Artificial Lung Fluid Research Articles

Enhanced Gastric/Lung Arsenic Bioaccessibility from Lignite Fly Ashes: Comparing Bioaccessibility Rates with Multiple Environmental Matrices.

Inorganic arsenic (As), a carcinogenic element to humans, is among the most dangerous and flammable substances that coal-burning plants could release. When coal is burned, large portions of arsenic are captured on fly-ash (FA) particles, but it could also contribute significantly to stack emissions of fine fly-ash particles. The aim of this study was to evaluate the oral and respiratory bioaccessibility of arsenic in lignite fly-ash (LFA) samples, and their contribution to total As exposure. Arsenic bioaccessibility fractions via ingestion and inhalation showed significant differences, suggesting the presence of highly soluble As-bearing phases in the studied LFA samples. The bioaccessible As fractions (BAF%) in the simulated gastric fluids (UBM protocol, ISO 17924:2018) showed a range of 45-73%, while the pulmonary bioaccessibility rates in the simulated lung fluid (artificial lung fluid (ALF)) exhibited significantly enhanced levels ranging from 86% to 95%. The obtained arsenic bioaccessibility rates were compared with previous data for multiple environmental matrices such as soil and dust-related materials, revealing that LFA exhibited significantly higher bioaccessibility (%) for the inhalation pathway.

Biotransformation of graphene oxide within lung fluids could intensify its synergistic biotoxicity effect with cadmium by inhibiting cellular efflux of cadmium

Graphene oxide (GO) has been widely studied and applied in numerous industrial fields and biomedical fields for its excellent physical and chemical properties. Along with the production and applications of GO persist increasing, the environmental health and safety risk (EHS) of GO has been widely studied. However, previous studies almost focused on the biotoxicity of pristine GO under a relatively high exposure dose, without considering its transformation process within environmental and biological mediums. Meanwhile, its secondary toxicity or synergistic effects have not been taken seriously. Here, two different kinds of artificial lung fluids were adopted to incubate pristine GO to mimic the biotransformation process of GO in the lung fluids. And, we explored that biotransformation within the artificial lung fluids could significantly change the physicochemical properties of GO and could enhance its biotoxicity. To reveal the synergistic effects of GO and toxic metal ions, we uncovered that GO could enhance the intracellular content of metal ions by inhibiting the efflux function of ATP binding cassette (ABC) transporters which are distributed on the cellular membrane, and artificial lung fluids incubation of GO could enhance this synergistic effect. Finally, toxic metal ions induced a series of toxic reactions through oxidative stress response and promoted cell death. Moreover, consistent with the results of in vitro experiments, the lungs of mice exposed to GOs combined with Cd exhibited significant inflammation and oxidative stress compared with Cd treatment alone, and it was more remarkable within the mice which were treated with bio-transformed GOs. In summary, this study explored the impact and mechanism of biotransformation of GO in the lung fluids on the synergistic and secondary effects between GO and metal ions.

Evaluating the inhalation bioaccessibility of traffic-impacted particulate matter-bound PAHs in a road tunnel by simulated lung fluids

