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The ubiquitous occurrence of microplastics (MPs) in the environment and the use of plastics in packaging materials result in the presence of MPs in the food chain and the exposure of consumers. Yet, no fully validated analytical method is available for microplastic (MP) quantification, thereby preventing the reliable estimation of the level of exposure and, ultimately, the assessment of the food safety risks associated with MP contamination. In this study, a novel approach is presented that exploits interactive artificial intelligence tools to enable the automation of MP analysis. An integrated method for the analysis of MPs in bottled water based on Nile Red staining and fluorescent microscopy was developed and validated, featuring a partial interrogation of the filter and a fully automated image processing workflow based on a Random Forest classifier, thereby boosting the analysis speed. The image analysis provided particle count, size and size distribution of the MPs. From these data, a rough estimation of the mass of the individual MPs, and consequently of the MP mass concentration in the sample, could be obtained as well. Critical materials, method performance characteristics, and final applicability were studied in detail. The method showed to be highly sensitive in sizing MPs down to 10 µm, with a particle count limit of detection and quantification of 28 and 85 items/500 mL, respectively. Linearity of mass concentration determined between 10 ppb and 1.5 ppm showed a regression coefficient of (R2) of 0.99. Method precision was demonstrated by repeatability of 9 - 16% RSD (n = 7) and within-laboratory reproducibility of 15 - 27 % RSD (n = 21). Accuracy based on recovery was 92 ± 15 % and 98 ± 23 % at a level of 0.1 and 1.0 ppm, respectively. The quantitative performance characteristics thus obtained complied with regulatory requirements. Finally, the method was successfully applied to the analysis of twenty commercial samples of bottled water, with and without gas and flavor additives, yielding results ranging from values below the limit of detection to 7237 (95% CI [6456, 8088]) items/500 mL.

Synthetic amorphous silica (SAS) is applied in food products as food additive E 551. It consists of constituent amorphous silicon dioxide (SiO2) nanoparticles that form aggregates and agglomerates. We reviewed recent oral toxicity studies with SAS. Some of those report tissue concentrations of silicon (Si). The results of those studies were compared with recently determined tissue concentrations of Si (and Si-particles) in human postmortem tissues. We noticed inconsistent results of the various toxicity studies regarding toxicity and reported tissue concentrations, which hamper the risk assessment of SAS. A broad range of Si concentrations is reported in control animals in toxicity studies. The Si concentrations found in human postmortem tissues fall within this range. On the other hand, the mean concentration found in human liver is higher than the reported concentrations causing liver effects in some animal toxicity studies after oral exposure to SAS. Also higher liver concentrations are observed in other, negative animal studies. Those inconsistencies could be caused by the presence of other Si-containing chemical substances or particles (which potentially also includes background SAS) and/or different sample preparation and analytical techniques that were used. Other factors which could explain the inconsistencies in outcome between the toxicity studies are the distinct SAS used and different dosing regimes, such as way of administration (dietary, via drinking water, oral gavage), dispersion of SAS and dose. More research is needed to address these issues and to perform a proper risk assessment for SAS in food. The current review will help to progress research on the toxicity of SAS and the associated risk assessment.

The advancement of analytical methods for nanoparticle measurements is critical both for the growing industrial exploitation of engineered nanoparticles and for developing robust strategies to understand and control the concentration of nanomaterials in humans and the environment. For high value nanoparticles, the measurement of nanoparticle number concentration in a liquid directly impacts the ability to assess the scale and reproducibility of the production process, it allows optimisation of efficiency and supports regulatory compliance. This measurement is also useful to monitor and control the intentional or accidental release of engineered nanoparticles into the environment at the production plant, as well as by end-users., peer-reviewed

Polybrominated diphenylethers (PBDEs), hexabromocyclododecanes (HBCDDs) and tetrabromobisphenol A (TBBPA) were monitored in various foods from terrestrial and aquatic animal origin (>850 samples), collected in the Netherlands between 2009 and 2014. The terrestrial samples included meat/fat from 7 animal species (including bovines, pigs, broilers and sheep), bovine milk and hen eggs. Dominant PBDE congeners in these samples were BDE-47, -99, -100, -153 and -183. The meat/fat generally contained the highest ∑PBDE concentrations compared to eggs and milk, with meat from deer, horse and sheep containing the highest concentrations. Generally declining ∑PBDE concentrations were observed between 2009 and 2014, however, this was only significant in pig meat and hen's eggs. The aquatic samples included fillets from 18 species (including herring, haddock and salmon), brown crab parts, shrimp and mussels, and the highest ∑PBDE concentrations were seen in body parts of brown crab, herring, mackerel, salmon and sea bass (on wet weight basis). Patterns generally contained more congeners (i.e., BDE-28, -49 and -66) additional to the aforementioned congeners found in terrestrial samples. Herring, sea bass and brown crab (body parts) contained among the highest PBDE concentrations. TBBPA was only detected in 3 individual samples (bovine and broiler meat and haddock), while α-HBCDD was the dominant diastereomer detected in several terrestrial and aquatic samples. When detected, TBBPA and HBCDD concentrations were generally in the same order as ∑PBDE concentrations in the same sample types.

Enteric methane (CH4) is the main source of greenhouse gas emissions from ruminants. The red seaweeds Asparagopsis taxiformis (AT) and Asparagopsis armata contain halogenated compounds, including bromoform (CHBr3), which may strongly decrease enteric CH4 emissions. Bromoform is known to have several toxicological effects in rats and mice and is quickly excreted by the animals. This study investigated the transfer of CHBr3 present in AT to milk, urine, feces, and animal tissue when incorporated in the diet of dairy cows. Twelve lactating Holstein-Friesian dairy cows were randomly assigned to three treatment groups, representing the target dose (low), 2× target dose (medium), and 5× target dose (high). The adaptation period lasted seven days, and subsequently cows were fed AT for 22 days maximally. The transfer of CHBr3 to the urine at days 1 and 10 (10–148 µg/L) was found with all treatments. On day 1, CHBr3 was detected in the milk of most cows in the low and medium treatment groups (9.1 and 11 µg/L, respectively), and detected in the milk of one cow in the high treatment group on day 9 (35 µg/L). Bromoform was not detected in milk and urine at day 17, nor at concentrations above the detection limit in feces and collected animal tissues. Two animals (low) were sacrificed, and their rumen wall showed abnormalities. Upon histological examination, signs of inflammation became visible. Animals regularly refused the feed or distinctively selected against AT. In conclusion, within the confines of the present experiment, CHBr3 does not accumulate in animal tissue, but can be excreted in urine and milk.

