In vitro studies of copper release from powder particles in synthetic biological media

Experimental factors influencing the bioaccessibility and the oxidative potential of transition metals from welding fumes

Inhalation of welding fumes (WFs) containing high levels of transition metals (Cr, Cu, Fe, Mn, Ni…) is associated with numerous health effects including oxidative stress. However, the measurements of the oxidative potential (OP) and bioaccessibility of WF transition metals depend on several physicochemical parameters and may be subject to several experimental artifacts. In this work, we investigated the influence of the experimental conditions that may affect the bioaccessibility of transition metals and their OP on stainless-steel WF extracts. WFs were produced using a generation bench and sampled on filters. The soluble fraction of the metals was analysed. Two different extraction fluids mimicking physiological pulmonary conditions were studied: phosphate buffer and Hatch's solution. Three extraction times were tested to determine the optimal time for a significant OPDTT using the dithiothreitol (DTT) method. The storage conditions of WFs after filter sampling such as duration, temperature and atmospheric conditions were investigated. The results indicate that experimental conditions can significantly affect the OPDTT and metal bioaccessibility analyses. Cr, Cu and Ni show higher solubility in Hatch's solution than in the phosphate buffer. Mn is highly sensitive to DTT and shows close solubility in the two fluids. An extraction time of 0.5 h in phosphate buffer allows a better sensitivity to OPDTT, probably by limiting complexations, interactions between metals and precipitation. Storage time and temperature can influence the physical or chemical evolution of the WFs, which can affect their OPDTT and Mn solubility. However, storage under N2(g) limits these changes. On-line measurements of OPDTT could provide an alternative to filter sampling to overcome these artifacts.

Chemical and toxicological studies on black crust formed over historical monuments as a probable health hazard

Studies to date have mostly investigated environmental factors responsible for deterioration of historical monuments. Black crusts formed on historical monuments are considered as factor for deterioration of structures or as an indicator of environmental status of the surrounding area. Black crust formed on historical monuments has never been investigated as a health hazard. Herein, for the first time, we performed in vitro and in vivo toxicology studies of black crust formed on three culturally-rich historical monuments (Rang Ghar, Kareng Ghar, and Talatal Ghar) of the Indian subcontinent to test their toxicological effect. Black crust suspension in ultrapure water was found not to be considerably toxic to the cells upon direct short-term exposure. However, the sub-acute nasal exposure of the black crust suspension in Swiss albino mice produced lung-specific pathologies and mortality. Additionally, structural formation of the black crust along with the speciation of potentially hazardous elements (PHEs), polyaromatic hydrocarbon (PAHs), and other metals were investigated. Overall, these results indicate the potential of black crust deposited on historical monuments as health hazard owing to the atmospheric pollution of the surroundings. However, it may be noted that black crust and its components have very low possibility of health implication unless they are disturbed without proper care.

Assessment of Be-7, Pb-210 and Po-210 Activities in Airborne Particulate Matter Over Istanbul, Türkiye

Airborne particulate matter is one of the air pollutants which can have detrimental health effects in the human body. Radionuclides adsorb onto air particles and make their way to humans primarily through inhalation. Naturally-occurring radionuclides, 210Pb and 210Po, are of notable health concern due to their relatively elevated ingestion and inhalation doses. In the current study, activity concentrations of 7Be, 210Pb and 210Po were determined in air particulate matter (PM). PM2.5 was collected on the European side, while PM10 was collected on the Anatolian side of Istanbul. Be-7, 210Pb and 210Po activities were found to be 5.17 ± 2.35, 0.96 ± 0.42; 0.25 ± 0.14 mBq m- 3 in Anatolian side, respectively. Be-7, 210Pb and 210Po activities were found to be 3.81 ± 2.27, 0.62 ± 0.29, 0.29 ± 0.26, mBq m- 3 in European side, respectively. The ratio of 210Po/210Pb was found to be higher (0.47 ± 0.31 for PM2.5 and 0.34 ± 0.27 for PM10) than the global average of 0.1. This result can be explained by the fact that Po is more volatile than Pb and enhanced in the air by the combustion process. Inhalation dose rates of 210Pb and 210Po due to PM10 exposure were calculated to be 7.70 ± 3.30 and 4.05 ± 2.31 µSv year- 1, respectively. Pb-210 bioaccessibility was assessed by the extraction of the particles in simulated lung fluids. Approximately 24.8% of inhaled 210Pb was estimated to be bioaccessible. This study suggests that 210Po and 210Pb activities are partially enhanced in the air particles in Istanbul and should be regularly monitored.

Potential release and bioaccessibility of metal/loids from mine wastes deposited in historical abandoned sulfide mines

This study deals with the potential release of metal/loids from sulfide mine wastes upon weathering and the health risks associated with their accidental ingestion. To address this, a complete chemical and mineralogical characterization of a variety of sulfide mine wastes was performed alongside a determination of metal/loid bioaccessibility through leaching tests simulating human digestive and lung fluids. The mine wastes consisted predominantly of Fe (35-55% of Fe₂O₃) and exhibited high concentrations of trace metalloids such as As (382-4310 mg/kg), Pb (205-15,974 mg/kg), Cu (78-1083 mg/kg), Zn (274-1863 mg/kg), or Sb (520-1816 mg/kg). Most wastes with high concentrations of soluble compounds are considered hazardous according to the European regulations due to the exceedance of threshold values for As, Pb, Cr, Cu, Sb, sulfates, and Zn determined by standardized tests. In general terms, the absorption of waste-hosted metals through both digestive and respiratory routes was low compared to the total metal contents of the wastes, with values below 8% of the total concentration in wastes for most metal/loids including Cu, Zn, As, Cd, Tl, or U. However, some metals exhibited a significantly higher absorption potential, especially through the respiratory route, reaching values of up to 17% for Cr and 75% for Pb, highlighting the strong bioaccessibility of Pb in certain sulfide wastes. Despite the high metal/loid concentrations observed in the studied wastes, a health risk assessment indicated that some non-carcinogenic effects could be observed in children only following the accidental digestion of Pb.

Dissolution Behaviour of Metal-Oxide Nanomaterials in Various Biological Media

Toxicological effects of metal-oxide-engineered nanomaterials (ENMs) are closely related to their distinct physical-chemical properties, especially solubility and surface reactivity. The present study used five metal-oxide ENMs (ZnO, MnO₂, CeO₂, Al₂O₃, and Fe₂O₃) to investigate how various biologically relevant media influenced dissolution behaviour. In both water and cell culture medium (DMEM), the metal-oxide ENMs were more soluble than their bulk analogues, with the exception that bulk-MnO₂ was slightly more soluble in water than nano-MnO₂ and Fe₂O₃ displayed negligible solubility across all tested media (regardless of particle size). Lowering the initial concentration (10 mg/L vs. 100 mg/L) significantly increased the relative solubility (% of total concentration) of nano-ZnO and nano-MnO₂ in both water and DMEM. Nano-Al₂O₃ and nano-CeO₂ were impacted differently by the two media (significantly higher % solubility at 10 mg/L in DMEM vs. water). Further evaluation of simulated interstitial lung fluid (Gamble's solution) and phagolysosomal simulant fluid (PSF) showed that the selection of aqueous media significantly affected agglomeration and dissolution behaviour. The solubility of all investigated ENMs was significantly higher in DMEM (pH = 7.4) compared to Gamble's (pH 7.4), attributable to the presence of amino acids and proteins in DMEM. All ENMs showed low solubility in Gamble's (pH = 7.4) compared with PSF (pH = 4.5), attributable to the difference in pH. These observations are relevant to nanotoxicology as increased nanomaterial solubility also affects toxicity. The results demonstrated that, for the purpose of grouping and read-across efforts, the dissolution behaviour of metal-oxide ENMs should be evaluated using aqueous media representative of the exposure pathway being considered.

