. There are few studies of the long-term consequences of nanoparticles on human health, but governmental agencies, including the United States National Institute for Occupational Safety and Health and Japan's Ministry of Health, have recently raised the question of whether seemingly innocuous materials such as carbon-based nanotubes should be treated with the same caution afforded known carcinogens such as asbestos. Since nanomaterials are increasing a part of everyday consumer products, manufacturing processes, and medical products, it is imperative that both workers and end-users be protected from inhalation of potentially toxic NPs. It also suggests that NPs may need to be sequestered into products so that the NPs are not released into the atmosphere during the product's life or during recycling. Further, non-inhalation routes of NP absorption, including dermal and medical injectables, must be studied in order to understand possible toxic effects. Fewer studies to date have addressed whether the body can eventually eliminate nanomaterials to prevent particle build-up in tissues or organs. This critical review discusses the biophysicochemical properties of various nanomaterials with emphasis on currently available toxicology data and methodologies for evaluating nanoparticle toxicity (286 references).

Gold nanoparticles administration induces disarray of heart muscle, hemorrhagic, chronic inflammatory cells infiltrated by small lymphocytes, cytoplasmic vacuolization and congested and dilated blood vessels

Background

Despite significant research efforts on cancer therapy, diagnostics and imaging, many challenges remain unsolved. There are many unknown details regarding the interaction of nanoparticles (NPs) and biological systems. The structure and properties of gold nanoparticles (GNPs) make them useful for a wide array of biological applications. However, for the application of GNPs in therapy and drug delivery, knowledge regarding their bioaccumulation and associated local or systemic toxicity is necessary. Information on the biological fate of NPs, including distribution, accumulation, metabolism, and organ specific toxicity is still minimal. Studies specifically dealing with the toxicity of NPs are rare. The aim of the present study was to investigate the effects of intraperitoneal administration of GNPs on histological alterations of the heart tissue of rats in an attempt to identify and understand the toxicity and the potential role of GNPs as a therapeutic and diagnostic tool.

Methods

A total of 40 healthy male Wistar-Kyoto rats received 50 μl infusions of 10, 20 and 50 nm GNPs for 3 or 7 days. Animals were randomly divided into groups: 6 GNP-treated rats groups and one control group (NG). Groups 1, 2 and 3 received infusions of 50 μl GNPs of size 10 nm (3 or 7 days), 20 nm (3 or 7 days) and 50 nm (3 or 7 days), respectively.

Results

In comparison with the respective control rats, exposure to GNPs doses produced heart muscle disarray with a few scattered chronic inflammatory cells infiltrated by small lymphocytes, foci of hemorrhage with extravasation of red blood cells, some scattered cytoplasmic vacuolization and congested and dilated blood vessels. None of the above alterations were observed in the heart muscle of any member of the control group.

Conclusions

The alterations induced by intraperitoneal administration of GNPs were size-dependent, with smaller ones inducing greater affects, and were also related to the time exposure to GNPs. These alterations may indicate scattered cytoplasmic vacuolization, which may induce the toxicity effect through an inability to deal with the accumulated residues resulting from metabolic and structural disturbances caused by these NPs. These histological alterations were more prominent with 10 nm size particles than with the larger ones. The interaction of GNPs with proteins and various cell types should be considered as part of the toxicological evaluation. Additional experiments related to plasma, tissues cytokine, antioxidant defense mechanism, lipid peroxidation, histomorphologcal and ultrastructure will be performed to identify and understand the toxicity and the potential use of GNPs as therapeutic and diagnostic tools.

Aqueous synthesis and concentration-dependent dermal toxicity of TiO2 nanoparticles in Wistar rats

A number of dermal toxicological studies using TiO(2) nanoparticles exist which are based on the study of various animal models like mice, rabbits etc. However, a well-defined study is lacking on the dermal toxic effects of TiO(2) nanoparticles on rats, which are the appropriate model for systemic absorption study of nanoparticles. Furthermore, toxicity of TiO(2) nanoparticles varies widely depending upon the size, concentration, crystallinity, synthesis method etc. This study was conducted to synthesize TiO(2) nanoparticles of different sizes (∼15 to ∼30 nm) by aqueous method, thereby evaluating the concentration-dependent toxicological effects of the ∼20-nm sized nanoparticles on Wistar rats. Characterization of the particles was done by transmission electron microscope, dynamic light scattering instrument, X-ray diffractrometer, and ultraviolet spectrophotometer. The toxicity study was conducted for 14 days (acute), and it is observed that TiO(2) nanoparticles (∼20 nm) at a concentration of 42 mg/kg, when applied topically showed toxicity on rat skin at the biochemical level. However, the histopathological studies did not show any observable effects at tissue level. Our data suggest that well-crystallized spherical-shaped ∼20 nm anatase TiO(2) nanoparticles synthesized in aqueous medium can induce concentration-dependent biochemical alteration in rat skin during short-term exposure.

