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RESPIRATORY DOSE OF INHALED FINE PARTICLES IN HEALTHY YOUNG AND ELDERLY SUBJECTS
Citation:
Kim, C. AND S. C. Hu. RESPIRATORY DOSE OF INHALED FINE PARTICLES IN HEALTHY YOUNG AND ELDERLY SUBJECTS. Presented at American Thoracic Society Annual Meeting, San Francisco, CA, May 18-23, 2001.
Description:
Particulate matter (PM) in the ambient air has been implicated as a key factor for increased morbidity and mortality in humans, particularly in elderly patients with respiratory, or cardiovascular disease. It has been speculated that such a PM effect might have been related partially to old age besides the more obvious role of disease itself. From the dosimetric point of view, if the respiratory dose is enhanced in elderly subjects, that certainly is a factor for concern. However, specific quantitative data are lacking for respiratory dose of inhaled particles in elderly subjects. We measured total (TDF) as well as detailed regional deposition values in healthy elderly male subjects (E; n=8, age = 69?5 years) and compared the results with those obtained from young normal subjects (Y; n=8, age = 31?8 years) for fine monodisperse aerosols (Dp = 1, 3 and 5 m diameter).The subject inhaled a series of bolus aerosols (50 ml volume) targeted to specific regions of the lung with controlled breathing at a tidal volume of 500 ml and breathing frequency of 15 breaths/min. After analyzing bolus recovery data from different regions of the lung, regional deposition values were obtained for 10 sequential volumetric compartments. Mean TDF in elderly subjects was 0.18 ?.06, 0.41 ?.05, and 0.60 ?.09 for Dp = 1, 3 and 5 m, respectively and these values were virtually identical to those from young subjects (i.e., 0.16?.04, 0.40?.04 and 0.58 ?.02). Regional deposition in ten different compartments was very similar between E and Y, except that there was a slight tendency of enhanced deposition in the shallow lung regions in E. The results suggest that normal elderly subjects are not subjected to a greater respiratory dose of fine particles and that the potential health risk to ambient PM may not be different for the elderly than young normal subjects. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.
RESPIRATORY DOSE OF INHALED FINE PARTICLES IN HEALTHY YOUNG AND ELDERLY SUBJECTS. Chong S. Kim and SC. Hu* , US EPA, National Health and Environmental Effects Research Laboratory, RTP, NC 27711 and *CEMLB, University of North Carolina-Chapel Hill, NC 27599, USA
Particulate matter (PM) in the ambient air has been implicated as a key factor for increased morbidity and mortality in humans, particularly in elderly patients with respiratory, or cardiovascular disease. It has been speculated that such a PM effect might have been related partially to old age besides the more obvious role of disease itself. From the dosimetric point of view, if the respiratory dose is enhanced in elderly subjects, that certainly is a factor for concern. However, specific quantitative data are lacking for respiratory dose of inhaled particles in elderly subjects. We measured total (TDF) as well as detailed regional deposition values in healthy elderly male subjects (E; n=8, age = 69?5 years) and compared the results with those obtained from young normal subjects (Y; n=8, age = 31?8 years) for fine monodisperse aerosols (Dp = 1, 3 and 5 m diameter).The subject inhaled a series of bolus aerosols (50 ml volume) targeted to specific regions of the lung with controlled breathing at a tidal volume of 500 ml and breathing frequency of 15 breaths/min. After analyzing bolus recovery data from different regions of the lung, regional deposition values were obtained for 10 sequential volumetric compartments. Mean TDF in elderly subjects was 0.18 ?.06, 0.41 ?.05, and 0.60 ?.09 for Dp = 1, 3 and 5 m, respectively and these values were virtually identical to those from young subjects (i.e., 0.16?.04, 0.40?.04 and 0.58 ?.02). Regional deposition in ten different compartments was very similar between E and Y, except that there was a slight tendency of enhanced deposition in the shallow lung regions in E. The results suggest that normal elderly subjects are not subjected to a greater respiratory dose of fine particles and that the potential health risk to ambient PM may not be different for the elderly than young normal subjects. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.