Optical properties, molecular characterizations, and oxidative potentials of different polarity levels of water-soluble organic matters in winter PM2.5 in six China's megacities

Humic-like substances (HULIS) accounted for a great fraction of water-soluble organic matter (WSOM) in PM_2.5, which efficiently absorb ultraviolet (UV) radiation and pose climate and health impacts. In this study, the molecular structure, optical properties, and oxidative potential (OP) of acid- and neutral-HULIS (denoted as HULIS-a, and HULIS-n, respectively), and high-polarity WSOM (HP-WSOM) were investigated in winter PM_2.5 collected at six China's megacities. For both carbon levels and optical absorption coefficients (b_{abs_365}), HULIS-a/HULIS-n/HP-WSOM showed significant spatial differences. For each city, the carbon levels and b_{abs_365} follow a similar order of HULIS-n > HULIS-a > HP-WSOM. Besides, the b_{abs_365} of HULIS-n and HULIS-a showed the same order of Harbin > Beijing ≈ Wuhan > Xi'an > Guangzhou > Chengdu, while HP-WSOM exhibited an order of Wuhan > Chengdu > Xi'an > Harbin > Beijing > Guangzhou. Both HULIS-a and HULIS-n were abundant in aromatic and aliphatic compounds, whereas HP-WSOM was dominated by a carboxylic acid group. The OP (in unit of nmol H₂O₂ μg^-1C) followed the order of HP-WSOM > HULIS-a > HULIS-n in all the cities. The OPs of HULIS-a, HULIS-n, and HP-WSOM in Harbin and Beijing were much higher than those of other cities, attributing to the high contribution from biomass burning. Highly positive correlations between reactive oxygen species (ROS) of HULIS-a and MAE₃₆₅ were obtained in Chengdu, Wuhan, and Harbin, but ROS of HULIS-n had stronger correlation with MAE₃₆₅ in Harbin, Chengdu, and Xi'an.

Time course of pulmonary inflammation and trace element biodistribution during and after sub-acute inhalation exposure to copper oxide nanoparticles in a murine model

Background

It has been shown that copper oxide nanoparticles (CuO NPs) induce pulmonary toxicity after acute or sub-acute inhalation exposures. However, little is known about the biodistribution and elimination kinetics of inhaled CuO NPs from the respiratory tract. The purposes of this study were to observe the kinetics of pulmonary inflammation during and after CuO NP sub-acute inhalation exposure and to investigate copper (Cu) biodistribution and clearance rate from the exposure site and homeostasis of selected trace elements in secondary organs of BALB/c mice.

Results

Sub-acute inhalation exposure to CuO NPs led to pulmonary inflammation represented by increases in lactate dehydrogenase, total cell counts, neutrophils, macrophages, inflammatory cytokines, iron levels in bronchoalveolar lavage (BAL) fluid, and lung weight changes. Dosimetry analysis in lung tissues and BAL fluid showed Cu concentration increased steadily during exposure and gradually declined after exposure. Cu elimination from the lung showed first-order kinetics with a half-life of 6.5 days. Total Cu levels were significantly increased in whole blood and heart indicating that inhaled Cu could be translocated into the bloodstream and heart tissue, and potentially have adverse effects on the kidneys and spleen as there were significant changes in the weights of these organs; increase in the kidneys and decrease in the spleen. Furthermore, concentrations of selenium in kidneys and iron in spleen were decreased, pointing to disruption of trace element homeostasis.

Conclusions

Sub-acute inhalation exposure of CuO NPs induced pulmonary inflammation, which was correlated to Cu concentrations in the lungs and started to resolve once exposure ended. Dosimetry analysis showed that Cu in the lungs was translocated into the bloodstream and heart tissue. Secondary organs affected by CuO NPs exposure were kidneys and spleen as they showed the disruption of trace element homeostasis and organ weight changes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00480-z.

Size-dependent in vitro inhalation bioaccessibility of PAHs and O/N PAHs - Implications to inhalation risk assessment

Size segregated samples (<0.49, 0.49-0.95, 0.95-1.5, 1.5-3.0, 3.0-7.2 and > 7.2 μm) of atmospheric particulate matter (APM) were collected at a traffic site in the urban agglomeration of Thessaloniki, northern Greece, during the cold and the warm period of 2020. The solvent-extractable organic matter was analyzed for selected organic contaminants including polycyclic aromatic hydrocarbons (PAHs), and their nitro- and oxy-derivarives (NPAHs and OPAHs, respectively). Mean concentrations of ∑₁₆PAHs, ∑₆NPAHs and ∑₁₀OPAHs associated to total suspended particles (TSP) were 18 ng m^-3, 0.2 ng m^-3 and 0.9 ng m^-3, respectively, in the cold period exhibiting significant decrease (6.4, 0.2 and 0.09 ng m^-3, respectively) in the warm period. The major amount of all compounds was found to be associated with the alveolar particle size fraction <0.49 μm. The inhalation bioaccessibility of PAHs and O/N PAHs was measured in vitro using two simulated lung fluids (SLFs), the Gamble's solution (GS) and the artificial lysosomal fluid (ALF). With both SLFs, the derived bioaccessible fractions (BAFs) followed the order PAHs > OPAHs > NPAHs. Although no clear dependence of bioaccessibility on particle size was obtained, increased bioaccessibility of PAHs and PAH derivatives in coarse particles (>7.2 μm) was evident. Bioaccessibility was found to be strongly related to the logK_OW and the water solubility of individual compounds hindering limited mobilization of the most hydrophobic and less water-soluble compounds from APM to SLFs. The lifetime cancer risk due to inhalation exposure to bioaccessible PAHs, NPAHs and OPAHs was estimated and compared to those calculated from the particulate concentrations of organic contaminants.

Assessment of dermal absorption of beryllium and copper contained in temple tips of eyeglasses

Dermal exposure to hazardous substances such as chemicals, toxics, metallic items and other contaminants may present substantial danger for health. Beryllium (Be) is a hazardous metal, especially when inhaled and/or in direct contact with the skin, associated with chronic beryllium disease (CBD) and Be sensitization (BeS). The objective of this study was to investigate the percutaneous penetration of beryllium and copper contained in metallic items as eyeglass temple tips (specifically BrushCAST® Copper Beryllium Casting Alloys containing Be 0.35 < 2.85%; Cu 95.3-98.7%), using Franz diffusion cells. This work demonstrated that the total skin absorption of Cu was higher (8.86%) compared to Be (4.89%), which was expected based on the high percentage of Cu contained in the eyeglass temple tips. However, Be accumulated significantly in the epidermis and dermis (up to 0.461 µg/cm²) and, to a lesser extent, in the stratum corneum (up to 0.130 µg/cm²) with a flux of permeation of 3.52 ± 4.5 µg/cm²/hour and lag time of 2.3 ± 1.3 h, after cutaneous exposure of temple tip into 1.0 mL artificial sweat for 24 h. Our study highlights the importance of avoiding the use of Be alloys in items following long-term skin contact.

