Superfund Research Program
A Holistochastic Approach to Human Exposure Assessment
Project Leader: George Christakos
Grant Number: P42ES005948
Funding Period: 1995 - 2006
This year project investigators focused on continuing the conceptual development and efficient application of the Holistochastic Human Exposure Framework (HHEF) that was introduced by this group in the early 1990s within the context of the SBRP project (human exposure and health risk assessment at Superfund sites). The most recent version of the HHEF is based on an innovative blending of various inter- and multi-disciplinary concepts and knowledge bases from the sciences of environmental fate/transport, toxicokinetics, epidemiology, human demographics, risk assessment, and temporal GIS. In the past year, (i) the researchers continue to improve the theoretical HHEF by means of a series of consecutive assessment steps using powerful space-time knowledge integration and prediction approaches developed by our group, and (ii) they incorporated in the applied HHEF new and advanced toxicokinetics models and space-time correlation functions for the prediction of dose distribution and resulting health effects at the population level.
Project investigators also maintained and expanded the high-quality computational HHEF libraries which have been made available to interested researchers worldwide. In this context, this group continues to offer theoretical and computational support and expertise. The BME technique was presented in detail in the book Modern Spatiotemporal Geostatistics, and the BMElib numerical package implementing BME in an integrated space-time domain was introduced in the book Temporal GIS. This past year they expanded the users' base of the HHEF computer libraries, which resulted in fostering collaborative efforts with other research groups interested in applying these methods, and which allows these researchers access to wider sources of data and scientific expertise.
Dr. Christakos' team is in the process of preparing a new book titled Multi-Disciplinary Integration of Uncertain Environmental Health Systems. This book is the product of their most recent expertise on the development and application of multi- and inter-disciplinary integration systems that was gained during the years following the publication of the earlier book titled Stochastic Environmental Health Modelling. This book was the first book published worldwide on the subject of stochastic multi- and inter-disciplinary environmental health modelling.
The HHEF has gained considerable international recognition as an efficient, flexible and general TGIS-based modeling tool for science-based human exposure analysis and risk assessment. It is currently used by many scientists and researchers in nineteen countries. As a result, these efforts have had a significant influence on modern environmental health research and development worldwide. The list of 30 scientific references describing the applications of the HHEF completed this past year cover a wide range of environmental health processes (such as arsenic, soil salinity, particulate matter, soil radioactivity, and mortality), they relate to sites located in different of geographical areas worldwide (such as New England, North Carolina, California, Bangladesh, and Chernobyl, Ukraine), and they present original methodological viewpoints (incorporation of physical laws such as subsurface flow equations; various sources of site-specific information; and novel space-time covariance models), which demonstrates the wide applicability of the HHEF approach in realistic human exposure situations of interest to the SBRP.