Search

The technologically interesting properties of palladium nanoparticles (Pd-NPs) allowed their widespread industrial application, although concerns emerged on increasing general and occupational levels of exposure. In this context, to assess the toxicological behavior of Pd-NPs, and particularly their endocrine disruptive potential, has become a public health priority. Therefore, we evaluated Pd-NP impact on the female endocrine reproductive system of Wistar rats sub-chronically treated for 90 days with increasing doses of this xenobiotic (0.12, 1.2, and 12 µg/kg, administered at days 1, 30, and 60 for cumulative doses of 0.36, 3.6, and 36 µg/kg) via the intravenous route. In this regard, we investigated potential alterations in different sex hormone, for example, estradiol, follicle-stimulating hormone (FSH), luteinizing hormone, progesterone, and testosterone, serum concentrations. All treated groups showed significantly greater levels of FSH compared to controls, suggesting a possible impact of Pd-NPs on the regulatory system that controls the normal physiology of female reproductive function. Although relevant, since obtained under sub-chronic, low-dose conditions of exposure resembling those encountered in real-world scenarios, the present results are preliminary and require confirmation as well as identification of the possible underlining molecular mechanisms. From a public and occupational health perspective, implications for the reproductive health of exposed subjects and the next generations of women exposed during their childbearing age or pregnancy should be elucidated. This information is essential to elaborate adequate preventive strategies for assessing and controlling possible Pd-NPs adverse effects on the endocrine system.

The aim of this study was to evaluate the mobility of platinum (Pt) and palladium (Pd) emissions from automotive catalysts in soils and to contribute to the risk assessment of platinum group metals (PGMs) discharged from catalysts in the environment. To address this question, for the first time risk assessment code (RAC) was applied to consider the results from sequential extraction of different Pd and Pt species from soils. For this purpose, model soil samples were prepared spiking defined Pd or Pt species, respectively, at known concentrations. In order to mimic emitted species as well as possible transformation products of traffic-related Pd and Pt emissions in soils, coated and uncoated elemental nanoparticles (cPd/cPt NPs, Pd/Pt NPs) and ionic divalent metal species (Pd(II)/Pt(II)) were applied. All model samples were characterized in detail and the developed sequential extraction scheme was validated. RAC values ranged between 24 and 8% revealing medium to low risk. The order of mobility for the studied species was found to be Pt(II) > cPd NPs » Pd(II) > Pd NPs > Pt NPs > cPt NPs. Furthermore, migration of Pd species in gravity columns was studied confirming highest transport of cPd NPs., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The widespread industrial application of nanomaterials (NMs) has dramatically increased the likelihood of environmental and occupational exposure of humans to such xenobiotics. This issue, together with the increasing public health interest in understanding the effects of chemicals on endocrine system, encouraged to investigate the disruptive potential of NMs on the endocrine function. Therefore, the aim of this study was to evaluate the effects of palladium nanoparticles (Pd-NPs) on the female reproductive system of Wistar rats, intravenously exposed to different doses (0.12, 1.2, and 12 µg/kg), through the assessment of possible quantitative changes in the serum concentrations of several sex hormones. Our results demonstrated that the highest exposure doses significantly reduced the estradiol and testosterone concentrations, while increased the luteinizing hormone levels in treated animals compared to controls. Such alterations are indicative for an abnormal reproductive axis function. However, further investigations are needed to clarify the role of the different NP physicochemical properties in determining such effects, and possible underlining molecular mechanisms, as well as their relevance for the development of diseases in the female reproductive system. Overall, this may be helpful to define accurate risk assessment and management strategies to protect the health of the general and occupational populations exposed to Pd-NPs.

Recently, palladium nanoparticles (PdNPs) have been increasingly used in many industrial sectors, and this has led to a significant release of nano-sized palladium particles into the environment. However, despite the increase in occupational and general population exposure, information on the potential adverse effects of these PdNPs is still limited and their impact on the immune system constitutes a major health concern. Therefore, the aim of this study was to investigate the potential adverse effects induced by subchronic intravenous administration of PdNPs on the immune system of female Wistar rats by evaluating alterations in Interleukin (IL)-1α, IL-2, IL-4, IL-6, IL-10, IL-12, granulocyte-macrophage colony-stimulating factor (GM-CSF), Interferon (INF)-γ, and Tumor Necrosis Factor (TNF)-α serum levels. Exposed and control animals were randomly divided into five groups (0, 0.012, 0.12, 1.2, and 12 μg PdNPs per kg body weight) which were treated with repeated intravenous injections of vehicle or PdNPs (on day 1, 30, and 60). Subchronic exposure to PdNPs induced a decreasing trend in serum levels in most of the cytokines investigated, with the highest concentration (12 μg/kg) determining significant inhibitory effects. Overall, these results showed that PdNPs are able to alter cytokine serum levels in subchronically treated Wistar rats, suggesting a possible impact of these xenobiotics on the immune system after long-term exposures.