Zinc induces chemokine and inflammatory cytokine release from human promonocytes

Our previous studies found that zinc oxide (ZnO) particles induced expression of intercellular adhesion molecule-1 (ICAM-1) protein in vascular endothelial cells via NF-κB and that zinc ions dissolved from ZnO particles might play the major role in the process. This study aimed to determine if zinc ions could cause inflammatory responses in a human promonocytic leukemia cell line HL-CZ. Conditioned media from the zinc-treated HL-CZ cells induced ICAM-1 protein expression in human umbilical vein endothelial cells (HUVEC). Zinc treatment induced chemokine and inflammatory cytokine release from HL-CZ cells. Inhibition of NFκB activity by over-expression of IκBα in HL-CZ cells did not block the conditioned medium-induced ICAM-1 protein expression in HUVEC cells. Zinc treatment induced activation of multiple immune response-related transcription factors in HL-CZ cells. These results clearly show that zinc ions induce chemokine and inflammatory cytokine release from human promonocytes, accompanied with activation of multiple immune response-related transcription factors. Our in vitro evidence in the zinc-induced inflammatory responses of vascular cells provides a critical linkage between zinc exposure and pathogenesis of those inflammatory vascular diseases.

Maternal inhalation of surface-coated nanosized titanium dioxide (UV-Titan) in C57BL/6 mice: effects in prenatally exposed offspring on hepatic DNA damage and gene expression

We investigated effects of maternal pulmonary exposure to titanium dioxide (UV-Titan) on prenatally exposed offspring. Time-mated mice (C57BL/6BomTac) were inhalation exposed (1 h/day to 42 mg UV-Titan/m(3) aerosolised powder or filtered air) during gestation days (GDs) 8-18. We evaluated DNA strand breaks using the comet assay in bronchoalveolar lavage (BAL) cells and livers of the time-mated mice (5 and 26-27 days after inhalation exposure), and in livers of the offspring (post-natal days (PND) 2 and 22). We also analysed hepatic gene expression in newborns using DNA microarrays. UV-Titan exposure did not induce DNA strand breaks in time-mated mice or their offspring. Transcriptional profiling of newborn livers revealed changes in the gene expression related to the retinoic acid signalling pathway in the females, while gene expression in male offspring was unaffected. Changes may be a secondary response to maternal inflammation although no direct link was evident through gene expression analysis.

Exposure to gold nanoparticles produces cardiac tissue damage that depends on the size and duration of exposure

Background

Current research focuses on cancer therapy, diagnostics and imaging, although many challenges still need to be solved. However, for the application of gold nanoparticles (GNPs) in therapy and diagnostics it is necessary to know the bioaccumulation and local or systemic toxicity associated to them. The aim of the present study was to investigate the effects of intraperitoneal administration of GNPs on the histological alterations of the heart tissue of rats in an attempt to cover and understand the toxicity and the potential role of GNPs in the therapeutic and diagnostic applications.

Methods

Animals were randomly divided into 3 GNPs-treated rats groups and one control group (CG). The 10, 20 and 50 nm GNPs were administered intraperitonealy at the rate of 3 or 7 days as follows: Group 1: received infusion of 100 μl GNPs of size 10 nm for 3 or 7 days; Group 2: received infusion of 100 μl GNPs of size 20 nm for 3 or 7 days; Group 3: received infusion of 100 μl GNPs of size 50 nm for 3 or 7 days. Control group: received no GNPs.

Results

In comparison with the respective control rats, GNPs-treated rat received 100 μl of 10 and 20 nm particles for 3 days or 7 days demonstrating congested heart muscle with prominent dilated blood vessels, scattered and extravasations of red blood cells, focus of muscle hyalinosis, disturbed muscle fascicles, dense prominent focus of inflammatory cells infiltrate by small lymphocytes and few plasma cells while GNPs-treated rat received 100 μl of 50 nm particles for 3 or 7 days demonstrating benign normal looking heart muscle with normal muscle direction and fascicles, and very few scattered small lymphocytes.

Conclusions

The histological alterations induced by intraperitoneal administration of GNPs were size-dependent with smaller ones induced more affects and related with time exposure of GNPs. This study suggests that interaction of GNPs with proteins and various cell types might be evaluated as part of the toxicological assessment in addition to further experiments related to tissues antioxidant enzymes, oxidative parameters, lipid peroxidation, production of free radicals and/or ROS and cytokine, histomorphologcal and ultrastrucural will be performed to cover and understand the toxicity and the potential use of GNPs as therapeutic and diagnostic tool.