Titanium dioxide is a white colourant authorised as food additive E 171 in the EU, where it is used in a range of alimentary products. As these materials may contain a fraction of particulates with sizes below 100 nm and current EU regulation requires specific labelling of food ingredient to indicate the presence of engineered nanomaterials there is now a need for standardised and validated methods to appropriately size and quantify (nano)particles in food matrices. A single-particle inductively coupled plasma mass spectrometry (spICP-MS) screening method for the determination of the size distribution and concentration of titanium dioxide particles in sugar-coated confectionery and pristine food-grade titanium dioxide was developed. Special emphasis was placed on the sample preparation procedure, crucial to reproducibly disperse the particles before analysis. The transferability of this method was tested in an interlaboratory comparison study among seven experienced European food control and food research laboratories equipped with various ICP-MS instruments and using different software packages. The assessed measurands included the particle mean diameter, the most frequent diameter, the percentage of particles (in number) with a diameter below 100 nm, the particles' number concentration and a number of cumulative particle size distribution parameters (D0, D10, D50, D99.5, D99.8 and D100). The evaluated method's performance characteristics were, the within-laboratory precision, expressed as the relative repeatability standard deviation (RSDr), and the between-laboratory precision, expressed as the relative reproducibility standard deviation (RSDR). Transmission electron microscopy (TEM) was used as a confirmatory technique and served as the basis for bias estimation. The optimisation of the sample preparation step showed that when this protocol was applied to the relatively simple sample food matrices used in this study, bath sonication turned out to be sufficient to reach the highest, achievable degree of dispersed constituent particles. For the pristine material, probe sonication was required. Repeatability and reproducibility were below 10% and 25% respectively for most measurands except for the lower (D0) and the upper (D100) bound of the particle size distribution and the particle number concentration. The broader distribution of the lower and the upper bounds could be attributed to instrument-specific settings/setups (e.g. the timing parameters, the transport efficiency, type of mass-spectrometer) and software-specific data treatment algorithms. Differences in the upper bound were identified as being due to the non-harmonised application of the upper counting limit. Reporting D99.5 or D99.8 instead of the effectively largest particle diameter (D100) excluded isolated large particles and considerably improved the reproducibility. The particle number-concentration was found to be influenced by small differences in the sample preparation procedure. The comparison of these results with those obtained using electron microscopy showed that the mean and median particle diameter was, in all cases, higher when using spICP-MS. The main reason for this was the higher size detection limit for spICP-MS plus the fact that some of the analysed particles remained agglomerated/aggregated after sonication. Single particle ICP-MS is a powerful screening technique, which in many cases provides sufficient evidence to confirm the need to label a food product as containing (engineered) titanium dioxide nanomaterial according to the current EU regulatory requirements. The overall positive outcome of the method performance evaluation and the current lack of alternative standardised procedures, would indicate this method as being a promising candidate for a full validation study., Highlights • Standardised methods for sizing of E171 particles in food matrices are unavailable. • Screening method based on spICP-MS is proposed. • Analytical performance parameters and transferability tested in ILC.

In the field of nanotechnology, analytical characterization plays a vital role in understanding the behavior and toxicity of nanomaterials (NMs). Characterization needs to be thorough and the technique chosen should be well-suited to the property to be determined, the material being analyzed and the medium in which it is present. Furthermore, the instrument operation and methodology need to be well-developed and clearly understood by the user to avoid data collection errors. Any discrepancies in the applied method or procedure can lead to differences and poor reproducibility of obtained data. This paper aims to clarify the method to measure the hydrodynamic diameter of gold nanoparticles by means of Nanoparticle Tracking Analysis (NTA). This study was carried out as an inter-laboratory comparison (ILC) amongst seven different laboratories to validate the standard operating procedure’s performance and reproducibility. The results obtained from this ILC study reveal the importance and benefits of detailed standard operating procedures (SOPs), best practice updates, user knowledge, and measurement automation.

Recent studies reported adverse liver effects and intestinal tumor formation after oral exposure to titanium dioxide (TiO2). Other oral toxicological studies, however, observed no effects on liver and intestine, despite prolonged exposure and/or high doses. In the present assessment, we aimed to better understand whether TiO2 can induce such effects at conditions relevant for humans. Therefore, we focused not only on the clinical and histopathological observations, but also used Adverse Outcome Pathways (AOPs) to consider earlier steps (Key Events). In addition, aiming for a more accurate risk assessment, the available information on organ concentrations of Ti (resulting from exposure to TiO2) from oral animal studies was compared to recently reported concentrations found in human postmortem organs. The overview obtained with the AOP approach indicates that TiO2 can trigger a number of key events in liver and intestine: Reactive Oxygen Species (ROS) generation, induction of oxidative stress and inflammation. TiO2 seems to be able to exert these early effects in animal studies at Ti liver concentrations that are only a factor of 30 and 6 times higher than the median and highest liver concentration found in humans, respectively. This confirms earlier conclusions that adverse effects on the liver in humans as a result of (oral) TiO2 exposure cannot be excluded. Data for comparison with Ti levels in human intestinal tissue, spleen and kidney with effect concentrations were too limited to draw firm conclusions. The Ti levels, though, are similar or higher than those found in liver, suggesting these tissues may be relevant too.

A multistep sample preparation method was developed to separate metal-based engineered nanoparticles (ENPs) from biological samples. The method was developed using spiked zebrafish tissues and standard titanium dioxide (TiO2) and cerium dioxide (CeO2) ENPs. Single-particle inductively coupled plasma mass spectrometry was used to quantify the separated particles in terms of number concentration. This method demonstrated mass recoveries of more than 90% and did not strikingly alter the median particles size. High number recoveries were calculated for CeO2 ENPs (>84%). Particle number recoveries were poor for TiO2 ENPs (48Ca with the measured isotope 48Ti. The method was verified using zebrafish exposed to CeO2 ENPs to test its applicability for nanotoxicokinetic investigations. Total mass of Ce and particle number concentration of CeO2 ENPs were measured in different tissues. Notably, the mass-based biodistribution of Ce in the tissues did not follow the number-based biodistribution of CeO2. Moreover, the calculated mass-based bioconcentration factors showed a different pattern in comparison to the number-based bioconcentration factors. Our findings suggest that considering mass as the sole dose-metric may not provide sufficient information to investigate toxicity and toxicokinetics of ENPs.

