Gemma Janer

Engineered Nanoscale Food Ingredients: Evaluation of Current Knowledge on Material Characteristics Relevant to Uptake from the Gastrointestinal Tract

The NanoRelease Food Additive project developed a catalog to identify potential engineered nanomaterials (ENMs) used as ingredients, using various food-related databases. To avoid ongoing debate on defining the term nanomaterial, NanoRelease did not use any specific definition other than the ingredient is not naturally part of the food chain, and its dimensions are measured in the nanoscale. Potential nanomaterials were categorized based on physical similarity; analysis indicated that the range of ENMs declared as being in the food chain was limited. Much of the catalogs information was obtained from product labeling, likely resulting in both underreporting (inconsistent or absent requirements for labeling) and/or overreporting (inability to validate entries, or the term nano was used, although no ENM material was present). Three categories of ingredients were identified: emulsions, dispersions, and their water-soluble powdered preparations (including lipid-based structures); solid encapsulates (solid structures containing an active material); and metallic or other inorganic particles. Although much is known regarding the physical/chemical properties for these ingredient categories, it is critical to understand whether these properties undergo changes following their interaction with food matrices during preparation and storage. It is also important to determine whether free ENMs are likely to be present within the gastrointestinal tract and whether uptake of ENMs may occur in their nanoform physical state. A practical decision-making scheme was developed to help manage testing requirements.

Cell uptake and oral absorption of titanium dioxide nanoparticles

Large efforts are invested on the development of in vitro tests to evaluate nanomaterial (NM) toxicity. In order to assess the relevance of the adverse effects identified in in vitro toxicity tests a thorough understanding of the biokinetics of NMs is critical. We used different in vitro and in vivo test methods to evaluate cell uptake and oral absorption of titanium dioxide nanoparticles (TiO2 NPs). These NPs were readily uptaken by A549 cells (carcinomic human alveolar basal epithelial cells) in vitro. Such rapid uptake contrasted with a very low oral absorption in a differentiated Caco-2 monolayer system (human epithelial colorectal adenocarcinoma cells) and after oral gavage administration to rats. In this oral study, no significant increase in the levels of titanium was recorded by ICP-MS in any of the tissues evaluated (including among other: small intestine, Peyers patches, mesenteric lymph nodes, liver, and spleen). No NPs were observed by TEM in sections of the small intestine, except for several particles in the cytoplasm of a cell from a Peyers Patch area. The observation of NPs in Peyers Patch suggests that the Caco-2 monolayer system is likely to underestimate the potential for oral absorption of NPs and that the model could be improved by including M-cells in co-culture.

Towards a nanospecific approach for risk assessment.

In the current paper, a new strategy for risk assessment of nanomaterials is described, which builds upon previous project outcomes and is developed within the FP7 NANoREG project. NANoREG has the aim to develop, for the long term, new testing strategies adapted to a high number of nanomaterials where many factors can affect their environmental and health impact. In the proposed risk assessment strategy, approaches for (Quantitative) Structure Activity Relationships ((Q)SARs), grouping and read-across are integrated and expanded to guide the user how to prioritise those nanomaterial applications that may lead to high risks for human health. Furthermore, those aspects of exposure, kinetics and hazard assessment that are most likely to be influenced by the nanospecific properties of the material under assessment are identified. These aspects are summarised in six elements, which play a key role in the strategy: exposure potential, dissolution, nanomaterial transformation, accumulation, genotoxicity and immunotoxicity. With the current approach it is possible to identify those situations where the use of nanospecific grouping, read-across and (Q)SAR tools is likely to become feasible in the future, and to point towards the generation of the type of data that is needed for scientific justification, which may lead to regulatory acceptance of nanospecific applications of these tools.

Exploring release and recovery of nanomaterials from commercial polymeric nanocomposites

Much concern has been raised about the risks associated with the broad use of polymers containing nanomaterials. Much is known about degradation and aging of polymers and nanomaterials independently, but very few studies have been done in order to understand degradation of polymeric nanocomposites containing nanomaterials and the fate of these nanomaterials, which may occur in suffering many processes such as migration, release and physicochemical modifications. Throughout the UE funded FP7 project NANOPOLYTOX, studies on the migration, release and alteration of mechanical properties of commercial nanocomposites due to ageing and weathering have been performed along with studies on the feasibility of recovery and recycling of the nanomaterials. The project includes the use as model nanocomposites of Polyamide-6 (PA), Polypropylene (PP) and Ethyl Vinyl Acetate (EVA) as polymeric matrix filled with a 3% in mass of a set of selected broadly used nanomaterials; from inorganic metal oxides nanoparticles (SiO2, TiO2 and ZnO) to multi-walled carbon nanotubes (MWCNT) and Nanoclays. These model nanocomposites were then treated under accelerated ageing conditions in climatic chamber. To determine the degree of degradation of the whole nanocomposite and possible processes of migration, release and modification of the nanofillers, nanocomposites were characterized by different techniques. Additionally, recovery of the nanomaterials fro m the polymeric matrix was addressed, being successfully achieved for PA and PP based nanocomposites. In the case of PA, dissolution of the polymeric matrix using formic acid and further centrifugation steps was the chosen approach, while for PP based nanocomposites calcination was performed.