Development of a French epidemiological surveillance system of workers producing or handling engineered nanomaterials in the workplace

OBJECTIVE

Concern has been raised about the potential impact of nanomaterials exposure on human health, and France has decided to implement a timely epidemiological surveillance tool of workers likely to be exposed to engineered nanomaterials that could accompany the development of nanotechnologies.

METHODS

A comprehensive review of the toxicological and epidemiological literature has been conducted together with an exploratory study among French companies producing or handling nanoobjects.

RESULTS

A double surveillance system is proposed consisting of a prospective cohort survey and repeated cross-sectional studies. The aim of the cohort is (1) to monitor long-term health effects and (2) to allow of further research. Setting-up an exposure registry is the first planned step.

CONCLUSIONS

The protocol is about to be submitted to the French Government for approval and funding.

Short term inhalation toxicity of a liquid aerosol of CdS/Cd(OH)₂ core shell quantum dots in male Wistar rats

Colloidal quantum dots (QD) show great promise as fluorescent markers. The QD used in this study were obtained in aqueous medium rather than the widely used colloidal QD. Both methodologies used for the production of QD are associated with the presence of heavy metals such as cadmium (Cd). Here we investigate the short-term inhalation toxicity of water-soluble core-shell CdS/Cd(OH)₂ QD. Male Wistar rats were head-nose exposed for 6 h/day on 5 days at the technically maximum concentration (0.52 mg Cd/m³). Histological examination was performed directly after the last exposure. Additional rats were used for Cd organ burden determinations. Clinical parameters in blood, bronchoalveolar lavage fluid and lung tissue were determined 3 days after the last exposure. To analyze the reversibility or progression of effects, the examinations were performed again after a recovery period of 3 weeks. The results of the study indicate that CdS/Cd(OH)₂ QD caused local neutrophil inflammation in the lungs that partially regressed after the 3-week recovery period. There was no evidence that QD were translocated to the central nervous system nor that a systemic acute phase response occurred.

Respiratory effects of manufactured nanoparticles

Nanotechnology is the set of techniques used to engineer, characterize, and produce materials that have at least one dimension within the nanoscale. These nanomaterials, or nanoobjects, include nanoparticles and nanotubes. As dictated by the laws of quantum physics, a size within the nanoscale results in unique physicochemical properties and distinctive behaviors. Nanotechnology has a host of applications in fields ranging from cosmetology to the industry and medicine. The production and use of nanomaterials are expanding at a brisk pace. However, concerns are emerging about the potential health effects of nanoparticles in the short and long terms. These concerns are rooted in data on the harmful health effects of micrometric airborne particulate matter. Conceivably, these adverse effects might be amplified when the particles are within the nanoscale. This article is a nonexhaustive overview of current data on the penetration, deposition, translocation, and elimination of inhaled nanoparticles and on the respiratory effects of metallic nanoparticles (with special attention to titanium dioxide) and carbon nanotubes. Both in vivo and in vitro studies consistently found biological effects of nanoparticles on the respiratory system, including oxidative stress generation, proinflammatory and prothrombotic effects, pulmonary fibrosis and emphysema, and DNA damage. Improved knowledge of the potential biological effects of nanoparticles is needed to guide preventive strategies for the workplace and/or general population if needed.

A comparative transmission electron microscopy study of titanium dioxide and carbon black nanoparticles uptake in human lung epithelial and fibroblast cell lines

Several studies suggest that the biological responses induced by manufactured nanoparticles (MNPs) may be linked to their accumulation within cells. However, MNP internalisation has not yet been sufficiently characterised. Therefore, the aim of this study was to compare the intracellular uptake of three different MNPs: two made of carbon black (CB) and one made of titanium dioxide (TiO(2)), in 16HBE bronchial epithelial cells and MRC5 fibroblasts. Transmission electron microscopy was used to evaluate the intracellular accumulation. Different parameters were analysed following a time and dose-relationship: localisation of MNPs in cells, percentage of cells having accumulated MNPs, number of aggregated MNPs in cells, and the size of MNP aggregates in cells. The results showed that MNPs were widely and rapidly accumulated in 16HBE cells and MRC5 fibroblasts. Moreover, MNPs accumulated chiefly as aggregates in cytosolic vesicles and were absent from the mitochondria or nuclei. CB and TiO(2) MNPs had similar accumulation patterns. However, TiO(2) aggregates had a higher size than CB aggregates. Intracellular MNP accumulation was dissociated from cytotoxicity. These results suggest that cellular uptake of MNPs is a common phenomenon occurring in various cell types.

