Spectroscopic Assessment of Platinum Group Elements of PM10 Particles Sampled in Three Different Areas in Jeddah, Saudi Arabia.

Platinum group elements (PGE) including Ru, Rh, Pt and Pd have been quantified in air particulate matter with an aerodynamic diameter equal or less than 10 microns (PM10) using inductively coupled plasma mass spectrometry (ICP-MS). PM10 aerosols have been collected from three sites representing various activities in Jeddah city, Saudi Arabia. These locations are residential site with heavy traffic, industrial site and heavy traffic and a light traffic site outside the city. To obtain reasonable data of the PGE concentrations, a group from 10 to 15 PM10 samples were collected every month. The annual and seasonal variation of the mass concentration of the PGE were demonstrated. In all locations, Pt and Pd were relatively higher than Ru and Rh possibly because their main use is in automobile catalytic converters. Concentrations of observed PGE in PM10 could be arranged in ascending order as: Rh < Ru < Pd < Pt. In case of Ru and Pt, there are clear similarities in terms of the overall mean concentrations at the sampling locations. Due to the high concentration of Ru, Rh and Pd at low traffic site, there are certainly other sources of these elements rather than vehicle catalytic converters. However, at the industrial/heavy traffic location, high concentrations of Ru were detected during February 2015. In addition, high Pt concentrations were also detected at the light traffic site during May 2015. Results indicate that Pt source in PM10 is mainly the automobile catalytic converters.

An assessment of the inhalation bioaccessibility of platinum group elements in road dust using a simulated lung fluid.

Metal enrichment of road dust is well characterized but available data on the bioaccessibility of metals in particle size fractions relevant to human respiratory health remain limited. The study goal was to investigate the bioaccessibility of platinum group elements (PGE), which are used as catalysts in automotive exhaust converters, in the inhalable fraction of road dust. Street sweepings were provided by the City of Toronto, Canada, collected as part of its Clean Roads to Clean Air program.The particle size relevance of road dust for inhalation exposures was confirmed using a laser diffraction particle size analyzer (mean Dx(50): 9.42 µm). Total PGE were determined in both bulk and inhalable fractions using nickel sulfide (NiS) fire-assay and instrumental neutron-activation analysis (INAA). PGE lung solubility was examined for the inhalable fraction using Gamble's extraction. Sample digests were co-precipitated with Te-Sn, to pre-concentrate and isolate PGE, prior to their measurement using inductively coupled plasma mass spectrometry (ICP-MS).Total PGE concentrations were enriched in the inhalable fraction of road sweepings. Geomean concentrations in the inhalable fraction were: palladium (Pd) (152 µg/kg), platinum (Pt) (55 µg/kg), rhodium (Rh) (21 µg/kg) and iridium (Ir) (0.23 µg/kg). Osmium (Os) concentrations were below the limit of detection (LOD). Bioaccessible PGEs (n = 16) using Gamble's solution were below LOD for Ir and ruthenium (Ru). For the remainder, the geomean % bioaccessibility was highest for platinum (16%), followed by rhodium (14%) and palladium (3.4%). This study provides evidence that PGE in road dust are bioaccessible in the human lung.

Global flows of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum.

This study, encompassing 231 countries and regions, quantifies the global transfer of three critical metals (neodymium, cobalt, and platinum) considered vital for low-carbon technologies by means of material flow analysis (MFA), using trade data (BACI) and the metal contents of trade commodities, resolving the optimization problem to ensure the material balance of the metals within each country and region. The study shows that in 2005 international trade led to global flows of 18.6 kt of neodymium, 154 kt of cobalt, and 402 t of platinum and identifies the main commodities and top 50 bilateral trade links embodying these metals. To explore the issue of consumption efficiency, the flows were characterized according to the technological level of each country or region and divided into three types: green ("efficient use"), yellow ("moderately efficient use"), and red ("inefficient use"). On this basis, the shares of green, yellow, and red flows in the aggregate global flow of Nd were found to be 1.2%, 98%, and 1.2%, respectively. For Co, the respective figures are 53%, 28%, and 19%, and for Pt 15%, 84%, and 0.87%. Furthermore, a simple indicator focusing on the composition of the three colored flows for each commodity was developed to identify trade commodities that should be prioritized for urgent technical improvement to reduce wasteful use of the metals. Based on the indicator, we discuss logical, strategic identification of the responsibilities and roles of the countries involved in the global flows.