Palladium nanoparticles have been increasingly used in catalytic processes, wastewater treatment, electronics, and biomedicine. However, recent evidence proved that these nanoparticles are able to induce adverse effects both in in vitro and in vivo models. Nevertheless, molecular mechanisms underlying the toxic effects are still poorly understood. Therefore, this study aimed to investigate the potential toxicological mechanisms of palladium nanoparticles assessing their effects on normal diploid rat fibroblast and lung carcinoma human epithelial cell lines. Several endpoints such as cell growth, cell cycle progression, DNA damage, induction of apoptosis, reactive oxygen species production and expression of cell cycle regulatory proteins were evaluated. Results showed that palladium nanoparticles inhibited cell growth in a dose- and time-dependent manner in both cell lines, although with a more evident action on fibroblasts. Interestingly, inhibition of cell growth was not associated with the induction of apoptosis. Cell cycle progression was arrested in the G0/G1 phase and DNA damage was evident in both cell lines even if only a slight increase in the intracellular reactive oxygen species levels was detected. These findings provide valuable insight into understanding the molecular mechanisms responsible of palladium nanoparticles toxicity whose identification is essential to define an adequate risk assessment process., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Roadside dust and soil samples were collected at different sites in the area of Ulm and Munich in Germany. Road dust samples were collected in tunnels where the traffic-related dust is less influenced by atmospheric conditions. Soil samples were taken with a drill bar at varying distances to motorways, district and regional roads with different traffic densities. The soil cylinders of 30cm length were divided into four sections in order to obtain depth profiles for palladium (Pd) distribution. Determination of Pd in total digests of the samples was performed by ligand-assisted selective separation and preconcentration of Pd(II) using solid phase extraction followed by high-resolution continuum source graphite furnace spectrometry. The analytical procedure was successfully validated using the certified reference material BCR-723 Road Tunnel Dust and by recovery experiments in spiked soil samples. The average Pd concentration found in the road dusts was 311μgkg -1 , the maximum Pd concentration in the topsoil layer was 193μgkg -1 . Pd depth profiles reveal transportation of Pd into deeper soil layers, where even at a depth of 25 to 30cm a Pd concentration of 19μgkg -1 was found, proving the high mobility of Pd. Different factors like traffic density and age of the soils are discussed in the context of the found Pd depth profiles., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Palladium (Pd) emitted from vehicles equipped with exhaust catalytic converters has been accumulating at a greater rate relative to other platinum group elements (PGE) in the last 10-20 years. Little is known, however, regarding the various environmental factors and conditions which are likely to modulate the chemical behavior and bioaccessibility of this element post-emission. To meet data needs, soils and a Pd model substance were treated with solutions containing common anions (Cl - , NO 3 - , SO 4 2- und PO 4 3- ) to shed light on the geochemical behavior of emitted Pd under ambient conditions. As part of this, the particle surface chemistry of treated residues (insoluble phase) and solutions (soluble phase) was examined using XPS to assess the chemical transformation of Pd in the presence of inorganic anions. The results show that Pd is the most soluble in the presence of anionic species, followed by rhodium (Rh) and platinum (Pt). Pd in field-collected samples was found to be considerably more soluble than the metallic Pd in the model substance, Pd black, when treated with anionic species. The results also demonstrate that the solubility of Pd black is strongly dependent on solution pH, concentration and the duration of reaction. The outer 3-4 atomic layers of metallic Pd was determined via XPS to be partially oxidized when treated with anion solutions, with the degree being dependent on anion type. The concentration of dissolved O 2 in solution was found to have little impact on the transformation of metallic Pd. Given the ubiquitous nature of the anions examined, we can expect that Pd will become more bioaccessible post-emission., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Risk assessments of platinum group metal (PGE) emissions, notably those of platinum (Pt), palladium (Pd) and rhodium (Rh), have been mostly based on data regarding the metallic forms used in vehicular exhaust converters, known to be virtually biologically inert and immobile. To adequately assess the potential impacts of PGE, however, data on the chemical behaviour of these metals under ambient conditions post-emission is needed. Complexing agents with a high affinity for metals in the environment are hypothesized to contribute to an increased bioaccessibility of PGE. The purpose of this study is to examine the modulating effects of the organic complexing agents, L-methionine and citric acid, on the geochemical behavior of Pd in soils and model substances (Pd black and PdO). Batch experimental tests were conducted with soils and model substances to examine the impacts of the concentration of complexing agents, pH and length of extraction period on Pd solubility and its chemical transformation. Particle surface chemistry was examined using X-ray photoelectron spectroscopy (XPS) on samples treated with solutions under various conditions, including low and high O2 levels. Pd was observed to be more soluble in the presence of organic complexing agents, compared to Pt and Rh. Pd in soils was more readily solubilized with organic complexing agents compared to the model substances. After 7 days of extraction, L-methionine (0.1 M) treated soil and Pd black samples, for instance, had mean soluble Pd fractions of 12.4 ± 5.9% and 0.554 ± 0.024%, respectively. Surface chemistry analyses (XPS) confirmed the oxidation of metallic Pd surfaces when treated with organic complexing agents. The type of organic complexing agent used for experimental purposes was observed to be the most important factor influencing solubility, followed by solution pH and time of extraction. The results demonstrate that metallic Pd can be transformed into more bioaccessible species in the presence of organic complexing agents which are ubiquitous in the environment.

