NanoTrust Dossiers

Nanocarriers are innovative delivery and encapsulation systems with different chemical compositions and structures and are classified as advanced materials. They are used in a variety of applications, especially in medicine, cosmetics, and agriculture, as well as in food supplements and household products. Nanocarriers can protect sensitive active ingredients, delay their release, and even enable targeted delivery to the site of action, thereby increasing effectiveness and reducing any side effects. In the scientific literature, the term “nanocarrier” covers not only nanomaterials up to a size of 100 nm according to the definition proposed by the European Commission, but also structures up to 1,000 nm. At present, there is no uniform definition or categorisation of nanocarriers. In this dossier, they are classified on the basis of their origin and chemical composition, and categorised as organic, inorganic, and hybrid systems (material combinations of organic and inorganic materials) as well as supraparticles. To date, there has been little research on how nanocarrier systems behave in the various environmental compartments (soil, water, air). Analytical challenges and the lack of standardised test protocols make comprehensive risk assessments difficult.

Quantum dots (QDs) are increasingly widespread in medicine and environmental research. Because of their specific optical characteristics, QDs can be detected by fluorescence analyses, even in complex media, such as environmental or tissue samples. Their unique properties make them useful for a variety of applications, such as for the use as fluorescent markers for cells, as contrast agents in deep tissue and tumour imaging, in biosensing or photodynamic therapy, and for targeted drug delivery. As a result, QDs could potentially be used as detectable and clearly identifiable “nanotracers” to mark or detect specific targets or to be able to draw general conclusions about the fate of engineered nanoparticles (ENPs) in environmentally relevant media, e.g. in wastewater. QDs mainly consist of metallic semiconductor compounds, such as cadmium selenide (CdSe), cadmium telluride (CdTe), lead sulphide (PbS) or indium phosphide (InP), which can have toxic effects on cells and organisms. Research is therefore being conducted on non­toxic carbon­based QDs, amongst others. QDs are already being used in products, such as TV screens and novel solar cell technologies. However, with an increasing number of applications and thusan increase in production volumes, potential exposure is also intensifying. Consequently, risks to humans and the environment are increasing as accidental release and resulting negative effects cannot be ruled out. To date,however, only limited data exist on possible environmental and health risks.

Quantum dots (QDs) are increasingly widespread in medicine and environmental research. Because of their specific optical characteristics, QDs can be detected by fluorescence analyses, even in complex media, such as environmental or tissue samples. Their unique properties make them useful for a variety of applications, such as for the use as fluorescent markers for cells, as contrast agents in deep tissue and tumour imaging, in biosensing or photodynamic therapy, and for targeted drug delivery. As a result, QDs could potentially be used as detectable and clearly identifiable “nanotracers” to mark or detect specific targets or to be able to draw general conclusions about the fate of engineered nanoparticles (ENPs) in environmentally relevant media, e.g. in wastewater. QDs mainly consist of metallic semiconductor compounds, such as cadmium selenide (CdSe), cadmium telluride (CdTe), lead sulphide (PbS) or indium phosphide (InP), which can have toxic effects on cells and organisms. Research is therefore being conducted on non­toxic carbon­based QDs, amongst others. QDs are already being used in products, such as TV screens and novel solar cell technologies. However, with an increasing number of applications and thusan increase in production volumes, potential exposure is also intensifying. Consequently, risks to humans and the environment are increasing as accidental release and resulting negative effects cannot be ruled out. To date,however, only limited data exist on possible environmental and health risks.

Titanium dioxide has been used as a food additive (E 171) in Europe since the 1960s. For a long time, it was assumed that this waterinsoluble material would not cause any negative health effects because of its low absorption rate. In recent years, however, animal studies have confirmed a dose-dependent toxic potential in the event of oral ingestion, with particular damage to the liver and kidneys, inflammatory reactions, and changes to the spleen and heart. The material was also found to accumulate in organs, and individual studies showed an effect on the intestinal flora and the immune system. One study also makes reference to a possible carcinogenic potential. The European Food Safety Authority (EFSA) rated the substance as safe when ingested orally. Up to 59% of the particles of E 171 can have a size of less than 100 nm. On the basis of the studies available to date, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) sees great uncertainties with regard to possible health effects, in particular because of the high proportion of nanoparticulates. The French government has therefore decided to ban E 171 for one year starting from 01.01.2020. Consumer protection organisations are calling for the ban to be extended to the entire European Union (EU). The industry stresses that E 171 is safe and fears negative economic consequences. However, some confectionery manufacturers have already changed their recipes and no longer use E 171. The European Commission is changing the specifications for E 171 so that it may only contain a maximum of 50% of nanoparticles in the future.