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.

Silver nanoparticles (AgNPs) are being used in many products as they have unique antimicrobial-biocidal properties. After disposal of these products AgNPs can reach the soil environment possibly affecting soil organisms and disrupting plants. This work aimed to study the transport of AgNPs by water and sediment during overland flow and soil erosion. This was done in a laboratory setting, using a flume and rainfall simulator. A low concentration of AgNPs (50 μg·kg− 1) was applied to two soil-flumes with slope percentages of 20% and 10%. The rainfall was applied in four events of 15 min each with a total amount of rainfall of 15 mm during each event. After applying the rainfall, samples of the non-transported background soil (BS) and the transported sediment (Sf) were collected from the flume surface. Runoff sediment (RS) and water (RW) were collected from the outlet. AgNPs were detected in all samples collected. However, concentration varied according to sample type (soil or water), time of collection (for runoff water and sediment) and the slope of the soil flume. Higher concentrations of AgNPs in soil were detected in the BS than in the Sf likely due to the BS having more fine particles (silt and clay). The AgNPs concentration in the runoff sediments increased with subsequent applied rain events. In addition, increasing the slope of the flume from 10% to 20% increased the total AgNPs transported with the runoff sediment by a factor 1.5. The study confirms that AgNPs can be transported by both overland flow and sediment due to erosion.

Single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) promises fast and selective determination of nanoparticle size and number concentrations. While several studies on practical applications have been published, data on formal, especially interlaboratory validation of sp-ICP-MS, is sparse. An international interlaboratory study was organized to determine repeatability and reproducibility of the determination of the median particle size and particle number concentration of Ag nanoparticles (AgNPs) in chicken meat. Ten laboratories from the European Union, the USA, and Canada determined particle size and particle number concentration of two chicken meat homogenates spiked with polyvinylpyrrolidone (PVP)-stabilized AgNPs. For the determination of the median particle diameter, repeatability standard deviations of 2 and 5% were determined, and reproducibility standard deviations were 15 and 25%, respectively. The equivalent median diameter itself was approximately 60% larger than the diameter of the particles in the spiking solution. Determination of the particle number concentration was significantly less precise, with repeatability standard deviations of 7 and 18% and reproducibility standard deviations of 70 and 90%. Electronic supplementary material The online version of this article (doi:10.1007/s00216-017-0427-2) contains supplementary material, which is available to authorized users.

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.

Background Silver nanoparticles (AgNPs) are used extensively in various consumer products because of their antimicrobial potential. This requires insight in their potential hazards and risks including adverse effects during pregnancy on the developing fetus. Using a combination of the BeWo b30 placental transport model and the mouse embryonic stem cell test (EST), we investigated the capability of pristine AgNPs with different surface chemistries and aged AgNPs (silver sulfide (Ag2S) NPs) to cross the placental barrier and induce developmental toxicity. The uptake/association and transport of AgNPs through the BeWo b30 was characterized using ICP-MS and single particle (sp)ICP-MS at different time points. The developmental toxicity of the AgNPs was investigated by characterizing their potential to inhibit the differentiation of mouse embryonic stem cells (mESCs) into beating cardiomyocytes. Results The AgNPs are able to cross the BeWo b30 cell layer to a level that was limited and dependent on their surface chemistry. In the EST, no in vitro developmental toxicity was observed as the effects on differentiation of the mESCs were only detected at cytotoxic concentrations. The aged AgNPs were significantly less cytotoxic, less bioavailable and did not induce developmental toxicity. Conclusions Pristine AgNPs are capable to cross the placental barrier to an extent that is influenced by their surface chemistry and that this transport is likely low but not negligible. Next to that, the tested AgNPs have low intrinsic potencies for developmental toxicity. The combination of the BeWo b30 model with the EST is of added value in developmental toxicity screening and prioritization of AgNPs.

The aim of this study was to evaluate the bioaccumulation of titanium dioxide nanoparticles (TiO2NPs) in edible mussels bred in polluted artificial seawater. An in vivo study was conducted by exposing mussels to different concentrations of TiO2NPs (0.25 mg/L and 2.5 mg/L) or ionic titanium (1.6 mg/L) for 4 days. Inductively coupled plasma mass spectrometry (ICP-MS) showed titanium presence in all groups proportional to exposure levels (concentration range: 209–1119 µg/kg). Single particle ICP-MS revealed NPs in both TiO2NP treated mussels (concentration range: 231–1778 µg/kg) and in ionic titanium treated mussels (concentration 1574 µg/kg), suggesting potential nanoparticle formation in vivo. These results were confirmed by transmission electron microscopy with energy dispersive X-ray detection. Nonetheless, mussels eliminated more than 70% of the TiO2NPs after 3 days’ depuration. These results show the potential for consumer exposure to TiO2NPs when contaminated mussels are consumed without a proper depuration process.

Microplastics (MPs) are considered an emerging issue as environmental pollutants and a potential health threat. This review will focus on recently published data on concentrations in food, possible effects, and monitoring methods. Some data are available on concentrations in seafood (fish, bivalves, and shrimps), water, sugar, salt, and honey, but are lacking for other foods. Bottled water is a considerable source with numbers varying between 2600 and 6300 MPs per liter. Particle size distributions have revealed an abundance of particles smaller than 25 µm, which are considered to have the highest probability to pass the intestinal border and to enter the systemic circulation of mammals. Some studies with mice and zebrafish with short- or medium-term exposure (up to 42 days) have revealed diverse results with respect to both the type and extent of effects. Most notable modifications have been observed in gut microbiota, lipid metabolism, and oxidative stress. The principal elements of MP monitoring in food are sample preparation, detection, and identification. Identified data gaps include a lack of occurrence data in plant- and animal-derived food, a need for more data on possible effects of different types of microplastics, a lack of in silico models, a lack of harmonized monitoring methods, and a further development of quality assurance.