Oral and inhalation bioaccessibility of potentially toxic elements in household dust from former Hg mining district, Idrija, Slovenia

One of the main sources of potential chronic exposure to potentially toxic elements is household dust, especially in an environment with known point sources of PTE pollution. The literature review clearly shows that the total concentrations of an element in the environment do not provide information to predict its bioavailability. The aim of the present study was to evaluate the oral and inhalation bioaccessibility of PTE present in household dust in the small town of Idrija, the site of the former mercury mine. Unified bioaccessibility method was used to assess oral bioaccessibility of PTE in the stomach and intestine, while inhalation bioaccessibility was assessed by extraction of household dust samples with two synthetic extraction solutions-Gamble's solution (GS) and artificial lysosomal fluid (ALF). A low bioaccessibility of mercury was observed in all synthetic solutions (less than 3%). The highest bioaccessibility of PTE was observed in ALF solution, especially for Zn, Pb and Cd. Only a slightly lower bioaccessibility of these three elements was also observed in the stomach, while the bioaccessibility of other elements in the gastric phase was less than 40%. In general, the bioaccessibility of all elements decreased in the intestine. With the exception of Cr, the lowest bioaccessibility of the elements was observed in GS. Daily ingestion and inhalation doses of PTE from household dust were calculated and their values were below the available recommended or tolerable daily intakes of PTE from food according to the European Food Safety Authority.

Metal(loid) bioaccessibility of atmospheric particulate matter from mine tailings at Zimapan, Mexico

Metal(loid)s are contaminants of concern emitted as particulate matter (PM) from several pollution sources. The objective was to characterize potential exposure from local airborne metal(loid)s in a community in proximity to mine tailings. Air samples were collected weekly at five sites around the municipal mine tailings using two Hi-volume samplers for simultaneously collecting PM₁₀ and PM_2.5. Total suspended particulates (TSP), concentrations, speciation, and bioaccessibility of metal(loid)s were quantified. The size and form of particles were determined by scanning electron microscopy. The concentration of TSP (μg m^-3) in the airborne samples ranged from 21.2 to 64.6 for PM_2.5 and 23.6 to 80.1 for PM₁₀. The profiles of analyzed quasi-total metal(loid) concentration from all sampling sites were similar between these aerosols PM sizes except at site 2 for Cd, at site 3 for Cu, and site 4 for Zn. The order of quasi-total metal(loid) concentration, in the airborne samples for both PM sizes, was As > Zn > Fe > Pb > Cu > Mn > Cd. As speciation included As-sulfite, As(III)-O, and As(V)-O with less concentration of As(III)-O in both PM sizes. Bioaccessible metal(loid) concentrations were very high and represented a great percentage from the quasi-total airborne concentrations, for instance, 10% and 37% for Pb and 8% and 6% for As in pulmonary and gastric bioaccessible concentrations, respectively. Knowing the toxic effects of these pollutants, there is an urgent need to establish environmental regulation of bioaccessible pollutant concentrations from PM dislodged from uncovered metal(loid) mine tailings affecting not only nearby human populations but also possible long-distance ecosystem transport.

Inhalation bioaccessibility and health risk assessment of flame retardants in indoor dust from Vietnamese e-waste-dismantling workshops

Although bioaccessibility testing is applied worldwide for appropriate chemical risk assessment, few studies have focused on the bioaccessibility of flame retardants (FRs), especially inhalation exposure. This study assessed inhalation exposure to FRs in indoor dust by workers at e-waste-dismantling workshops in northern Vietnam, by using modified simulated epithelial lung fluid (SELF) and artificial lysosomal fluid (ALF). The average mass concentrations of FRs were 130,000 ng/g for workplace dust (n = 3), 140,000 ng/g for floor dust (n = 3), and 74,000 ng/g for settled dust (n = 2), whereas the average bioaccessible concentrations of FRs were 1900, 1400, and 270 ng/g in the SELF condition and 2600, 770, and 490 ng/g in the ALF condition, respectively. Results clearly indicate that the bioaccessible concentrations of FRs are markedly lower than their mass concentrations. Tris(2-chloroethyl) phosphate (TCEP, ~19%), tris(2-chloroisopropyl) phosphate (TCIPP, ~35%), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP, ~22%) showed comparably high bioaccessibility in both SELF and ALF conditions. In contrast, the bioaccessibility of tetrabromobisphenol A (TBBPA, ~20%) was high in the SELF condition, but not in the ALF condition. With regard to the test compounds' physicochemical properties, the inhalation bioaccessibility of FRs in both conditions increased as molecular weight or octanol-water partition coefficient decreased, and it decreased as water solubility decreased. Health risk assessment clearly indicated that the hazard quotient of FRs via inhalation exposure for workers in the e-waste-dismantling workshops was less than 1, suggesting that the inhalation exposure to FRs during indoor dismantling of e-waste at this site was negligible based on the current methodology of non-cancer health risk assessment used in this study.

Understanding how methodological aspects affect the release of trace metal(loid)s from urban dust in inhalation bioaccessibility tests

The bioaccessibility of metal(loid)s in ambient particulate matter (PM) has been recently used to represent the risk of inhalation exposure. Nevertheless, different methodological factors affect the bioaccessibility values; among these, the type and composition of surrogate biological fluids and the liquid to solid ratio have been revealed to be the most important. To better understand how these methodological aspects affect the bioaccessibility, a reference material corresponding to urban dust (SRM1648a) was contacted with synthetic biological fluids commonly used in the literature representing surrogate fluids that may interact with fine (Gamble's solutions, artificial lysosomal fluid (ALF)) and coarse particles (gastric fluid), for liquid to solid (L/S) ratios ranging from 500 to 20,000. Visual MINTEQ 3.1. was used to enhance the discussion on how the solubility of metals in the leaching solution depends on the composition of the simulated fluids and the speciation of metals. The results obtained indicate that a small change in the composition of Gamble's solution (the presence of glycine) may increase significantly the bioaccessibility at a L/S ratio of 5,000. The highest bioaccessibility of most of the studied metal(loid)s at a L/S ratio of 5,000 was found for ALF fluid. The study of the effect of the L/S ratio showed that metal(loid)s bioaccessibility in Gamble's fluid increased logarithmically with increasing L/S ratio, while it remained practically constant in ALF and gastric fluid. This different behavior is explained assuming that the leaching of metal(loid)s in Gamble's solution is solubility-controlled, while in ALF and gastric fluid is availability-controlled.

Bioaccessiblity and exposure assessment of PM2.5- and PM10-bound rare earth elements in Oil City, Northeast China

In this study, an in vitro method was used to simulate lung fluids [Artificial lysosomal fluid (ALF) and Gamble's solution (GS)] to assess how the bioaccessibility of rare earth elements (REEs) in airborne particulate matter (PM) affects human health. Airborne PM samples (PM₁₀ and PM_2.5) were collected in Daqing in Northeast China. The bioaccessible proportions determined for REEs in PM₁₀ and PM_2.5 had high variability, which can be attributable to the heterogenic feature of airborne PM and its components, as well as sampling time. Overall, the bioaccessiblity of the REEs in the airborne PM samples was time-dependent. The bioaccessiblity of the REEs varied in PM with different sizes, and it was an order of magnitude higher in ALF than in GS. During both heavy and light pollution, the bioaccessiblity of the REEs in PM_2.5 was higher than in PM₁₀ after 24 h of ALF extraction, whereas bioaccessiblity of the REEs in GS followed the opposite trend. The REEs associated with airborne PM had much greater bioaccessiblity as the exposure time increased. The results of this study emphasize the necessity of conducting bioaccessibility experiments with field samples for the proper evaluation of human health risks.