This dossier explores bio-inspired and biomimetic nanomaterials, differentiating between bio-inspired or biomimetic nanotechnology and bio-nanotechnology. Following a clarification of these terms, the basics of bio-inspired and biomimetic nanomaterials are then presented. Subsequently, a systematic classification of synthetic methods of bio-inspired and biomimetic nanomaterials is demonstrated. This classification is based on the method of manufacturing and not on the functionality of the materials. This enables a more coherent correlation with security aspects, which are yet to be defined in many cases. Due to the great variety, a categorization according to material properties or material compositions is not considered practical. In addition to chemical properties and behavior, physical parameters such as size, structure and surface quality also play an important role in the categorization. In summary, it can be said that bio-inspired and biomimetic nanomaterials represent important base materials as so-called functional advanced materials in research, development and industry – provided that the material development is accompanied by a corresponding safety and sustainability-oriented technology assessment.

Numerous research projects within the 8th Framework Programme for Research and Innovation of the European Commission – Horizon 2020 – are dedicated to environment, health and safety aspects of nanotechnologies, in continuation of the preceding 7th Framework Programme1. Many of the Horizon 2020 projects are devoted to the following subjects: risk assessment, regulation, standardization of measurement and analytical methods. Furthermore, some projects are focusing their research on production techniques and quality standards. Further research topics include life cycle analyses, safeby-design approaches and processes regarding sustainable production. Projects surrounding the subject of toxicity of nanomaterials are increasingly focusing on long-term studies and the (further) development of test methods. A number of Horizon 2020 projects are also dedicated to the consolidation and harmonization of data and databases. An increasing number of projects investigate computer models for the analysis of health risks and exposure scenarios, which are made available in the form of online platforms or tools for regulators, developers and researchers. Compared to the 7th Framework Programme, Horizon 2020 includes more projects dedicated to physicochemical characterization and the development of measurement and analysis methods of nanomaterials, as well as an increased number of nanoinformatic projects, which are intended to pool existing data on a European level.

A number of concepts address safety-relevant issues of innovative materials and products. The Safe-by-Design (SbD) concept is one of these, and aims to take account of these safety issues early on and during the entire product development process. The nano-specific concepts of SbD are intended to address prevailing uncertainties about potential risks to the environment and human health at the beginning stages in the development of new nanomaterials and products. The basic assumption of the SbD concept is that risks can be reduced through the choice of materials, products, tools and technologies, making them as safe as possible. Particular attention is paid to the product development stage, when it is still possible to intervene to control the selection of these factors. In line with the precautionary principle, the early integration of safety in the innovation process is generally seen as desirable.

A number of concepts address safety-relevant issues of innovative materials and products. The Safe-by-Design (SbD) concept is one of these, and aims to take account of these safety issues early on and during the entire product development process. The nano-specific concepts of SbD are intended to address prevailing uncertainties about potential risks to the environment and human health at the beginning stages in the development of new nanomaterials and products. The basic assumption of the SbD concept is that risks can be reduced through the choice of materials, products, tools and technologies, making them as safe as possible. Particular attention is paid to the product development stage, when it is still possible to intervene to control the selection of these factors. In line with the precautionary principle, the early integration of safety in the innovation process is generally seen as desirable.

Nanomaterials can improve the properties of food contact materials. Innovations of this kind are of particular interest for food packaging made out of plastic materials. The purpose of their use is to improve food storage and so to guarantee both freshness and quality. A further goal is to improve the technical properties of materials in order to make them sturdier more resistant to abrasion, and easier to process. Food contact materials are subject to a number of EU consumer protection regulations. Nanomaterials require authorisation by the European Food Safety Authority (EFSA), being responsible for assessing their safety. For nanomaterials authorised for use in the EU, specifications and restrictions are laid down in order to prevent consumers being exposed to them or to keep exposure as low as possible, and so to rule out any danger to health. At the end of the product lifetime, workers of recycling and waste treatment facilities may be exposed to higher levels of ultra ne particles or particulate matter may also be released unintentionally. To date, however, it has not been demonstrated that recycling polymers containing nanomaterials leads to any increased exposure of employees. With regard to environmental protection, little is known at present about the specific behaviour of nanomaterials and composites during waste treatment processes. There is also a need for comprehensive research on how far nanomaterials can be recycled, in order to develop sustainable nanotechnology.

The green nano design principles developed by the German NanoCommission constitute an attempt to establish consensus-based guidelines for environmentally friendly and sustainable production. This initiative fits into the objective of international research and development policy (e.g., Responsible Research and Innovation, RRI) and shall enable to incorporate desired societal aspects into technology developments as soon as possible. The present dossier is concerned with the question to what extent a concept along those lines can contribute to environmentally friendly developments in the area of nanotechnology. For this purpose, it introduces research projects which have implemented certain aspects of the green nano design principles. Moreover, on the basis of technological and scientific research and development, the question is raised whether or not, and if so, to what extent concepts such as green nano design principles can support the incorporation of environmental aspects into research.

