Carbon nanotubes (CNTs) are increasingly being used in industrial applications, but their toxicological data in animals and humans are still sparse. To assess the toxicological dose-response of CNTs and to evaluate their pulmonary biopersistence, their quantification in tissues, especially lungs, is crucial. There are currently no reference methods or reference materials for low levels of CNTs in organic matter. Among existing analytical methods, few have been fully and properly validated. To remedy this, we undertook an inter-laboratory comparison on samples of freeze-dried pig lung, ground and doped with CNTs. Eight laboratories were enrolled to analyze 3 types of CNTs at 2 concentration levels each in this organic matrix. Associated with the different analysis techniques used (specific to each laboratory), sample preparation may or may not have involved prior digestion of the matrix, depending on the analysis technique and the material being analyzed. Overall, even challenging, laboratories' ability to quantify CNT levels in organic matter is demonstrated. However, CNT quantification is often overestimated. Trueness analysis identified effective methods, but systematic errors persisted for some. Choosing the assigned value proved complex. Indirect analysis methods, despite added steps, outperform direct methods. The study emphasizes the need for reference materials, enhanced precision, and organized comparisons.

Background An important aspect of nanomaterial (NM) risk assessment is establishing relationships between physicochemical properties and key events governing the toxicological pathway leading to adverse outcomes. The difficulty of NM grouping can be simplified if the most toxicologically relevant dose metric is used to assess the toxicological dose-response. Here, we thoroughly investigated the relationship between acute and chronic inflammation (based on polymorphonuclear neutrophil influx (% PMN) in lung bronchoalveolar lavage) and the retained surface area in the lung. Inhalation studies were performed in rats with three classes of NMs: titanium dioxides (TiO 2 ) and carbon blacks (CB) as poorly soluble particles of low toxicity (PSLT), and multiwall carbon nanotubes (MWCNTs). We compared our results to published data from nearly 30 rigorously selected articles. Results This analysis combined data specially generated for this work on three benchmark materials - TiO 2 P25, the CB Printex-90 and the MWCNT MWNT-7 - following subacute (4-week) inhalation with published data relating to acute (1-week) to subchronic (13-week) inhalation exposure to the classes of NMs considered. Short and long post-exposure recovery times (immediately after exposure up to more than 6 months) allowed us to examine both acute and chronic inflammation. A dose-response relationship across short-term and long-term studies was revealed linking pulmonary retained surface area dose (measured or estimated) and % PMN. This relationship takes the form of sigmoid curves, and is independent of the post-exposure time. Curve fitting equations depended on the class of NM considered, and sometimes on the duration of exposure. Based on retained surface area, long and thick MWCNTs (few hundred nm long with an aspect ratio greater than 25) had a higher inflammatory potency with 5 cm 2 /g lung sufficient to trigger an inflammatory response (at 6% PMN), whereas retained surfaces greater than 150 cm 2 /g lung were required for PSLT. Conclusions Retained surface area is a useful metric for hazard grouping purposes. This metric would apply to both micrometric and nanometric materials, and could obviate the need for direct measurement in the lung. Indeed, it could alternatively be estimated from dosimetry models using the aerosol parameters (rigorously determined following a well-defined aerosol characterization strategy).

Despite their numerous possible applications, the potential impact of carbon engineered nanomaterials (CEN) on human health, especially after inhalation exposure, is still questioned. Quantification of CEN in the respiratory system is a recurring issue and deposition and pulmonary biopersistence data are essential for toxicological evaluation. In this context, a fully validated standard method for CEN quantification in lung tissue is therefore imperative. The present method, based on the National Institute for Occupational Safety and Health 5040 method for atmospheric elemental and organic carbon analysis as well as on previous developments on biological matrices, involves a simple thermogravimetric analysis (TGA) of lyophilized samples, possibly preceded by a step of chemical digestion of the tissues depending on the nature of CEN investigated. The analytical method was validated for 4 CEN (carbon black as well as 3 long and thick or short and thin carbon nanotubes) for selectivity, linearity, detection and quantification limits, bias, and within-batch and between-batch precision. Calibration curves show linearity in the range of 1-40 mg/g lyophilized lung. Limits of detection for the different CEN range from 6 to 18 mu g in 20 mg dry test sample. On average, within-batch precision was kept below 20 and 10% for analysis with or without a prior digestion step, respectively, whereas the corresponding between-batch precision levels reached almost 20 and 15%, respectively. The method was successfully applied to toxicological investigations for the quantitative analysis of CEN contents in rat lung exposed by inhalation.