Background: Information currently available on the impact of palladium on the immune system mainly derives from studies assessing the biological effects of palladium salts. However, in the last years, there has been a notable increase in occupational and environmental levels of fine and ultrafine palladium particles released from automobile catalytic converters, which may play a role in palladium sensitization. In this context, the evaluation of the possible effects exerted by palladium nanoparticles (Pd-NPs) on the immune system is essential to comprehensively assess palladium immunotoxic potential., Aim: Therefore, the aim of this study was to investigate the effects of Pd-NPs on the immune system of female Wistar rats exposed to this xenobiotic for 14 days, by assessing possible quantitative changes in a number of cytokines: IL-1α, IL-2, IL-4, IL-6, IL-10, IL-12, GM-CSF, INF-γ and TNF-α., Methods: Twenty rats were randomly divided into four exposure groups and one of control. Animals were given a single tail vein injection of vehicle (control group) and different concentrations of Pd-NPs (0.012, 0.12, 1.2 and 12 μg/kg). A multiplex biometric enzyme linked immunosorbent assay was used to evaluate cytokine serum levels., Results: The mean serum concentrations of all cytokines decreased after the administration of 0.012 μg/kg of Pd-NPs, whereas exceeded the control levels at higher exposure doses. The highest concentration of Pd-NPs (12 μg/kg) induced a significant increase of IL-1α, IL-4, IL-6, IL-10, IL-12, GM-CSF and INF-γ compared to controls., Discussion and Conclusions: These results demonstrated that Pd-NP exposure can affect the immune response of rats inducing a stimulatory action that becomes significant at the highest administered dose. Our findings did not show an imbalance between cytokines produced by CD4+ T helper (Th) cells 1 and 2, thus suggesting a generalized stimulation of the immune system with a simultaneous activation and polarization of the naïve T cells towards Th1 and Th2 phenotype.

The environmental occurrence of elevated concentrations of platinum (Pt), palladium (Pd) and rhodium (Rh) from automotive catalytic converters has been well-documented. Limited information exists regarding their chemical behavior post-emission, however, especially in the presence of commonly occurring complexing agents. The purpose of this study is to examine the influence of ethylenediamine tetra acetic acid (EDTA) on the possible environmental transformation and solubility of Pd by conducting batch experiments using metallic palladium (Pd black) and palladium(ii) oxide (PdO). Changes in the particle surface chemistry of treated samples were analyzed using X-ray Photoelectron Spectroscopy (XPS) and Transition Electron Microscopy/Energy Dispersive X-ray Spectrometry (TEM/EDX) techniques. Metallic palladium was partially transformed into PdOx (x < 1), while PdO remained largely unaffected. The pH of EDTA solutions was observed to modulate Pd solubility, with Pd black demonstrating a higher solubility compared to PdO. Solubility was also found to increase with a corresponding increase in the strength of EDTA solution concentrations, as well as with the length of extraction time. The overall solubility of Pd remained relatively low for most samples (<1 wt%). A dissolution rate of 2.01 ± 0.17 nmol m(-2) h(-1) was calculated for Pd black in 0.1 M EDTA (pH 7). In contrast to previously held assumptions about the environmental immobility of Pd, small amounts of this element emitted in metallic form are likely to be soluble in the presence of complexing agents such as EDTA.