TiO2 nanoparticles induce insulin resistance in liver-derived cells both directly and via macrophage activation

Upon exposure, TiO(2) nanoparticles (NPs) have been recovered in internal organs such as the liver, and are proposed to cause cellular/organ dysfunction, particularly in the liver and lungs. We hypothesized that despite being considered "inert" as bulk material, TiO(2) NPs may impair insulin responses in liver-derived cells, either indirectly by inflammatory activation of macrophages, and/or by directly interfering with insulin signaling. Using qRT-PCR and conditioned medium (CM) approaches, we show that exposure to TiO(2) NPs activates macrophages' expression of TNF-α, IL-6, IL-8, IL-1α and IL-1β and the resulting CM induces insulin resistance in Fao cells. Furthermore, direct exposure of Fao cells to TiO(2) results in activation of the stress kinases JNK and p38MAP kinase, and in induction of insulin resistance at the signaling and metabolic levels. Collectively, our findings provide a proof-of-concept for the ability of man-made NPs to induce insulin resistance in liver-derived cells, an endocrine abnormality underlying some of the most common human diseases.

Exposure of pregnant mice to carbon black by intratracheal instillation: toxicogenomic effects in dams and offspring

Exposure to nanomaterials (NM) during sensitive developmental stages may predispose organisms to diseases later in life. However, direct translocation of NM from mother to fetus through the placenta is limited. The present study tests the hypothesis that pulmonary exposure to NM and NM-induced response, such as inflammation during gestation, leads to secondary effects in the fetus. Time-mated C57BL/6BomTac mice were exposed by intratracheal instillation to vehicle (Nanopure water) or one of three concentrations (2.75, 13.5 or 67 μg in 40 μl Nanopure water) of carbon black Printex 90 (CB) on gestational days 7, 10, 15 and 18, to final cumulative doses of 11, 54 or 268 μg/animal. Samples from a subset of male and female newborns were collected on postnatal day 2 (4 days after the last maternal exposure) and from dams 26 to 27 days post-exposure (post-weaning period). Histopathology, DNA microarrays, pathway-specific RT-PCR arrays, focussed RT-PCR, and tissue protein analysis were employed to characterize pulmonary response in dams exposed to CB during pregnancy. Hepatic gene expression in newborns was interpreted in light of the observed biological responses and gene expression changes arising in the lungs of dams following CB exposure. Although retention of CB particles was observed in dams from both the medium and the high dose groups, neutrophil-marked inflammation and altered expression of several cytokines and chemokines, both at the transcriptional and tissue protein levels, was significant only in the high dose group. Analysis of newborn livers by DNA microarrays revealed that female offspring were more sensitive to maternal exposure than male offspring. Cellular signalling, inflammation, cell cycle and lipid metabolism were among the biological pathways affected in female offspring. Males, however, responded with subtle changes in metabolism-related genes. Further investigation is required to determine the long-term health consequences of the gene expression changes in offspring and response to environmental stresses.

Effects of manufactured nanomaterials on fishes: a target organ and body systems physiology approach

Manufactured nanomaterials (NM) are already used in consumer products and exposure modelling predicts releases of ng to low µg l(-1) levels of NMs into surface waters. The exposure of aquatic ecosystems, and therefore fishes, to manufactured NMs is inevitable. This review uses a physiological approach to describe the known effects of NMs on the body systems of fishes and to identify the internal target organs, as well as outline aspects of colloid chemistry relevant to fish biology. The acute toxicity data, suggest that the lethal concentration for many NMs is in the mg l(-1) range, and a number of sublethal effects have been reported at concentrations from c. 100 µg to 1 mg l(-1). Exposure to NMs in the water column can cause respiratory toxicity involving altered ventilation, mucus secretion and gill pathology. This may not lead, however, to overt haematological disturbances in the short term. The internal target organs include the liver, spleen and haematopoietic system, kidney, gut and brain; with toxic effects involving oxidative stress, ionoregulatory disturbances and organ pathologies. Some pathology appears to be novel for NMs, such as vascular injury in the brain of rainbow trout Oncorhynchus mykiss with carbon nanotubes. A lack of analytical methods, however, has prevented the reporting of NM concentrations in fish tissues, and the precise uptake mechanisms across the gill or gut are yet to be elucidated. The few dietary exposure studies conducted show no effects on growth or food intake at 10-100 mg kg(-1) inclusions of NMs in the diet of O. mykiss, but there are biochemical disturbances. Early life stages are sensitive to NMs with reports of lethal toxicity and developmental defects. There are many data gaps, however, including how water quality alters physiological responses, effects on immunity and chronic exposure data at environmentally relevant concentrations. Overall, the data so far suggest that the manufactured NMs are not as toxic as some traditional chemicals (e.g. some dissolved metals) and the innovative, responsible, development of nanotechnology should continue, with potential benefits for aquaculture, fisheries and fish health diagnostics.