Nanomaterials, especially silver nanoparticles (AgNPs), are used in a broad range of products owing to their antimicrobial potential. Oral ingestion is considered as a main exposure route to AgNPs. This study aimed to investigate the impact of the biochemical conditions within the human digestive tract on the intestinal fate of AgNPs across an intestinal

Estimating consumer exposure to nanomaterials (NMs) in food products and predicting their toxicological properties are necessary steps in the assessment of the risks of this technology. To this end, analytical methods have to be available to detect, characterize and quantify NMs in food and materials related to food, e.g. food packaging and biological samples following metabolization of food. The challenge for the analytical sciences is that the characterization of NMs requires chemical as well as physical information. This article offers a comprehensive analysis of methods available for the detection and characterization of NMs in food and related products. Special attention was paid to the crucial role of sample preparation methods since these have been partially neglected in the scientific literature so far. The currently available instrumental methods are grouped as fractionation, counting and ensemble methods, and their advantages and limitations are discussed. We conclude that much progress has been made over the last 5 years but that many challenges still exist. Future perspectives and priority research needs are pointed out. Graphical Abstract Two possible analytical strategies for the sizing and quantification of Nanoparticles: Asymmetric Flow Field-Flow Fractionation with multiple detectors (allows the determination of true size and mass-based particle size distribution); Single Particle Inductively Coupled Plasma Mass Spectrometry (allows the determination of a spherical equivalent diameter of the particle and a number-based particle size distribution).

Silver nanoparticles (AgNPs) are used in a growing number of applications and products. Previous studies showed AgNPs can leach from these products to the environment. As a result of AgNPs leaching, sediment, soil and sludge-treated soils may be contaminated with AgNPs. Methods to detect, quantify and characterize AgNPs in soil are urgently needed. This study describes the development and validation of a method for the extraction, quantification and particle size determination of AgNPs in soils. The final method consists of pre-wetting the sample followed by an aqueous extraction, using sonication to re-suspend adsorbed AgNPs, and analysis of the aqueous extract with single particle ICP-MS. Validation of the method showed that the recovery of AgNPs spiked to soil was 44% for sandy soil and 42% for clayey soil. Although this recovery is relatively low, the repeatability and reproducibility values of the particle concentration were within the limits of Horwitz ratio, which makes the method suitable for its purpose. Further, the method concentration detection limit, LODc., is 5 μg kg −1 soil. The developed method can be applied in eco-toxicological and risk-assessments studies for AgNP in the soil environment.

Background Food contact materials (FCM) may contain non-intentionally added substances (NIAS) as a result of reaction by-products, oligomers, degradation processes, chemical reactions between packaging materials and foodstuff, or as impurities from the raw materials used for their production. Scope and approach In this review, current approaches for the detection and identification of NIAS from paper and board FCM are presented. Reviewed are the definition of NIAS, approaches for NIAS identification and quantification, the comprehensive analysis of NIAS and the role of in silico tools and bioassays. Key Findings and Conclusions NIAS in paper and board are mostly components from printing inks, adhesives, sizing agents and surface coatings. Recycled paper contains overall more NIAS than fresh paper. Targeted analysis is generally performed for predicted NIAS, whereas an untargeted, or full-scan screening method is applied to detect and identify unpredicted NIAS. Sample preparation and contact conditions fall in two categories; migration and extraction. Migration studies are performed with food simulants while extraction studies are Soxhlet or ultrasound assisted solvent extraction. In untargeted analysis in silico tools are gaining importance in the identification of NIAS. Bioassays are used to determine the bioactivity of extracts or fractions in order to assess the potential toxicity of NIAS present in the mixture. A combination of bioassays and chemical analysis is used to direct the identification of unknown bioactive NIAS in complex mixtures like those from paper and board FCM. However, future research is required into the selection of bioassays since these should not only be sensitive enough for detecting all compounds of concern but should also have a relevance with human health.

Measuring the number concentration of colloidal nanoparticles (NPs) is critical for assessing reproducibility, enabling compliance with regulation, and performing risk assessments of NP-enabled products. For nanomedicines, their number concentration directly relates to their dose. However, the lack of relevant reference materials and established traceable measurement approaches make the validation of methods for NP number concentration difficult. Furthermore, commercial products often exhibit agglomeration, but guidelines for dealing with nonideal samples are scarce. We have compared the performance of five benchtop measurement methods for the measurement of colloidal number concentration in the presence of different levels of agglomeration. The methods are UV-visible spectroscopy, differential centrifugal sedimentation, dynamic light scattering, particle tracking analysis, and single-particle inductively coupled plasma mass spectrometry. We find that both ensemble and particle-by-particle methods are in close agreement for monodisperse NP samples and three methods are within 20% agreement for agglomerated samples. We discuss the sources of measurement uncertainties, including how particle agglomeration affects measurement results. This work is a first step toward validation and expansion of the toolbox of methods available for the measurement of real-world NP products.

Nanomaterials, especially silver nanoparticles (AgNPs), are used in a broad range of products owing to their antimicrobial potential. Oral ingestion is considered as a main exposure route to AgNPs. This study aimed to investigate the impact of the biochemical conditions within the human digestive tract on the intestinal fate of AgNPs across an intestinal in vitro model of differentiated Caco-2/HT29-MTX cells. The co-culture model was exposed to different concentrations (250–2500 µg/L) of pristine and in vitro digested (IVD) AgNPs and silver nitrate for 24 h. ICP-MS and spICP-MS measurements were performed for quantification of total Ag and AgNPs. The AgNPs size distribution, dissolution, and particle concentration (mass- and number-based) were characterized in the cell fraction and in the apical and basolateral compartments of the monolayer cultures. A significant fraction of the AgNPs dissolved (86–92% and 48–70%) during the digestion. Cellular exposure to increasing concentrations of pristine or IVD AgNPs resulted in a concentration dependent increase of total Ag and AgNPs content in the cellular fractions. The cellular concentrations were significantly lower following exposure to IVD AgNPs compared to the pristine AgNPs. Transport of silver as either total Ag or AgNPs was limited (IVD AgNPs. We conclude that the surface chemistry of AgNPs and their digestion influence their dissolution properties, uptake/association with the Caco-2/HT29-MTX monolayer. This highlights the need to take in vitro digestion into account when studying nanoparticle toxicokinetics and toxicodynamics in cellular in vitro model systems.

