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Inhalation Toxicity of Metal Particles and Vapors
Published in Jacob Loke, Pathophysiology and Treatment of Inhalation Injuries, 2020
The distribution of aerodynamic diameters of a particular aerosol can be measured experimentally and the frequency distribution can be determined. The size distribution of particles in a heterodispersed aerosol is usually log-normal. The count mean and median diameters are measures of the frequency at which particles of various sizes occur in the population. The count mean diameter is thus the mean of the diameters of all particles in the aerosol, and the count median diameter is the diameter above which there are as many larger particles as there are smaller ones below it. The mass mean diameter is the diameter of a particle with a mass equal to the mass of all the particles in the aerosol divided by the number of particles, and the mass median diameter is the diameter of a particle with the median mass. The mass mean and median diameters are measures of the mass distribution of the aerosol. Note that the mass (or volume) median diameter is often much larger than the count median diameter, because the larger particles make a greater contribution to the total mass of the aerosol. The mass median diameter and especially the mass median aerodynamic diameter are important in determining pulmonary deposition of particles. For a more detailed discussion of aerosol properties, generation, and measurement, see Raabe (1970), Mercer (1973), and Willeke (1980).
Kinetics and Metabolism
Published in Lars Friberg, Tord Kjellström, Carl-Gustaf Elinder, Gunnar F. Nordberg, Cadmium and Health: A Toxicological and Epidemiological Appraisal, 2019
Gunnar F. Nordberg, Tord Kjellström, Monica Nordberg
The size, shape, and density of the particles, as they occur in the respiratory tract, determine in which part of the respiratory tract the particles will be deposited. Together these characteristics of an airborne particle are often termed “equivalent aerodynamic diameter” or “mass median aerodynamic diameter”.27
Environmental and Cytotoxicity Risks of Graphene Family Nanomaterials
Published in Suresh C. Pillai, Yvonne Lang, Toxicity of Nanomaterials, 2019
The dimensions and shape of GFNs may also define the degree of bioavailability in an organism, for instance the scope of airborne GFN deposition and clearance in the lung (Park et al., 2017). Determining the amount of airborne GFNs capable of adverse inhalation and deposition is a crucial parameter in the consideration of GFN toxicity often unseen. Park et al., in accordance with the Multiple-Path Particle Dosimetry (MPPD) model (www.ara.com), recently highlighted that the physiochemical properties of materials devising a mass median aerodynamic diameter (MMAD) less than 10 μm can be inhaled, those less than 4 μm moving as far as the lower respiratory tract (Park et al., 2017). GFNs with an area diameter of 25 μm and a thickness of 0.1 μm can generate a MMAD < 3 μm and deposit in the alveoli (Schinwald et al., 2012). The MMAD of GFNs should thus be determined during early stages of initial screening and preliminary toxicity investigation. The flake-like shape and diverse physiochemical properties of GFNs may, however, promote aerodynamic behaviour atypical of spherical particles. For this reason, the outcome generated using the MPPD model, which does not directly consider the dissimilar nature of sheet-like nanostructures, should carefully be construed (Park et al., 2017).
Lung toxicity profile of inhaled copper-nickel welding fume in A/J mice
Published in Inhalation Toxicology, 2022
Patti C. Zeidler-Erdely, Aaron Erdely, Vamsi Kodali, Ronnee Andrews, James Antonini, Taylor Trainor-DeArmitt, Rebecca Salmen, Lori Battelli, Lindsay Grose, Michael Kashon, Samantha Service, Walter McKinney, Samuel Stone, Lauryn Falcone
ICP-AES elemental analysis indicated that Cu-Ni fume was primarily Cu and Ni (Figure 1, top left). Cu content by weight percent averaged 76.3% and Ni was 11.6%. Approximately 5% of fume consisted of other metals including Fe, Ti and Mn and the remaining metal content of the fume was trace metals (<1%). Because welding is known to generate a significant number of nanosized particles, both MOUDI and Nano-MOUDI samplers were used to determine particle size distribution. Most of the particles were between 0.1 and 1 µm in diameter, with a mass median aerodynamic diameter of 0.43 µm (Figure 1, top right). SEM-EDS spectral analysis confirmed the ICP-AES results and showed the predominant metal components of the fume were Cu and Ni (Figure 1, bottom left). FESEM image of the generated welding fume that shows primary particles in the nanometer size range linked together in elongated chain-like structures often with several branches (Figure 1, bottom right).
Utilizing literature-based rodent toxicology data to derive potency estimates for quantitative risk assessment
Published in Nanotoxicology, 2021
Theresa E. Boots, Alyssa M. Kogel, Nathan M. Drew, Eileen D. Kuempel
All BMD estimates were normalized to the particle mass deposited in the lungs (µg/g lung) in order to account for variation in animal models (species/strain/sex) and exposure route and duration. Deposited doses (in mg) were calculated based on route of exposure. For inhalation studies, the deposited dose was calculated using Equation (1), where dose represents the administered dose concentration, duration represents the total duration of exposure, ventilation rate is the standard rate of ventilation by species, and the deposition fraction of particles in the lung was calculated using the Multiple Path Particle Dosimetry modeling for that species/strain (MPPD, v3.04) (ARA 2015). The calculated deposition fractions ranged from 0.97 to 23.23% and utilized ventilation rates according to the EPA (US EPA 1994) guidance. Particle size distribution inputs include median aerodynamic diameter and geometric standard deviation. Equation (1):
Design, optimization, and in-vivo hypoglycaemic effect of nanosized glibenclamide for inhalation delivery
Published in Journal of Liposome Research, 2021
Rania S. Abdel-Rashid, Fathy I. Abd Allah, Abdelsabour A. Hassan, Fahima M. Hashim
The in-vitro aerodynamic assessment of the Gbn loaded niosomes inhalation was carried out using a next-generation impactor, NGI (Copley Scientific Ltd., Nottingham, UK) equipped with the induction port and operated at 60 L/min the collection cups for the NGI were each coated by 2% PEG 400 (European Pharmacopoeia: Preparations for Inhalation 2013). Three doses of the Gbn nanoniosomes MDI were actuated into NGI for each experiment and the test was performed in triplicate. Gbn was recovered from each cup of the impactor system using Methanol and subsequently assayed by means of HPLC procedure (British Pharmacopiea 2019). The fine particle dose (FPD) and the fine particle fraction percent (FPF%) were calculated in the next equation. The mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD) were obtained from a plot of the logarithm of the percentage less than a stated size on a probability scale against the logarithm of the effective cut-off diameter of the stage using Copley Inhaler Testing Data Analysis Software (CITDAS) (Abdelbary et al.2015, Buttini et al.2016)