| A health risk assessment performed for a site contaminated by a former petroleum processing facility had identified consumption of vegetation grown in soil contaminated by polycyclic aromatic hydrocarbons (PAHs) to be major route of exposure. Consequently, PAH uptake by three types of vegetation was evaluated in growth experiments, namely: carrots (Daucus carota), lettuce (Lactuca sativa) and barley (Hordeum vulgare). Greenhouse experiments were used to study the uptake from soils amended with creosote, while on-site growth experiments allowed the study of uptake from the abandoned Borradaile oil refinery site. In both experiments, three exposure pathways were considered: particulate deposition, vapor transfer and root uptake.;For the particular experimental conditions used the dominant route of PAH exposure was volatilization from the soil to the foliage, with the low molecular weight PAH compounds (3 and 4 rings) dominating individual components of the total PAH load. Lettuce accumulated higher levels of PAHs than barley and carrots, under the treatment where the plants were exposed to the soil surface. The PAH concentrations detected in the carrot root peels were substantially higher than in the core, suggesting little transfer from the peel to the core. Approximately 70 to 80% of the PAH burden found in the carrots was associated with the peel.;In the evaluation the Borradaile human health risk assessment, experimental vegetation and authentic soil data collected from the site were input into dose estimate models and compared to previously estimated values used in the assessment. The authentic and experimental data collected from the site produced a field estimate case two orders of magnitude lower than the base case estimated by the original risk assessment. (Abstract shortened by UMI.). |