A method was developed for the detection of nanoparticles and their state of agglomeration by combining hydrodynamic chromatography (HDC) with single particle inductively coupled plasma mass spectrometry (spICP-MS). Gold nanoparticles were measured under different conditions including the simulation of one of the most important human body functions, the human digestion. Nanoparticle detection and characterization was clearly demonstrated by the analysis of individual particles and a mixture of 30, 60, 100 and 200 nm particles at mass-based concentrations in the ngL-1 (ppt) range. For HDC a clear linear relationship was found between the retention time and the square root of the particle diameter. An agglomeration experiment to determine the packing density of the detected particles showed that it is possible to determine whether the detected particles are primary particles or agglomerates. In addition, the application of HDC hyphenated with spICP-MS was able to elucidate the fate of nanoparticles in the gastrointestinal track. The results showed that primary gold particles that enter the body in the saliva stage, agglomerate in the stomach to larger sized agglomerates which de-agglomerate back to the primary particles in the intestine stage. The results of this experiment show that HDC-spICP-MS is able to detect nanoparticles and agglomerates there of in complex matrices.

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.

Background Titanium dioxide (TiO2) is produced at high volumes and applied in many consumer and food products. Recent toxicokinetic modelling indicated the potential of TiO2 to accumulate in human liver and spleen upon daily oral exposure, which is not routinely investigated in chronic animal studies. A health risk from nanosized TiO2 particle consumption could not be excluded then. Results Here we show the first quantification of both total titanium (Ti) and TiO2 particles in 15 post-mortem human livers and spleens. These low-level analyses were enabled by the use of fully validated (single particle) inductively coupled plasma high resolution mass spectrometry ((sp)ICP-HRMS) detection methods for total Ti and TiO2 particles. The presence of TiO2 in the particles in tissues was confirmed by Scanning Electron Microscopy with energy dispersive X-ray spectrometry. Conclusions These results prove that TiO2 particles are present in human liver and spleen, with ≥24% of nanosize (

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.

In the Netherlands, the EU-mandated nationwide monitoring programme and emergency response plan for radioactivity in food is implemented by RIKILT (the Dutch institute for food safety) by means of the National Monitoring Network for Radioactivity in Food (LMRV). The LMRV consists of 48 individual gamma spectrometers (Food Monitoring System, or FMS) that require little maintenance, are hosted at food processing companies and institutes throughout the Netherlands, and are operated by local personnel. From 2010 to 2013, approximately 900 samples of milk and 500 samples of other food categories were analysed on the FMSs annually, and another 1400 in the specialized radionuclide laboratories operated by RIKILT. The anthropogenic radionuclide cesium-137 (137Cs) was detected in 93 out of 11,143 samples (0.8%), mostly in wild mushrooms, game and honey. Two samples of wild boar exceeded the limit of 600 Bq/kg. In case of a nuclear accident the FMSs are used to validate the radioactive deposition calculated by dispersion models by measuring radionuclides in grass samples. No deposition of artificial radionuclides was measured in the Netherlands after the Fukushima nuclear incident. The precision of the FMSs is within the pre-set tolerance limits of 80–120% for 137Cs, cobalt-60 (60Co) and iodine-131 (131I). For potassium-40 (40K) a systematic error of +10% was observed. The recalibration of the FMSs in 2012 resulted in a reduction of almost 40% in the variation of the precision for 131I (compared to 2010 and 2011). This article describes the network and the individual FMSs, the routine measurements of food and special measurements in case of radioactive contamination, and the performance of the network.

Nanotechnology has the potential to innovate the agricultural, feed and food sectors (hereinafter referred to as agri/feed/food). Applications that are marketed already include nano-encapsulated agrochemicals or nutrients, antimicrobial nanoparticles and active and intelligent food packaging. Many nano-enabled products are currently under research and development, and may enter the market in the near future. As for any other regulated product, applicants applying for market approval have to demonstrate the safe use of such new products without posing undue safety risks to the consumer and the environment. Several countries all over the world have been active in examining the appropriateness of their regulatory frameworks for dealing with nanotechnologies. As a consequence of this, different approaches have been taken in regulating nano-based products in agri/feed/food. The EU, along with Switzerland, were identified to be the only world region where nano-specific provisions have been incorporated in existing legislation, while in other regions nanomaterials are regulated more implicitly by mainly building on guidance for industry. This paper presents an overview and discusses the state of the art of different regulatory measures for nanomaterials in agri/feed/food, including legislation and guidance for safety assessment in EU and non-EU countries.

The increasing use of nanoparticles in products likely results in increased exposure of both workers and consumers. Because of their small size, there are concerns that nanoparticles unintentionally cross the barriers of the human body. Several in vivo rodent studies show that, dependent on the exposure route, time, and concentration, and their characteristics, nanoparticles can cross the lung, gut, skin, and placental barrier. This review aims to evaluate the performance of in vitro models that mimic the barriers of the human body, with a focus on the lung, gut, skin, and placental barrier. For these barriers, in vitro models of varying complexity are available, ranging from single-cell-type monolayer to multi-cell (3D) models. Only a few studies are available that allow comparison of the in vitro translocation to in vivo data. This situation could change since the availability of analytical detection techniques is no longer a limiting factor for this comparison. We conclude that to further develop in vitro models to be used in risk assessment, the current strategy to improve the models to more closely mimic the human situation by using co-cultures of different cell types and microfluidic approaches to better control the tissue microenvironments are essential. At the current state of the art, the in vitro models do not yet allow prediction of absolute transfer rates but they do support the definition of relative transfer rates and can thus help to reduce animal testing by setting priorities for subsequent in vivo testing.

