Deposition of Refractory Ceramic Fibers (RCF) in the Human Respiratory Tract and Comparison with Rodent Studies

Abstract

A mathematical model has been developed to calculate the deposition of refractory ceramic fibers (RCF) in the human respiratory tract. For a typical size distribution of airborne RCF found in the work place, the fractional deposition and size distribution of deposited fibers in various regions of the respiratory tract are determined. These results are compared with those obtained earlier in rats and hamsters. The deposition fraction in the human lung is higher consisting of more coarse and long deposited fibers. This is caused by less efficient filtration of RCF in the human extrathoracic airways. Over the same exposure period however, total number of fibers deposited in the pulmonary region of the humans lung is about 5–10 times smaller per gram of lung or 1–2.5 times smaller per unit lung surface area than the rodents, depending upon the mode of breathing.