Development and Validation of a Method for the Detection of Titanium Dioxide Particles in Human Tissue with Single Particle ICP-MS

Human biomonitoring studies to determine total titanium (total-Ti) and titanium dioxide (TiO2) particles require very sensitive inductively coupled plasma high resolution mass spectrometry (ICP-HRMS) methods. The result of such studies can only be reliably when used in a risk assessment if the analytical methods are fully validated, as reported here for human liver and spleen. For total-Ti an acidic HNO3/HF digestion was applied, followed by ICP-HRMS analysis of the acidic digests. For TiO2 particles a two-step digestion procedure was developed. In the first step the formaldehyde-fixed tissue was depolymerized and in the second step an enzymatic digestion was performed. Sample digests were analyzed with ICP-HRMS operated in single particle mode to detect TiO2 particles. Both methods were validated according to NEN 7777 using a scheme of duplicate analysis over an eight day period. Detection limits for total-Ti and TiO2 particles were 0.01 and 0.005 mg Ti/kg with a particle size quantification limit of 85 nm for TiO2 particles. Repeatability and reproducibility were 24% and 31% for the total titanium concentration, 22% and 39% for the particle titanium concentration, and 29% and 24% for the titanium dioxide particle size. In total 30 human tissue samples were analyzed with the developed and validated method. The results show a total-Ti content in the range of 0.02-0.09 mg Ti/kg in liver and 0.02-0.4 mg Ti/kg in spleen. The concentrations of particle TiO2 ranged from 0.01-0.08 mg Ti/kg in liver and from 0.01-0.1 mg Ti/kg in spleen. On the average, particle TiO2 explained up to 67% of the total-Ti concentrations. The detected TiO2 particles had a particle size range of 85 to 720 nm

Detection of nanoparticles in Dutch surface waters

Nano-enabled consumer products are a likely source of nanoparticles in the environment and a number of studies have shown the release of nanoparticles from commercial products. Predicted environmental concentrations have been calculated but there is a need for real measurement data to validate these calculations. However, the detection of engineered nanoparticles in environmental matrices is challenging because of the low predicted environmental concentrations which may be in the ng/L range. In this study nanosized Ag, CeO2 and TiO2 have been measured in multiple surface water samples collected along the rivers Meuse and IJssel in the Netherlands using single-particle ICP-MS as measurement technique. Validation of the analytical method showed its capability to quantitatively determine nanoparticles at low concentrations. Concentration mass detection limits for Ag, CeO2 and TiO2 were 0.1 ng/L, 0.05 ng/L and 10 ng/L respectively. Size detection limits for Ag, CeO2 and TiO2 were 14, 10 and 100 nm. The results of the study confirm the presence of nano-sized Ag and CeO2 particles and micro-sized TiO2 particles in these surface waters. n-Ag was present in all samples in concentrations ranging from 0.3 to 2.5 ng/L with an average concentration of 0.8 ng/L and an average particle size of 15 nm. n-CeO2 was found in all samples with concentrations ranging from 0.4 to 5.2 ng/L with an average concentration of 2.7 ng/L and an average particle size of 19 nm. Finally, μ-TiO2 was found in all samples with a concentration ranging from 0.2 to 8.1 μg/L with an average concentration of 3.1 μg/L and an average particle size of 300 nm. The particle sizes that were found are comparable with the particle sizes that are used in nanomaterial applications and consumer products. The nanoparticle concentrations confirm the predicted environmental concentrations values in water for all three nanoparticles.</p

Development and Validation of a Method for the Detection of Titanium Dioxide Particles in Human Tissue with Single Particle ICP-MS