Interaction of industrial smelting soot particles with pulmonary surfactant: Pulmonary toxicity of heavy metal-rich particles

Inhalable particles can influence the interfacial behavior of pulmonary surfactant (PS) resulting in various pulmonary diseases. However, the effects of actually airborne particles on the interfacial behavior of PS and its role in the alteration for soluble metal fraction in particles are entirely unexplored. Herein, we investigated the interaction of PS extracted from porcine lungs with smelting soot fine particles as a model of inhaled heavy metal-rich particles. Our results showed that the phase behavior and foamability of PS were obviously altered in the presence of smelting soot fine particles. In addition, the soluble heavy metals in smelting soot fine particles notably increased in the presence of PS as compared to that of saline solution. Further experiments conducted by adding PS's major components (dipalmitoylphosphatidylcholine, DPPC; bovine serum albumin, BSA) demonstrated that comparison of DPPC, adsorbed BSA is beneficial for the dissolution of heavy metals in smelting soot fine particles. Dynamic light scattering experiments verified that the well dispersion of smelting soot fine particles in the presence of BSA may be responsible for the higher solubility of heavy metals. These findings indicate that PS's interfacial behavior change and PS-enhanced solubilization release of metal components may increase the potentially pulmonary risk in the exposure of airborne fine particles enriched with heavy metals.

Impact of Endocytosis and Lysosomal Acidification on the Toxicity of Copper Oxide Nano- and Microsized Particles: Uptake and Gene Expression Related to Oxidative Stress and the DNA Damage Response

The toxicity of the copper oxide nanoparticles (CuO NP) has been attributed to the so-called "Trojan horse"-type mechanism, relying on the particle uptake and extensive intracellular release of copper ions, due to acidic pH in the lysosomes. Nevertheless, a clear distinction between extra- and intracellular-mediated effects is still missing. Therefore, the impact of the endocytosis inhibitor hydroxy-dynasore (OH-dyn), as well as bafilomycin A1 (bafA1), inhibiting the vacuolar type H⁺-ATPase (V-ATPase), on the cellular toxicity of nano- and microsized CuO particles, was investigated in BEAS 2 B cells. Selected endpoints were cytotoxicity, copper uptake, glutathione (GSH) levels, and the transcriptional DNA damage and (oxidative) stress response using the high-throughput reverse transcription quantitative polymerase chain reaction (RT-qPCR). OH-dyn markedly reduced intracellular copper accumulation in the cases of CuO NP and CuO MP; the modulation of gene expression, induced by both particle types affecting especially HMOX1, HSPA1A, MT1X, SCL30A1, IL8 and GADD45A, were completely abolished. BafA1 lowered the intracellular copper concentration in case of CuO NP and strongly reduced transcriptional changes, while any CuO MP-mediated effects were not affected by bafA1. In conclusion, the toxicity of CuO NP depended almost exclusively upon dynamin-dependent endocytosis and the intracellular release of redox-active copper ions due to lysosomal acidification, while particle interactions with cellular membranes appeared to be not relevant.

Inhalation bioaccessibility of polycyclic aromatic hydrocarbons in heavy PM2.5 pollution days: Implications for public health risk assessment in northern China

Airborne (PM_2.5) with aerodynamic diameter ≤ 2.5 μm was collected from 4 types of cities in northeast China during the heating period. The objectives of this study were to assess the concentrations variation of PM_2.5-bound 12 carcinogenic polycyclic aromatic hydrocarbons (PAH₁₂), to study the influence of simulated lung fluids on bioaccessibility of PAH₁₂ and to estimate the variation of lifetime excess cancer risk to the residents, artificial lysosomal fluid (ALF) and Gamble's solution were used. The number of lifetime excess cancer cases (determined by California Environmental Protection Agency method) as a result of PAH₁₂ exposure (total concentration) was 4.00-430 (provincial central cities), 24.0-261 (energy-mining cities), 17.0-109 (forested city), and 20.0-69.0 (agricultural city) per million people, which relatively corresponded to a 92.2% and 96.2%, 92.6% and 97.3%, 92.2% and 94.2%, and 86.5% and 92.6% decrease after considering bioaccessibility following 24-h of Gamble's solution and ALF extraction, respectively. Phenanthrene (Phe), dibenz[a,h]anthracene (DahA) and benzo[a]pyrene (BaP) were found to be the most bioaccessible types of PAH₁₂ after the Gamble's solution and ALF extraction in the PM_2.5 samples from all the studied cities. Based on the point-estimate approach, short-term predictions of pulmonary toxicity caused by potential inhalation of airborne PM into the pulmonary system might be overestimated if bioaccessibility of PM_2.5-bound PAH₁₂ is not fully evaluated.

A method for assessing carcinogenic risk of air fine particle-associated polycyclic aromatic hydrocarbons by considering bioaccessibility in lung fluids

This study was conducted to evaluate the inhalation carcinogenic risk of PAHs in biochar fine particles using total concentration-based assessment approach and bioaccessibility-based assessment approach. Only limit PAHs in particles can be released in simulated lung fluids, leading to a low bioaccessibility (only ranging from 0.34% to 1.48% for biochar fine particles and from 3.21% to 44.2% for PM2.5), which would significantly affect health risk assessment. Therefore, bioaccessibility should always be favored over more traditional evaluations based on total concentration, while evaluating inhalation health risks of biochar-bound PAHs. To prove the broad applicability of bioaccessibility-based assessment approaches, we also compared health risk of actual atmospheric particles (PM2.5 collected from Nanjing, China) using total concentration-based approaches and bioaccessibility-based approaches. •Proposed bioaccessibility-based approaches for assessing biochar risk are more accurate than traditional total concentration-based approaches;•Proposed bioaccessibility-based approaches can be applied to health risk assessment of actual air particles;•A more practical method was proposed to evaluate the bioaccessibility of PAHs in biochar fine particles or other specific component of atmospheric particle matters: using wet sieving method to prepare fine particles, using volatile organic solvent-drying method to load 14C-PAHs on fine particles, and using desorption experiments to determine bioaccessibility of PAHs.

Release of polycyclic aromatic hydrocarbons from biochar fine particles in simulated lung fluids: Implications for bioavailability and risks of airborne aromatics

Airborne carbonaceous fine particles, such as soot and biochar, represent a significant fraction of air particulate matter and have received widespread concern due to their health effects. Atmospheric carbonaceous particles can contain high concentration of polycyclic aromatic hydrocarbons (PAHs), and may pose significant health risks when carried into respiratory system from inhalation of particulates. In this study, the bioaccessibility of two PAH compounds, phenanthrene and pyrene, bound to biochar fine particles was assessed by examining their release in two simulated lung fluids: Gamble's solution and artificial lysosomal fluid (ALF). We observed that only 0.47 to 0.75% of biochar-bound PAHs were released in the simulated lung fluids, most likely due to the physical entrapment of PAH molecules in the micropore regimes of biochar, resulting in strong desorption hysteresis, even though apparent desorption equilibrium was reached within 30 min, well within the average clearance time of particulate matter in lung system. The inorganic and organic salts in the simulated lung fluids were found to inhibit the release of PAHs by exerting the pore blockage effect and salting-out effect. Moreover, the low molecular weight organic acids (LMWOAs) in the lung fluids further inhibited PAH release by increasing the micropore volume and surface area of biochar fine particles. When taking into account the inhibited release, the estimated carcinogenic risks of biochar-bound PAHs are typically low, even under extreme conditions wherein both biochar concentrations and PAH loadings on biochar are very high. An important implication is that contaminant bioavailability needs to be taken into account when assessing the risks of the contaminants bound to airborne carbonaceous materials.