High concentrations of plastic debris have been observed in the oceans. Much of the recent concern has focused on microplastics in the marine environment. Recent studies of the size distribution of the plastic debris suggested that continued fragmenting of microplastics into nanosized particles may occur. In this review we assess the current literature on the occurrence of environmentally released micro- and nanoplastics in the human food production chain and their potential health impact. The currently used analytical techniques introduce a great bias in the knowledge, since they are only able to detect plastic particles well above the nanorange. We discuss the potential use of the very sensitive analytical techniques that have been developed for the detection and quantification of engineered nanoparticles. We recognize three possible toxic effects of plastic particles: first due to the plastic particles themselves, second to the release of persistent organic pollutant adsorbed to the plastics, and third to the leaching of additives of the plastics. The limited data on microplastics in foods do not predict adverse effect of these pollutants or additives. Potential toxic effects of microplastic particles will be confined to the gut. The potential human toxicity of nanoplastics is poorly studied. Based on our experiences in nanotoxicology we prioritized future research questions.

Determining composition, shape, and size of nanoparticles dispersed in a complex matrix is necessary in the assessment of toxicity, for regulatory actions, and environmental monitoring. Many types of nanoparticles that are currently used in consumer products contain more than one metal which are often not uniformly distributed (e.g., core-shell nanoparticles). This compositional and structural complexity makes their characterization difficult. In this study, we investigate the capability of single particle inductively coupled plasma mass spectrometry (spICP-MS) using time-of-flight (TOF) and quadrupole (Q) mass analyzers to determine the composition, size distribution, and concentration of a series of nanoparticles that are used in a variety of industrial applications: BiVO4, (Bi0.5Na0.5)TiO3 and steel (which contains Fe, Cr, Ni, Mo) nanoparticles. In addition, we tested both types of mass analyzers with Au-core/Ag-shell nanoparticles, which are well-characterized and have already been used for assessment of multi-element capabilities of spICP-MS. The results confirm that both types of mass analyzers produce accurate estimations of the size of Au-core/Ag-shell particles. For other multi-element nanoparticles, spICP-MS provided the size of aggregates and/or agglomerates in the prepared suspensions. In general, particle size detection limits (dLOD) of spICP-TOFMS instruments with values of 29 nm for Ti, 14 nm for Mo, and 7 nm for Au, are smaller than those obtained for the quadrupole instruments. This study finds that only spICP-TOFMS can accurately assess the elemental composition of nano-steel particles. By contrast, spICP-QMS is limited to the detection of 2 elements in an individual particle and the elemental composition of nano-steel particles is less accurate. In general, spICP-TOFMS was able to quantify multiple elements with high precision and that currently makes it the first choice for multi-element detection of unknown nanoparticles.

Silver nanoparticles (AgNPs) can enter the environment when released from products containing them. As AgNPs enter soil, they are often retained in the soil profile and/or leached to the groundwater. This research assessed the transport of AgNPs in their “particle form” through the soil profile using a series of columns. Three soil types were put into soil columns: LSH (loam with high organic matter (OM)), LSL (loam with low OM), and Sand (no OM). The results showed that AgNP transport and retention in soil as well as particle size changes are affected by soil organic matter (OM) and the cation exchange capacity (CEC) of soil. OM affected the transport and retention of AgNPs. This was evident in the LSH columns where the OM concentration was the highest and the AgNP content the lowest in the soil layers and in the effluent water. The highest transported AgNP content was detected in the Sand columns where OM was the lowest. CEC had an impact on the particle size of the AgNPs that were retained in the soil layers. This was clear in columns packed with high CEC-containing soils (LSL and LSH) where AgNP particle size decreased more substantially than in the columns packed with sand. However, the decrease in AgNP sizes in the effluent water was less than the decrease in particle size of AgNPs transported through but retained in the soil. This means that the AgNPs that reached the effluent were transported directly from the first layer through the soil macropores. This work highlights the ability to track AgNPs at low concentrations (50 μg kg−1) and monitor the changes in particle size potential as the particles leach through soil all of which increases our knowledge about AgNP transport mechanisms in porous media.

This chapter provides a state-of-the-art description, as of November 2017, of legislation covering food-related applications of nanotechnology and nanomaterials in the European Union (EU). These applications include novel foods, food contact materials, feed and food additives, food supplements, and plant protection products. In general, the EU legislation requires a market authorization of nanomaterial applications in foods on the basis of a safety assessment by the European Food Safety Authority (EFSA) of the potential health risks, which may be associated with nanomaterials in foods. EFSA is an integral part of the EU's food safety system to ensure the safety of foods and to protect the health of consumers, animals, and the environment from food-related risks. Among others, EFSA evaluates and assesses the risk of nanomaterials and develops scientific methodologies and guidance needed for identifying emerging risks to food safety. In addition to EFSA, the Joint Research Centre of the European Commission provides technical and scientific support to the policies on nanomaterials in foods.

Background: 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 Ho-165 or In-111) 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 (Ho-165-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 (Ho-165), 3) compare in vivo biodistribution patterns obtained with ICP-MS (Ho-165) and radiodetection (In-111) after intravenous administration of hybrid-Cy5-Ac-TZ4011 in tumor-bearing mice. Finally, LA-ICP-MS-imaging (Ho-165) 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 (Ho-165) 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 (Ho-165) and radiodetection (In-111) 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. Conclusion: Lanthanide-isotope chelation expands the scope of fluorescent/ radioactive hybrid tracers to include MS-based analytical tools such as mass-cytometry, ICP-MS and LA-ICP-MS imaging in molecular pathology. In contradiction to common expectations, MS detection using a single chelate imaging agent was shown to be feasible, enabling a direct link between nuclear medicine-based imaging and theranostic methods.

Nanomaterials are developed for and applied in food, food additives, supplements and food contact materials. In an inventory of internet databases 140 products in the food and food-related sectors were identified that claim to contain nanomaterials. A great diversity of nanomaterials is applied, ranging from inorganic metal and metal oxides to organic nanomaterials that carry bioactive ingredients. Here we present an overview of nanomaterial applications that are currently available, discuss state of the art analytical chemical characterization and toxicological assessment methods, as well as categorization methods to support the safety evaluation of the application of nanomaterials throughout food production.