Polycyclic aromatic hydrocarbons (PAHs) are the most highly concerned pollutants bound on traffic-impacted particulate matter (TIPM). The inhaled TIPM-bound PAHs risk has attracted much attention, whereas the inhalation bioaccessibility, a method to refine the exposure risk assessment, has not yet been extensively introduced in the exposure risk assessment. Thus, in vitro assays using artificial lung fluids including artificial lysosomal fluid (ALF), Gamble's solution (GS), and modified GS (MGS) were conducted to assess the inhalation bioaccessibility of USEPA 16 PAHs in TIPM collected from an expressway tunnel, the influence factors of PAHs' inhalation bioaccessibility were explored, and the exposure risk of TIPM-bound PAHs was estimated based on inhalation bioaccessibility. Results showed that the average PAHs concentrations were 30.5 ± 12.9 ng/m3, 36.2 ± 5.19 ng/m3, and 39.9 ± 4.31 ng/m3 in the tunnel inlet PM2.5, TSP, and tunnel center PM2.5, respectively. Phe, Flt, Pyr, Nap, Chr, BbF, and BkF were found as the dominant species in TSP and PM2.5, indicating a dominant contribution of PAHs from diesel-fueled vehicular emissions. The bioaccessible fractions measured for different PAH species in tunnel PM2.5 and TSP were highly variable, which can be attributed to PAHs' physicochemical properties, size, and carbonaceous materials of TIPM. The addition of Tenax into SLF as an “adsorption sink” can greatly increase PAHs' inhalation bioaccessibility, but DPPC has a limited effect on tunnel PM-bound PAHs' bioaccessibility. The incremental lifetime carcinogenic risk (ILCR) of tunnel inlet PM2.5-bound PAHs evaluated according to their total mass concentration exceeded the threshold (1.0 × 10−6) set by the USEPA, whereas the ILCRs estimated based on the inhalation bioaccessibility were far below the threshold. Hence, it is vitally important to take into consideration of pollutant's bioaccessibility to refine health risk assessment.

The underlying mode of action for lung tumors in a tiered approach to the assessment of inhaled cobalt compounds

A mode of action (MOA) for cobalt substances based on the “International Programme on Chemical Safety Conceptual Framework for Evaluating a MOA for Chemical Carcinogenesis” is presented. The data recorded therein were generated in a tiered testing program described in the preceding papers of this special issue, as well as data from the public domain. The following parameters were included in the evaluation: solubility of cobalt substances in artificial lung fluids (bioelution), in vitro biomarkers for cytotoxicity, reactive oxygen species and hypoxia mimicry, inhalation toxicity following acute exposure and repeated dose inhalation effects. Two distinct groups of cobalt substances emerged: substances inducing all effects across the MOA form one group, associated with the adverse outcome of lung cancer in rodents upon chronic exposure. Another group of cobalt substances induces no or very limited effects in the in vitro and acute testing. Higher tier testing with a representative of this group, tricobalt tetraoxide, showed a response resembling rat lung overload following exposure to high concentrations of poorly soluble particles. Based on the fundamental differences in the lower tier toxicological profile, cobalt substances with an unknown hazard profile can be assigned to either group based on lower tier testing alone.

A tiered approach to investigate the inhalation toxicity of cobalt substances. Tier 1: Bioaccessibility testing

Bioelution tests measure in vitro the release of metal ion in surrogate physiological conditions (termed “bioaccessibility”) and estimate the potential bioavailability relative to that of a known reference metal substance. Bioaccessibility of cobalt ion from twelve cobalt substances was tested in three artificial lung fluids (interstitial, alveolar and lysosomal) to gather information about the substances’ fate and potential bioavailability in the respiratory tract after inhalation. The results can be used as one line of evidence to support grouping and read-across for substances lacking in vivo data, and where in vivo testing is not readily justifiable. Strong differences were observed in the dissolution behaviour of the substances in the different fluids, with the cobalt substances generally being less soluble in neutral pH fluids and more soluble in the acidic pH fluid. The resulting database, presented with its strengths and limitations, was used to support the formulation of an initial grouping of these cobalt substances into three categories.

A tiered approach to investigate the inhalation toxicity of cobalt substances. Tier 2a: Grouping cobalt compounds based on their capacity to stabilize HIF-1α in human alveolar epithelial cells in vitro

Excessive inhalation of cobalt (Co) dust can have harmful effects on the respiratory tract, yet all cobalt substances do not have the same potential for inducing toxicity. The prevalent hypothesis is that the potential of Co substances to release Co2+ ions in the organism and in cells drives their toxicity profile. Here, we explored the possibility of grouping Co substances for predicting inhalation toxicity based on in vitro data using the stabilization of hypoxia-inducible factor (HIF)-1α as a read out for intracellular Co ion content. We evaluated the potential of 11 inorganic Co compounds and two Co metal powder samples to stabilize intracellular HIF-1α in alveolar epithelial cells (A549) after 24 h exposure to 250–1000 μM Co equivalents. Cytotoxic activity of the substances was assessed in parallel after 72 h at the same doses. Two groups were identified: (1) substances with high intracellular bioavailability (n=9), causing cytotoxicity and stabilizing HIF-1α and (2) substances with low intracellular bioavailability (n = 4), and not inducing these effects. This study provides a link between screening-level data (solubility in artificial lung fluids, Tier 1) and hypothesized biological key events.