Human biomonitoring studies to determine total titanium (total-Ti) and titanium dioxide (TiO2) particles require very sensitive inductively coupled plasma high resolution mass spectrometry (ICP-HRMS) methods. The result of such studies can only be reliably when used in a risk assessment if the analytical methods are fully validated, as reported here for human liver and spleen. For total-Ti an acidic HNO3/HF digestion was applied, followed by ICP-HRMS analysis of the acidic digests. For TiO2 particles a two-step digestion procedure was developed. In the first step the formaldehyde-fixed tissue was depolymerized and in the second step an enzymatic digestion was performed. Sample digests were analyzed with ICP-HRMS operated in single particle mode to detect TiO2 particles. Both methods were validated according to NEN 7777 using a scheme of duplicate analysis over an eight day period. Detection limits for total-Ti and TiO2 particles were 0.01 and 0.005 mg Ti/kg with a particle size quantification limit of 85 nm for TiO2 particles. Repeatability and reproducibility were 24% and 31% for the total titanium concentration, 22% and 39% for the particle titanium concentration, and 29% and 24% for the titanium dioxide particle size. In total 30 human tissue samples were analyzed with the developed and validated method. The results show a total-Ti content in the range of 0.02-0.09 mg Ti/kg in liver and 0.02-0.4 mg Ti/kg in spleen. The concentrations of particle TiO2 ranged from 0.01-0.08 mg Ti/kg in liver and from 0.01-0.1 mg Ti/kg in spleen. On the average, particle TiO2 explained up to 67% of the total-Ti concentrations. The detected TiO2 particles had a particle size range of 85 to 720 nm

Oral intake of added titanium dioxide and its nanofraction from food products, food supplements and toothpaste by the Dutch population

Titanium dioxide (TiO2) is commonly applied to enhance the white colour and brightness of food products. TiO2 is also used as white pigment in other products such as toothpaste. A small fraction of the pigment is known to be present as nanoparticles (NPs). Recent studies with TiO2 NPs indicate that these particles can have toxic effects. In this paper, we aimed to estimate the oral intake of TiO2 and its NPs from food, food supplements and toothpaste in the Dutch population aged 2 to over 70 years by combining data on food consumption and supplement intake with concentrations of Ti and TiO2 NPs in food products and supplements. For children aged 2–6 years, additional intake via ingestion of toothpaste was estimated. The mean long-term intake to TiO2 ranges from 0.06 mg/kg bw/day in elderly (70+), 0.17 mg/kg bw/day for 7–69-year-old people, to 0.67 mg/kg bw/day in children (2–6 year old). The estimated mean intake of TiO2 NPs ranges from 0.19 μg/kg bw/day in elderly, 0.55 μg/kg bw/day for 7–69-year-old people, to 2.16 μg/kg bw/day in young children. Ninety-fifth percentile (P95) values are 0.74, 1.61 and 4.16 μg/kg bw/day, respectively. The products contributing most to the TiO2 intake are toothpaste (in young children only), candy, coffee creamer, fine bakery wares and sauces. In a separate publication, the results are used to evaluate whether the presence of TiO2 NPs in these products can pose a human health risk

Oral intake of added titanium dioxide and its nanofraction from food products, food supplements and toothpaste by the Dutch population

Titanium dioxide (TiO2) is commonly applied to enhance the white colour and brightness of food products. TiO2 is also used as white pigment in other products such as toothpaste. A small fraction of the pigment is known to be present as nanoparticles (NPs). Recent studies with TiO2 NPs indicate that these particles can have toxic effects. In this paper, we aimed to estimate the oral intake of TiO2 and its NPs from food, food supplements and toothpaste in the Dutch population aged 2 to over 70 years by combining data on food consumption and supplement intake with concentrations of Ti and TiO2 NPs in food products and supplements. For children aged 2–6 years, additional intake via ingestion of toothpaste was estimated. The mean long-term intake to TiO2 ranges from 0.06 mg/kg bw/day in elderly (70+), 0.17 mg/kg bw/day for 7–69-year-old people, to 0.67 mg/kg bw/day in children (2–6 year old). The estimated mean intake of TiO2 NPs ranges from 0.19 μg/kg bw/day in elderly, 0.55 μg/kg bw/day for 7–69-year-old people, to 2.16 μg/kg bw/day in young children. Ninety-fifth percentile (P95) values are 0.74, 1.61 and 4.16 μg/kg bw/day, respectively. The products contributing most to the TiO2 intake are toothpaste (in young children only), candy, coffee creamer, fine bakery wares and sauces. In a separate publication, the results are used to evaluate whether the presence of TiO2 NPs in these products can pose a human health risk.</p

Silicon dioxide and titanium dioxide particles found in human tissues.