The potential impact of nanomaterials on the environment and on human health has already triggered legislation requiring labelling of products containing nanoparticles. However, so far, no validated analytical methods for the implementation of this legislation exist. This paper outlines a generic approach for the validation of methods for detection and quantification of nanoparticles in food samples. It proposes validation of identity, selectivity, precision, working range, limit of detection and robustness, bearing in mind that each “result” must include information about the chemical identity, particle size and mass or particle number concentration. This has an impact on testing for selectivity and trueness, which also must take these aspects into consideration. Selectivity must not only be tested against matrix constituents and other nanoparticles, but it shall also be tested whether the methods apply equally well to particles of different suppliers. In trueness testing, information whether the particle size distribution has changed during analysis is required. Results are largely expected to follow normal distributions due to the expected high number of particles. An approach of estimating measurement uncertainties from the validation data is given.

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. Chemicals/CAS: silver, 7440-22-4; Anti-Bacterial Agents; Silver

et al., Physicochemical properties of nanoparticles influence their environmental fate and toxicity, and studies investigating this are vital for a holistic approach towards a comprehensive and adequate environmental risk assessment. In this study, we investigated the effects of size, surface coating (charge) of silver nanoparticles (AgNPs) – a most commonly-used nanoparticle-type, on the bioaccumulation in, and toxicity (survival, growth, cocoon production) to the earthworm Lumbricus rubellus. AgNPs were synthesized in three sizes: 20, 35 and 50 nm. Surface-coating with bovine serum albumin (AgNP_BSA), chitosan (AgNP_Chit), or polyvinylpyrrolidone (AgNP_PVP) produced negative, positive and neutral particles respectively. In a 28-day sub-chronic reproduction toxicity test, earthworms were exposed to these AgNPs in soil (0–250 mg Ag/kg soil DW). Earthworms were also exposed to AgNO3 at concentrations below known EC50. Total Ag tissue concentration indicated uptake by earthworms was generally highest for the AgNP_BSA especially at the lower exposure concentration ranges, and seems to reach a plateau level between 50 and 100 mg Ag/kg soil DW. Reproduction was impaired at high concentrations of all AgNPs tested, with AgNP_BSA particles being the most toxic. The EC50 for the 20 nm AgNP_BSA was 66.8 mg Ag/kg soil, with exposure to AgNP_PVP (neutral) > Chitosan (positive). Size had an influence on uptake and toxicity of the AgNP_PVP, but not for AgNP_BSA nor AgNP_Chit. This study provides essential information on the role of physicochemical properties of AgNPs in influencing uptake by a terrestrial organism L. rubellus under environmentally relevant conditions. It also provides evidence of the influence of surface coating (charge) and the limited effect of size in the range of 20–50 nm, in driving uptake and toxicity of the AgNPs tested., This work was financially supported by NanoNextNL, a micro- and nano-technology consortium of the Government of The Netherlands and 130 partners; funding was also received from Managing Risks of Nanoparticles, MARINA (EU-FP7, contract CP-FP 263215), and; the Strategic Research Funds titled Novel technologies by the Ministry of Economic Affairs of The Netherlands. Synthesis and characterization of the AgNPs used in this study received support from the QualityNano Project http://www.qualitynano.eu/which is financed by the European Community Research Infrastructures under the FP7 Capacities Programme (Grant No. INFRA-2010-262163).

Seven commercial titanium dioxide pigments and two other well-defined TiO2 materials (TiMs) were physicochemically characterised using asymmetric flow field flow fractionation (aF4) for separation, various techniques to determine size distribution and inductively coupled plasma mass spectrometry (ICPMS) for chemical characterization. The aF4-ICPMS conditions were optimised and validated for linearity, limit of detection, recovery, repeatability and reproducibility, all indicating good performance. Multi-element detection with aF4-ICPMS showed that some commercial pigments contained zirconium co-eluting with titanium in aF4. The other two TiMs, NM103 and NM104, contained aluminium as integral part of the titanium peak eluting in aF4. The materials were characterised using various size determination techniques: retention time in aF4, aF4 hyphenated with multi-angle laser light spectrometry (MALS), single particle ICPMS (spICPMS), scanning electron microscopy (SEM) and particle tracking analysis (PTA). PTA appeared inappropriate. For the other techniques, size distribution patterns were quite similar, i.e. high polydispersity with diameters from 20 to >700 nm, a modal peak between 200 and 500 nm and a shoulder at 600 nm. Number-based size distribution techniques as spICPMS and SEM showed smaller modal diameters than aF4-UV, from which mass-based diameters are calculated. With aF4-MALS calculated, light-scattering-based “diameters of gyration” (Øg) are similar to hydrodynamic diameters (Øh) from aF4-UV analyses and diameters observed with SEM, but much larger than with spICPMS. A Øg/Øh ratio of about 1 indicates that the TiMs are oblate spheres or fractal aggregates. SEM observations confirm the latter structure. The rationale for differences in modal peak diameter is discussed.

Oral ingestion is an important exposure route for silver nanoparticles (AgNPs), but their fate during gastrointestinal digestion is unknown. This was studied for 60 nm AgNPs and silver ions (AgNO₃) using in vitro human digestion model. Samples after saliva, gastric and intestinal digestion were analysed with SP-ICPMS, DLS and SEM-EDX. In presence of proteins, after gastric digestion the number of particles dropped significantly, to rise back to original values after the intestinal digestion. SEM-EDX revealed that reduction in number of particles was caused by their clustering. These clusters were composed of AgNPs and chlorine. During intestinal digestion, these clusters disintegrated back into single 60 nm AgNPs. The authors conclude that these AgNPs under physiological conditions can reach the intestinal wall in their initial size and composition. Importantly, intestinal digestion of AgNO₃ in presence of proteins resulted in particle formation. These nanoparticles (of 20-30 nm) were composed of silver, sulphur and chlorine.