Preparation of Curcumin Solid Lipid Nanoparticles Loaded with Flower-Shaped Lactose for Lung Inhalation and Preliminary Evaluation of Cytotoxicity In Vitro.

The purpose of this study is to design a flower-shaped lactose loaded curcumin solid lipid nanoparticles dry powder inhaler and characterize it to improve the solubility and dissolution rate of curcumin in lung. Curcumin solid lipid nanoparticles (Cur-SLNs) were prepared by solvent evaporation method, and then they were micronized by freeze-drying technology. Finally, Cur-SLN micropowder obtained by freeze-drying was mixed with flower-shaped lactose (FL) at a ratio of 2 : 1 and then passed through a 200-mesh sieve to obtain Cur-SLN-FL powder. Tween-80 was selected as the surfactant to inhibit the aggregation of drug solid lipid nanoparticles. Under the optimum conditions, the solid lipid nanoparticles (SLN) were relatively spherical, with an average particle size of 14.7 nm, narrow distribution, Zeta potential of −22.5 mV, encapsulation efficiency of 90.21%, and drug loading of 8.56%. According to the particle size, PI, Zeta potential, drug loading (LC%), encapsulation efficiency (EE%), morphology, and in vitro release characteristics, the prescription of solid lipid nanoparticles was screened. Dry powder inhaler (DPI) was characterized by differential scanning calorimetry, scanning electron microscopy, particle size, density, and in vitro release performance. Its cytotoxicity to mouse fibroblasts (L929) and human normal lung epithelial cells (BEAS-2B) in vitro was investigated, and its safety for pulmonary inhalation was preliminarily determined. FTIR analysis shows that the micronized Cur-SLN-FL has the same chemical structure as FL. FTIR and DSC analysis confirmed that the characteristic absorption peak of curcumin was not found in Cur-SLN-FL, showing similar structure to SLN and FL. In addition, curcumin was coated in solid lipid nanoparticles to make powder mist, which increased its drug loading, kept its aerodynamic particle size (4.03 ± 0.40) μm, and significantly improved its drug release performance in artificial lung fluid. In vitro cytotoxicity test results confirmed that Cur-SLN-FL was less toxic to BEAS-2B cells than L929 cells. Therefore, curcumin was prepared into solid lipid nanoparticles by emulsion evaporation-low temperature solidification method and then micronized and mixed with FL to prepare curcumin solid lipid nanoparticle powder mist loaded with flower-shaped lactose. The process is simple and feasible, and it has better safety performance for lung cells, which is expected to become a safe and effective delivery system for pulmonary inhalation drugs.

Atomic Absorption Spectrometry Methods to Access the Metal Solubility of Aerosols in Artificial Lung Fluid