Hexavalent chromium (Cr(VI)) compounds are classified as carcinogenic to humans. Whereas chromium measurements in urine and plasma attest to the last few hours of total chromium exposure (all oxidation states of chromium), chromium in red blood cells (RBC) is attributable specifically to Cr(VI) exposure over the last few days. Before recommending Cr in RBC (CrIE) as a biological indicator of Cr(VI) exposure, in vivo studies must be undertaken to assess its reliability. The present study examines the kinetics of Cr(VI) in rat after a single intravenous dose of ammonium dichromate. Chromium levels were measured in plasma, red blood cells and urine. The decay of the chromium concentration in plasma is one-phase-like (with half-life time of 0.55 day) but still measurable two days post injection. The excretion of urinary chromium peaks between five and six hours after injection and shows large variations. Intra-erythrocyte chromium (CrIE) was very constant up to a minimum of 2 days and half-life time was estimated to 13.3 days. Finally, Cr(III) does not interfere with Cr(VI) incorporation in RBC. On the basis of our results, we conclude that, unlike urinary chromium, chromium levels in RBC are indicative of the amount of dichromate (Cr(VI)) in blood.

Abstract Beryllium (Be) is a metal mainly used in the form of alloys, with copper (Cu) and aluminium (Al) in the metal industry. Be is an extremely toxic element which must be handled under strictly controlled conditions to avoid health hazards to workers. Exposure to Be can be responsible for Chronic Beryllium Disease, a pulmonary disease preceded by sensitization to the element, and for lung cancer. The goals of the current study were to investigate Be exposure in France, to determine the airborne Be occupational exposure levels, the associated impregnation of employees through their urinary Be levels and the factors that might affect them, and finally to study a possible relation between biomonitoring and airborne data. Seventy-five volunteer subjects were thus atmospherically and biologically monitored in five French companies involved in Cu or Al casting, Al smelting, CuBe machining or AlBe general mechanical engineering. Airborne exposure was quite low with only 2% of measurements above the current French Occupational Exposure Limit (2 µg/m3); the population potentially most exposed was foundry workers. Impregnation with Be was also low with only 10% of quantified urinary Be measurements above the current German BAR value (0.05 µg/L). Using a Bayesian statistical modelling approach, the mean subject-specific urinary excretion of Be was found to increase significantly with the mean subject-specific exposure to airborne Be. From this relationship, and based on the current French OEL-8 hr, a Biological Limit Value of 0.08 µg/L (= 0.06 µg/g creatinine) could be proposed.

Exposure to titanium (Ti), via the ingestion of pigment grade Ti dioxide (TiO2), is commonplace for westernised populations. It may also occur as a consequence of metal ion leaching in subjects bearing Ti-containing implants. Accurate exposure analysis requires fit-for-purpose analytical methodology, especially for true measures of baseline levels. Inductively coupled plasma (ICP) techniques are, mainly, now used for bio-analysis of Ti. Since whole blood reference materials, certified for natural low levels of Ti, are not currently available, we undertook an inter-laboratory comparison of pooled human blood from fasted volunteers ±low level (+∼2.5 μg L-1) or high level (+10-20 μg L-1) spikes of soluble Ti or TiO2 particles. Seven established laboratories were enrolled to analyse the samples using ICP based techniques, which included at least one of ICP optical emission spectrometry (ICP-OES), high resolution ICP mass spectrometry (HR-ICP-MS), triple quadrupole ICP-MS (ICP-MS/MS) or single quadrupole ICP-MS (SQ-ICP-MS). Five laboratories diluted the blood for analysis whilst two performed acid digestion. Overall, we showed that the laboratories could, mostly, quantitatively detect modest levels of spiked Ti in blood. Markedly varying levels of Ti, however, were reported for the same baseline pooled sample (0.4-24.6 μg L-1) and, in this study, specificity was poor for SQ-ICP-MS. Digestion of samples caused sample contamination compromising limits of detection and accuracy, whilst simple dilution had no such problem, and remained linear in response for spikes with ionic and TiO2 particles. We conclude that measuring baseline levels of Ti in whole blood is challenging but should be readily achievable down to 0.5-1.5 μg L-1, if sample preparation avoids contamination and instrument techniques are used that negate polyatomic or isobaric interferences from the sample matrix. We also remind those relying upon Ti bio-analytical data for their experimental outcomes that (a) spiking and recovery experiments provide information only on linearity of detection but not at all on accuracy as this will not detect constant positive errors and that (b) biological standard materials for Ti generally contain high levels of the analyte and tend to mask baseline analytical errors. Caution may be required in interpreting the findings of some published Ti/TiO2 bio-exposure studies.

