A simple approach to validation of directed‐flow nose‐only inhalation chambers
Tóm tắt
Directed‐flow nose‐only exposure systems are designed and operated so that the genuine test atmosphere is dynamically delivered to each exposure port and exhaled air from exposed animals is immediately exhausted without the possibility of other animals rebreathing this atmosphere. This technique is particularly useful for preventing uncontrolled changes of exposure atmospheres, stimulating breathing activity due to the rebreathing of exhaled carbon dioxide, and the conserving a test material that is available only in limited quantities. The intricate relationship of the delivered flow of air at each exposure port relative to the respiratory minute volume of the exposed animal appears to be critical for the state‐of‐the‐art performance of directed‐flow nose‐only exposure systems. This analysis revealed that the determination of carbon dioxide concentrations at different inhalation chamber locations, including exposure ports, is a simple and cost‐effective procedure to evaluate whether the rebreathing of atmospheres can be excluded. It has been shown that directed‐flow systems need to be operated at an exposure air flow rate greater than 2.5 times the respiratory minute volume of the exposed animal or optimally ∼0.75 l min−1 per rat exposure port (∼3.75 times the minute volume of young adult rats) to prevent higher CO2‐concentrations occurring. Copyright © 2007 John Wiley & Sons, Ltd.
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Tài liệu tham khảo
Dennis R, 1976, Handbook of Aerosols, 93
Greenspan L, 1977, Humidity fixed points of binary saturated aqueous solutions, J. Res. National Bureau of Standards, 81, no. 1
OECD.1981.Organization for Economic Cooperation and Development (OECD)‐Guideline for Testing of Chemicals No. 403. Acute Inhalation Toxicity adopted May 12 (1981).http://www.oecd.org/document/55/0 2340 en_2649_34377_ 2349687_1_1_1_1 00.html
OECD, 2006, OECD Environment, Health and Safety Publications — Series on Testing and Assessment No. 39
OPPTS 870.1300.1998.US‐EPA Health Effects Test Guidelines 870.1300 — Acute Inhalation Toxicity. United States Environmental Protection Agency Office of Prevention Pesticides and Toxic Substances EPA 712C‐98‐193 August 1998.http://www.epa.gov/opptsfrs/publications/OPPTS_Harmonized/870_Health_Effects_Test_Guidelines/index.html
Pauluhn J, 2003, Encyclopedia of Agrochemicals, 893
Phalen RF, 1984, Inhalation Studies: Foundations and Techniques
Willeke K, 1993, Aerosol Measurement. Principles, Techniques, and Applications