Recent studies to quantify the health risks that fine particulate matter with an aerodynamic less than 2.5 µm (PM2.5) pose use invitro approaches. One of these approaches is to incubate PM2.5 in artificial lysosomal fluid for a given period at body temperature. These body fluids used have a high ionic strength and as such can be challenging samples to analyze with atomic spectroscopy techniques. As PM2.5 is a primary health hazard because it is tiny enough to penetrate deep into the lungs and could, in addition, dissolve in the lung fluid it is important to quantify elements of toxic and/or carcinogenic concerns, reliably and accurately. Sophisticated instrumentation and expensive pre-treatment of challenging samples are not always available, especially in developing countries. To evaluate the applicability of graphite furnace atomic absorption spectrometry (GFAAS) without Zeeman correction capability to detect trace quantities of heavy metals leached from PM2.5 on to artificial lung fluid, univariate and multivariate approaches have been used for optimization purposes. The limits of quantification, LOQ, obtained by the optimized method were: 2 µg L-1 (Cu), 3 µg L-1 (Cr), 1 µg L-1 (Mn), and 10 µg L-1 (Pb). The addition/recovery experiments had a mean accuracy of: (Cu) 99 ± 7%; 110 ± 8% (Cr); 95 ± 9% (Mn), and 96 ± 11% (Pb). The average soluble fractions of PM2.5 incubated in artificial lysosomal fluid (ALF) for 1 h were: 1.2 ± 0.01 ng m-3 Cu, 0.4 ± 0.01 ng m-3 Cr, 0.6 ± 0.01 ng m-3 Mn, and 4.8 ± 0.03 ng m-3 Pb. Using historical elemental averages of PM2.5 in Curitiba (Cu 3.3 ng m-3, Cr 2.1 ng m-3, Mn 6.1 ng m-3, Pb 21 ng m-3), the percentage bioaccessibility were determined to be Cu 38%, Cr 20%, Mn 10%, and Pb 23%. The elemental values of the atmospheric soluble fraction of Cu, Cr, and Mn were below the inhalation risk concentrations. However, for Pb, the atmospheric soluble fraction exceeded the inhalation unit risk of 0.012 ng m-3. This robust and straightforward GF AAS method is pivotal for low and middle-income countries were most air pollution adverse effects occur and established lower-cost technologies are likely unavailable.

Single platform spin-spin nuclear relaxation time (1H NMR) based technique for assessing dissolution and agglomeration of CuO nanoparticles

This study proposes a single platform tool to capture aggregation and dissolution behaviour of copper oxide nanoparticles in acellular conditions using spin-spin nuclear relaxation time data. The spin-spin nuclear relaxation time gathered from pulsed 1H Nuclear magnetic resonance (NMR) spectroscopy can be mathematically translated to the wetted surface area of nanoparticles. The effect of suspension media (artificial lung fluid, algal growth media, and 1 mM NaNO3) and CuO nanoparticle concentrations (500 mg/L, 250 mg/L, and 100 mg/L) on dissolution, hydrodynamic size, and wetted surface area were determined for seven days. The data obtained through 1H NMR spectroscopy was compared with conventional techniques used for measuring dissolution (atomic absorption spectroscopy) and agglomeration (Centrifugal particle sedimentation, Dynamic light scattering). Dissolution experiments showed CuO nanoparticles to have a range of dissolution from 6% to 90%, based on the nature of media. Hydrodynamic size measurements captured the increment in the size of nanoparticles (73% increase) due to aggregation, and reduction in the size of the nanoparticles (88% decline) due to dissolution. Similarly, the temporal variation in the spin-spin nuclear relaxation time of the nanoparticles ranging from 0.25% to 72% detected dissolution and agglomeration of nanoparticles in three different media conditions. The temporal variation in the wetted surface area with respect to concentration and suspension media ranged from 2 m2/g to 380 m2/g. We have determined experimentally the complex interplay between size reduction-wetted surface area-dissolution of nanoparticles and how it evolves over 7 days period for CuO nanoparticles.

Distribution and potential health impacts of microplastics and microrubbers in air and street dusts from Asaluyeh County, Iran

