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Journal ArticleDOI

Deposition of Ultrafine (NANO) Particles in the Human Lung

01 Oct 2007-Inhalation Toxicology (Inhal Toxicol)-Vol. 19, Iss: 13, pp 1045-1054
TL;DR: A mathematical model of nanoparticle transport by airflow convection, axial diffusion, and convective mixing (dispersion) was developed in realistic stochastically generated asymmetric human lung geometries and good agreement was found between predicted depositions of ultrafine (nano) particles with measurements in the literature.
Abstract: Increased production of industrial devices constructed with nanostructured materials raises the possibility of environmental and occupational human exposure with consequent adverse health effects. Ultrafine (nano) particles are suspected of having increased toxicity due to their size characteristics that serve as carrier transports. For this reason, it is critical to refine and improve existing deposition models in the nano-size range. A mathematical model of nanoparticle transport by airflow convection, axial diffusion, and convective mixing (dispersion) was developed in realistic stochastically generated asymmetric human lung geometries. The cross-sectional averaged convective-diffusion equation was solved analytically to find closed-form solutions for particle concentration and losses per lung airway. Airway losses were combined to find lobar, regional, and total lung deposition. Axial transport by diffusion and dispersion was found to have an effect on particle deposition. The primary impact was in the pulmonary region of the lung for particles larger than 10 nm in diameter. Particles below 10 nm in diameter were effectively removed from the inhaled air in the tracheobronchial region with little or no penetration into the pulmonary region. Significant variation in deposition was observed when different asymmetric lung geometries were used. Lobar deposition was found to be highest in the left lower lobe. Good agreement was found between predicted depositions of ultrafine (nano) particles with measurements in the literature. The approach used in the proposed model is recommended for more realistic assessment of regional deposition of diffusion-dominated particles in the lung, as it provides a means to more accurately relate exposure and dose to lung injury and other biological responses.
Citations
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Journal ArticleDOI
TL;DR: A critical review of the biophysicochemical properties of various nanomaterials with emphasis on currently available toxicology data and methodologies for evaluating nanoparticle toxicity suggests that NPs may need to be sequestered into products so that the NPs are not released into the atmosphere during the product's life or during recycling.
Abstract: Nanoscience has matured significantly during the last decade as it has transitioned from bench top science to applied technology. Presently, nanomaterials are used in a wide variety of commercial products such as electronic components, sports equipment, sun creams and biomedical applications. There are few studies of the long-term consequences of nanoparticles on human health, but governmental agencies, including the United States National Institute for Occupational Safety and Health and Japan's Ministry of Health, have recently raised the question of whether seemingly innocuous materials such as carbon-based nanotubes should be treated with the same caution afforded known carcinogens such as asbestos. Since nanomaterials are increasing a part of everyday consumer products, manufacturing processes, and medical products, it is imperative that both workers and end-users be protected from inhalation of potentially toxic NPs. It also suggests that NPs may need to be sequestered into products so that the NPs are not released into the atmosphere during the product's life or during recycling. Further, non-inhalation routes of NP absorption, including dermal and medical injectables, must be studied in order to understand possible toxic effects. Fewer studies to date have addressed whether the body can eventually eliminate nanomaterials to prevent particle build-up in tissues or organs. This critical review discusses the biophysicochemical properties of various nanomaterials with emphasis on currently available toxicology data and methodologies for evaluating nanoparticle toxicity (286 references).

1,138 citations

Journal ArticleDOI
TL;DR: This review critically examines the use of NDs for biomedical applications based on type (i.e., high-pressure high-temperature [HPHT], CVD diamond, detonation ND [DND]), post-synthesis processing and modifications, and resultant properties including bio-interfacing.
Abstract: Nanodiamonds (NDs) are members of the diverse structural family of nanocarbons that includes many varieties based on synthesis conditions, post-synthesis processes, and modifications. First studied in detail beginning in the 1960s in Russia, NDs have now gained world-wide attention due to their inexpensive large-scale synthesis based on the detonation of carbon-containing explosives, small primary particle size (∼ 4 to 5 nm) with narrow size distribution, facile surface functionalization including bio-conjugation, as well as high biocompatibility. It is anticipated that the attractive properties of NDs will be exploited for the development of therapeutic agents for diagnostic probes, delivery vehicles, gene therapy, anti-viral and anti-bacterial treatments, tissue scaffolds, and novel medical devices such as nanorobots. Additionally, biotechnology applications have shown the prospective use of NDs for bioanalytical purposes, such as protein purification or fluorescent biolabeling. This review critically e...

715 citations

Journal ArticleDOI
TL;DR: Physicochemical characteristics of nanoparticles and engineered nanomaterials including size, shape, chemical composition, physiochemical stability, crystal structure, surface area, surface energy, and surface roughness generally influence the toxic manifestations of these nanom materials.
Abstract: Nanotechnology has emerged as one of the leading fields of the science having tremendous application in diverse disciplines. As nanomaterials are increasingly becoming part of everyday consumer products, it is imperative to assess their impact on living organisms and on the environment. Physicochemical characteristics of nanoparticles and engineered nanomaterials including size, shape, chemical composition, physiochemical stability, crystal structure, surface area, surface energy, and surface roughness generally influence the toxic manifestations of these nanomaterials. This compels the research fraternity to evaluate the role of these properties in determining associated toxicity issues. Reckoning with this fact, in this paper, issues pertaining to the physicochemical properties of nanomaterials as it relates to the toxicity of the nanomaterials are discussed.