The effects of iridium on the renal function of female Wistar rats

Despite the widespread use of iridium (Ir) in catalytic converters for improved capacity for reducing carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NO(x)) emissions, there is a lack of studies that have assessed possible toxicological hazards of exposure to Ir. The present investigation indicates that female Wistar rats exposed to Ir in the drinking water for 90 days displayed renal toxicity based on the elevated urinary retinol binding protein (RBP) and albumin. The RBP was more sensitive to albumin, showing significant increases at 0.01 mg/L.

Exposure to silver nanoparticles induces oxidative stress and memory deficits in laboratory rats

Currently most of the applications of silver nanoparticles are in antibacterial/antifungal agents in medicine and biotechnology, textile engineering, water treatment and silver-based consumer products. However, the effects of silver nanoparticles on human body, especially on the central nervous system, are still unclear. To study the mechanisms underlying the effects of silverpoly(amidehydroxyurethane) coated silver nanoparticles on brain functions, we subjected male Wistar rats to chronic treatments with silver-29 nm (5 µg/kg and 10 µg/kg) and silver-23 nm (5 µg/kg and 10 µg/kg) nanoparticles for 7 days. We evaluated the effects of nanoparticles size and structure on rat memory function. Memory processes were studied by means of two cognitive tasks (Y-maze and radial arm-maze). Exposure to silver nanoparticles significantly decreased spontaneous alternation in the Y-maze task and working memory functions in the radial arm-maze task, suggesting that nanoparticles have effects on short-term memory. We found no effects on long-term memory, which we assessed by reference memory trials in the radial arm-maze task. We found that memory deficits were significantly correlated with oxidative stress generation only in the Y-maze task. Our findings suggest that silver nanoparticles may induce an impairment of memory functions by increasing oxidative stress in the brain. The use of silver nanoparticles for medical purposes therefore requires careful consideration, particularlyif it involves exposure of the human brain.

Toxicogenomics to improve comprehension of the mechanisms underlying responses of in vitro and in vivo systems to nanomaterials: a review

Engineered nanomaterials are commonly defined as materials with at least one dimension of 100 nanometers or less. Such materials typically possess nanostructure-dependent properties (e.g., chemical, mechanical, electrical, optical, magnetic, biological), which make them desiderable for commercial or medical application. However, these same properties may potentially lead to nanostructure-dependent biological activity that differs from and is not directly predicted by the bulk properties of the constitutive chemicals and compounds. Nanoparticles and nanomaterials can be on the same scale of living cells components, including proteins, nucleic acids, lipids and cellular organelles. When considering nanoparticles it must be asked how man-made nanostructures can interact with or influence biological systems. Carbon nanotubes (CNTs) are an example of carbon-based nanomaterial, which has won a huge spreading in nanotechnology. The incorporation of CNTs in living systems has raised many concerns because of their hydrophobicity and tendency to aggregate and accumulate into cells, organs, and tissues with dangerous effects. Applications of toxicogenomics to both investigative and predictive toxicology will contribute to the in-depth investigation of molecular mechanisms or the mode of nanomaterials action that is achieved by using conventional toxicological approaches. Parallel toxicogenomic technologies will promote a valuable platform for the development of biomarkers, in order to predict possible nanomaterial's toxicity. The potential of characteristic gene expression profiles ("fingerprint") of exposure or toxicological response to nanoparticles will be discussed in the review to enhance comprehension of the molecular mechanism of in vivo and in vitro system exposed to nanomaterials.

Factor XII activation is essential to sustain the procoagulant effects of particulate matter

BACKGROUND

Particulate matter (PM) is a key component of ambient air pollution and has been associated with an increased risk of thrombotic events and mortality. The underlying mechanisms remain unclear.

OBJECTIVES

 To study the mechanisms of PM-driven procoagulant activity in human plasma and to investigate mainly, the coagulation driven by ultrafine particles (UFPs; < 0.1 μm) in genetically modified mice.

METHODS

Thrombin generation in response to PM of different sizes was assessed in normal human platelet-poor plasma, as well as in plasmas deficient in the intrinsic pathway proteases factors XII (FXII) or XI (FXI). In addition, UFPs were intratracheally instilled in wild-type (WT) and FXII-deficient (FXII(-/-) ) mice and plasma thrombin generation was analyzed in plasma from treated mice at 4 and 20 h post-exposure.