A number of studies have shown that palladium nanoparticles are able to exert some adverse health effects, such as concentration-dependent cytotoxicity, induction of apoptosis and alterations of the release and expression of numerous cytokines. Nevertheless, our current knowledge of the potential toxic effects induced by exposure to these nanoparticles is far from being complete. For this reason, the present study assessed the possible renal toxicity of palladium nanoparticles by investigating urinary excretion of retinol binding protein, β(2)-microglobulin and albumin in female Wistar rats intravenously exposed to different nanoparticle concentrations (0.012, 0.12, 1.2 and 12 µg/kg) and by carrying out a morphological observation of the kidneys of treated animals. Results showed a significant increase in urinary retinol binding protein and β(2)-microglobulin levels in rats that were administered 12 µg/kg compared to controls. Moreover, an ultrastructural study of the kidneys revealed significant alterations in the proximal and distal tubular epithelium were observed, with a range of severity, in all experimental conditions. Collectively, our findings suggest that exposure to palladium nanoparticles is able to induce a significant renal tubular dysfunction, whereas it does not seem to affect kidney glomerular filtration. However, further studies are needed to confirm our results, to understand the molecular mechanisms of toxic action and to evaluate the potential adverse effects of these nanoparticles also on the glomerular section of the kidney.

There is concern about the possible toxicity of palladium nanoparticles (Pd-NP), as they are released in the environment through many applications. We previously studied the toxicity of Pd-NP at high concentrations; here we address the possible toxicity of Pd-NP at low, subtoxic doses. In particular, we have exposed normal human PBMC entering into the first in vitro mitotic division to Pd-NP and to Pd(IV) ions to evaluate ROS generation and cell cycle progression. We have measured a statistically significant increase of intracellular ROS in Pd(IV) exposed cells, but not in Pd-NP exposed cells. TEM revealed accumulation of lipid droplets and autophagic and mitophagic vacuoles, which appeared more conspicuous in cells exposed to Pd(IV) ions than to Pd-NP. Pd-NP were visible in the cytoplasm of Pd-NP exposed cells. Pd-NP addition was associated with a significant increase of cells within the G0/G1-phase and a significant reduction in GS- and G2/M-phases. Cells exposed to Pd(IV) ions showed a significant amplification of these cell cycle alterations. These results suggest that ions, per se or released by NPs, are the true inducers of Pd toxicity. It will be essential to verify whether the observed disturbance represents a temporary response or might result in permanent alterations.

Capable of preserving the size and shape of nanoparticles, a novel method to effectively and selectively extract noble metal nanoparticles even at the 80 ng L(-1) level from real environmental water was designed and performed using a noncovalent reversible adsorption onto an ionic exchange resin.

Objective: To investigate the effects of palladium (Pd) nanoparticles on cytokine release from peripheral blood mononuclear cells (PBMCs) of control or Pd-sensitized nonatopic women., Methods: TNF-α, IL-5, IL-10 and IFN-γ release and/or expression from PBMCs incubated in presence of 5 to 10 nm Pd nanoparticles or Pd salt (potassium hexachloropalladate) were determined by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction analysis. Transmission electronmicroscopy was performed., Results: In lipopolysaccharide-stimulated PBMCs from controls, Pd salt inhibited IFN-γ and IL-10 release, whereas Pd nanoparticles enhanced IFN-γ release and inhibited TNF-α secretion. In lipopolysaccharide-stimulated PBMCs from Pd-sensitized women showing high IFN-γ release, Pd nanoparticles inhibited TNF-α release and Pd salt IL-10 release. TNF-α and IFN-γ release and messenger RNA expression were correlated. Transmission electronmicroscopy demonstrated uptake of nanoparticles in the endocytic compartment and activation of autophagy., Conclusions: Palladium ions and nanoparticles exert different effects in vitro on the expression and release of cytokines., ((C)2011The American College of Occupational and Environmental Medicine)

