Material assessment nanomaterials

For nanomaterials this is especially true if the exposure scenarios used in the test system are not representative of those likely to be found in the field [91, 92]. For example, the degree of toxicity observed in aquatic invertebrates exposed to multi-walled nanotubes (MWNTs) in water and sediment was influenced by the functional groups on the MWNTs and their preparation for dispersal into the test systems [93]. As noted, even the concept of what constitutes nanomaterials is not fixed [87], so these emerging materials will likely require a rethinking of how their toxicity is assessed and the hazards and risks they might pose to ecosystems [90]. For more information on nanomaterials, including application of life-cycle concepts to their design, see Chapter 8. 

Imaging is a common technique for assessing materials. For example, airliner structural materials are often X-ray-imaged to check for hairline cracks or other signs of imminent failure. In scientific applications, advances in nanotechnology have produced a parallel need for improved methods of imaging nanomaterials on the molecular scale. 

Two obvious routes of human contact with nanoparticulates are the skin and via inhalation. Given the size of the particles, there may be a propensity for absorption into the systemic circulation. In some cases the nanosystems are engineered to achieve enhanced systemic absorption. The established methodology for toxicological assessment of new materials should be adhered to, and the discussion below is intended only to touch upon some of the immediate safety concerns that should be understood and addressed when dealing with nanomaterials. 

Research is needed to explore the impacts of nanomaterials and nanomaterial production on the environment and public health. One framework for assessing these impacts is that of comparative risk assessment. Applied to an assessment of the production, use, and disposal of nanomaterials, a risk assessment typically considers both the potential for exposure to a given material and (once exposed) potential impacts such as toxicity or mutagenicity. The need to elucidate both of these components of risk in assessing the consequences of nanomaterials on the environment and public health is essential. 

Nanotechnology is enabling new developments in material science, while providing innovations for industries such as construction, information and communications, healthcare, energy, transportation and security. The sustainable development of nanomaterials, including their potential for environmental protection and the appropriate assessment of possible risks, will contribute to sustainable economic growth. 

In January 2009 EPA issued an interim assessment of the NMSP. It called the basic phase of the program a success, although it did not receive enough information to determine the molecular identity of many of the nanoscale materials that were the subject of the submissions. The EPA noted that it received 123 submissions on 58 different chemicals. Because there is no inventory of nanoscale materials EPA devoted considerable effort to estimating how many commercial nanomaterials are currently made in order to determine if there was a gap between the number of commercial nanomaterials and the number of commercial nanomaterials that were the subject of NMSP reporting. It estimated that NMSP participants reported on only approximately one-third of the chemicals from which commercially available nanomaterials are made, and only approximately one-tenth of the commercially available nanomaterials, which may be composed of multiple chemicals. ... 

CNCs are becoming an important class of renewable nanomaterials with many applications in different areas, including biomedicine. A number of reviews on the bioapplications of CNCs can be found in the literature. The U.S. Food and Drug Administration (FDA) has listed CNCs as a Generally Regarded As Safe (GRAS) material. The toxicity assessment of CNCs in the microvascular endothelial cells of human brain was conducted and CNCs were found to be non-toxic to cells and therefore could be used as carriers in the targeted delivery of therapeutics. The non-toxicity of CNCs has been confirmed by interactions with rainbow trout hepatocytes and microvascular endothelial cells. The biocompatibility of CNCs has also been verified in a recent study. " ... 

Taking into consideration the differences in the effect of nanomaterials on living cells, before their clinical application, an assessment of their biocompatibility should be performed. This chapter presented the obtaining and testing of bactericidal composite materials confronted with Grampositive and Gram-negative bacteria and then, the assessment of their biocompatibility under in vitro conditions. 

The use of nanotechnologies in the food industry may present potential risks to both human health and the environment due to the use of novel materials in novel ways, and risk assessments must be carried out. Three different ways of entrance penetration of nanoparticles in the organism are possible inhalation, skin penetration and ingestion. Free nanoparticles can cross cellular barriers and that exposure may lead to oxidative damage and inflammatory reactions. In the case of nanomaterials for food packaging, many people fear risk of indirect exposure due to potential migration of nanoparticles from packaging materials, in particular nanobiocomposites. 

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