Engineered nanomaterials (ENMs) can potentially be released during all waste treatment processes and can accumulate in residual materials, scrap materials, secondary raw materials or composts. Nonetheless, only few studies are available on the fate and behavior of ENMs during recycling and disposal. In Austria more than half of the waste produced by households is collected separately and undergoes further treatment as recoverables, biogenic waste, hazardous household waste or as waste electrical and electronic equipment. The remainder is processed either in waste incineration facilities or in mechanical-biological waste treatment facilities. Initial studies in waste incineration facilities show that thermally stable ENMs (metal oxides) accumulate mostly in the solid residues (slag, flue dust). In Austria, these are largely disposed of in residual-waste landfills. ENMs can also be released again during the recycling of products (for example quantum dots from LEDs of waste electrical and electronic equipment or CNTs made of composite materials). During recycling, nanosilver apparently negatively affects the mechanical properties of plastics. ENMs can be disposed of directly as production wastes, as components of “nanoproducts” or as secondary wastes such as ENM-containing sewage sludge or combustion residues. Worldwide, an estimated 60 to 86 % of the most commonly used ENMs end up in landfills. Currently, no generalized statements can be made because ENMs are applied in very diverse sectors and their fates in the environment can differ considerably.

Synthetically produced nanomaterials (Engineered Nanomaterials – ENMs) can potentially be released along the entire lifecycle of a product. The use of products with suspended ENMs, such as sunscreen lotions, almost certainly leads to an immediate environmental input. In contrast, ENMs that are solidly integrated in a product matrix can only be released by mechanical and/or chemical processes. ENMs can enter the environment either directly or indirectly (e.g. during the disposal phase), where both their properties and environmental conditions can determine their aggregation behavior. Weathering experiments with facade paints show that only a very small proportion of the contained titanium dioxide nanoparticles (TiO2-NPs) are released. In paints with silver nanoparticles (Ag-NPs), however, up to 30% of the particles can leach out over time. In the case of textiles treated with Ag-NPs, up to 10% of the silver contents can be washed out and enter the wastewater. Tests show that Ag-NPs can be transported over long distances in sewers without deposition. These are partly transformed into water-insoluble silver sulfide. Up to 85% of the TiO2-NPs and up to 99% of the Ag-NPs are removed via sewage sludge during waste water treatment, whereby Ag-NPs and other silver forms are transformed into water-insoluble silver chloride and -sulfide. Once ENMs enter surface waters, a differentiation between natural and engineered nanoparticles becomes complicated. Studies on TiO2-NPs, which can enter swimming waters via sunscreen lotions, show that these aggregate quickly and can subsequently be measured in the sediment.

Considering the public perception of risks with regard to technology controversies has increasingly become important since the debates on genetically modified organisms (GMOs) in Europe. The perception of risks by the population is not comparable with assessments by experts as the concerns stem from a possible direct effect on citizens’ lives, thus subject to different dynamics. This dossier focusses on factors which influence the public perception of risks and elaborates on their relevance for regulatory policies. Moreover, it introduces several European studies on familiarity and risk perception of nanotechnology. The studies’ results are similar: While citizens know comparatively little about nanotechnology, the questioned subjects also perceived it as having a relatively low risk potential. There are several possible explanations: Alongside a general technology-friendly attitude, positive media reporting and the broad range of the technology – which makes it difficult to scandalize it as a whole -, a basic trust in institutions concerned with risks and an accurate, proactive regulatory policy could play an important role.

Based on their special chemical and physical properties, synthetically produced nanomaterials are currently being used in a wide range of products and applications. At the end of their product life cycle, nanomaterials can enter waste treat ment plants and landfills via diverse waste streams. Little, however, is known about how nanomaterials behave in the disposal phase and whether potential environmental or health risks arise. There are no specific legal requirements for a separate treatment of nanomaterial-containing wastes. Virtually no information is available about the nanomaterials currently in use, their form and composition, or about their amounts and concentrations. The current assumption is that stable nanoparticles (e.g. metal oxides) are neither chemically nor physically altered in waste incineration plants and that they accumulate especially in the residues (e.g. slag). These residues are ultimately dumped. The disposal problem in the case of stable nanoparticles is therefore merely shifted to the subsequent steps in the waste treatment process. Carbon nanotubes (CNT) are almost completely combusted in incineration plants. Filter systems seem to be only partially efficient, and a release of nanoparticles into the environment cannot be excluded. Incinerating nanomaterials contained in products can also promote the development of organic pollutants as undesired by-products. Only few studies are available on the behavior of nanomaterials in landfills. Moreover, recycling such products could release nanomaterials, most likely when these are shredded and crushed.