Toxicology of Nanoparticles

While funding for and implementation of research and development is proceeding at a rapid rate, research on potential toxicity associated with these particles is not. Little work has been done in this area, and only quite recently have focused toxicology studies been conducted on nanoparticles. 

The most important exposure route for nanoparticles is likely to be inhalation. Research has so far indicated that, due to their extremely small size, nanoparticles will deposit in the lung to a greater extent than larger respirable particles. Some of the particles inhaled through the nose of rats can actually be transported directly to the brain via the olfactory nerve. This transport has yet to be studied in humans. So far, research has demonstrated that the following toxic effects can be caused or aided by nanoparticles in rats  

Recent research has indicated that, when evaluated on a normalized size basis, insoluble nanoparticles are more potent than larger particles of the same composition in causing lung inflammation and tumors in animals. A complicating factor in this research is that nanoparticle toxicity is also affected by the chemicals that comprise individual particles. For example, nanoparticles made of titanium oxide showed little if any lung toxicity, while particles made of crystallized silica caused severe lung toxicity. 

Single-walled nanotubes have gained much interest recently with regard to medical and other applications. However, toxicological research has not progressed to the point where occupational exposure levels can be developed. Therefore, scientists have exposed laboratory rats to concentrations that are equal to the safe occupational limits of other fine particulate matter, such as quartz and carbon black, to evaluate the applicability of these limits to single-walled nanotubes. Results suggest 

It should be understood that the types of toxic effects discussed above are limited to situations where nanoparticles ctfe inhcded or placed in the trachea as insoluble particles. The form of nanoparticles in applications are either dissolved in solution (e.g., through injection for medical uses) or inside components (e.g., computers) and are likely not available for exposure in these ways. We expect that the risk of toxic effects is significantly reduced in these types of products. However, incidental inhalation exposure by workers in the industry represents a potential health issue that requires more research. This is well understood by the U.S. National Institute of Occupational Safety and Health (NIOSH). They recommend limiting exposure to workers until more knowledge is gained, and have identified ten key research topics, including  

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In the study conducted by Hurt et al. [43], toxicology of nanoparticles (nanotoxicology) with a special emphasis on CNT was considered. The necessity of carrying out toxicology research as well as the lack of such work in this area was highlighted. It was considered that the future development of nanotoxicology is associated with the following ... 

Oberdorster, G., Stone, V, Donaldson, K., 2007. Toxicology of nanoparticles a historical perspective. Nanotoxicology 1(1), 2-25. 

As we mentioned previously, the research on the field of nanomaterials is at a primitive stage and literature mainly focuses on the benefits of using such particles for environmental load reduction, waste treatment, and source pollution control, as well as the toxicological and health issues accompanying the use of such materials. As a consequence, there are still few methods developed for food matrices and even lesser monitoring schemes applied. Currently, no data have been noticed reporting the occurrence on nanomaterial residues in food and just one work has been published till now reporting the occurrence of nanoparticle (fullerenes) in real environmental samples [6]. 

A variety of new materials had been produced using nanoparticles before scientists became concerned about their possible negative impact and consequences for the human body and the environment. The toxicology of carbon nanomaterials. 

Toxicology of Nano-Objects Nanoparticles, Nanostructures and Nanophases... 

A common theme throughout this volume involves the adsorption and interfacial, especially biointerfacial, behaviour of all of the above mentioned nanomaterials. For environmental and human protection, the adsorption of heavy metal ions, toxins, pollutants, drugs, chemical warfare agents, narcotics, etc. is often desirable. A healthy mix of experimental and theoretical approaches to address these problems is described in various contributions. In other cases the application of materials, particularly for biomedical applications, requires a surface rendered inactive to adsorption for long term biocompatibility. Adsorption, surface chemistry, and particle size also plays an important role in the toxicological behaviour of nanoparticles, a cause for concern in the application of nanomaterials. Each one of these issues is addressed in one or more contributions in this volume. 

Jiang. J.K., Oberdorster, G., and Biswas, P., Characterization of size, surface charge, and agglomeration state of nanoparticle dispersions for toxicological studies, J. Nanopart. Res., 11, 77, 2009. 

The highest priority threats in this area include nanoparticles capable of destroying brain tissue or cells through inhalation or ingestion in food or water supplies. Studies of air pollution, particulate matter, and nanoparticle toxicology have lead to the development of a framework related to the potential consequences of inhalation exposure of nanoparticles, including lung inflammation and cardiovascular injury... 

The potential consequences of inhalation exposure to nanoparticles are only beginning to be nnderstood. The toxicology of metal fumes, radionuclides, nuisance dusts, rat lung overload, the toxicology of sihca, asbestos, synthetic vitreous fibers, and pollution particles can aU be used to gain insight into the behavior of nanoparticles. Currently, there is no model to predict the toxicity or safety of nanoparticles, and little information is available with regard to human exposure and risks related to levels and duration of exposure. 

Hussain, S.M., Hess, K.L., Gearhart, J.M., Geiss, K.T., Schlager, J.J. In vitro toxicity of nanoparticles in BRL 3A rat liver cells. Toxicology in Vitro An International Journal Published in Association with BIBRA 19, 975-983 (2005)... 

Dahle, J.T., Arai, Y., 2015. Review environmental geochemistry of cerium applications and toxicology of cerium oxide nanoparticles. Int. J. Environ. Res. Public Health 12, 1253-1278. 

Shadman, F., 2015. Physical, chemical, and in vitro toxicological characterization of nanoparticles in chemical mechanical planarization suspensions used in the semiconductor industry towards environmental health and safety assessments. Environ. Sci. Nano 2, 227-244. 

Recently, the influence of size, shape, and surface chemistry of nanoparticle systems on drug delivery performance and modalities like blood circulation time, biodistribution, pharmacokinetics, toxicology, targeting ability, and internalization have been comprehensively reviewed and outlined by Petros and DeSimone [107]. Nanoparticle uptake by, e.g., internalization in the target cells, is still treated as the key factor in this and other earlier articles. Important properties and requirements in this respect were identified and can be summarized by the following four points ... 

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