Deposition of graphene nanomaterial aerosols in human upper airways.

Graphene nanomaterials have attracted wide attention in recent years on their application to state-of-the-art technology due to their outstanding physical properties. On the other hand, the nanotoxicity of graphene materials also has rapidly become a serious concern especially in occupational health. Graphene naomaterials inevitably could become airborne in the workplace during manufacturing processes.

Carbon nanotubes size classification, characterization and nasal airway deposition.

Workers and researchers in the carbon nanotubes (CNT)-related industries and laboratories might be exposed to CNT aerosols while generating and handling CNT materials. From the viewpoint of occupational health, it is essential to study the deposition of CNT aerosol in the human respiratory tract to investigate the potential adverse health effects. In this study, a human nasal airway replica and two types of CNT materials were employed to conduct CNT nasal airway deposition studies.

Deposition of Particles in Human Mouth-Throat Replicas and a USP Induction Port.

Background: Oral inhalation is the common route of drug delivery to pulmonary airways. In general, deposition in the oropharyngeal airways from a drug-delivery device makes up a substantial portion of the emitted dose, which affects the dose delivered to the lung. Studies with airway replicas made from cadaver or magnetic resonance imaging scans show that for micrometer-sized particles, impaction is the dominant deposition mechanism.

Mechanisms of pharmaceutical aerosol deposition in the respiratory tract.

Aerosol delivery is noninvasive and is effective in much lower doses than required for oral administration. Currently, there are several types of therapeutic aerosol delivery systems, including the pressurized metered-dose inhaler, the dry powder inhaler, the medical nebulizer, the solution mist inhaler, and the nasal sprays. Both oral and nasal inhalation routes are used for the delivery of therapeutic aerosols.

Evaluation of a novel personal nanoparticle sampler.

This work investigated the performance in terms of collection efficiency and aspiration efficiency of a personal sampler capable of collecting ultrafine particles (nanoparticles) in the occupational environment. This sampler consists of a cyclone for respirable particle classification, micro-orifice impactor stages with an acceleration nozzle to achieve nanoparticle classification and a backup filter to collect nanoparticles. Collection efficiencies of the cyclone and impactor stages were determined using monodisperse polystyrene latex and silver particles, respectively.

Nasal deposition in infants and children.

Background: The variability of particle deposition in infant and child nasal airways is significant due to the airway geometry and breathing rate. Estimation of particle deposition in the nasal airway of this age group is necessary, especially for inhalation drug delivery application. Previous studies on nasal aerosol deposition were focused mostly on adult.

Thoracic fraction of inhaled fiber aerosol.

Size-selective sampling is a health-related method to collect airborne particles based on penetration of inhaled particles into different regions of the human respiratory tract; thus, it is the most relevant sampling method to correlate health risks with occupational exposure. The current practice of sampling asbestos and other fibers is not a size-selective method. The thoracic size fraction, defined as the portion of inhaled particles that can penetrate through the larynx, has been suggested as the most relevant size-selective sampling method for fiber aerosol.

A wind tunnel test of newly developed personal bioaerosol samplers.

In this study the performance of two newly developed personal bioaerosol samplers was evaluated. The two test samplers are cyclone-based personal samplers that incorporate a recirculating liquid film. The performance evaluations focused on the physical efficiencies that a personal bioaerosol sampler could provide, including aspiration, collection, and capture efficiencies.

Determination of in vitro lung solubility and intake-to-dose conversion factor for tritiated lanthanum nickel aluminum alloy.

A sample of tritiated lanthanum nickel aluminum alloy (LaNi4.25Al0.75 or LANA.

The effect of ventilation, age, and asthmatic condition on ultrafine particle deposition in children.

Ultrafine particles (UFPs) contribute to health risks associated with air pollution, especially respiratory disease in children. Nonetheless, experimental data on UFP deposition in asthmatic children has been minimal. In this study, the effect of ventilation, developing respiratory physiology, and asthmatic condition on the deposition efficiency of ultrafine particles in children was explored.