Bioaccessibility of polycyclic aromatic hydrocarbons in central air conditioner filter dust and its occupational exposure to shopping mall employees

The assessment of the human health risk of dust exposure to polycyclic aromatic hydrocarbons (PAHs) has been hampered by a lack of data on the bioaccessibility. The purpose of this study was to apply in vitro methods using simulated lungs with artificial lysosomal fluid (ALF) and Gamble's solution and digestive fluid to assess the bioaccessibility of 8 high molecular weight PAH (PAH₈) in central air conditioner (AC) filter dust from a shopping mall in northeast China. Overall, the bioaccessible PAH₈ concentration (μg/g) in AC filter dust samples after ALF and Gamble's solution extraction for 24 h were notable, with a mean of 1.71 ± 0.6 and 1.92 ± 0.5 in the sales areas, and a mean of 1.61 ± 0.2 and 1.85 ± 0.2 in the office areas. AC filter dust exposed to simulated digestive fluid had a mean bioaccessible PAH₈ concentration (μg/g) of 1.60 ± 0.4 in the sales areas and 1.15 ± 0.2 in the office areas. Benzo[b]fluoranthene (BbF) made the most significant contribution to the total and bioaccessible PAH₈ concentrations in all of the AC filter dust after simulated digestive fluid extraction, while the bioaccessibility was driven by chrysene (Chr, sales areas) and indeno[1,2,3-c,d]pyrene (Ind, office areas). Both the bioaccessibility and concentration of PAH8 in simulated lung fluid were mainly driven by benzo[a]pyrene (BaP). This study highlights the need to conduct bioaccessibility experiments for an adequate exposure assessment of health risk.

Pulmonary bioaccessibility of trace metals in PM2.5 from different megacities simulated by lung fluid extraction and DGT method

Atmospheric fine particulate matters (PM_2.5) pose significant risks to human health through inhalation, especially in the rapidly developing China due to air pollution. The harmful effects of PM_2.5 are determined not only by its concentrations and hazardous components from diverse sources, but more by their bioavailable fractions actually absorbed by human body. To accurately estimate the inhalation risks of airborne metals, a physiologically based bioaccessibility method combining Simulated Lung Fluid (SLF) extraction and Diffusive Gradients in Thin-films (DGT) approaches was developed, representing the dissolution of particulate metals into lung fluid and the subsequent lung absorption of free metal cations in solution, respectively. The new method was used to compare the lung bioaccessibility of typical trace metals in PM_2.5 from three China megacities (Shanghai and Nanjing in the east, Guangzhou in south) during heavy pollution seasons. Generally, the SLF bioaccessibility (%) simulating the solubility of particulate metals in alveolar lung fluid was in order of Ni > Cd > Mn » Pb, while the succeeding DGT bioaccessibility representing labile metal fractions in solution phase absorbed directly by lung was lower and ranked as Ni ∼ Mn > Cd » Pb, thus Ni and Cd posed relatively higher potential risks owing to their high air pollution level and higher pulmonary bioaccessibility. Due to varied particle sources such as coal combustion and traffic emissions, some airborne metal concentrations (Pb, Ni) showed inconsistent spatial patterns with bulk PM_2.5 concentrations, and also varied bioaccessibility in different regions. The framework for PM_2.5 pollution risk assessments should be refined by considering both aerosol components and associated pollutants' bioaccessibility.

Real-Time Observation of Fibrous Zeolites Reactivity in Contact with Simulated Lung Fluids (SLFs) Obtained by Atomic Force Microscope (AFM)

Inhalation of fibrous erionite particles has been linked to malignant mesothelioma. Accordingly, erionite is considered the most carcinogenic mineral. The reactivity and the nature of erionite biotoxicity has been the subject of intensive research. Despite very close chemical and structural relationships between erionite and offretite, the reactivity of offretite in lung fluids remains unknown. In this paper, the interaction of erionite and offretite surfaces with simulated lung fluids was investigated by means of in situ atomic force microscope (AFM). To simulate different environments in the lungs, artificial lysosomal fluid (ALF) and Gamble’s solution were used. In ALF (4.15 < pH < 4.31) the dissolution of erionite and offretite surfaces was detected, as well as an evident removal of particles (mainly attributed to impurities) from the crystal faces. Instead, the growth of a layer of a yet unknown phase on the surface of both zeolites was observed during the interaction with Gamble’s solution (7.4 < pH < 8.48). The thickness of this layer reached a few tens of nanometers and covered all the observed areas. The understanding of the observed processes is of paramount importance, since they could be potentially involved in the mechanisms triggering the toxicological effects of erionite fibres.

Metal(loid) bioaccessibility and inhalation risk assessment: A comparison between an urban and an industrial area

The content of metal(loid)s in particulate matter (PM) is of special concern due to their contribution to overall (PM) toxicity. In this study, the bioaccessibility and human health risk of potentially toxic metal(loid)s associated with PM₁₀ were investigated in two areas of the Cantabrian region (northern Spain) with different levels of exposure: an industrial area mainly influenced by a ferromanganese alloy plant; and an urban area consisting mainly of residential and commercial activities, but also affected, albeit to a lesser extent by the ferroalloy plant. Total content and bioaccessible fractions in simulated lung fluids (SLFs) of Fe, Mn, Zn, Ni, Cu, Sb, Mo, Cd and Pb were determined by ICP-MS. Gamble's solution and artificial lysosomal fluid (ALF) were used to mimic different conditions inside the human respiratory system. A health risk assessment was performed based on the United States Environmental Protection Agency's (USEPA) methodology. Most metal(loid)s showed moderate and high bioaccessibility in Gamble's solution and ALF, respectively. Despite the high variability between the samples, metal(loid) bioaccessibility was found to be higher on average at the industrial site, suggesting a greater hazard to human health in the proximity of the main metal(loid) sources. Based on the results of the risk assessment, the non-carcinogenic risk associated with Mn exposure was above the safe limit (HQ> 1) under all the studied scenarios at the industrial site and under some specific scenarios at the urban location. The estimated carcinogenic inhalation risk for Cd exposure at the industrial site was found to be within the range between 1.0 × 10^-6 to 1.0 × 10^-4 (uncertainty range) under some scenarios. The results obtained in this study indicate that Mn and Cd inhalation exposure occurring in the vicinities of the studied areas may pose a human health risk.

