PAH Interactions with Soil and Effects on Bioaccessibility and Bioavailability to Humans
ER-1743
Objective
Polycyclic aromatic hydrocarbons (PAHs) have emerged as one of the most important contaminants driving risk estimates and remedial decisions for soils at Department of Defense (DoD) sites. Substantial research efforts have focused on PAH bioavailability from solid matrices, including investigations into the chemistry of PAH interactions with soil and sediments, the oral and dermal uptake of PAHs into ecological and human receptors, extraction methods that are predictive of bioavailability measures, and in situ methods to reduce the bioavailability of PAHs in soil and sediments. This research has yielded an extensive understanding of PAH chemistry and bioavailability. However, the ability to apply these research findings broadly to human exposures at contaminated sites remains elusive due to the narrow focus of prior studies.
The objective of this project is to examine the fundamental physical and chemical interactions between PAHs and soils and how these interactions control the oral and dermal bioavailability of PAHs in soil to humans. A broad-based understanding will be achieved by tying together research on soil/PAH chemistry with in vivo measures of bioavailability across a diversity of soil types and contaminant sources.
Technical Approach
To focus research where it can be most effective, specific PAH sources, exposure pathways, and individual PAHs that are driving risk assessments and remedial decisions will be identified. Researchers will develop an understanding of the mechanisms by which PAHs are sequestered in soil, so that the magnitude of bioavailability adjustments can be predicted, and examine whether soil/chemical interactions might cause bioavailability values to change over time. An animal model that provides quantitative measures of the relative oral bioavailability of PAHs in soil will be developed, and a database of information will be generated from this animal model to understand bioavailability across a diversity of soil types and contaminant sources. A simple, reproducible in vitro extraction test that is predictive of in vivo measures of relative bioavailability (as indicated by the in vivo model) also will be developed. Researchers will assess the effect of soil/chemical interactions and contaminant sources on the dermal absorption of PAHs. The geochemical and other data on factors that influence bioavailability and the in vitro test will serve to support site-specific evaluations that reduce uncertainty associated with estimating exposures to PAHs at DoD sites. It is a goal of this project that the research results be sufficiently robust that the resulting bioavailability adjustments will be acceptable to regulatory agencies and will ultimately support new guidance.
Benefits
This research will lead to an improved understanding of soil/PAH interactions, development of an in vivo model for measuring site-specific PAH bioavailability, development of an efficient and inexpensive method to predict the relative bioavailability of PAHs from soil on a site-specific basis, and revised estimates of the dermal absorption of PAHs from soil. In aggregate, this new information and assessment tools will support more accurate human health risk assessments, which may result in higher cleanup goals and more cost-effective, health-protective remediation plans for PAHs in soil. (Anticipated Project Completion - 2013)
Points of Contact
Principal Investigator
Ms. Yvette Lowney
Exponent
Phone: 303-245-7082
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.