While the distribution and effects of microplastics (MPs) have been extensively studied in aquatic systems, there exits little information on their occurrence in the terrestrial environment and their potential impacts on human health. In the present study, street dust and suspended dust were collected from the city and county of Asaluyeh, Iran. Samples were characterized by various microscopic techniques (fluorescence, polarized light, SEM) in order to quantify and classify MPs and microrubbers (MRs) in the urban and industrial environments that are potentially ingestible or inhalable by humans. In < 5-mm street dust retrieved from 15 sites, there were an average of 900 MPs and 250 MRs per 15 g of sample, with MPs exhibiting a range of colours and sizes (<100 to >1000 μm). Most street dust samples were dominated by spherical and film-like particles and MRs largely made up of different sizes of black fragments and fibrous particulates. Airborne dust collected daily over an eight-day period at two locations revealed the ubiquity of fibrous MPs of sizes ranging from about 2 μm to 100 μm and an abundance of about 1 per m−3. These samples contained small MR fragments whose precise characteristics were more difficult to define. Based on the median concentrations in street dust, estimates of acute exposure through ingestion are about 5 and 15 MP d−1 and 2 and 7 MR d−1 for construction workers and young children, respectively. Quantities of inhalable particulates were more difficult to define but the potential toxicity of MPs and MRs taken in by this route was evaluated from assays performed using particulates isolated from street dusts in the presence of an artificial lung fluid. Both types of particle exhibited oxidative potential, with MPs displaying consumptions of different antioxidants that were comparable with corresponding values for a reference urban particulate dust but lower than those for London ambient particulate matter. Thus, MPs and MRs contribute towards the health impacts of urban and industrial dusts but their precise roles remain unclear and warrant further study.

Bioaccessibility and health risk of trace elements in fine particulate matter in different simulated body fluids

Health risk assessment of trace elements (TrElems) in fine particulate matter (PM2.5) has been studied based on the total element concentrations or more recently on the phosphate buffered saline (PBS)-soluble concentrations. However, behaviors of the TrElems released from PM2.5 change considerably as the interacting media change. In this study, the bioaccessibility of particulate-bound TrElems (V, Mn, Co, Ni, Cu, As, Cd and Pb) were investigated using three kinds of simulated body fluids, artificial lung fluid (ALF), artificial sweat (AS), and artificial gastric juice (AGJ), comparing with the commonly used PBS. Many TrElems, especially Pb, showed lower solubility in PBS than that in other fluids. Cu, Mn, V and As were observed to be the most soluble TrElems in all simulated body fluids. Carcinogenic and non-carcinogenic effects were evaluated using ALF, AS and AGJ-soluble fractions (representing the corresponding exposure routes: inhalation, dermal contact and ingestion) according to the United States Environmental Protection Agency (USEPA) human health risk assessment model. The carcinogenic risks of As and Pb were higher than 1 × 10−6 (the acceptable level) for both adults and children. High hazard quotient (HQ) values for As and Pb were also observed for children, indicating a potential non-carcinogenic risk posed by these toxic elements. Our results demonstrated that the health risks of particulate-bound TrElems might be misjudged if using the PBS-soluble or total element contents alone.

In Vitro Inhalation Bioaccessibility of Phthalate Esters and Alternative Plasticizers Present in Indoor Dust Using Artificial Lung Fluids

Phthalate esters (PEs) are used as plasticizers in consumer products. Their low migration stability has resulted in the classification of PEs as major indoor contaminants. Because of PE’s ubiquity and adverse health effects on humans and especially children, non-phthalate alternative plasticizers have been introduced into the market. This is the first study of in vitro inhalation bioaccessibility of PEs (e.g., DMP, DEP, and DEHP) and alternative plasticizers (e.g., DEHT and DINCH) via indoor dust to assess inhalation as an alternative route of exposure. Two artificial lung fluids were used, mimicking two distinctively different pulmonary environments: (1) artificial lysosomal fluid (ALF, pH 4.5) representing the intracellular acidic lung fluid inhaled particle contact after phagocytosis by alveolar macrophages and (2) Gamble’s solution (pH 7.4), the extracellular healthy fluid for deep lung deposition of dust. DMP and DEP were highly bioaccessible (>75%), whereas highly hydrophobic compounds such as DEHP,...