Speciation, bioaccessibility and potential risk of chromium in Amazon forest soils

Even though the Amazon region is widely studied, there is still a gap regarding Cr exposure and its risk to human health. The objectives of this study were to 1) determine Cr concentrations in seven chemical fractions and 6 particle sizes in Amazon soils, 2) quantify hexavalent Cr (CrVI) concentrations using an alkaline extraction, 3) determine the oral and lung bioaccessible Cr, and 4) assess Cr exposure risks based on total and bioaccessible Cr in soils. The total Cr in both A (0-20 cm) and B (80-100 cm) horizons was high at 2346 and 1864 mg kg^-1. However, sequential extraction indicated that available Cr fraction was low compared to total Cr, with Cr in the residual fraction being the highest (74-76%). There was little difference in total Cr concentrations among particle sizes. Hexavalent Cr concentration was also low, averaging 0.72 and 2.05 mg kg^-1 in A and B horizon. In addition, both gastrointestinal (21-22 mg kg^-1) and lung (0.95-1.25 mg kg^-1) bioaccessible Cr were low (<1.2%). The low bioavailability of soil Cr and its uniform distribution in different particle sizes indicated that Cr was probably of geogenic origin. Exposure based on total Cr resulted in daily intake > the oral reference dose for children, but not when using CrVI or bioaccessible Cr. The data indicated that it is important to consider both Cr speciation and bioaccessibility when evaluating risk from Cr in Amazon soils.

In Vitro Investigations of Human Bioaccessibility from Reference Materials Using Simulated Lung Fluids

An investigation for assessing pulmonary bioaccessibility of metals from reference materials is presented using simulated lung fluids. The objective of this paper was to contribute to an enhanced understanding of airborne particulate matter and its toxic potential following inhalation. A large set of metallic elements (Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, and Zn) was investigated using three lung fluids (phosphate-buffered saline, Gamble's solution and artificial lysosomal fluid) on three standard reference materials representing different types of particle sources. Composition of the leaching solution and four solid-to-liquid (S/L) ratios were tested. The results showed that bioaccessibility was speciation- (i.e., distribution) and element-dependent, with percentages varying from 0.04% for Pb to 86.0% for Cd. The higher extraction of metallic elements was obtained with the artificial lysosomal fluid, in which a relative stability of bioaccessibility was observed in a large range of S/L ratios from 1/1000 to 1/10,000. For further investigations, it is suggested that this method be used to assess lung bioaccessibility of metals from smelter-impacted dusts.

Lung bioaccessibility of contaminants in particulate matter of geological origin

Human exposure to particulate matter (PM) has been associated with adverse health effects. While inhalation exposure to airborne PM is a prominent research subject, exposure to PM of geological origin (i.e., generated from soil/soil-like material) has received less attention. This review discusses the contaminants in PM of geological origin and their relevance for human exposure and then evaluates lung bioaccessibility assessment methods and their use. PM of geological origin can contain toxic elements as well as organic contaminants. Observed/predicted PM lung clearance times are long, which may lead to prolonged contact with lung environment. Thus, certain exposure scenarios warrant the use of in vitro bioaccessibility testing to predict lung bioavailability. Limited research is available on lung bioaccessibility test development and test application to PM of geological origin. For in vitro tests, test parameter variation between different studies and concerns about physiological relevance indicate a crucial need for test method standardization and comparison with relevant animal data. Research is recommended on (1) developing robust in vitro lung bioaccessibility methods, (2) assessing bioaccessibility of various contaminants (especially polycyclic aromatic hydrocarbons (PAHs)) in PM of diverse origin (surface soils, mine tailings, etc.), and (3) risk characterization to determine relative importance of exposure to PM of geological origin.

Solubility-driven toxicity of CuO nanoparticles to Caco2 cells and Escherichia coli: Effect of sonication energy and test environment

Due to small size and high surface energy nanoparticles (NPs) tend to agglomerate and precipitate. To avoid/diminish that, sonication of NPs stock suspensions prior toxicity testing is often applied. Currently, there is no standardized particle sonication protocol available leading to inconsistent toxicity data, especially if toxicity is driven by NPs' dissolution that may be enhanced by sonication. In this study we addressed the effect of sonication on hydrodynamic size (Dh), dissolution and toxicity of copper oxide (CuO) NPs to mammalian cell line Caco-2 in vitro and bacteria Escherichia coli in the respective test environments (cell culture MEM medium, bacterial LB medium and deionised (DI) water). NPs were suspended using no sonication, water bath and probe sonication with different energy intensities. Increased sonication energy (i) decreased the Dh of CuO NPs in all three test environments; (ii) increased dissolution of NPs in MEM medium and their toxicity to Caco-2; (iii) increased dissolution of NPs in LB medium and their bioavailability to E. coli; and (iv) had no effect on dissolution and antibacterial effects of NPs in DI water. Thus, to reduce variations in dissolution and toxicity, we recommend sonication of NPs in DI water following the dilution into suitable test media.

The suitability of extraction solutions to assess bioaccessible trace metal fractions in airborne particulate matter: a comparison of common leaching agents

The determination of bioaccessible metal concentrations and/or fractions is a prerequisite for reliable assessment of the hazardous potential of toxic trace metals present in airborne particulate matter (APM). For this purpose, the use of various leaching agents has been reported in literature. The applied reagents reveal severe differences in composition. Therefore, variations in the amounts of trace metals released from APM samples could be expected with the use of these agents, hampering comparison of literature data. In this work, bioaccessible metal fractions were determined in PM10 samples from Graz, Austria, and Karachi, Pakistan, using synthetic gastric juice (SGJ), artificial lysosomal fluid (ALF), Gamble's solution, aqueous solutions of sodium chloride, ammonium acetate, ammonium citrate, and water for sample extraction. Investigated trace metals showed distinct differences in extractable fractions for the same extractant. For example, bioaccessible contents ranged from 34.8 ± 13.3% for Ni (n = 12) to 77.9 ± 14.8% for Cd (n = 12) when SGJ was used for extraction. Furthermore, extraction yields for the applied leaching agents were determined, indicating for all investigated elements two to four times more efficient extraction with SGJ, ammonium citrate buffer, and ALF as compared to water and simple inorganic salt solutions, indicating that ammonium citrate buffer could be used as an alternative for synthetic body fluids with rather complex composition.

Considerable Variation of Antibacterial Activity of Cu Nanoparticles Suspensions Depending on the Storage Time, Dispersive Medium, and Particle Sizes

Suspensions of Cu nanoparticles are promising for creating the new class of alternative antimicrobial products. In this study we examined copper nanoparticles of various sizes obtained by the method of wire electric explosion: nanopowder average size 50 nm (Cu 50) and 100 nm (Cu 100). The paper presents the complex study of the influence of physicochemical properties such as particle size and concentration of the freshly prepared and 24-hour suspensions of Cu nanoparticles in distilled water and physiological solution upon their toxicity to bacteria E. coli M-17. Ionic solution of Cu²⁺ and sodium dichloroisocyanurate was used for comparison study. It has been shown that decrease in the nanoparticle size leads to changes in the correlation between toxicity and concentration as toxicity peaks are observed at low concentrations (0.0001⋯0.01 mg/L). It has been observed that antibacterial properties of Cu 50 nanoparticle suspensions are ceased after 24-hour storage, while for Cu 100 suspensions no correlation between antibacterial properties and storage time has been noted. Cu 100 nanoparticle suspensions at 10 mg/L concentration display higher toxicity at substituting physiological solution for water than Cu 50 suspensions. Dependence of the toxicity on the mean particle aggregates size in suspension was not revealed.

