Toxicity of inhaled nanomaterials

Lungs are another part of the body which is particularly exposed to silver nanoparticies. Experiments investigating the effect of inhaled nanomaterials demonstrated that lungs are an easy target for nanosilver, which may additionally migrate via the nasal pathway to the brain. However, there is a limited amount of evidence concerning toxic effects on lung cells (Soto et al., 2007). 

Nanoscale materials are known to have various shapes and structures such as spherical, needle-like, tubes, platelets, and so on. The effects of the shape on the toxicity of nanomaterials are unclear. The shape of nanomaterials may have effects on the kinetics of deposition and absorption to the body. Inhaled particles in the nanosize range can certainly deposit in all parts of the respiratory tract including the alveolar region of the lungs. Dependent upon the specific application, oral, dermal, and other routes of exposure are also possible for nanoparticles. Because of their small size, they may pass into cells directly through the cell membrane or penetrate the skin and distribute throughout the body once translocated to the blood circula-... 

The toxicity of nanomaterials is not well understood, and many commentators have expressed concern that the unique properties of nanomaterials maybe associated with unknown risks. Some of the concern is because of the ability of small particles to penetrate Hving tissue. There are conflicting study conclusions on whether inhaled nanoparticles may mimic the action of asbestos in the lungs. Some studies conclude that they do cause inflammation because they can reach the lung structures that exchange oxygen and carbon dioxide from the blood. However, other studies conclude that the results are equivocal. Similarly, titanium dioxide nanoparticles have been the subject of several studies to determine whether or not they can penetrate human skin when they are used in sunscreen formulations. While studies have shown that they do not penetrate beyond the outer layer of skin, the studies have been criticized because they were aU on intact, unabraded healthy adult skin, and so the risks in actual use may not be the same as indicated by those studies. In addition, many formulations contain moisturizers that are designed to penetrate skin, and the effects of these moisturizers on the skin penetration of titanium dioxide nanoparticles are unknown. ... 

Landsiedel, R., Ma-Hock, L, Hofmann, T, Wiemann, M., Strauss, V, Treumann, S., Wohlleben, W, Groters, S., Wiench, K. Van Ravenzwaay, B. 2014. Application of short-term inhalation studies to assess the inhalation toxicity of nanomaterials. Particle and Fibre Toxicology, 11, 16. 

CNTs are of importance as useful bio-nanomaterials for pharmaceutical applications and biomedical engineering. However, despite the contribution of CNTs to bio-nanomaterials for pharmaceutical applications, the potential risks of CNTs about the exposure to human health have not been adequately assessed. Toxicology issues associated with CNT inhalation, dermal toxicity, pulmonary, biodistribution, biocompatibility, blood compatibility, and elimination need to be addressed prior to their pharmacological application in humans. 

Determining anticipated route and magnitude of exposure is an important component in the overall assessment of safety and must be done on a nanomaterial-by-nanomaterial basis, with secondary exposures taken into consideration when necessary. The estimated exposure levels for a nanomaterial may then be compared with the calculated safe dose derived from the hazard identification evaluation. The procedures and factors considered in the exposure assessment process are not expected to be any different for nanomaterials than for larger particles or chemicals. The degree of hazard associated with exposure to any chemical or substance, regardless of its physicochemical characteristics, depends on several factors, including its toxicity, dose-response curve, concentration, route of exposure, duration and/or frequency of exposure. However, depending on the route of anticipated exposure (dermal, inhalation, oral) and types of associated toxicities (local or systemic), a chemical may not pose any risk of adverse effects if there is no... 

Respiratory tract exposure is the most common and widely studied pathway of particulate matter invasion [14, 32, 35, 51, 84], and the same is true for nanomaterials. The inhalation of airborne natural particulate matter or engineered nanomaterials may lead to serious toxic effects for example, the prolonged exposure and uptake of these materials in the human lung can cause chronic obstructive pulmonary disease and pulmonary morbidity, both of which may lead to death [32]. Therefore, it is crucial to understand how these materials enter and reside in... 

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