Application of the ICRP respiratory tract model to estimate pulmonary retention of industrially sampled indium-containing dusts

Inhalation of indium-containing dusts is associated with the development of indium lung disease. Workers may be exposed to several different chemical forms of indium; however, their lung dosimetry is not fully understood. We characterized the physicochemical properties and measured the lung dissolution kinetics of eight indium-containing dusts. Indium dissolution rates in artificial lung fluids spanned two orders of magnitude. We used the International Commission on Radiological Protection (ICRP) human respiratory model (HRTM) to estimate pulmonary indium deposition, retention and biokinetic clearance to blood. For a two-year (median workforce tenure at facility) exposure to respirable-sized particles of the indium materials, modeled indium clearance (>99.99% removed) from the alveolar-interstitial compartment was slow for all dusts; salts would clear in 4 years, sintered indium–tin oxide (ITO) would clear in 9 years, and indium oxide would require 48 years. For this scenario, the ICRP HRTM predicted that indium translocated to blood would be present in that compartment for 3.5–18 years after cessation of exposure, depending on the chemical form. For a 40-year exposure (working lifetime), clearance from the alveolar–interstitial compartment would require 5, 10 and 60 years for indium salts, sintered ITO and indium oxide, respectively and indium would be present in blood for 5–53 years after exposure. Consideration of differences in chemical forms of indium, dissolution rates, alveolar clearance and residence time in blood should be included in exposure assessment and epidemiological studies that rely on measures of total indium in air or blood to derive risk estimates.

Does carbonation of steel slag particles reduce their toxicity? An in vitro approach

Mineral carbonation can stabilize industrial residues and, in the steel industry, may contribute to simultaneously valorize CO2 emissions and slag. We hypothesized that, by restricting the leaching of metals of toxicological concern such as Cr and V, carbonation can suppress the toxicity of these materials. The cytotoxic activity (WST1 assay) of slag dusts collected from a stainless and a Linz-Donawitz (LD) steel plant, before and after carbonation, was examined in J774 macrophages. The release of Cr, V, Fe, Mn and Ni was measured after incubation in artificial lung fluids mimicking the extracellular and phagolysosomal milieu to which particles are confronted after inhalation.LD slag had the higher Fe, Mn and V content, and was more cytotoxic than stainless steel slag. The cytotoxic activity of LD but not of stainless dusts was reduced after carbonation. The cytotoxic activity of the dusts toward J774 macrophages necessitated a direct contact with the cells and was reduced in the presence of inhibitors of phagocytosis (cytochalasin D) or phagolysosome acidification (bafilomycin), pointing to a key role of metallic constituents released in phagolysosomes. This in vitro study supports a limited reduction of the cytotoxic activity of LD, but not of stainless, steel dusts upon carbonation.

Methodological aspects of in vitro assessment of bio-accessible risk element pool in urban particulate matter.

In vitro tests simulating the elements release from inhaled urban particulate matter (PM) with artificial lung fluids (Gamble's and Hatch's solutions) and simulated gastric and pancreatic solutions were applied for an estimation of hazardous element (As, Cd, Cr, Hg, Mn, Ni, Pb and Zn) bio-accessibility in this material. An inductively coupled plasma optical emission spectrometry (ICP-OES) and an inductively coupled plasma mass spectrometry (ICP-MS) were employed for the element determination in extracted solutions. The effect of the extraction agent used, extraction time, sample-to-extractant ratio, sample particle size and/or individual element properties was evaluated. Different patterns of individual elements were observed, comparing Hatch's solution vs. simulated gastric and pancreatic solutions. For Hatch's solution, a decreasing sample-to-extractant ratio in a PM size fraction of <0.063mm resulted in increasing leached contents of all investigated elements. As already proved for other operationally defined extraction procedures, the extractable element portions are affected not only by their mobility in the particulate matter itself but also by the sample preparation procedure. Results of simulated in vitro tests can be applied for the reasonable estimation of bio-accessible element portions in the particulate matter as an alternative method, which, consequently, initiates further examinations including potential in vivo assessments.

