Dosimetry Modeling of Inhaled Formaldehyde: Comparisons of Local Flux Predictions in the Rat, Monkey, and Human Nasal Passages

Kimbell, Julia S.; Subramaniam, Ravi P.; Gross, Elizabeth A.; Schlosser, Paul M.; Morgan, K.T.

doi:10.1093/toxsci/64.1.100

Cited by 110 publications

(92 citation statements)

References 21 publications

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“…A few CFD studies of the human nasal airflow were conducted. Most of these investigations were performed just with a single model [14][15][16][17][18][19]. A research with a larger sample for a profound understanding on the relationship between airflow and physiological nasal function was required.…”

Section: Discussionmentioning

confidence: 99%

Numerical simulation of normal nasal cavity airflow in Chinese adult: a computational flow dynamics model

Tan

Han

Wang

et al. 2011

Eur Arch Otorhinolaryngol

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Our purpose is to simulate the airflow inside the healthy Chinese nose with normal nasal structure and function by computational fluid dynamics (CFD) method and to analyze the relationship between the airflow and physiological function. In this study, we used the software MIMICS 13.0 to construct 20 3-dimensional (3-D) models based on the computer tomography scans of Chinese adults' nose with normal nasal structure and function. Thereafter, numerical simulations were carried out using the software FLUENT 6.3. Then the characteristics of airflow inside the airway and sinuses were demonstrated qualitatively and quantitatively in steady state. We found that during the inhalation phase, the vortices and turbulences were located at anterior part and bottom of the nasal cavity. But there is no vortex in the whole nasal cavity during the expiratory phase. The distributions of pressure and wall shear stress are different in two phases. The maximum airflow velocity occurs around the plane of palatine velum during both inspiratory and expiratory phases. After the airflow passed the nasal valve, the peak velocity of inhaled airflow decreases and it increases again at the postnaris. Vice versa, the exhaled airflow decelerates after it passed the postnaris and it accelerates again at nasal valve. The data collected in this presentation validates the effectiveness of CFD simulation in the study of airflow in the nasal cavity. Nasal airflow is closely related to the structure and physiological functions of the nasal cavity. CFD may thus also be used to study nasal airflow changes resulting from abnormal nasal structure and nasal diseases.

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Section: Discussionmentioning

confidence: 99%

Numerical simulation of normal nasal cavity airflow in Chinese adult: a computational flow dynamics model

Tan

Han

Wang

et al. 2011

Eur Arch Otorhinolaryngol

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“…While the mechanism by which formaldehyde exerts its cytotoxic effects is not known, formaldehyde reacts directly with tissue constituents, and cytotoxicity is presumably a function of this reactivity. (14). Lesions primarily develop in the epithelium lining the nasal septum and the ventral meatus of the turbinates.…”

Section: Discussionmentioning

confidence: 99%

Formaldehyde-Induced Damage in Lungs and Effects of Caffeic Acid Phenethyl Ester: A Light Microscopic Study

et al. 2008

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Aim:The aim of this study was to investigate the toxicity of formaldehyde on lung and protective effects of caffeic acid phenethyl ester against these toxic effects.Methods: For this purpose, 21 male Wistar rats were divided into three groups. The rats in Group I comprised the controls, while the rats in Group II were injected with formaldehyde (FA). The rats in Group III received CAPE daily while exposed to formaldehyde. After the treatment, lungs tissues were evaluated by microscopic examination. Results:In the microscopic examination of FA group, fatty and cellular infiltration in the pulmonary interstitium and thickening in the bronchiolar wall were evident. Dilatation and congestion were prominent in the alveolar septal vessels. In FA+CAPE group, dilatation of interalveolar septal vessels was less observed than FA group. Bronchial wall structures are similar with control.Conclusion: It was thought that FA exposure leads to inflammation and injury in lungs. CAPE shows protective and anti inflammatory activity against these adverse effects.

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“…Some highly soluble compounds like formaldehyde are almost completely absorbed in the extrathoracic airways during nasal inhalation. 7,10,26 Even relatively insoluble compounds like ozone are largely absorbed in the lower tracheobronchial airways as surface area increases, thereby significantly reducing the amount reaching the alveolar region. For species absorbed in the URT, the mucus layer serves as a barrier that reduces absorption in the tissue and blood components of the wall structure.…”

Section: Introductionmentioning

confidence: 99%

Transient Absorption of Inhaled Vapors into a Multilayer Mucus–Tissue–Blood System

Tian

Longest

2009

Ann Biomed Eng

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Previous studies have approximated the absorption of vapors into the walls of the respiratory tract as a steady state process. However, non-dimensional analysis indicates that the absorption of vapors in the conducting airways is time-dependent over the timescale of a breathing cycle. The objective of this study was to evaluate the mass transport of sample chemical species through a simple multilayer system composed of mucus, tissue, and blood components on a transient basis. Individual multilayer models were considered that represent the wall dimensions of the nasal extrathoracic (ET(2)), bronchial (BB), and bronchiolar (bb) airways. Sample vapors considered were acetaldehyde and benzene, which are highly soluble and moderately soluble in mucus, respectively. To determine absorption, mass transport was calculated based on an existing analytical steady state solution, a new analytical transient solution, and a numerical transient solution. Results indicated that concentrations within the mucus and tissue layers were highly time dependent in the ET(2) and BB regions and moderately time dependent in the bb airways over the timescale of an inhalation cycle, which is approximately 1-2 s. Fluxes of vapors into the tissue and blood varied with time for approximately 6-8 s in the BB region and 0.6-0.8 s in the bb model. The associated transient blood uptake of acetaldehyde and benzene in the upper ET(2) and BB regions varied from steady state values by a factor of approximately 30 after 1 s. Under similar conditions, transient uptake in the bb model varied from steady state conditions by a factor of approximately 1.3. Surprisingly, inclusion of chemical reactions in the mucus and tissue modified the transient uptake predictions only for very large values of reaction rate coefficients (K > 100 min(-1)). In summary, transient effects significantly impact the absorption of vapors into the walls of the upper respiratory tract (ET(2) and BB regions) and may largely diminish the effects of chemical reactions over the timescale of an inhalation cycle. Furthermore, the transient analytical solution that was developed provides the basis for an improved boundary condition in future CFD simulations of air-phase transport and wall absorption.

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Dosimetry Modeling of Inhaled Formaldehyde: Comparisons of Local Flux Predictions in the Rat, Monkey, and Human Nasal Passages

Cited by 110 publications

References 21 publications

Numerical simulation of normal nasal cavity airflow in Chinese adult: a computational flow dynamics model

Numerical simulation of normal nasal cavity airflow in Chinese adult: a computational flow dynamics model

Formaldehyde-Induced Damage in Lungs and Effects of Caffeic Acid Phenethyl Ester: A Light Microscopic Study

Transient Absorption of Inhaled Vapors into a Multilayer Mucus–Tissue–Blood System

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