531 citations


Cites background from "Deposition of Ultrafine (NANO) Part..."

  • ...It has been observed that ultrafine particles with diameters <100 nm deposits in all regions, whereas particles <10 nm deposits in the tracheobronchial region, while particles between 10 and 20 nm deposits in the alveolar region [27]....

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Journal ArticleDOI
TL;DR: An overview of the potential usefulness of nanoparticles and nanotechnology in respiratory research and medicine is provided and important issues and recent data pertaining to nanoparticle-related pulmonary toxicity are highlighted.
Abstract: Because of their unique physicochemical properties, engineered nanoparticles have the potential to significantly impact respiratory research and medicine by means of improving imaging capability and drug delivery, among other applications. These same properties, however, present potential safety concerns, and there is accumulating evidence to suggest that nanoparticles may exert adverse effects on pulmonary structure and function. The respiratory system is susceptible to injury resulting from inhalation of gases, aerosols, and particles, and also from systemic delivery of drugs, chemicals, and other compounds to the lungs via direct cardiac output to the pulmonary arteries. As such, it is a prime target for the possible toxic effects of engineered nanoparticles. The purpose of this article is to provide an overview of the potential usefulness of nanoparticles and nanotechnology in respiratory research and medicine and to highlight important issues and recent data pertaining to nanoparticle-related pulmonary toxicity.

284 citations


Cites background from "Deposition of Ultrafine (NANO) Part..."

  • ...As summarized elsewhere (7, 107), inhaled particles of different sizes exhibit different fractional depositions within the human respiratory tract....

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  • ...Although inhaled ultrafine particles ( 100 nm) deposit in all regions, tracheobronchial deposition is highest for particles 10 nm in size, whereas alveolar deposition is highest for particles approximately 10–20 nm in size (7, 107)....

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Journal ArticleDOI
TL;DR: This review summarizes the present state of knowledge concerning airborne AgNPs to shed light on the possible environmental exposure scenarios that may accompany the production and popularization of silver nanotechnology consumer products.
Abstract: Silver nanoparticles (AgNPs) are gaining attention from the academic and regulatory communities, not only because of their antimicrobial effects and subsequent product applications, but also because of their potential health and environmental risks. Whereas AgNPs in the aqueous phase are under intensive study, those in the atmosphere have been largely overlooked, although it is well established that inhalation of nanoparticles is associated with adverse health effects. This review summarizes the present state of knowledge concerning airborne AgNPs to shed light on the possible environmental exposure scenarios that may accompany the production and popularization of silver nanotechnology consumer products. The current understanding of the toxicity of AgNPs points toward a potential threat via the inhalation exposure route. Nanoparticle size, chemical composition, crystal structure, surface area, and the rate of silver ion release are expected to be important variables in determining toxicity. Possible routes of aerosolization of AgNPs from the production, use, and disposal of existing consumer products are presented. It is estimated that approximately 14% of silver nanotechnology products that have been inventoried could potentially release silver particles into the air during use, whether through spraying, dry powder dispersion, or other methods. In laboratory and industrial settings, six methods of aerosolization have been used to produce airborne AgNPs: spray atomization, liquid-flame spray, thermal evaporation-condensation, chemical vaporization, dry powder dispersion, and manual handling. Fundamental uncertainties remain about the fate of AgNPs in the environment, their short- and long-term health effects, and the specific physical and chemical properties of airborne particles that are responsible for health effects. Thus, to better understand the risks associated with silver nanotechnology, it is vital to understand the conditions under which AgNPs could become airborne.

214 citations

References
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Journal Article

1,869 citations


"Deposition of Ultrafine (NANO) Part..." refers background in this paper

  • ...Convective mixing has often been assumed to be diffusive in nature, propagating by dispersion (Darquenne et al., 1997; Edwards, 1994; Egan et al., 1989; Hofmann et al., 1994; Taulbee & Yu, 1975)....

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  • ...(2) and other similar equations have been extended to particles (Darquenne & Paiva, 1994; Hofmann et al., 1994; Taulbee & Yu, 1978) despite being specifically developed for gases....