The interaction between manganese exposure and alcohol on neurobehavioral outcomes in welders

Neurobehavioral functions were studied in 137 welders exposed to the geometric mean (GM) air concentration of 214μg/m3 (range 1–3230) of manganese (Mn) based on the individual mean from two days of air sampling. Only 22μg/m3 (GM) was soluble in the artificial lung fluid Hatch solution. The welders were compared to 137 referents (turner/fitters) recruited from the same plants. The GM concentrations of Mn in whole blood (B-Mn) and urine (U-Mn) were 12.8μg/L and 0.36μg/g creatinine versus 8.0μg/L and 0.07μg/g creatinine in the referents. Alcohol consumption was assessed by measuring carbohydrate deficient transferrin in serum (sCDT). The welders had poorer performance than the referents on the Grooved Pegboard, Finger Tapping, Simple Reaction Time (SRT) and possibly the Maximum Frequency tests. They also reported more subjective symptoms. Welders with sCDT above the upper reference limit had substantially poorer performances on the Grooved Pegboard test, Finger Tapping test and SRT than welders with sCDT below this level. No effect of high sCDT was observed in the referents, indicating an interaction between high sCDT and exposure to Mn for these tests. Self-reported alcohol consumption had no impact on these neurobehavioral test results. A statistically significant difference in the SRT and Grooved Pegboard test results remained after excluding all subjects with sCDT above the normal level, but the difference in test scores between the groups was smaller. These welders also reported more subjective symptoms than the referents. The results suggest that sCDT should be measured in neurobehavioral studies of occupationally Mn exposed populations for a more precise estimation of high alcohol consumption.

Characterisation and modelling of mercury speciation in urban air affected by gold mining - assessment of bioavailability

The growing global concern over the release of mercury to the environment has prompted specific inventories that quantify mercury emissions from various sources. Investigations of atmospheric mercury have been mostly done on gaseous species. Although, to assess human expose to mercury, especially in urban areas, the inhalable dust should be included in a study. The Witwatersrand Basin in South Africa is one of the most important gold mining regions in the world. Mercury (Hg), which occurs in gold-bearing ores, was also used for gold recoveries in previous centuries (19th and early 20th century) and presently in illegal artisanal mining. The consequences of these mining activities were the release of Hg to the environment, mainly due to AMD from tailings dumps which are presently reprocessed. The city of Johannesburg is a multimillion population exposed strongly to industrial pollution. The aim of this study was to determine the magnitude of mercury pollution in this urban area and assess its bioavailability. The gaseous samples were collected by trapping mercury on various gold traps. Dust samples were collected from a ground and on inhalation levels (1–2 m above a ground). They were later separated into different fractions by micro sieving. Bioavailability of mercury in inhalable dust (25 μm) was tested by leaching collected samples with artificial lung fluid (ALF, pH 4.5), Gray’s solution (pH 7.4) and water. The leaching conditions were selected to mimic lungs environment (incubator at 30°C, time 24 hrs, rotation of samples 150 rpm). Total concentrations of mercury in dust fractions were also determined after microwave digestion. The results showed extremely high concentration levels of mercury in air and dust in industrial areas. Especially high levels were found around presently reprocessed old gold tailings dumps, up to 900 000 μgl–1 . The levels dropped significantly in CBD area but still showing elevated concentrations up to 10 μgl−1 . They depend strongly on prevailing wind directions, dry and wet seasons, and day time. Leaching experiments showed that the Gray’s solution extracts more mercury from the dust followed by ALF and much lower by water. This suggests that most of the mercury inhaled with dust will be extracted in the deep interstitial parts of the lungs. In the upper region of lungs extraction will occur to a lesser extent.

Comparison of the extraction efficiencies of different leaching agents for reliable assessment of bio-accessible trace metal fractions in airborne particulate matter

In present study, an in-vitro physiologically based extraction test has been applied for extraction of bio-accessible trace metal fractions in airborne particulate matter (APM) samples collected from different urban sites in Austria and Pakistan using the leaching agents H2O, sodium chloride, ammonium acetate, ammonium citrate, synthetic gastric juice and artificial lung fluids. Obtained extracts were then measured using an ETV-ICP-OES procedure which allowed highly sensitive measurement of dissolved analytes even in the presence of leaching agents. Derived results indicated that the investigated leaching agents extract different amounts of trace metals. In general, leaching agents with organic nature yielded comparatively greater extractable and thus bio-accessible trace metal fractions to that of simple solvents like H2O or aqueous NaCl solution. With water, only 26.3±4.0% of Cd was found to be bio-accessible whereas 88.4±24.8 of Cd was obtained as bio-accessible fraction with the use of synthetic gastric juice. The concentrations of bio-accessible metal fractions varied from 0.4 ng m−3 (Cd) to 714 ng m−3 (Zn) and 0.3 ng m−3 (Cd) to 190 ng m−3 (Zn) for PM10 samples collected from Karachi (Pakistan) and Graz (Austria) respectively.