Notwithstanding potential neurotoxicity of inhaled titanium dioxide nanoparticles (TiO2 NPs), the toxicokinetics and consequences on blood-brain barrier (BBB) function remain poorly characterized. To improve risk assessment, we need to evaluate the impact on BBB under realistic environmental conditions and take into account vulnerability status such as age. 12–13 week and 19-month-old male rats were exposed by inhalation to 10 mg/m3 of TiO2 nano-aerosol (6 hrs/day, 5 day/week, for 4 weeks). We showed an age-dependent modulation of BBB integrity parameters suggesting increased BBB permeability in aging rats. This alteration was associated with a significant increase of cytokines/chemokines in the brain, including interleukin-1β, interferon-γ, and fractalkine as well as a decreased expression of synaptophysin, a neuronal activity marker. These observations, in absence of detectable titanium in the brain suggest that CNS-related effects are mediated by systemic-pathway. Moreover, observations in terms of BBB permeability and brain inflammation underline age susceptibility. Even if TiO2 NPs were not evidenced in the brain, we observed an association between the exposure to TiO2 NPs and the dysregulation of BBB physiology associated with neuroinflammation and decreased expression of neuronal activity marker, which was further exacerbated in the brain of aged animal’s.

The increasing industrial use of nanoparticles (NPs) has raised concerns about their impact on human health. Since aging and exposure to environmental factors are linked to the risk for developing pathologies, we address the question of TiO2 NPs toxicokinetics in the context of a realistic occupational exposure. We report the biodistribution of titanium in healthy young adults (12-13-week-old) and in elderly rats (19-month-old) exposed to 10 mg/m(3) of a TiO2 nanostructured aerosol 6 h/day, 5 days/week for 4 weeks. We measured Ti content in major organs using inductively coupled plasma mass spectrometry immediately and up to 180 days after the end of exposure. Large amounts of titanium were initially found in lung which were slowly cleared during the post-exposure period. From day 28, a small increase of Ti was found in the spleen and liver of exposed young adult rats. Such an increase was however never found in their blood, kidneys or brain. In the elderly group, translocation to extrapulmonary organs was significant at day 90. Ti recovered from the spleen and liver of exposed elderly rats was higher than in exposed young adults. These data suggest that TiO2 NPs may translocate from the lung to extra-pulmonary organs where they could possibly promote systemic health effects. (C) 2016 Published by Elsevier Ireland Ltd.

Le développement important des nanotechnologies est associé à l’exposition croissante de salariés et de la population générale et l’émergence de nouvelles nanoparticules amène à se poser la question des risques encourus pour la santé des personnes exposées. Les nanoparticules de dioxyde de titane (nano-TiO2) sont souvent présentes dans de nombreux produits d’usage courant (peinture, crème solaire, dentifrice, etc.). Bien que des études récentes commencent à évaluer l’impact de ces nanoparticules sur la santé, peu de travaux ont été consacrés à leurs conséquences sur le système nerveux central. La TSPO est une protéine faiblement exprimée dans le cerveau à l’état normal et surexprimée dans des modèles de neuroinflammation et constitue un biomarqueur de l’inflammation cérébrale. La TEP permet un suivi in vivo de la TSPO avec le 18F-DPA-714. Le but de ce travail est d’étudier les conséquences de l’exposition aux nano-TiO2 en TEP en utilisant le 18F-DPA-714 chez des rats jeunes-adultes. Les animaux (rats Fischer, 344, 300–320 g) sont exposés aux nano-TiO2 selon le protocole décrit par Gaté et al. (2017) (10 mg/m3, 6 h/jour, 5 jours par semaine pendant 4 semaines). Deux jours après l’exposition aux nano-TiO2, 6 rats (3 contrôles + 3 exposés) sont anesthésiés (isoflurane 1 à 2 %). Après injection de 18F-DPA-714 (47,6 ± 5,9 MBq), une acquisition dynamique est réalisée pendant 60 min (micro-PET/CT Inveon, Siemens). L’activité de la TSPO est mesurée dans 3 régions (cerveau, cervelet et bulbes olfactifs) et est exprimée en pourcentage de dose injectée par cm3 de tissu ( %ID/cm3). Les résultats montrent que, chez les contrôles, le 18F-DPA-714 se fixe rapidement dans le cerveau (0,46 ± 0,11), le cervelet (0,54 ± 0,07) et les bulbes olfactifs (0,52 ± 0,11) à 0,75 min après l’injection du radiotraceur. Cette radioactivité décroît rapidement dès 3 min et atteint 0,24 ± 0,01 % et 0,29 ± 0,05 à 40 min dans le cerveau et le cervelet, respectivement. Dans les bulbes olfactifs, l’élimination de 18F-DPA-714 est moins rapide (0,45 ± 0,03 à 40 min) confirmant une concentration plus élevée de la TSPO dans cette région. Chez les animaux exposés aux nano-TiO2, les résultats restent comparables à ceux obtenus chez les rats contrôles dans les 3 structures étudiées. Ce travail montre que, dans nos conditions expérimentales, l’exposition aux nano-TiO2 n’induit pas l’activation de la TSPO chez les rats jeunes-adultes, indiquant une absence de neuroinflammation cérébrale suite à cette exposition.

