Risk analysis is broadly defined to include risk assessment, risk characterization, risk communication, risk management, and policy relating to risk, in the context of risks of concern to individuals, to public- and private-sector organizations, and to society at a local, regional, national, or global level [1].In general, the term "risk" denotes the potential loss of something of value, e.g. health or an intact environment or simply your purse. A risk exists only if hazard and exposure occur together. A complete risk analysis of a new material is a multi-step process.Important...

Risk assessment
Risk is defined differently depending on the (scientific) discipline. In general, the term "risk" denotes the potential loss of something of value, e.g. health or an intact environment or simply your purse. A risk exists only if hazard and exposure occur together.In toxicology, the term risk describes the function of the probability of "exposure" to the "hazard" potential a given material exhibits: RiskTox = f{exposure; hazard}. In contrast to the simplified explanation given in the basics article Do nanomaterials harbour risks? a closer look shows that the definition of...

Risk management
The definition of a level of acceptable risk of new nanomaterials is defined on a societal consensus and political decision based on scientific risk assessment. The measures to reduce or prevent risks are part of adapted or new laws and regulations which stand at the end of a sophisticated process called risk management. During the process and at the very end the measures have to be disseminated and explained properly. Risk management of nanomaterials is an integral part of risk analysis and is directly based on risk assessment. For nanomaterials, usually a chemical risk assessment is...

Lung © Nerthuz / fotolia.com
The air-blood barrier is a structure present in the lungs that controls gas exchange in the lungs by means of pressure and concentration gradients. However, all other foreign material in our breathing air will be inhaled too if it is small enough, such as bacteria, viruses including nanomaterials. With this being a very thin barrier, the chance for nanoparticles to cross and enter the interior of our body is relatively high. The adult human lung has a huge surface area of around 120 m2 to 140 m2 for gas exchange of oxygen and carbon dioxide. Anatomically it is made of a cascade of...

Coloured clothing taken from a washing machine. © kalcutta / fotolia.com
The textile industry is one of the most important industries for consumer goods worldwide generating textiles for clothing, household goods, furnishing and technical purposes. Like other chemical processes and technologies, nanomaterials are used to add or improve different functionalities of the textiles. These materials could have an adverse effect on humans and environment. Proper selection of nanomaterials and their careful integration in the fabric will help to reduce these possible impacts.From the raw material (e.g. cotton) to the final textile products. all images © fotolia.com...

Nanomaterials represent important new options for the treament of a variety of diseases. In medicine nanomaterials already are employed for various drugs, diagnostics, and implants. Presently, intense reseach is performed to explore further opportunities for using nanomaterials in the health sector, making nanomedicine an area that - including the public - receives strong attention What really is available right now and which new agents may become available in the foreseeable future? And how prudent should we be in order to prevent disappointments caused by exaggerated...

Immune defenses © ag visuell / fotolia.com
Nanoparticles that are present in the body (i.e. after injection) are largely taken up and eliminated by the reticulohistocytic system (RHS). This system represents a network of cells that are distributed throughout the body within its organs. The function of the RHS is the inactivation and elimination of dead cells, bacteria, viruses, and infiltrated small particulates. Nanoparticles also belong to these "infiltrates". The reticulohistocytic system, also named reticuloendothelial system (RES) or mononuclear phagocyte system (MPS) is a network of cells and tissues that are distributed...

[© Gray38.png: User Magnus Manske on en.wikipedia derivative work: Amada44
The placenta is an important tissue barrier that separates the unborn child from the mother. The foetus is totally dependent on proper functioning of the placenta during its development as it is fed and protected by the unique physiology and structural complexity of this organ. As nutrients and oxygen have to penetrate to the foetus, waste and carbon dioxide have to be transported in the other direction. Nanoparticles may cross this barrier and affect the unborn child. The placental barrier is mainly formed by two different cell layers, one from the mother's side and one from the...

Colourful house facades (c) HuxFlux / fotolia.com
In general terms paint depicts a liquid that is used to coat a solid surface in order to protect, seal or colour it. For this purpose pigments such as solid particulates play an important role and have been used since millennia e.g. for cave painting. Today, nanomaterials are being used in order to improve the efficiency and to provide new functionalities to the paints. There are already several nano-enhanced paints on the market. Recent studies have investigated the benefits and risks of paints containing nanomaterials. Exploring the benefits and risks during early stages of...

Cross-section through the skin © 7activestudio / fotolia.com
The skin is the body's largest organ and protects the body against diseases caused by organisms, toxic chemicals, and mechanical damage. Nanoparticles are neither able to easily penetrate intact skin nor through superficial injuries within the skin. Low level mechanical stresses applied to the skin are buffered by a layer called the stratum corneum. Secretion of ichor and other blood components protect deeper abraded skin sites from harmful impacts. Nanoparticles, however, can be deposited in the hair follicles, and this route is used in medicine for the release of nanoparticle-bound drugs...

Immune system © ag visuell / fotolia
The immune system recognizes both self and non-self-entities. When non-self agents are recognized, like nanoparticles, immune cells decide whether they constitute a danger or not. If the body recognizes non-self and considers it dangerous, the immune system responds with inflammation. In the case of pathogens which induce disease, they are confined to a local site, are destroyed, and if an injury has occurred, wound healing is induced. Some technically produced nanomaterials are suspected to promote inflammation. However, an ability to influence immune responses can be medically...

Using the copy machine © Smileus / fotolia.com.
Toners are very fine powders mainly used in copy machines and laser printers. They are often composed of particles with 2-30 microns in diameter. The small particle sizes cause the powders to behave like liquids. Consumers can come into contact with toner particles or paper dust during maintenance work in the resting state of the device e.g. when toner cartridges are replaced or a paper jam has to be removed. During the printing operation with closed housings volatile substances and nanoparticles can be released through the ventilation system of the device into the ambient air leading...

Schematic sketch showing the blood-brain barrier © von Kuebi = Armin Kübelbeck, and for the brain: Patrick J. Lynch [CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
The blood-brain barrier separates the vascular system from the brain and is formed by endothelial cells which are enclosing the brain capillary blood vessels. Under normal circumstances this barrier is impermeable to nanoparticles. The cellular barrier, which separates the brain from the vascular system, is formed by endothelial cells [1]. Our capillary blood vessels are enclosed with these cells (endothelial cells), that are connected to each other with circumventing tight junctions that abolish all substance transport between the cells. Only very small lipophilic molecules can...

Lattice structure of NaCl crystals. © natros / fotolia.com
Depending on external conditions such as temperature or pressure, atoms may arrange themselves in various ways in lattice structures. Therefore, for some materials with the same proportions of contained elements, different crystal structures exist. Nanomaterials with different crystal structures may differ in important physicochemical properties (e.g. reactivity or photocatalytic activity). Accordingly, in such cases only a specific crystal structure is used for a given application. The different crystal structures are not only relevant for the various technical applications, but can also...

Different forms of coatings for nanoparticles
When talking about surface coatings of nanomaterials often terms such as modification, functionalisation or stabilisation are used. This diversity in terms reflects the different motivations for using a coating or for its intended function.Generally, surface coatings of nanomaterials are applied in order to selectively change or influence distinct particle properties. For this purpose, the surface of a particle (the “core“) can be covered with a wide variety of substances which in return generates single- or multi-layers layer(s) (the “shell”) that can be either complete or incomplete...