The object of this study is to determine the cytokine release from PBMCs exposed to Pd model nanoparticles emitted from catalytic converters. PBMCs of 8 healthy non-atopic women were incubated in the presence of Pd nanoparticles (5-10 nm) or salt (potassium hexa-chloropalladate) 10-5 and 10-6 M. Release of cytokines in supernatant of PBMCs was then determined. In cultures without LPS, IL-10 and IL-17 release from PBMCs was inhibited by Pd salt, while Pd nanoparticles inhibited TNF-alpha and IL-17 release. In LPS-stimulated cultures, release of IFN-gamma, TNF-alpha, IL-10 and IL-17 was inhibited by Pd salt, whereas IFN-gamma release was enhanced and TNF-alpha and IL-17 release was inhibited by Pd nanoparticles. In conclusion, Pd salt inhibits cytokine release, whereas Pd nanoparticles exert modulatory effects enhancing the release of IFN-gamma, a Th1 cytokine typical of delayed allergic reactions. This result is interesting considering the increase of allergic contact dermatitis to Pd in people exposed to Pd nanoparticles in urban environments.

In the present study, endpoints including in vitro pollen performance (i.e., germination and tube growth) and lethality were used as assessments of nanotoxicity. Pollen was treated with 5-10 nm-sized Pd particles, similar to those released into the environment by catalytic car exhaust converters. Results showed Pd-nanoparticles altered kiwifruit pollen morphology and entered the grains more rapidly and to a greater extent than soluble Pd(II). At particulate Pd concentrations well below those of soluble Pd(II), pollen grains experienced rapid losses in endogenous calcium and pollen plasma membrane damage was induced. This resulted in severe inhibition and subsequent cessation of pollen tube emergence and elongation at particulate Pd concentrations as low as 0.4 mg L(-1). Particulate Pd emissions related to automobile traffic have been increasing and are accumulating in the environment. This could seriously jeopardize in vivo pollen function, with impacts at an ecosystem level., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

The present work summarizes data about palladium contents of road tunnel dust from 1994 to 2007 and sewage sludge ash from 1972 to 2006. Since palladium is emitted from automotive catalytic converters as elemental particles, road dust is quiet useful to study traffic-related Pd emissions. Very high Pd values of up to 516 microg Pd kg(-1) were found in the road dust samples collected in 2007. Heavy metals of all urban emissions, also dental practice effluent, are enriched in sewage sludge ash and thus this matrix is useful for the documentation of palladium emission caused by the use of Pd alloys in dental medicine. In sewage sludge ash highest Pd contents of maximum 460 microg Pd kg(-1) were found in the years 1986-1997. In both matrices correlations of Pd content to Pd demand of industry are discussed.

Palladium model particles similar to those emitted from catalytic car exhaust converters were prepared and characterized with the intention of providing a standardized material for investigations of the chemical behavior and bioavailability of traffic related Pd emissions. Two series of Pd particles were prepared and characterized in detail: Pd nanoparticles (2-4 nm) dispersed on aluminum oxide particles of a diameter range between 0.1 to 30 microm and "Pd-only" nanoparticles of 5-10 nm in diameter. The Pd/alpha-Al2O3 particles are very similar to particles emitted from catalytic converters by mechanical abrasion. The Pd-only particles are useful e.g. for exposure studies in which the presence of aluminum could lead to interferences when studying biological and biochemical effects. The sample preparation procedure of both series was optimized in order to achieve elemental particles with proper sizes and a narrow size distribution. The obtained particles were characterized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selective area diffraction (SAD), laser granulometry and graphite furnace atomic absorption spectrometry (GFAAS) for the measurement of Pd concentrations.

Motor vehicles are now equipped with exhaust gas catalytic converters containing rare metals, such as palladium (Pd), platinum and rhodium, as catalytic active materials, leading to significantly increased emission of these metals. Compared with platinum and rhodium, low concentrations of Pd have been shown to have more serious effects on cells and organisms. In the present study, uptake of Pd by barley and behaviour of Pd nanoparticles in nutrient solutions used to grow plants were observed in order to develop a model of Pd exposure of plant systems. Pd determination was performed using a selective separation and pre-concentration procedure, which was further developed for this study, and coupled to graphite furnace atomic absorption spectrometry. The results show that uptake of Pd depends on Pd particle diameter. Compared to other toxic metals, like mercury, Pd causes stress effects in leaves at lower concentrations in nutrient solutions. Furthermore, Pd particles are dissolved at different rates, depending on size, in the nutrient solution during plant growth.