Cytotoxicity and genotoxicity of nano - and microparticulate copper oxide: role of solubility and intracellular bioavailability

Background

Nano- or microscale copper oxide particles (CuO NP, CuO MP) are increasingly applied as catalysts or antimicrobial additives. This increases the risk of adverse health effects, since copper ions are cytotoxic under overload conditions.

Methods

The extra- and intracellular bioavailability of CuO NP and CuO MP were explored. In addition, different endpoints related to cytotoxicity as well as direct and indirect genotoxicity of the copper oxides and copper chloride (CuCl₂) were compared.

Results

Comprehensively characterized CuO NP and CuO MP were analysed regarding their copper ion release in model fluids. In all media investigated, CuO NP released far more copper ions than CuO MP, with most pronounced dissolution in artificial lysosomal fluid. CuO NP and CuCl₂ caused a pronounced and dose dependent decrease of colony forming ability (CFA) in A549 and HeLa S3 cells, whereas CuO MP exerted no cytotoxicity at concentrations up to 50 μg/mL. Cell death induced by CuO NP was at least in part due to apoptosis, as determined by subdiploid DNA as well as via translocation of the apoptosis inducing factor (AIF) into the cell nucleus. Similarly, only CuO NP induced significant amounts of DNA strand breaks in HeLa S3 cells, whereas all three compounds elevated the level of H₂O₂-induced DNA strand breaks. Finally, all copper compounds diminished the H₂O₂-induced poly(ADP-ribosyl)ation, catalysed predominantly by poly(ADP-ribose)polymerase-1 (PARP-1); here, again, CuO NP exerted the strongest effect. Copper derived from CuO NP, CuO MP and CuCl₂ accumulated in the soluble cytoplasmic and nuclear fractions of A549 cells, yielding similar concentrations in the cytoplasm but highest concentrations in the nucleus in case of CuO NP.

Conclusions

The results support the high cytotoxicity of CuO NP and CuCl₂ and the missing cytotoxicity of CuO MP under the conditions applied. For these differences in cytotoxicity, extracellular copper ion levels due to dissolution of particles as well as differences in physicochemical properties of the particles like surface area may be of major relevance. Regarding direct and indirect genotoxicity, especially the high copper content in the cell nucleus derived after cell treatment with CuO NP appears to be decisive.

Bioaccessibility of metals in alloys: evaluation of three surrogate biofluids

Bioaccessibility in vitro tests measure the solubility of materials in surrogate biofluids. However, the lack of uniform methods and the effects of variable test parameters on material solubility limit interpretation. One aim of this study was to measure and compare bioaccessibility of selected economically important alloys and metals in surrogate physiologically based biofluids representing oral, inhalation and dermal exposures. A second aim was to experimentally test different biofluid formulations and residence times in vitro. A third aim was evaluation of dissolution behavior of alloys with in vitro lung and dermal biofluid surrogates. This study evaluated the bioaccessibility of sixteen elements in six alloys and 3 elemental/metal powders. We found that the alloys/metals, the chemical properties of the surrogate fluid, and residence time all had major impacts on metal solubility. The large variability of bioaccessibility indicates the relevancy of assessing alloys as toxicologically distinct relative to individual metals.

Quantification of ZnO nanoparticle uptake, distribution, and dissolution within individual human macrophages

The usefulness of zinc oxide (ZnO) nanoparticles has led to their wide distribution in consumer products, despite only a limited understanding of how this nanomaterial behaves within biological systems. From a nanotoxicological viewpoint the interaction(s) of ZnO nanoparticles with cells of the immune system is of specific interest, as these nanostructures are readily phagocytosed. In this study, rapid scanning X-ray fluorescence microscopy was used to assay the number ZnO nanoparticles associated with ∼1000 individual THP-1 monocyte-derived human macrophages. These data showed that nanoparticle-treated cells endured a 400% elevation in total Zn levels, 13-fold greater than the increase observed when incubated in the presence of an equitoxic concentration of ZnCl2. Even after excluding the contribution of internalized nanoparticles, Zn levels in nanoparticle treated cells were raised ∼200% above basal levels. As dissolution of ZnO nanoparticles is critical to their cytotoxic response, we utilized a strategy combining ion beam milling, X-ray fluorescence and scanning electron microscopy to directly probe the distribution and composition of ZnO nanoparticles throughout the cellular interior. This study demonstrated that correlative photon and ion beam imaging techniques can provide both high-resolution and statistically powerful information on the biology of metal oxide nanoparticles at the single-cell level. Our approach promises ready application to broader studies of phenomena at the interface of nanotechnology and biology.

Upon exposure to Cu nanoparticles, accumulation of copper in the isopod Porcellio scaber is due to the dissolved Cu ions inside the digestive tract

The fate of nanoparticles in organisms is of significant interest. In the current work, we used a test system with terrestrial isopods (Porcellio scaber) fed with food spiked with Cu NPs or soluble Cu salt for 14 days. Two different doses were used for spiking to yield final concentrations of 2000 and 5000 μg Cu/g dry food. After the exposure period, part of the exposed group of animals was transferred to clean food to depurate. Cu content was analyzed in the digestive glands, gut, and the 'rest' of the body. Similar patterns of (i) assimilated and depurated amounts of Cu, (ii) Cu body distribution, and (iii) effect on isopods feeding behavior were observed regardless of whether the animals were fed with Cu NPs or soluble Cu salt spiked food. Thus, Cu ions and not Cu NPs were assimilated by the digestive gland cells. Solubilization of the Cu NPs applied to the leaves was also analyzed with chemical methods and recombinant Cu-sensing bacteria. The comparison of the in vitro data on solubilization of Cu NPs and in vivo data on Cu accumulation in the animal tissues showed that about 99% of accumulated copper ions was dissolved from ingested Cu NPs in the digestive system of isopods.

Manganese in occupational arc welding fumes--aspects on physiochemical properties, with focus on solubility

Physicochemical properties, such as particle sizes, composition, and solubility of welding fumes are decisive for the bioaccessibility of manganese and thereby for the manganese cytotoxic and neurotoxic effects arising from various welding fumes. Because of the diverse results within the research on welding fume solubility, this article aims to review and discuss recent literature on physicochemical properties of gas metal arc welding, shielded metal arc welding, and flux-cored arc welding fumes, with focus on solubility properties. This article also presents a short introduction to the literature on arc welding techniques, health effects from manganese, and occupational exposure to manganese among welders.

In vitro investigations of platinum, palladium, and rhodium mobility in urban airborne particulate matter (PM10, PM2.5, and PM1) using simulated lung fluids

Environmental concentrations of platinum group elements (PGE) have been increasing since the introduction of automotive catalytic converters to control harmful emissions. Assessments of the human health risks of exposures to these elements, especially through the inhalation of PGE-associated airborne particulate matter (PM), have been hampered by a lack of data on their bioaccessibility. The purpose of this study is to apply in vitro methods using simulated human lung fluids [artificial lysosomal fluid (ALF) and Gamble's solution] to assess the mobility of the PGE, platinum (Pt), palladium (Pd), and rhodium (Rh) in airborne PM of human health concern. Airborne PM samples (PM(10), PM(2.5), and PM(1)) were collected in Frankfurt am Main, Germany. For comparison, the same extraction experiments were conducted using the standard reference material, Used Auto Catalyst (monolith) (NIST 2557). Pt and Pd concentrations were measured using isotope dilution ICP-Q-MS, while Rh was measured directly with ICP-Q-MS (in collision mode with He), following established matrix separation and enrichment procedures, for both solid (filtered residues) and extracted sample phases. The mobilized fractions measured for PGE in PM(10), PM(2.5), and PM(1) were highly variable, which can be attributed to the heterogenic nature of airborne PM and its composition. Overall, the mobility of PGE in airborne PM samples was notable, with a mean of 51% Rh, 22% Pt, and 29% Pd present in PM(1) being mobilized by ALF after 24 h. For PM(1) exposed to Gamble's solution, a mean of 44% Rh, 18% Pt, and 17% Pd was measured in solution after 24 h. The mobility of PGE associated with airborne PM was also determined to be much higher compared to that measured for the auto catalyst standard reference material. The results suggest that PGE emitted from automotive catalytic converters are likely to undergo chemical transformations during and/or after being emitted in the environment. This study highlights the need to conduct bioaccessibility experiments using samples collected in the field to enable an adequate assessment of risk.