RESULTS

In normal human plasma, thrombin generation was enhanced in the presence of PM, whereas PM-driven thrombin formation was completely abolished in FXII- and FXI-deficient plasma. UFPs induced a transient increase in tissue factor (TF)-driven thrombin formation at 4 h post-instillation in WT mice compared with saline instillation. Intratracheal instillation of UFPs resulted in a procoagulant response in WT mice plasma at 20 h, whereas it was entirely suppressed in FXII(-/-) mice.

CONCLUSIONS

 Overall, the data suggest that PM promotes its early procoagulant actions mostly through the TF-driven extrinsic pathway of coagulation, whereas PM-driven long lasting thrombogenic effects are predominantly mediated via formation of activated FXII. Hence, FXII-driven thrombin formation may be relevant to an enhanced thrombotic susceptibility upon chronic exposure to PM in humans.

¹¹¹Indium-labeled ultrafine carbon particles; a novel aerosol for pulmonary deposition and retention studies

Continuous environmental or occupational exposure to airborne particulate pollution is believed to be a major hazard for human health. A technique to characterize their deposition and clearance from the lungs is fundamental to understand the underlying mechanisms behind their negative health effects. In this work, we describe a method for production and follow up of ultrafine carbon particles labeled with radioactive ¹¹¹Indium (¹¹¹In). The physicochemical and biological properties of the aerosol are described in terms of particle size and concentration, agglomeration rate, chemical bonding stability, and human lung deposition and retention. Preliminary in vivo data from a healthy human pilot exposure and 1-week follow up of the aerosol is presented. More than 98% of the generated aerosol was labeled with Indium and with particle sizes log normally distributed around 79  nm count median diameter. The aerosol showed good generation reproducibility and chemical stability, about 5% leaching 7 days after generation. During human inhalation, the particles were deposited in the alveolar space, with no central airways involvement. Seven days after exposure, the cumulative activity retention was 95.3%. Activity leaching tests from blood and urine samples confirmed that the observed clearance was explained by unbound activity, suggesting that there was no significant elimination of ultrafine particles. Compared to previously presented methods based on Technegas, ¹¹¹In-labelled ultrafine carbon particles allow for extended follow-up assessments of particulate pollution retention in healthy and diseased lungs.

Pulmonary exposure to carbon black by inhalation or instillation in pregnant mice: effects on liver DNA strand breaks in dams and offspring

Effects of maternal pulmonary exposure to carbon black (Printex 90) on gestation, lactation and DNA strand breaks were evaluated. Time-mated C57BL/6BomTac mice were exposed by inhalation to 42 mg/m³ Printex 90 for 1 h/day on gestation days (GD) 8-18, or by four intratracheal instillations on GD 7, 10, 15 and 18, with total doses of 11, 54 and 268 (μg/animal. Dams were monitored until weaning and some offspring until adolescence. Inflammation was assessed in maternal bronchoalveolar lavage (BAL) 3-5 days after exposure, and at weaning. Levels of DNA strand breaks were assessed in maternal BAL cells and liver, and in offspring liver. Persistent lung inflammation was observed in exposed mothers. Inhalation exposure induced more DNA strand breaks in the liver of mothers and their offspring, whereas intratracheal instillation did not. Neither inhalation nor instillation affected gestation and lactation. Maternal inhalation exposure to Printex 90-induced liver DNA damage in the mothers and the in utero exposed offspring.

Comparative gene responses to collected ambient particles in vitro: endothelial responses

Epidemiologic studies associate exposure to ambient particulate matter (APM) with increased cardiovascular mortality. Since both pulmonary inflammation and systemic circulation of ultrafine particles are hypothesized as initiating cardiovascular effects, we examined responses of potential target cells in vitro. Human aortic endothelial cells (HAEC) were exposed to 10 μg/ml fine and ultrafine APM collected in an urban setting in summer 2006 or winter 2007 in the San Joaquin Valley, California. RNA isolated after 3 h was analyzed with high-density oligonucleotide arrays. Summer APM treatment affected genes involved in xenobiotic and oxidoreductase activity, transcription factors, and inflammatory responses in HAEC, while winter APM had a robust xenobiotic but lesser inflammatory response. Real-time polymerase chain reaction analysis confirmed that particulate matter (PM)-treated HAEC increased mRNA levels of xenobiotic response enzymes CYP1A1, ALDH1A3, and TIPARP and cellular stress response transcription factor ATF3. Inflammatory response genes included E-selectin, PTGS2, CXCL-2 (MIP-2α), and CCL-2 (MCP-1). Multiplex protein assays showed secretion of IL-6 and MCP-1 by HAEC. Since induction of CYP1A1 is mediated through the ligand-activated aryl hydrocarbon receptor (AhR), we demonstrated APM induced AhR nuclear translocation by immunofluorescence and Western blotting and activation of the AhR response element using a luciferase reporter construct. Inhibitor studies suggest differential influences of polycyclic aromatic hydrocarbon signaling, ROS-mediated responses and endotoxin alter stress and proinflammatory endothelial cell responses. Our findings demonstrate gene responses correlated with current concepts that systemic inflammation drives cardiovascular effects of particulate air pollution. We also demonstrate a unique pattern of gene responses related to xenobiotic metabolism in PM-exposed HAEC.

