Human respiratory tract

FIGURE 5.14 (a) Anatomical overview of che human respiratory tract. The larynx generally... 

International Commission on Radiological Protection. (1994). Human Respiratory Tract Model for Radiological Protection (Vol. Publication 6 ). Elsevier. Science, Tarrytown, NY. 

Daviskas, E., Gonda, I., and Anderson, S. D. (1990). Mathematical modeling of heat and water transport in human respiratory tract. /. Appl. Physiol. 69, 362-372. 

Hanna, L. M. (1983). Modeling of heat and water vapor transport in the human respiratory tract. Ph.D. Dissertation, University of Pennsylvania, Philadelphia. 

Scheuch, G., and Stahlhofen, W. (1992). Deposition and dispersion of aerosols in the airways of the human respiratory tract the effect of particle size. Exper. Lung Res. 18, 343-358. 

Studies on the particulate distributions from compressed natural gas (CNG) or diesel-fuelled engines with diesel oxidation catalyst (DOC) or partial diesel particle filter (pDPF) have also been performed. The results obtained are used as data for the model, to study the particle penetration into the human respiratory tracts. As a result, the number distribution of particles in different parts of lungs can be modeled [99-101]. Understanding the particle formation and their effects and finding the methods to ehminate the formed particulates from exhaust gas contribute to a cleaner urban environment and thus to a better quality of life. 

The Human Respiratory Tract Model Absorption into Blood 3-6. ICRP (1989) Model of Americium Biokinetics 3-7. Leggett (1992) Model of Americium Biokinetics... 

Particle Transport from the Human Respiratory Tract... 

Available information from human exposures indicates that airborne americium-containing particles are deposited in the respiratory tract, cleared to some extent via mucociliary action, and swallowed or expelled (Edvardsson and Lindgren 1976 Fry 1976 Newton et al. 1983 Sanders 1974 Toohey and Essling 1980). Descriptions of human respiratory tract models that can be used for radiation protection also include relevant information regarding biokinetics of inhaled particles (ICRP 1994b, 1995 NCRP 1997). Quantitative data are not available, however. Supporting animal studies include inhalation exposure to aerosols of americium (Buldakov et al. 1972 DOE 1978 Gillett et al. 1985 Sanders and Mahaffey 1983 Talbot et al. 1989 Thomas et al. 1972) or intratracheal instillation of americium compounds (Moushatova et al. 1996). 

The ICRP (1994b, 1995) developed a Human Respiratory Tract Model for Radiological Protection, which contains respiratory tract deposition and clearance compartmental models for inhalation exposure that may be applied to particulate aerosols of americium compounds. The ICRP (1986, 1989) has a biokinetic model for human oral exposure that applies to americium. The National Council on Radiation Protection and Measurement (NCRP) has also developed a respiratory tract model for inhaled radionuclides (NCRP 1997). At this time, the NCRP recommends the use of the ICRP model for calculating exposures for radiation workers and the general public. Readers interested in this topic are referred to NCRP Report No. 125 Deposition, Retention and Dosimetry of Inhaled Radioactive Substances (NCRP 1997). In the appendix to the report, NCRP provides the animal testing clearance data and equations fitting the data that supported the development of the human mode for americium. 

Human Respiratory Tract Model for Radiological Protection (ICRP 1994b)... 

Figure 3-5. The Human Respiratory Tract Model Absorption into Blood...

Figure 3-8. Leggett (1992) Model of Deposition and Retention of Americium in the Human Respiratory Tract...

ICRP. 1994b. Human respiratory tract model for radiological protection. International Commission of Radiological Protection. ICRP Publication 66. New York Pergamon Press. 

Highly toxic perfluoroisobutylene (PFIB) poses a serious health hazard to the human respiratory tract. PFIB is a thermal decomposition of polytetrafluo-roethylene (PTFE), e.g., Teflon. PFIB is approximately lOx as toxic as phosgene. Inhalation of this gas can cause pulmonary edema, which can lead to death. PFIB is included in Schedule 2 of the Chemical Weapons Convention (CWC), the aim of the inclusion of chemicals such as PFIB was to cover those chemicals, which would pose a high risk to the CWC. 

GA Ferron, G Oberdorster, R Henneberg. Estimation of the deposition of aerosolized drugs in the human respiratory tract due to hygroscopic growth. J Aerosol Med 2 271-283, 1989. 

HD Landahl. On the removal of air-borne droplets by the human respiratory tract. I. The lung Bull Math Biophys 12 43, 1950. 

PR Byron. Prediction of drug residence times in regions of the human respiratory tract following aerosol inhalation. J Pharm Sci 75 433-438, 1986. 

James, A.C., Greenhalgh, J.R., and A. Birchall, A Dosimetric Model for Tissues of the Human Respiratory Tract at Risk from Inhaled Radon and Radon Daughters - A Systematic Approach to Safety, Proc. 5th Cong. IRPA, Jerusalem 1980, Perg. Press, Oxford, vol 2, 1045-1048, (1980). 

Tu and Knutson (1984) also measured the particle deposition of hydrophobic and hygroscopic particles in the human respiratory tract. They showed that the hygroscopic particles grow by a factor of 3.5 to 4.5 at the saturated humidity present in the lung. For the purpose of calculating bronchial deposition for a hygroscopic aerosol we assume an increase in size by a factor of 4 upon entry into the bronchial tree. 

ICRP (1966). International Commission on Radiological Protection, Deposition and retention models for internal dosimetry of the human respiratory tract, Health Phys. 12,173. 

Lippmann, M. (1977). Regional deposition of particles in the human respiratory tract , Section 9, page 213 in HANDBOOK OF PHYSIOLOGY, Lee, H. D. K. Sect. Ed., (American Physiological Society, Bethesda, Md.). 

Davis, C.N. (1961). A formalized anatomy of the human respiratory tract. In Inhaled Particles and Vapours. (Davis, C.N., Ed.). Pergamon Press, London, pp. 82-91. 

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