Distribution of CuO nanoparticles in juvenile carp (Cyprinus carpio) and their potential toxicity

Adverse effect of engineered nanoparticles (NPs) on the aquatic environment and organisms has recently drawn much attention. This paper reports on the toxicity of CuO NPs to juvenile carp (Cyprinus carpio) and their distribution in the fish. CuO NPs and its counterpart bulk particles (BPs) (10, 50, 100, 200, 300, 500 and 1000 mg L(-1)) exhibited no acute toxicity (96 h), while during the 30 day sub-acute toxicity test, carp growth was significantly inhibited by CuO NPs (100 mg L(-1)) in comparison to control, CuO BPs and Cu(2+) groups. CuO NPs (or released Cu(2+) ions inside the fish body) could distribute in various tissues/organs and followed an order: intestine>gill>muscle>skin and scale>liver>brain. For time-related distribution, Cu content (expressed on a dry mass basis) in intestine, gill and liver increased faster (within 1 day) and they had obviously higher Cu content than other tissues/organs at all exposure times. CuO NPs could be excreted by carp to lower their toxicity. Cholinesterase activity was inhibited during CuO NPs exposure, suggesting NPs exposure could have potential neurotoxicity, and free Cu(2+) ions dissolved inside the carp body was responsible for the cholinesterase inhibition. Finally, actual suspended NPs concentrations should be used instead of initially added concentrations whenever possible in nanotoxicity studies.

Yttrium and lanthanides in human lung fluids, probing the exposure to atmospheric fallout

Inhalation of airborne particles can produce crystallization of phosphatic microcrysts in intraaveolar areas of lungs, sometimes degenerating into pulmonary fibrosis. Results of this study indicate that these pathologies are induced by interactions between lung fluids and inhaled atmospheric dust in people exposed to volcanic dust ejected from Mount Etna in 2001. Here, the lung solid-liquid interaction is evaluated by the distribution of yttrium and lanthanides (YLn) in fluid bronchoalveolar lavages on selected individuals according the classical geochemical approaches. We found that shale-normalised patterns of yttrium and lanthanides have a 'V shaped' feature corresponding to the depletion of elements from Nd to Tb when compared to the variable enrichments of heavy lanthanides, Y, La and Ce. These features and concurrent thermodynamic simulations suggest that phosphate precipitation can occur in lungs due to interactions between volcanic particles and fluids. We propose that patterns of yttrium and lanthanides can represent a viable explanation of some pathology observed in patients after prolonged exposure to atmospheric fallout and are suitable to become a diagnostic parameter of chemical environmental stresses.

Development of an in vitro method to estimate lung bioaccessibility of metals from atmospheric particles

The research presented here was initiated to improve the current knowledge on easily released metals from atmospheric particles. The objectives of this paper were to develop an in vitro method to estimate lung bioaccessibility and to provide quantitative data on metals bioaccessibility. A large set of metals has been investigated (Ba, Cd, Ce, Co, Cu, La, Mn, Mo, Ni, Pb, Rb, Sb and Zn) using two distinct fluids (water and Gamble solution) on four reference materials representing different types of particle sources. Through this study, different parameters such as extraction-time, composition of the leaching solution and solid-to-liquid (S/L) ratios were investigated. The findings obtained for four SRMs suggest that the bioaccessibility is maximized after a 24 h extraction for a range of S/L ratios varying from 1/500 to 1/50,000. We clearly demonstrate that the higher bioaccessibility of metals is obtained with the Gamble solution. Moreover, our results imply that bioaccessibility is speciation and element dependent with percentages varying from 3.3% for Pb to 92.5% for Zn. An estimation of uncertainties of 11% to 30% was obtained for metals bioaccessibility in the four reference materials. In addition, the extraction procedure was validated by performing a mass balance on both soluble and insoluble fractions. This developed method may be used to evaluate the pulmonary bioaccessibility of trace elements present in the atmospheric particles without major artefacts.

Effect of sonication and serum proteins on copper release from copper nanoparticles and the toxicity towards lung epithelial cells

Abstract Different methodological settings can influence particle characteristics and toxicity in nanotoxicology. The aim of this study was to investigate how serum proteins and sonication of Cu nanoparticle suspensions influence the properties of the nanoparticles and toxicological responses on human lung epithelial cells. This was investigated by using methods for particle characterization (photon correlation spectroscopy and TEM) and Cu release (atomic absorption spectroscopy) in combination with assays for analyzing cell toxicity (MTT-, trypan blue- and Comet assay). The results showed that sonication of Cu nanoparticles caused decreased cell viability and increased Cu release compared to non-sonicated particles. Furthermore, serum in the cell medium resulted in less particle agglomeration and increased Cu release compared with medium without serum, but no clear difference in toxicity was detected. Few cells showed intracellular Cu nanoparticles due to fast release/dissolution processes of Cu. In conclusion; sonication can affect the toxicity of nanoparticles.

Characterization of artificially generated PbS aerosols and their use within a respiratory bioaccessibility test

A new method is presented for the preparation, characterization and use of PbS (galena) nanoparticles within an in vitro bioaccessibility test representing the respiratory tract, specifically the conditions occurring in conjunction with phagocytosis by cells using artificial lysosomal fluid. Particle production through nanosecond laser ablation enables their rapid production with a relatively narrow particle size distribution, and a diameter enabling them to represent particles that can enter the alveolar region of the respiratory tract (<3 microm). The PbS nanoparticles were characterized by cascade impaction to define their particle size distribution and through the use of X-ray diffraction (XRD) and electron microprobe analysis (EMPA) to define their mineralogy and homogeneity respectively. The particles were collected via liquid impingement in artificial lysosomal fluid and the undissolved material was separated via ultrafiltration after a contact time of 7-140 hours to define the bioaccessibility. The particles produced by the laser ablation of PbS have a homogenous composition and are 0.083-0.75 microm in diameter, spherical, crystalline, and have the same stoichiometry as the target material. Despite the low solubility constant of PbS in water (K(sp) = 3.4 x 10(-28)), 53% +/- 2.25 (SD) (n = 3) of the Pb was leached after ca. 48 hours, at which point equilibrium is reached. The competing effects of citrate and tartrate in the artificial lysosomal fluid are responsible for this high level of bioaccessibility. Nanoparticles of PbS display a level of bioaccessibility within human lungs that suggests they represent a significant risk to human health through the inhalation pathway as a result of phagocytosis, although this needs to be supported by in vivo tests.