Diesel exhaust particulate--exposed macrophages cause marked endothelial cell activation

Exposure to air pollution containing diesel exhaust particulate (DEP) is linked to adverse cardiovascular events. This study tested the hypothesis that DEP not only causes direct endothelial cell injury, but also induces indirect endothelial cell activation via the release of soluble proinflammatory cytokines from macrophages. Human umbilical vein endothelial cells (HUVECs) and monocyte-derived macrophages (MDMs) were incubated with DEP (1-100 μg/ml; 24 h). Supernatants were analyzed for monocyte chemotactic protein (MCP)-1, IL6, IL8, and TNF-α. Indirect actions of DEP were investigated by incubating HUVECs with conditioned media from DEP-exposed MDMs in the presence and absence of the TNF-α inhibitor, etanercept. A modified Boyden chamber assay was used to determine whether HUVECs treated in this manner induced monocyte chemotaxis. Direct incubation with DEP induced a modest increase in MCP-1 concentration, but had no effect on IL-6 or IL-8 release from HUVECs. In contrast, direct treatment of MDMs with DEP had no effect on MCP-1, but elevated IL-8 and TNF-α concentrations. Incubation with conditioned media from DEP-exposed MDMs caused a dramatic amplification in MCP-1 and IL-6, but not IL-8, release from HUVECs. The potentiation of HUVEC activation was suppressed by TNF-α inhibition. MCP-1- and IL-6-containing HUVEC supernatants caused increased monocyte chemotaxis that was not inhibited by anti-MCP-1 antibodies. We conclude that DEP has only modest direct endothelial effects. In contrast, proinflammatory cytokines released from particle-laden MDMs appear to exacerbate endothelial activation after DEP exposure.

Chemical compositions and source identification of PM₂.₅ aerosols for estimation of a diesel source surrogate

Exposure to traffic-related pollution during childhood has been associated with asthma exacerbation, and asthma incidence. The objective of the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) is to determine if the development of allergic and respiratory disease is associated with exposure to diesel engine exhaust particles. A detailed receptor model analyses was undertaken by applying positive matrix factorization (PMF) and UNMIX receptor models to two PM₂.₅ data sets: one consisting of two carbon fractions and the other of eight temperature-resolved carbon fractions. Based on the source profiles resolved from the analyses, markers of traffic-related air pollution were estimated: the elemental carbon attributed to traffic (ECAT) and elemental carbon attributed to diesel vehicle emission (ECAD). Application of UNMIX to the two data sets generated four source factors: combustion related sulfate, traffic, metal processing and soil/crustal. The PMF application generated six source factors derived from analyzing two carbon fractions and seven factors from temperature-resolved eight carbon fractions. The source factors (with source contribution estimates by mass concentrations in parentheses) are: combustion sulfate (46.8%), vegetative burning (15.8%), secondary sulfate (12.9%), diesel vehicle emission (10.9%), metal processing (7.5%), gasoline vehicle emission (5.6%) and soil/crustal (0.7%). Diesel and gasoline vehicle emission sources were separated using eight temperature-resolved organic and elemental carbon fractions. Application of PMF to both datasets also differentiated the sulfate rich source from the vegetative burning source, which are combined in a single factor by UNMIX modeling. Calculated ECAT and ECAD values at different locations indicated that traffic source impacts depend on factors such as traffic volumes, meteorological parameters, and the mode of vehicle operation apart from the proximity of the sites to highways. The difference in ECAT and ECAD, however, was less than one standard deviation. Thus, a cost benefit consideration should be used when deciding on the benefits of an eight or two carbon approach.