Soil mesofauna as bioindicators to assess environmental disturbance at a platinum mine in South Africa.

South Africa is rich in mineral resources and is one of the leading raw material exporters in the world. Mining is essential for economic development, but also has detrimental environmental consequences in the form of chemical waste products which are being dumped as tailings material. The aim of this study was to establish whether mesofauna could be utilized to assess the influence of the tailings disposal facility on the surrounding soil environment. The sampled soil was chemically analyzed and the extracted mesofauna identified. High metal concentrations on the tailings dam (Cu, Cr and Ni), apparently had the greatest influence on the soil mesofauna. Only a few mite species were abundant at the two sites on the tailings dam, representing the prostigmatic-, cryptostigmatic- and the mesostigmatic-taxa. Metal pollution is evident in the sites on the tailings dam facility and the number of species generally increased towards the more natural environment.

Cisplatin-conjugated porous gelatin particles: assessment of optimal conditions for binding and release.

This study was designed to evaluate the optimal conditions for binding cisplatin and porous gelatin particles (PGPs) and to establish in vivo drug release pharmacokinetics. PGPs were immersed in cisplatin solutions under different conditions: concentration, immersion time, and temperature. Thereafter, PGPs were washed in distilled water to remove uncombined cisplatin and were then freeze-dried. The platinum concentration (PC) in the PGPs was then measured. For the in vivo release test, 50 mg/kg of the cisplatin-conjugated PGPs was implanted subcutaneously in the abdominal region of two rabbits. PCs in the blood were measured at different time intervals. PCs significantly increased in direct proportion to the concentration and immersion time (p < 0.01). Although PC increased at higher solution temperature, it was not a linear progression. For the in vivo release test, platinum was released from cisplatin-conjugated PGPs after 1 day, and the peak PC was confirmed 2 days after implantation. Platinum in the blood was detected until 7 days after implantation in one rabbit and 15 days after administration in the other rabbit. Platinum binding with PGPs increased with a higher concentration of cisplatin solution at a higher temperature over a longer duration of time. Release of cisplatin from cisplatin-conjugated PGPs was confirmed in vivo.

Targeted delivery of chemotherapeutic agents using improved radiosensitive liquid core microcapsules and assessment of their antitumor effect.

PURPOSE: Radiation-sensitive microcapsules composed of alginate and hyaluronic acid are being developed. We report the development of improved microcapsules that were prepared using calcium- and yttrium-induced polymerization. We previously reported on the combined antitumor effect of carboplatin-containing microcapsules and radiotherapy. METHODS AND MATERIALS: We mixed a 0.1% (wt/vol) solution of hyaluronic acid with a 0.2% alginate solution. Carboplatin (l mg) and indocyanine green (12.5 microg) were added to this mixture, and the resultant material was used for capsule preparation. The capsules were prepared by spraying the material into a mixture containing a 4.34% CaCl(2) solution supplemented with 0-0.01% yttrium. These capsules were irradiated with single doses of 0.5, 1.0, 1.5, or 2 Gy (60)Co gamma-rays. Immediately after irradiation, the frequency of microcapsule decomposition was determined using a microparticle-induced X-ray emission camera. The amount of core content released was estimated by particle-induced X-ray emission and colorimetric analysis with 0.25% indocyanine green. The antitumor effect of the combined therapy was determined by monitoring its effects on the diameter of an inoculated Meth A fibrosarcoma. RESULTS: Microcapsules that had been polymerized using a 4.34% CaCl(2) solution supplemented with 5.0 x 10(-3)% (10(-3)% meant or 10%(-3)) yttrium exhibited the maximal decomposition, and the optimal release of core content occurred after 2-Gy irradiation. The microcapsules exhibited a synergistic antitumor effect combined with 2-Gy irradiation and were associated with reduced adverse effects. CONCLUSION: The results of our study have shown that our liquid core microcapsules can be used in radiotherapy for targeted delivery of chemotherapeutic agents.