In vitro toxicity of functionalised nanoclays is mainly driven by the presence of organic modifiers

Abstract Little information exists on the toxicological hazards associated to organo-modified clays. We evaluated the cytotoxicity of a series of pristine and organo-modified nanoclays in different cell lines. The calculated IC50 values for cell viability ranged from 1.4 to 47 µg/mL for the six organoclays used and were above 100 µg/mL for the pristine nanoclays. The IC50 values of the organoclays were driven by the proportion and structure of the quaternary ammonium compound used as surface organic modifier. No differences in cell toxicity were observed between the large and small-sized (additional milling step) nanoclay batches, although their size differences related mostly to upper range of the size distribution. Despite their lower toxicity, pristine nanoclays induced apoptosis and were found in cytoplasmic vesicles of exposed cells. Organoclays were also found in cytoplasmic vesicles, although the size of the agglomerates was larger and the efficiency of uptake was considerably lower.

Influence of Nanomaterial Compatibilization Strategies on Polyamide Nanocomposites Properties and Nanomaterial Release during the Use Phase

The incorporation of small amounts of nanofillers in polymeric matrices has enabled new applications in several industrial sectors. The nanofiller dispersion can be improved by modifying the nanomaterial (NM) surface or predispersing the NMs to enhance compatibility. This study evaluates the effect of these compatibilization strategies on migration/release of the nanofiller and transformation of polyamide-6 (PA6), a thermoplastic polymer widely used in industry during simulated outdoors use. Two nanocomposites (NCs) containing SiO2 nanoparticles (NPs) with different surface properties and two multiwalled carbon nanotube (MWCNT) NCs obtained by different addition methods were produced and characterized, before and after accelerated wet aging conditions. Octyl-modified SiO2 NPs, though initially more aggregated than uncoated SiO2 NPs, reduced PA6 hydrolysis and, consequently, NM release. Although no clear differences in dispersion were observed between the two types of MWCNT NCs (masterbatch vs direct addition) after manufacture, the use of the MWCNT masterbatch reduced PA6 degradation during aging, preventing MWCNT accumulation on the surface and further release or potential exposure by direct contact. The amounts of NM released were lower for MWCNTs (36 and 108 mg/m(2)) than for SiO2 NPs (167 and 730 mg/m(2)), being lower in those samples where the NC was designed to improve the nanofiller-matrix interaction. Hence, this study shows that optimal compatibilization between NM and matrix can improve NC performance, reducing polymer degradation and exposure and/or release of the nanofiller.

Quality evaluation of human and environmental toxicity studies performed with nanomaterials – the GUIDEnano approach

The European Union FP-7 project GUIDEnano developed a web-based guidance tool, which guides users to assess human and environmental risks of nanomaterial-enabled products throughout their life cycle. One of the aims in the GUIDEnano hazard assessment strategy is to derive safety limit values based on existing human toxicity and ecotoxicological studies. Clear criteria needed to be established to select studies that could be used for such purpose. In the present paper, we present an approach for a systematical and quantitative evaluation of the quality of environmental and human toxicity studies performed with nanomaterials. The approach builds upon previous initiatives and includes refinements to facilitate its application by users with limited toxicological expertise. It covers in vivo and in vitro human toxicity studies as well as ecotoxicological studies addressing the toxicity to all environmental compartments. A scoring system related to test design and reporting considerations was developed following the principles of the Klimisch score (K score). In addition, the approach includes a scoring system based on the physicochemical properties that have been characterized and reported for the nanomaterial, including properties characterized in the exposure medium (S score). These two scores (K and S) are combined to obtain an overall quality score (Q score) that can be used to select studies, to weight different studies, and/or to introduce uncertainty factors in the risk assessment process. During its development, the approach has been tested and refined with 137 peer-reviewed articles. The final quality assessment approach and the results of its evaluation are presented here.

The Life Cycle of Engineered Nanoparticles

The first years in the twenty-first century have meant the inclusion of nanotechnology in most industrial sectors, from very specific sensors to construction materials. The increasing use of nanomaterials in consumer products has raised concerns about their potential risks for workers, consumers and the environment. In a comprehensive risk assessment or life cycle assessment, a life cycle schema is the starting point necessary to build up the exposure scenarios and study the processes and mechanisms driving to safety concerns. This book chapter describes the processes that usually occur at all the stages of the life cycle of the nano-enabled product, from the nanomaterial synthesis to the end-of-life of the products. Furthermore, release studies reported in literature related to these processes are briefly discussed.

Development of a systematic method to assess similarity between nanomaterials for human hazard evaluation purposes – lessons learnt

Abstract Within the EU FP-7 GUIDEnano project, a methodology was developed to systematically quantify the similarity between a nanomaterial (NM) that has been tested in toxicity studies and the NM for which risk needs to be evaluated, for the purpose of extrapolating toxicity data between the two materials. The methodology is a first attempt to use current knowledge on NM property–hazard relationships to develop a series of pragmatic and systematic rules for assessing NM similarity. Moreover, the methodology takes into account the practical feasibility, in that it is based on generally available NM characterization information. In addition to presenting this methodology, the lessons learnt and the challenges faced during its development are reported here. We conclude that there is a large gap between the information that is ideally needed and its application to real cases. The current database on property–hazard relationships is still very limited, which hinders the agreement on the key NM properties constituting the basis of the similarity assessment and the development of associated science-based and unequivocal rules. Currently, one of the most challenging NM properties to systematically assess in terms of similarity between two NMs is surface coating and functionalization, which lacks standardized parameters for description and characterization methodology. Standardization of characterization methods that lead to quantitative, unambiguous, and measurable parameters describing NM properties are necessary in order to build a sufficiently robust property–hazard database that allows for evidence-based refinement of our methodology, or any other attempt to systematically assess the similarity of NMs.