The presence, dissolution, agglomeration state, and release of materials in the nano-size range from food containing engineered nanoparticles during human digestion is a key question for the safety assessment of these materials. We used an in vitro model to mimic the human digestion. Food products subjected to in vitro digestion included (i) hot water, (ii) coffee with powdered creamer, (iii) instant soup, and (iv) pancake which either contained silica as the food additive E551, or to which a form of synthetic amorphous silica or 32 nm SiO2 particles were added. The results showed that, in the mouth stage of the digestion, nano-sized silica particles with a size range of 5-50 and 50-500 nm were present in food products containing E551 or added synthetic amorphous silica. However, during the successive gastric digestion stage, this nano-sized silica was no longer present for the food matrices coffee and instant soup, while low amounts were found for pancakes. Additional experiments showed that the absence of nano-sized silica in the gastric stage can be contributed to an effect of low pH combined with high electrolyte concentrations in the gastric digestion stage. Large silica agglomerates are formed under these conditions as determined by DLS and SEM experiments and explained theoretically by the extended DLVO theory. Importantly, in the subsequent intestinal digestion stage, the nano-sized silica particles reappeared again, even in amounts higher than in the saliva (mouth) digestion stage. These findings suggest that, upon consumption of foods containing E551, the gut epithelium is most likely exposed to nano-sized silica. © 2012 American Chemical Society.

Silver nanoparticles are recognized as effective antimicrobial agents and have been implemented in various consumer products including washing machines, refrigerators, clothing, medical devices, and food packaging. Alongside the silver nanoparticles benefits, their novel properties have raised concerns about possible adverse effects on biological systems. To protect consumer’s health and the environment, efficient monitoring of silver nanoparticles needs to be established. Here, we present the development of human metallothionein (MT) based surface plasmon resonance (SPR) sensor for rapid detection of nanosilver. Incorporation of human metallothionein 1A to the sensor surface enables screening for potentially biologically active silver nanoparticles at parts per billion sensitivity. Other protein ligands were also tested for binding capacity of the nanosilver and were found to be inferior to the metallothionein. The biosensor has been characterized in terms of selectivity and sensitivity towards different types of silver nanoparticles and applied in measurements of real-life samples—such as fresh vegetables and river water. Our findings suggest that human MT1-based SPR sensor has the potential to be utilized as a routine screening method for silver nanoparticles, that can provide rapid and automated analysis dedicated to environmental and food safety monitoring. Figure Surface plasmon resonance biosensor for rapid detection of silver nanoparticles was developed. Human metallothionein 1A (hMT1A) was immobilized on the sensor chip surface and showed dose dependent binding to the silver nanoparticles with part per billion sensitivity. Electronic supplementary material The online version of this article (doi:10.1007/s00216-012-5920-z) contains supplementary material, which is available to authorized users.

Interest in nanoparticles (NPs) has increased explosively over the past two decades. Using NPs, high loadings of vitamins and health-benefit actives can be achieved in food, and stable flavors as well as natural food-coloring dispersions can be developed. Detection and characterization of NPs are essential in understanding the benefits as well as the potential risks of the application of such materials in food. While many such applications are described in the literature, methods for detection and characterization of such particles are lacking. Organic NPs suitable for application in food are lipid-, protein- or polysaccharide-based particles, and this review describes current analytical techniques that are used, or could be used, for identification and characterization of such particles in food products. We divide the analytical approaches into four sections: sample preparation; separation; imaging; and, characterization. We discuss techniques and reported applications for NPs or otherwise related particle compounds. The results of this investigation show that, for a successful characterization of NPs in food, at least some kind of sample preparation will be required. While a simple sample preparation may be satisfactory for imaging techniques for known analytes, for other techniques, a further separation using chromatography, field-flow fractionation or ion-mobility separation is necessary. Subsequently, photon-correlation spectroscopy and especially mass spectrometry techniques as matrix-assisted laser desorption/ionization combined with time-of-flight mass spectrometry, seem suitable techniques for characterizing a wide variety of organic NPs.

This study uniquely describes all steps of the risk assessment process for the use of one specific nanomaterial (nanosilica) in food products. The aim was to identify gaps in essential knowledge and the difficulties and uncertainties associated with each of these steps. Several food products with added silica (E551) were analyzed for the presence, particle size and concentration of nanosilica particles, using experimental analytical data, and the intake of nanosilica via food was estimated. As no information is available on the absorption of nanosilica from the gastrointestinal tract, two scenarios for risk assessment were considered. The first scenario assumes that the silica is absorbed as dissolved silica, while the second scenario assumes that nanosilica particles themselves are absorbed from the gastrointestinal tract. For the first scenario no adverse effects are expected to occur. For the second scenario there are too many uncertainties to allow proper risk assessment. Therefore, it is recommended to prioritize research on how nanosilica is absorbed from the gastrointestinal tract. Read More: http://informahealthcare.com/doi/abs/10.3109/17435390.2010.519836

A common trend in food contaminants and sports doping control is towards a limited number of targeted, full-scan, accurate-mass spectrometry (MS) methods based on time-of-flight (TOF) or Fourier-transform orbital trap (Orbitrap) mass analyzers. Retrospective analysis of the full-scan datasets of signals from emerging contaminants, novel metabolites and illegal designer substances is a major step forward. We present data from recent applications of gas chromatography with TOF-MS, ultra-high-performance liquid chromatography (LC) with TOF-MS and LC-Orbitrap MS in the screening of European Commission-regulated veterinary drugs and other contaminants in foods, and World Anti-Doping Agency-prohibited substances. We discuss the potential impact of these new approaches on future developments.

Unification of the screening protocols for a wide range of doping agents has become an important issue for doping control laboratories. This study presents the development and validation of a generic liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) screening method of 241 small molecule analytes from various categories of prohibited substances (stimulants, narcotics, diuretics, s2-agonists, s-blockers, hormone antagonists and modulators, glucocorticosteroids and anabolic agents). It is based on a single-step liquid-liquid extraction of hydrolyzed urine and the use of a rapid-resolution liquid chromatography/high-resolution time-of-flight mass spectrometric system acquiring continuous full scan data. Electrospray ionization in the positive mode was used. Validation parameters consisted of identification capability, limit of detection, specificity, ion suppression, extraction recovery, repeatability and mass accuracy. Detection criteria were established on the basis of retention time reproducibility and mass accuracy. The suitability of the methodology for doping control was demonstrated with positive urine samples. The preventive role of the method was proved by the case where full scan acquisition with accurate mass measurement allowed the retrospective reprocessing of acquired data from past doping control samples for the detection of a designer drug, the stimulant 4-methyl-2-hexanamine, which resulted in re-reporting a number of stored samples as positives for this particular substance, when, initially, they had been reported as negatives.