On the re-assessment of the optimum conditions for the determination of platinum, palladium and rhodium in environmental samples by electrothermal atomic absorption spectrometry and microwave digestion.

The experimental conditions for the determination of platinum, palladium and rhodium by graphite furnace atomic absorption spectrometry (GFAAS) are re-assessed. A certified material (BCR-723) was used as a working sample and analyzed using various extraction and atomization procedures in order to find the optimal experimental conditions that enable the quantitative and reproducible detection of platinum, palladium and rhodium in environmental matrices. Evidently, literature observations regarding the atomization conditions were proven fairly adequate. However, the provision of the optimum extraction conditions revealed several parameters that lie behind the reported uncertainties. The appropriate combination between extraction conditions and atomization programs afforded a considerable improvement in the recoveries and analytical features of platinum, palladium and rhodium determination with GFAAS. Cross-examination of the analytical data with various CRMs (certified reference materials) was used to validate the robustness of the method in heterogeneous matrices bearing different element levels. Under the optimum experimental conditions the method permits the determination at concentrations as low as (LOD(3S/N)) 1.9 ng g(-1), 0.45 ng g(-1) and 0.6 ng g(-1) for Pt, Pd and Rh, respectively affording recoveries in the range of 93-101%. The method was successfully applied to the assessment of Pt, Pd and Rh accumulation in real road dust and soil samples in Greece.

Assessment of the FDA backgrounder on platinum in silicone breast implants: implications for public health policy.

A recent report by the U.S. Food and Drug Administration reviewed the literature on the subject of platinum in silicone gel-filled breast implants. In this study the author evaluates the FDA report for scientific accuracy and impartiality, and provides relevant discussions on financial conflicts of interest, an Institute of Medicine report, and public health policy. The study suggests that the FDA used discredited scientific practices in compiling its report. Reports by regulatory agencies should be scientifically accurate, with no partiality to industry. The current policy of one-way information flow from the FDA directly to those being informed needs to be revised. Greater importance should be placed on studies in which authors have no financial conflicts of interest.

An evaluation of the environmental and health effects of vehicle exhaust catalysts in the UK.

Since 1993, all new gasoline-engine automobiles in the United Kingdom have been supplied with three-way vehicle exhaust catalytic converters (VECs) containing platinum, palladium, and rhodium, to comply with European Commission Stage I limits on emissions of regulated pollutants: carbon monoxide, hydrocarbons, and oxides of nitrogen. We conducted a physical and economic evaluation of the environmental and health benefits from a reduction in emissions through this mandated environmental technology against the costs, with reference to urban areas in Great Britain. We made both an ex post assessment--based on available data to 1998--and an ex ante assessment--projected to 2005, the year when full penetration of VECs into the fleet is expected. Substantial health benefits in excess of the costs of VECs were indicated: By 1998 the estimated net societal health benefits were approximately 500 million British pounds, and by 2005 they were estimated to rise to as much as 2 billion British pounds. We also found through environmental surveys that although lead in road dust has fallen by 50% in urban areas, platinum accumulations near roads have risen significantly, up to 90-fold higher than natural background levels. This rapid accumulation of platinum suggests further monitoring is warranted, although as yet there is no evidence of adverse health effects.

A comparison between EGS4 and MCNP computer modeling of an in vivo X-ray fluorescence system.