Evaluation of physical sampling efficiency for cyclone-based personal bioaerosol samplers in moving air environments.

The need to determine occupational exposure to bioaerosols has notably increased in the past decade, especially for microbiology-related workplaces and laboratories. Recently, two new cyclone-based personal bioaerosol samplers were developed by the National Institute for Occupational Safety and Health (NIOSH) in the USA and the Research Center for Toxicology and Hygienic Regulation of Biopreparations (RCT & HRB) in Russia to monitor bioaerosol exposure in the workplace. Here, a series of wind tunnel experiments were carried out to evaluate the physical sampling performance of these two samplers in moving air conditions, which could provide information for personal biological monitoring in a moving air environment.

Exhaled aerosol transmission of pandemic and seasonal H1N1 influenza viruses in the ferret.

Person-to-person transmission of influenza viruses occurs by contact (direct and fomites) and non-contact (droplet and small particle aerosol) routes, but the quantitative dynamics and relative contributions of these routes are incompletely understood. The transmissibility of influenza strains estimated from secondary attack rates in closed human populations is confounded by large variations in population susceptibilities. An experimental method to phenotype strains for transmissibility in an animal model could provide relative efficiencies of transmission.

Novel active personal nanoparticle sampler for the exposure assessment of nanoparticles in workplaces.

A novel active personal nanoparticle sampler (PENS), which enables the collection of both respirable particulate mass (RPM) and nanoparticles (NPs) simultaneously, was developed to meet the critical demand for personal sampling of engineered nanomaterials (ENMs) in workplaces. The PENS consists of a respirable cyclone and a micro-orifice impactor with the cutoff aerodynamic diameter (d(pa50)) of 4 μm and 100 nm, respectively. The micro-orifice impactor has a fixed micro-orifice plate (137 nozzles of 55 μm in the inner diameter) and a rotating, silicone oil-coated Teflon filter substrate at 1 rpm to achieve a uniform particle deposition and avoid solid particle bounce.

Aerosol-assisted synthesis of monodisperse single-crystalline α-cristobalite nanospheres.

Monodisperse single-crystalline α-cristobalite nanospheres have been synthesized by hydrocarbon-pyrolysis-induced carbon deposition on amorphous silica aerosol nanoparticles, devitrification of the coated silica at high temperature, and subsequent carbon removal by oxidation. The nanosphere size can be well controlled by tuning the size of the colloidal silica precursor. Uniform, high-purity nanocrystalline α-cristobalite is important for catalysis, nanocomposites, advanced polishing, and understanding silica nanotoxicology.

Florida Red Tide Toxins (Brevetoxins) and Longitudinal Respiratory Effects in Asthmatics.

Having demonstrated significant and persistent adverse changes in pulmonary function for asthmatics after 1 hour exposure to brevetoxins in Florida red tide (Karenia brevis bloom) aerosols, we assessed the possible longer term health effects in asthmatics from intermittent environmental exposure to brevetoxins over 7 years. 125 asthmatic subjects were assessed for their pulmonary function and reported symptoms before and after 1 hour of environmental exposure to Florida red tide aerosols for upto 11 studies over seven years. As a group, the asthmatics came to the studies with normal standardized percent predicted pulmonary function values.

Transmission of aerosolized seasonal H1N1 influenza A to ferrets.

Influenza virus is a major cause of morbidity and mortality worldwide, yet little quantitative understanding of transmission is available to guide evidence-based public health practice. Recent studies of influenza non-contact transmission between ferrets and guinea pigs have provided insights into the relative transmission efficiencies of pandemic and seasonal strains, but the infecting dose and subsequent contagion has not been quantified for most strains. In order to measure the aerosol infectious dose for 50% (aID(50)) of seronegative ferrets, seasonal influenza virus was nebulized into an exposure chamber with controlled airflow limiting inhalation to airborne particles less than 5 µm diameter.