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Journal ArticleDOI
TL;DR: The present study suggests that the size distribution of ambient particles helps to elucidate the properties of ambient aerosols responsible for health effects.
Abstract: The association between fine and ultrafine particles and respiratory health was studied in adults with a history of asthma in Erfurt, Eastern Germany. Twenty-seven nonsmoking asthmatics recorded their peak expiratory flow (PEF) and respiratory symptoms daily. The size distribution of ambient particles in the range of 0.01 to 2.5 microm was determined with an aerosol spectrometer during the winter season 1991-1992. Most of the particles (73%) were in the ultrafine fraction (smaller than 0.1 microm in diameter), whereas most of the mass (82%) was attributable to particles in the size range of 0.1 to 0.5 microm. Because these two fractions did not have similar time courses (correlation coefficient r = 0.51), a comparison of their health effects was possible. Both fractions were associated with a decrease of PEF and an increase in cough and feeling ill during the day. Health effects of the 5-d mean of the number of ultrafine particles were larger than those of the mass of the fine particles. In addition, the effects of the number of the ultrafine particles on PEF were stronger than those of particulate matter smaller than 10 microm (PM10). Therefore, the present study suggests that the size distribution of ambient particles helps to elucidate the properties of ambient aerosols responsible for health effects.

1,290 citations


"Deposition of Ultrafine (NANO) Part..." refers background in this paper

  • ...Exposure to nanoparticles can exacerbate respiratory disease (Peters et al., 1997) and produces toxicity even at low concentrations (Johnston et al., 2000)....

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Journal ArticleDOI
TL;DR: In this paper, the authors presented experimentally determined total and regional deposition data for breathing monodisperse aerosols of a wide particle size range at different patterns through the mouth and nose.

1,002 citations


"Deposition of Ultrafine (NANO) Part..." refers background or methods in this paper

  • ...…were made for particles between 5 nm and 100 nm. Figure 7 A and B, shows the comparison of predicted total deposition fraction against measurements of Heyder et al. (1986), Jaques and Kim (2000), Schiller et al. (1988), and Tu and Knudson (1984) in the SBAN and LBAN stochastic lungs, respectively....

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  • ...The agreement with Heyder et al. (1986) and Tu and Knudson is excellent, while comparison with the measurements of Schiller et al. (1988) shows some scatter around the line of identity for the SBAN stochastic lung....

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Journal ArticleDOI
TL;DR: Although laboratory studies indicated that with sufficient agitation, unrefined SWCNT material can release fine particles into the air, concentrations generated while handling material in the field were very low, and estimates of the airborne concen-tration of nanotube material generated during handling suggest that concentrations were lower than 53μg/m3 in all cases.
Abstract: Carbon nanotubes represent a relatively recently discovered allotrope of carbon that exhibits unique properties. While commercial interest in the material is leading to the development of mass production and handling facilities, little is known of the risk associated with exposure. In a two-part study, preliminary investigations have been carried out into the potential exposure routes and toxicity of single-walled carbon nanotube material (SWCNT)--a specific form of the allotrope. The material is characterized by bundles of fibrous carbon molecules that may be a few nanometers in diameter, but micrometers in length. The two production processes investigated use-transition metal catalysts, leading to the inclusion of nanometer-scale metallic particles within unrefined SWCNT material. A laboratory-based study was undertaken to evaluate the physical nature of the aerosol formed from SWCNT during mechanical agitation. This was complemented by a field study in which airborne and dermal exposure to SWCNT was investigated while handling unrefined material. Although laboratory studies indicated that with sufficient agitation, unrefined SWCNT material can release fine particles into the air, concentrations generated while handling material in the field were very low. Estimates of the airborne concentration of nanotube material generated during handling suggest that concentrations were lower than 53 microg/m(3) in all cases. Glove deposits of SWCNT during handling were estimated at between 0.2 mg and 6 mg per hand.

767 citations


"Deposition of Ultrafine (NANO) Part..." refers background in this paper

  • ...Due to their physicochemical characteristics that give them enhanced properties (Maynard et al., 2004), manufactured nanoparticles may be biopersistant and remain intact and cause toxicity....

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Journal ArticleDOI
TL;DR: Both acute instillation and subchronic inhalation studies showed that ultrafine particles at equivalent masses access the pulmonary interstitium to a larger extent than fine particles (integral of 250 nm).
Abstract: In aerosol research, particle size has been mainly considered in the context of the role it plays in particle deposition along the respiratory tract. The possibility that the primary particle size may affect the fate of particles after they are deposited was explored in this study. Rats were exposed for 12 wk to aerosolized ultrafine (∼21 nm diameter) or fine (∼250 nm diameter) titanium dioxide (TiO2) particles. Other rats were exposed to TiO2 particles of various sizes (12, 21, 230, and 250 nm) by intratracheal instillation. After the rat lungs were extensively lavaged, analysis of particle content in the lavaged lungs, lavage fluid, and of lymphatic nodes was performed. Electron and light microscopy was also performed using unlavaged lungs. Both acute instillation and subchronic inhalation studies showed that ultrafine particles (∼20 nm) at equivalent masses access the pulmonary interstitium to a larger extent than fine particles (∼250 nm). An increasing dose in terms of particle numbers and a decreasin...

713 citations


"Deposition of Ultrafine (NANO) Part..." refers background in this paper

  • ...E-mail: Asgharian@thehamner.org related to the ultrafine, nanosized fraction of the products (Ferin & Oberdörster, 1992; Oberdörster et al., 1992)....

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