The Monte Carlo computer codes EGS4 and MCNP were used to develop a theoretical model of a 180 degrees geometry in vivo X-ray fluorescence system for the measurement of platinum concentration in head and neck tumors. The model included specification of the photon source, collimators, phantoms and detector. Theoretical results were compared and evaluated against X-ray fluorescence data obtained experimentally from an existing system developed by the Swansea In Vivo Analysis and Cancer Research Group. The EGS4 results agreed well with the MCNP results. However, agreement between the measured spectral shape obtained using the experimental X-ray fluorescence system and the simulated spectral shape obtained using the two Monte Carlo codes was relatively poor. The main reason for the disagreement between the results arises from the basic assumptions which the two codes used in their calculations. Both codes assume a "free" electron model for Compton interactions. This assumption will underestimate the results and invalidates any predicted and experimental spectra when compared with each other.

Computer aided design of a polarised source for in vivo X-ray fluorescence analysis.

A system has been developed which uses Monte Carlo computer simulations to aid the design and optimisation of a polarised source for in vivo X-ray fluorescence (XRF) analysis of heavy metals: The system is based on a version of the Monte Carlo code EGS4 which includes polarised photon interactions, running on a personal computer. The code was used to construct a model of a clinical polarised XRF system (based on a 300 kV therapy X-ray source) under development at Swansea for the measurement of Pt-based chemotherapy drugs in head and neck tumours. Several simulations were performed to investigate the variation of XRF measurement sensitivity with the material composition and geometry of the system components. Pt XRF spectra generated by the model were found to be in good agreement with experimental data. The optimum operating voltage for the system, predicted by the simulations and confirmed by experiment, was approx. 200 kV. The accuracy of the results obtained to date indicates that this technique will greatly facilitate future design and optimisation studies of a wide variety of XRF systems.

A new Monte Carlo program for computing low-energy gamma- and X-ray propagation in an axially-symmetric XRF system. Swansea In Vivo Analysis and Cancer (SIVAC) Group.

Annular XRF systems, using backscattering geometry, have advantages of convenience of use, but it is difficult to predict their sensitivity to concentrations of heavy metals ta different depths, or the contribution of scattered radiation to the background. A Monte Carlo program has therefore been developed to carry out calculations of this type. Several variance-reduction techniques are included. Preliminary results for the detection of platinum are given.

Optimization of a polarized source for in vivo x-ray fluorescence analysis of platinum and other heavy metals.

The Monte Carlo method was used to optimize a polarized photon source for the x-ray fluorescence analysis of platinum and other heavy metals in vivo. The source consisted of a 140 kVp, 25 mA x-ray tube with the photons plane-polarized by 90 degrees scattering. The use of plane-polarized photons results in a significant reduction in background when the fluorescent radiation is measured along the direction of polarization. A Monte Carlo computer programme was written to simulate the production and interaction of polarized photons in order to determine the optimal polarizing material and dimensions, together with beam width and geometrical arrangement of source, polarizer and beam collimators. Calculated photon energy distributions are compared with experimental data to test the validity of the model. The best configuration of the polarization system for the in vivo analysis of platinum consisted of a 20 mm Cu polarizing block with a secondary collimator subtending a 0.1 radian angle at the polarizer.

[Assessment of tissue platinum concentration, X-ray computed tomogram, and microangiography after CDDP intraperitoneal administration in VX2 ovarian tumor].

After intraperitoneal administration of cis-diamine-dichloroplatinum, tissue Pt concentration, dynamic CT, and microangiography were estimated in white rabbit model having been transplanted with VX2 ovarian tumor. The high Pt concentration resulting from CDDP intraperitoneal administration was recognized in kidney, liver, and VX2 ovarian tumor. CT scans demonstrated that CDDP administration inhibited the development of VX2 tumor, revealing the appearance of small areas with no enhancement corresponding to necrotic regions in the tumor external rim. A tumor time-density curve showed a significantly delayed washout of the excretory phase following CDDP administration. Regarding microangiography models, tumor vessels of less than 30 microns decreased. It was suggested that the tumor microcirculation diminished because of the increased tissue pressure concomitant with tumor necrosis.