Acute inhalation toxicity of cerium oxide nanoparticles in rats

The aim of the present study was to assess the acute toxic potential of cerium oxide nanoparticles (CeO(2) NPs) in rats when exposed through the head and nose inhalation route. The rats were exposed to CeO(2) NPs and the resultant effects if any, to cause cytotoxicity, oxidative stress and inflammation in the lungs were evaluated on a 24h, 48h and 14 day post exposure period. Our results showed a significant decrease in the cell viability, with the increase of lactate dehydogenase, total protein and alkaline phosphatase levels in the bronchoalveolar lavage fluid (BALF) of the exposed rats. Total leukocyte count and the percentage of neutrophils in BALF were elevated within 24h of post exposure. The concentrations of pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) were significantly increased in the BALF and in the blood throughout the observation period. The level of malondialdehyde was elevated with the decreased levels of intracellular reduced glutathione (GSH) in the lung after exposure. The alveolar macrophages (AMs) and neutrophils overloaded with phagocytosed CeO(2) NPs were observed along with non-phagocytosed free CeO(2) NPs that were deposited over the epithelial surfaces of the bronchi, bronchiole and alveolar regions of lungs within 24h of post exposure and were consistent throughout the observation period. A well distributed, multifocal pulmonary microgranulomas due to impairment of clearance mechanism leading to biopersistence of CeO(2) NPs for an extended period of time were observed at the end of the 14 day post exposure period. These results suggest that acute exposure of CeO(2) NPs through inhalation route may induce cytotoxicity via oxidative stress and may lead to a chronic inflammatory response.

Development of a PIXE analysis method for the determination of the biopersistence of SiC and TiC nanoparticles in rat lungs

With the advent of nanoparticles produced in high quantities and employed in products or processes, the need to evaluate their potential toxicological effects is necessary. For this purpose, biopersistence studies are needed to assess the possible effects of nanoparticles in parallel with a proper characterization. The insoluble character of many nanomaterials makes traditional chemical analytical methods unapplicable for the ex-vivo measurements of their concentration in organs. Ion beam-based techniques such as Particle-Induced X-ray Emission (PIXE) can solve this difficulty. We illustrate that by the measurement of biopersistence of SiC and TiC nanoparticles instilled in rats lungs and investigated over a 60-day time span. The results can be obtained within minutes and the limits of detection are within ppm levels.

Particle size-dependent and surface charge-dependent biodistribution of gold nanoparticles after intravenous administration

Gold nanoparticles (GNP) provide many opportunities in imaging, diagnostics, and therapies of nanomedicine. Hence, their biokinetics in the body are prerequisites for specific tailoring of nanomedicinal applications and for a comprehensive risk assessment. We administered (198)Au-radio-labelled monodisperse, negatively charged GNP of five different sizes (1.4, 5, 18, 80, and 200 nm) and 2.8 nm GNP with opposite surface charges by intravenous injection into rats. After 24h, the biodistribution of the GNP was quantitatively measured by gamma-spectrometry. The size and surface charge of GNP strongly determine the biodistribution. Most GNP accumulated in the liver increased from 50% of 1.4 nm GNP to >99% of 200 nm GNP. In contrast, there was little size-dependent accumulation of 18-200 nm GNP in most other organs. However, for GNP between 1.4 nm and 5 nm, the accumulation increased sharply with decreasing size; i.e. a linear increase with the volumetric specific surface area. The differently charged 2.8 nm GNP led to significantly different accumulations in several organs. We conclude that the alterations of accumulation in the various organs and tissues, depending on GNP size and surface charge, are mediated by dynamic protein binding and exchange. A better understanding of these mechanisms will improve drug delivery and dose estimates used in risk assessment.

Engineered nanomaterials: exposures, hazards, and risk prevention

Nanotechnology presents the possibility of revolutionizing many aspects of our lives. People in many settings (academic, small and large industrial, and the general public in industrialized nations) are either developing or using engineered nanomaterials (ENMs) or ENM-containing products. However, our understanding of the occupational, health and safety aspects of ENMs is still in its formative stage. A survey of the literature indicates the available information is incomplete, many of the early findings have not been independently verified, and some may have been over-interpreted. This review describes ENMs briefly, their application, the ENM workforce, the major routes of human exposure, some examples of uptake and adverse effects, what little has been reported on occupational exposure assessment, and approaches to minimize exposure and health hazards. These latter approaches include engineering controls such as fume hoods and personal protective equipment. Results showing the effectiveness - or lack thereof - of some of these controls are also included. This review is presented in the context of the Risk Assessment/Risk Management framework, as a paradigm to systematically work through issues regarding human health hazards of ENMs. Examples are discussed of current knowledge of nanoscale materials for each component of the Risk Assessment/Risk Management framework. Given the notable lack of information, current recommendations to minimize exposure and hazards are largely based on common sense, knowledge by analogy to ultrafine material toxicity, and general health and safety recommendations. This review may serve as an overview for health and safety personnel, management, and ENM workers to establish and maintain a safe work environment. Small start-up companies and research institutions with limited personnel or expertise in nanotechnology health and safety issues may find this review particularly useful.