Data Larynx

It is well known that enhanced deposition in the first few airways occurs due to the turbulence produced. Turbulent diffusion is accounted for by using factors (ratio of observed deposition to calculated diffusion deposition) to correct the diffusion deposition. These had formerly been measured by Martin and Jacobi (1972) in a dichotomous plastic model of the upper airways. The data used here are from measurements performed by Cohen (1986) using hollow casts of the upper bronchial tree which included a larynx. This cast was tested using cyclic flow with deposition measured for 0.03, 0.15 and 0.20 urn diameter particles. Her turbulent diffusion factors are used in the calculation here (14 for generation 0, and 2 for generations 1 to 6). 

For each of the three particles sizes studied, the deposition efficiency in the trachea was much greater than predicted if uniform deposition is assumed. In each data set the ratio at the lower flow rate exceeded that at a higher flow. If the increase results from turbulence introduced by the larynx it might be expected to be more effective at the higher flow rate. The discrepency may result from the jet formed downstream of the larynx. The center line velocity substantially exceeds the mean velocity of the air stream and secondary circulation patterns are set up near the wall which can act as dead zones (Ultman, 1 985) ... 

Two cohort studies, two proportionate mortality studies and two nested case-control studies looked at cancer mortality or incidence among workers using metalworking fluids with ethanolamines as additives, with or without sodium nitrite. Small excesses were observed for cancers at various sites, in particular, stomach, oesophagus and larynx. In most of these studies, only associations with use of soluble oils or synthetic fluids were presented and no results were given specifically in relation to triethanolamine exposure. It is difficult to draw conclusions regarding triethanolamine using data from studies of exposures to these complex mixtures. 

These data are confined to particles fully entrained in the inspired air. When particles are, however, inspired from propellant-based metered-dose or dry-powder inhalers, their velocity is much greater than that of the inspired air, and only a small mass fraction (nonballistic fraction) escapes inertial deposition in the oropharynx and enters the trachea. The mass fraction of particles deposited in the oropharynx (ballistic fraction) can be determined experimentally. It comprises more than 50% of the mass released from inhaler devices and therefore is much larger than that deposited in the larynx. It is usually assumed that the ballistic fraction is equal to the mass fraction collected in an induction port placed in front of a cascade impactor. Collection of particles in the impactor allows the estimation of the mass distribution of particles entering the respiratory tract. Finally, these distributions can be used to calculate regional mass depositions with a deposition model. 

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