Many employees in the aluminum industry are exposed to a range of aluminum compounds by inhalation, and the presence of ultrafine particles in the workplace has become a concern to occupational health professionals. Some metal salts and metal oxides have been shown to enter the brain through the olfactory route, bypassing the blood-brain barrier, but few studies have examined whether aluminum compounds also use this pathway. In this context, we sought to determine whether aluminum was found in rat olfactory bulbs and whether its transfer depended on physicochemical characteristics such as solubility and granulometry. Aluminum salts (chloride and fluoride) and various nanometric aluminum oxides (13nm, 20nm and 40-50nm) were administered to rats by intranasal instillation through one nostril (10μg Al/30μL for 10days). Olfactory bulbs (ipsilateral and contralateral relative to instilled nostril) were harvested and the aluminum content was determined by graphite furnace atomic absorption spectrometry after tissue mineralization. Some transfer of aluminum salts to the central nervous system via the olfactory route was observed, with the more soluble aluminum chloride being transferred at higher levels than aluminum fluoride. No cerebral translocation of any of the aluminas studied was detected.

This paper presents a life history-oriented modeling framework to investigate residential location decisions as a two-tier process of location search and location choice. In the first tier, a stress-based location search model is developed by assuming that households search for a new location due to continual stress at different life-domains. The search model adopts a fuzzy logic-based modeling method that mimics the inter-dependencies between push and pull factors. In the second tier, a location choice model is developed that accommodates how location decisions interact with life-cycle events at different life-domains. The model utilizes a latent segmentation-based logit modeling technique to address the panel effect of the households’ housing career. The model results suggest that households in general show preference for larger lots, and locations closer to work place, transit stop, and health service. Location choice is found to be significantly influenced by the life-cycle events as well as the lead and lagged effects. For example, the birth of a child magnifies the need of larger lots. The life-history effects, however vary across two segments. Suburbanite households in segment two prefer larger lots following a job change; whereas, urbanite households in segment one show a negative relationship. The adjustment period for a job change is longer than that of addition of a new job. A longer adjustment time is also found in the case of the first time vehicle purchase than acquisition of a vehicle. Presence of children influences suburbanite households to reside closer to work place. Urbanite households with children prefer to live closer to school.

Chromium(VI) compounds are classified as carcinogenic to humans. Whereas chromium measurements in urine and whole blood (i.e., including plasma) are indicative of recent exposure, chromium in red blood cells (RBC) is attributable specifically to Cr(VI) exposure. Before recommending Cr in RBC as a biological indicator of Cr(VI) exposure, in-vitro studies must be undertaken to assess its reliability. The present study examines the relationship between the chromium added to a blood sample and that subsequently found in the RBC. After incubation of total blood with chromium, RBC were isolated, counted and their viability assessed. Direct analysis of chromium in RBC was conducted using Atomic Absorption Spectrometry. Hexavalent, but not trivalent Cr, was seen to accumulate in the RBC and we found a strong correlation between the Cr(VI) concentration added to a blood sample and the amount of Cr in RBC. This relationship appears to be independent of the chemical properties of the human blood samples (e.g., different blood donors or different reducing capacities). Even though in-vivo studies are still needed to integrate our understanding of Cr(VI) toxicokinetics, our findings reinforce the idea that a single determination of the chromium concentration in RBC would enable biomonitoring of critical cases of Cr(VI) exposure.

In order to draw appropriate conclusions about the possible adverse biological effects of titanium dioxide nanoparticles (TiO2—NPs), the so-called “dose?effect” relationship must be explored. This requires proper quantification of titanium in complex matrices such as animal organs for future toxicological studies. This study presents the method development for mineralizing TiO2—NPs for analysis of biological tissues. We compared the recovery and quantification limits of the four most commonly used mineralization methods for metal oxides. Microwave-assisted dissolution in an HNO3–HF mixture followed by H2O2 treatment produced the best results for a TiO2—NPs suspension, with 96 ± 8% recovery and a limit of quantification as low as 0.9 µg/L. This method was then used for the determination of titanium levels in tissue samples taken from rats. However, our tests revealed that even this method is not sensitive enough for quantifying titanium levels in single olfactory bulbs or hippocampus in control animals.