Silicon dioxide (silica, SiO2, SAS) and titanium dioxide (TiO2) are produced in high volumes and applied in many consumer and food products. As a consequence, there is a potential human exposure and subsequent systemic uptake of these particles. In this study we show the characterization and quantification of both total silicon (Si) and titanium (Ti), and particulate SiO2 and TiO2 in postmortem tissue samples from 15 deceased persons. Included tissues are liver, spleen, kidney and the intestinal tissues jejunum and ileum. Low-level analysis was enabled by the use of fully validated sample digestion methods combined with (single particle) inductively coupled plasma high resolution mass spectrometry techniques (spICP-HRMS). The results show a total-Si concentration ranging from <2 to 191 mg Si/kg (median values of 5.8 (liver), 9.5 (spleen), 7.7 (kidney), 6.8 (jejunum), 7.6 (ileum) mg Si/kg) while the particulate SiO2 ranged from <0.2 to 25 mg Si/kg (median values of 0.4 (liver), 1.0 (spleen), 0.4 (kidney), 0.7 (jejunum, 0.6 (ileum) mg Si/kg), explaining about 10% of the total-Si concentration. Particle sizes ranged from 150 to 850 nm with a mode of 270 nm. For total-Ti the results show concentrations ranging from <0.01 to 2.0 mg Ti/kg (median values of 0.02 (liver), 0.04 (spleen), 0.05 (kidney), 0.13 (jejunum), 0.26 (ileum) mg Ti/kg) while particulate TiO2 concentrations ranged from 0.01 to 1.8 mg Ti/kg (median values of 0.02 (liver), 0.02 (spleen), 0.03 (kidney), 0.08 (jejunum), 0.25 (ileum) mg Ti/kg). In general, the particulate TiO2 explained 80% of the total-Ti concentration. This indicates that most Ti in these organ tissues is particulate material. The detected particles comprise primary particles, aggregates and agglomerates, and were in the range of 50-500 nm with a mode in the range of 100-160 nm. About 17% of the detected TiO2 particles had a size <100 nm. The presence of SiO2 and TiO2 particles in liver tissue was confirmed by scanning electron microscopy with energy dispersive X-ray spectrometry

Silicon dioxide and titanium dioxide particles found in human tissues

Silicon dioxide (silica, SiO2, SAS) and titanium dioxide (TiO2) are produced in high volumes and applied in many consumer and food products. As a consequence, there is a potential human exposure and subsequent systemic uptake of these particles. In this study we show the characterization and quantification of both total silicon (Si) and titanium (Ti), and particulate SiO2 and TiO2 in postmortem tissue samples from 15 deceased persons. Included tissues are liver, spleen, kidney and the intestinal tissues jejunum and ileum. Low-level analysis was enabled by the use of fully validated sample digestion methods combined with (single particle) inductively coupled plasma high resolution mass spectrometry techniques (spICP-HRMS). The results show a total-Si concentration ranging from 2 ranged from 2 concentrations ranged from 0.01 to 1.8 mg Ti/kg (median values of 0.02 (liver), 0.02 (spleen), 0.03 (kidney), 0.08 (jejunum), 0.25 (ileum) mg Ti/kg). In general, the particulate TiO2 explained 80% of the total-Ti concentration. This indicates that most Ti in these organ tissues is particulate material. The detected particles comprise primary particles, aggregates and agglomerates, and were in the range of 50–500 nm with a mode in the range of 100–160 nm. About 17% of the detected TiO2 particles had a size 2 and TiO2 particles in liver tissue was confirmed by scanning electron microscopy with energy dispersive X-ray spectrometry.</p

Hybrid imaging labels : Providing the link between mass spectrometry-based molecular pathology and theranostics