Comparison of deposition in the USP and physical mouth-throat models with solid and liquid particles.

Background: Experimental deposition was studied using three different mouth-throat models: (1) the standard United States Pharmacopeia induction port (IP), (2) the idealized human mouth and throat replica developed by the University of Alberta (UofA replica), and (3) the conductive rubber mouth-throat cast from a human subject developed by Lovelace Respiratory Research Institute (LRRI cast).

Methods: Both solid and liquid monodispersed fluorescent particles in the size range of 2-30 μm in diameter were delivered into the devices at flow rates of 15, 30, and 60 L min(-1). For solid particles, the study was conducted with and without grease coating inside the devices to investigate the effects of particle bounce.

Aerosolized Red Tide Toxins (Brevetoxins) and Asthma: Continued health effects after 1 hour beach exposure.

Blooms of the toxic dinoflagellate, Karenia brevis, produce potent neurotoxins in marine aerosols. Recent studies have demonstrated acute changes in both symptoms and pulmonary function in asthmatics after only 1 hour of beach exposure to these aerosols. This study investigated if there were latent and/or sustained effects in asthmatics in the days following the initial beach exposure during periods with and without an active Florida red tide.

Dermal and ocular exposure systems for the development of models of sulfur mustard-induced injury.

Sulfur mustard (SM) is a chemical threat agent for which the effects have no current treatment. Due to the ease of synthesis and dispersal of this material, the need to develop therapeutics is evident. The present article details the techniques used to develop SM laboratory exposure systems for the development of animal models of ocular and dermal injury.

Review of Florida Red Tide and Human Health Effects.

This paper reviews the literature describing research performed over the past decade on the known and possible exposures and human health effects associated with Florida red tides. These harmful algal blooms are caused by the dinoflagellate, Karenia brevis, and similar organisms, all of which produce a suite of natural toxins known as brevetoxins. Florida red tide research has benefited from a consistently funded, long term research program, that has allowed an interdisciplinary team of researchers to focus their attention on this specific environmental issue-one that is critically important to Gulf of Mexico and other coastal communities.

Compositional changes in neurotoxins and their oxidative derivatives from the dinoflagellate, Karenia brevis, in seawater and marine aerosol.

The harmful alga, Karenia brevis, produces a suite of polyether neurotoxins, brevetoxins or PbTx, that cause marine animal mortality and neurotoxic shellfish poisoning (NSP). A characteristic of K. brevis blooms is associated airborne toxins that result in severe respiratory problems.

Exposing animals to oxidant gases: nose only vs. whole body.

Inhalation experiments using laboratory animals are performed under controlled conditions to assess the toxicity of and to investigate interventional strategies to ameliorate injury resulting from oxidant gas exposures. A variety of dynamic inhalation exposure systems that use whole-body or nose-only exposure chambers have been developed for rodents. In a whole-body exposure chamber, the animals are immersed in the test atmosphere, whereas in nose-only or head-only exposure systems, exposures are localized primarily to the head and/or nasal regions.

Aerosol fabrication of hollow mesoporous silica nanoparticles and encapsulation of L-methionine as a candidate drug cargo.

Hollow spherical nanoparticles with ordered mesoporous silica shells were fabricated by evaporation-induced self-assembly using (NH(4))(2)SO(4) and cetyltrimethyl ammonium bromide (CTAB) as templates. The model drug, L-methionine, was encapsulated within the spherical void at high loadings by repeated crystallization.

Dissolution rate and biokinetic model of zirconium tritide particles in rat lungs.

Metal tritide has been used for different areas such as research, purification, compression, and storage of tritium. Current radiation protection guidelines for tritium compounds describe the behavior of the metal tritide as the same as that of organically bound tritium. However, the biokinetic behavior of metal tritide varies according to materials.