Methods to characterize ingestion and inhalation intake levels of airborne emitted polycyclic aromatic hydrocarbons (PAHs).

摘要

This dissertation presents three case studies, which fill current methodological gaps and evaluate uncertainties in assessing intake levels of atmospherically emitted polycyclic aromatic hydrocarbons (PAHs). Source-to-intake relationships representing the linkages connecting outdoor air releases of polycyclic aromatic hydrocarbons (PAHs) to the potential dose received by the human population are currently lacking. In Chapter 2, we present a useful framework and starting point for outdoor air source-to-dietary intake assessments to assess the contribution of local sources of food to cumulative PAH intake. As part of this approach, we estimate that potential intake through ingestion can be up to 1000 times that of inhalation for benzo(a)pyrene (BaP), a representative PAR.;In Chapter 3, we estimate the relative magnitude of PAH source strengths to outdoor air from population-based and power-generation activities that are often unaccounted for in current emissions inventories, or if included, usually are not reported for individual PAHs. We demonstrate how a qualitative application of the Bayesian melding approach, using the CalTOX multimedia regional modeling framework as a "melding" tool, can characterize outdoor air levels of exposure from PAH emission estimates and improve the degree of overlap between source-to-intake relationships derived from empirical data and model predictions.;Because the availability of measured ambient air concentrations to characterize source-to-intake relationships of PAHs is extremely limited, in Chapter 4 we estimate outdoor air levels of a representative PAH, BaP. We use multivariate linear regression techniques, based on reported PM2.5 concentrations in four California air basins, adjusted for spatial, temporal and meteorological parameters. R2-values ranging from 0.56--0.63 per basin and 0.52 when data from all basins are combined are found. Based on the standard error statistic, our one standard deviation range for estimating the reported BaP concentrations is less than a factor of two, indicating that this method reliably characterizes reported outdoor air exposure levels in these basins.;These results are intended to inform and supplement human health and environment policy to reduce adverse health effects resulting from inhalation and ingestion of PAHs emitted to outdoor air.