Development of theranostic concepts that include inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) imaging can be hindered by the lack of a direct comparison to more standardly used methods for in vitro and in vivo evaluation; e.g. fluorescence or nuclear medicine. In this study a bimodal (or rather, hybrid) tracer that contains both a fluorescent dye and a chelate was used to evaluate the existence of a direct link between mass spectrometry (MS) and in vitro and in vivo molecular imaging findings using fluorescence and radioisotopes. At the same time, the hybrid label was used to determine whether the use of a single isotope label would allow for MS-based diagnostics. Methods: A hybrid label that contained both a DTPA chelate (that was coordinated with either 165Ho or 111In) and a Cy5 fluorescent dye was coupled to the chemokine receptor 4 (CXCR4) targeting peptide Ac-TZ14011 (hybrid-Cy5-Ac-TZ4011). This receptor targeting tracer was used to 1) validate the efficacy of (165Ho-based) mass-cytometry in determining the receptor affinity via comparison with fluorescence-based flow cytometry (Cy5), 2) evaluate the microscopic binding pattern of the tracer in tumor cells using both fluorescence confocal imaging (Cy5) and LA-ICP-MS-imaging (165Ho), 3) compare in vivo biodistribution patterns obtained with ICP-MS (165Ho) and radiodetection (111In) after intravenous administration of hybrid-Cy5-Ac-TZ4011 in tumor-bearing mice. Finally, LA-ICP-MS-imaging (165Ho) was linked to fluorescence-based analysis of excised tissue samples (Cy5). Results: Analysis with both mass-cytometry and flow cytometry revealed a similar receptor affinity, respectively 352 ± 141 nM and 245 ± 65 nM (p = 0.08), but with a much lower detection sensitivity for the first modality. In vitro LA-ICP-MS imaging (165Ho) enabled clear discrimination between CXCR4 positive and negative cells, but fluorescence microscopy was required to determine the intracellular distribution. In vivo biodistribution patterns obtained with ICP-MS (165Ho) and radiodetection (111In) of the hybrid peptide were shown to be similar. Assessment of tracer distribution in excised tissues revealed the location of tracer uptake with both LA-ICP-MS-imaging and fluorescence imaging

Transfer Study of Silver Nanoparticles in Poultry Production

Silver nanoparticles (AgNPs) are of interest due to their antimicrobial activity and are seen as potential candidates to replace antibiotics in animal husbandry. A few studies have focused on this new application, but they lack any considerations about residual accumulation of AgNPs in edible animal tissues and animal products. In this research, a 22 day in vivo study was carried out by oral administration of 20 nm spherical PVP coated AgNPs to hens. Six doses of approximately 1 mg kg-1 of AgNPs-PVP each were administered to animals throughout the experimentation. Atomic absorption spectroscopy (AAS) was used for quantitative determination of residual total Ag in different organs and matrices. The analyses showed that Ag accumulates in livers (concentration ranging from 141 μg kg-1 to 269 μg kg-1) and yolks (concentration ranging from 20 μg kg-1 to 49 μg kg-1) but not in muscles, kidneys, and albumen belonging to hens of the treated group (tG2). Ag was not detected in animals of the control group (uG1) (i.e., total Ag < LOD = 10 μg kg-1). Single particle inductively coupled plasma mass spectrometry (spICP-MS) and scanning electron microscopy with energy dispersive X-ray detection (SEM-EDX) were employed to elucidate the presence of AgNPs in livers and yolks belonging to tG2 animals. spICP-MS highlighted that part of residual Ag found in livers (about 5-20%) is in NP form with an average dimension of approximately 20 nm. SEM-EDX technique confirmed the presence of AgNPs only in livers of treated animals. The results show that feeding AgNPs to hens may become a source of consumer exposure to AgNPs. As far as we know this is the first study showing transfer of AgNPs or reaction products thereof from animal feed to animal products.</p

Oral intake of added titanium dioxide and its nanofraction from food products, food supplements and toothpaste by the Dutch population

<p>Titanium dioxide (TiO₂) is commonly applied to enhance the white colour and brightness of food products. TiO₂ is also used as white pigment in other products such as toothpaste. A small fraction of the pigment is known to be present as nanoparticles (NPs). Recent studies with TiO₂ NPs indicate that these particles can have toxic effects. In this paper, we aimed to estimate the oral intake of TiO₂ and its NPs from food, food supplements and toothpaste in the Dutch population aged 2 to over 70 years by combining data on food consumption and supplement intake with concentrations of Ti and TiO₂ NPs in food products and supplements. For children aged 2–6 years, additional intake via ingestion of toothpaste was estimated. The mean long-term intake to TiO₂ ranges from 0.06 mg/kg bw/day in elderly (70+), 0.17 mg/kg bw/day for 7–69-year-old people, to 0.67 mg/kg bw/day in children (2–6 year old). The estimated mean intake of TiO₂ NPs ranges from 0.19 μg/kg bw/day in elderly, 0.55 μg/kg bw/day for 7–69-year-old people, to 2.16 μg/kg bw/day in young children. Ninety-fifth percentile (P95) values are 0.74, 1.61 and 4.16 μg/kg bw/day, respectively. The products contributing most to the TiO₂ intake are toothpaste (in young children only), candy, coffee creamer, fine bakery wares and sauces. In a separate publication, the results are used to evaluate whether the presence of TiO₂ NPs in these products can pose a human health risk.</p