Beryllium Metal I. Experimental Results on Acute Oral Toxicity, Local Skin and Eye Effects, and Genotoxicity

The toxicity of soluble metal compounds is often different from that of the parent metal. Since no reliable data on acute toxicity, local effects, and mutagenicity of beryllium metal have ever been generated, beryllium metal powder was tested according to the respective Organisation for Economical Co-Operation and Development (OECD) guidelines. Acute oral toxicity of beryllium metal was investigated in rats and local effects on skin and eye in rabbits. Skin-sensitizing properties were investigated in guinea pigs (maximization method). Basic knowledge about systemic bioavailability is important for the design of genotoxicity tests on poorly soluble substances. Therefore, it was necessary to experimentally compare the capacities of beryllium chloride and beryllium metal to form ions under simulated human lung conditions. Solubility of beryllium metal in artificial lung fluid was low, while solubility in artificial lysosomal fluid was moderate. Beryllium chloride dissolution kinetics were largely different, and thus, metal extracts were used in the in vitro genotoxicity tests. Genotoxicity was investigated in vitro in a bacterial reverse mutagenicity assay, a mammalian cell gene mutation assay, a mammalian cell chromosome aberration assay, and an unscheduled DNA synthesis (UDS) assay. In addition, cell transformation was tested in a Syrian hamster embryo cell assay, and potential inhibition of DNA repair was tested by modification of the UDS assay. Beryllium metal was found not to be mutagenic or clastogenic based on the experimental in vitro results. Furthermore, treatment with beryllium metal extracts did not induce DNA repair synthesis, indicative of no DNA-damaging potential of beryllium metal. A cell-transforming potential and a tendency to inhibit DNA repair when the cell is severely damaged by an external stimulus were observed. Beryllium metal was also found not to be a skin or eye irritant, not to be a skin sensitizer, and not to have relevant acute oral toxic properties.

Persistence of tungsten oxide particle/fiber mixtures in artificial human lung fluids.

BackgroundDuring the manufacture of tungsten metal for non-sag wire, tungsten oxide powders are produced as intermediates and can be in the form of tungsten trioxide (WO3) or tungsten blue oxides (TBOs). TBOs contain fiber-shaped tungsten sub-oxide particles of respirable or thoracic size. The aim of this research was to investigate whether fiber-containing TBOs had prolonged biodurability in artificial lung fluids compared to tungsten metal or WO3 and therefore potentially could pose a greater inhalation hazard.MethodsDissolution of tungsten metal, WO3, one fiber-free TBO (WO2.98), and three fiber-containing TBO (WO2.81, WO2.66, and WO2.51) powders were measured for the material as-received, dispersed, and mixed with metallic cobalt. Solubility was evaluated using artificial airway epithelial lining fluid (SUF) and macrophage phagolysosomal simulant fluid (PSF).ResultsDissolution rates of tungsten compounds were one to four orders of magnitude slower in PSF compared to SUF. The state of the fiber-containing TBOs did not influence their dissolution in either SUF or PSF. In SUF, fiber-containing WO2.66 and WO2.51 dissolved more slowly than tungsten metal or WO3. In PSF, all three fiber-containing TBOs dissolved more slowly than tungsten metal.ConclusionsFiber-containing TBO powders dissolved more slowly than tungsten metal and WO3 powders in SUF and more slowly than tungsten metal in PSF. Existing pulmonary toxicological information on tungsten compounds indicates potential for pulmonary irritation and possibly fibrosis. Additional research is needed to fully understand the hazard potential of TBOs.