BACKGROUND:Notwithstanding increasing knowledge of titanium dioxide nanoparticles (TiO2 NPs) passing through biological barriers, their biodistribution to the central nervous system (CNS) and potential effects on blood-brain barrier (BBB) physiology remain poorly characterized.METHODS:Here, we report time-related responses from single-dose intravenous (IV) administration of 1 mg/kg TiO2 NPs to rats, with particular emphasis on titanium (Ti) quantification in the brain. Ti content in tissues was analyzed using inductively coupled plasma mass spectrometry. Integrity and functionality of the BBB as well as brain inflammation were characterized using a panel of methods including RT-PCR, immuno-histo chemistry and transporter activity evaluation.RESULTS:Biokinetic analysis revealed Ti biopersistence in liver, lungs and spleen up to one year after TiO2 NPs administration. A significant increase of Ti in the brain was observed at early end points followed by a subsequent decrease. In-depth analysis of Ti in the total brain demonstrated quantitative Ti uptake and clearance by brain microvasculature endothelial cells (BECs) with minimal translocation in the brain parenchyma. The presence of Ti in the BECs did not affect BBB integrity, despite rapid reversible modulation of breast cancer resistance protein activity. Ti biopersistence in organs such as liver was associated with significant increases of tight junction proteins (claudin-5 and occludin), interleukin 1β (IL-1β), chemokine ligand 1 (CXCL1) and γ inducible protein-10 (IP-10/CXCL10) in BECs and also increased levels of IL-1β in brain parenchyma despite lack of evidence of Ti in the brain. These findings mentioned suggest potential effect of Ti present at a distance from the brain possibly via mediators transported by blood. Exposure of an in vitro BBB model to sera from TiO2 NPs-treated animals confirmed the tightness of the BBB and inflammatory responses.CONCLUSION:Overall, these findings suggest the clearance of TiO2 NPs at the BBB with persistent brain inflammation and underscore the role of Ti biopersistence in organs that can exert indirect effects on the CNS dependent on circulating factors.

Cadmium and lead are persistent and ubiquitous metals that can cause several deleterious effects in living beings. Apoptosis and necrosis are two types of cell death that can be found after in vivo and in vitro exposure to these metals. In this study, isolated red blood cells from living captive Common buzzard (Buteo buteo) were exposed in vitro to different concentrations of lead, cadmium, and the mixture lead–cadmium in a proportion of 1:10 (similar to that found in previous field studies). Data obtained from dose–response curves were used to evaluate the interactive effects of metal mixtures on cell viability. In general, except for the exposure to NOEC, additivity was the most frequently observed response. As described in human, after in vitro exposure, lead was highly accumulated in buzzard erythrocytes, while cadmium accumulation was scarce. Finally, the type of cell death (apoptosis or necrosis) induced by the exposure to different concentrations of these heavy metals and their mixtures was evaluated in the red blood cells. Apoptosis was found to be the main type of cell death observed after cadmium and/or lead exposure. However, this exposure caused an increase in lysis or necrosis, especially if red blood cells were exposed to high doses.

The potential toxicity of beryllium at low levels of exposure means that a biological and/or air monitoring strategy may be required to monitor the exposure of subjects. The main objective of the work presented in this manuscript was to develop and validate a sensitive and reproducible method for determining levels of beryllium in human urine and to establish reference values in workers and in non-occupationally exposed people. A chelate of beryllium acetylacetonate formed from beryllium(II) in human urine was pre-concentrated on a SPE C18 cartridge and eluted with methanol. After drying the eluate, the residue was solubilised in nitric acid and analysed by atomic absorption spectrometry and/or inductively coupled plasma mass spectrometry. The proposed method is 4 to 100 times more sensitive than other methods currently in routine use. The new method was validated with the concordance correlation coefficient test for beryllium concentrations ranging from 10 to 100 ng/L. Creatinine concentration, urine pH, interfering compounds and freeze-thaw cycles were found to have only slight effects on the performance of the method (less than 6%). The effectiveness of the two analytical techniques was compared statistically with each other and to direct analysis techniques. Even with a detection limit of 0.6 ng/L (obtained with inductively coupled plasma mass spectrometry), the method is not sensitive enough to detect levels in non-occupationally exposed persons. The method performance does however appear to be suitable for monitoring worker exposure in some industrial settings and it could therefore be of use in biological monitoring strategies.