Application of a Lung Deposition Model to Fiber Data from Three North Carolina Asbestos Textile Plants

We applied a lung deposition model to fiber data to produce nasopharyngeal, tracheobronchial, and pulmonary dose estimates received by workers in three asbestos Textile plants. A published fiber deposition model was chosen and the TPSPLINE SAS procedure was used to fit nonparametric regression models to estimate regional lung deposition fractions based on fiber aerodynamic diameter and length. These models were then applied to size-specific fiber data by transmission electron microscopy (TEM) to estimate size-specific fiber deposition by lung region. These size-specific deposition fractions were used in conjunction with the TEM-size data to estimate adjustments to phase contrast microscopy (PCM) fiber concentrations to express equivalent regional lung doses. The resulting deposition factors were compared across plants and departments. The Marshville plant had the highest deposition factor averages for all lung regions while the Davidson plant had the lowest averages for all lung regions. The range of these factors was 1.44-3.40 fibers deposited per unit PCM for nasopharyngeal deposition, 0.45-1.30 fibers deposited per unit PCM for tracheobronchial deposition, and 2.89-11.13 fibers deposited per unit PCM for pulmonary deposition. The plant and department-specific deposition factors, when multiplied by estimated daily average PCM concentrations and estimated inhaled air volumes, will result in lung region-specific fiber dose estimates. These resulting dose estimates will be used in a cohort mortality study.Master of Science in Public Healt