Superfund Research Program
A Holistochastic Approach to Human Exposure Assessment
Project Leader: George Christakos
Grant Number: P42ES005948
Funding Period: 1995 - 2006
This year Dr. Christakos and his research team have continued to work on (1) real-world applications of the composite space-time analysis framework for human exposure that they developed in previous years, and (2) advancing the conceptual and methodological framework for the assimilation of new intradisciplinary knowledge (i.e., knowledge within the environmental sciences discipline) as well as new interdisciplinary knowledge (i.e., including also the health disciplines).
Real-world applications were concerned with the estimation of environmental contaminants across space and time at specific contaminated sites and geographical regions. The researchers conducted a space-time mapping analysis of arsenic in the New England area and in contaminated sites of New Jersey. This work is leading to several publications dealing with important aspects of arsenic data, such as measurement errors, detection limit, risk factors providing useful secondary information (such as soil pH), and data censored for confidentiality issues. Another substantial area of progress was the estimation of exposure to polycyclic aromatic hydrocarbons (PAH) across space and time after the collapse of the World Trade Center (WTC) on 9/11/01, funded by a supplement to the researchers SBRP grant. Progress on this PAH work in 2004 has resulted in the preparation of two publications, and will provide valuable lessons for assessing PAH at Superfund sites. Besides these two major applications (on arsenic and PAH), the researchers have also continued to develop and provide technical support for their BMElib space/time estimation numerical library, which is now used by users in over 20 countries. In 2004 this has led to several publications from their group (arsenic, pH, soil contamination, morbidity, etc.), as well as applications from other researchers and students on contaminants of interest to the Superfund program (lead, mercury, chromium, cadmium, etc.).
In 2004 project investigators also made substantial progress in the continuing development of the methodological underpinnings of the holistochastic human exposure framework (HHEF) pioneered by their group and used for the Superfund applications described above. This conceptual development has led to numerous intradisciplinary and interdisciplinary advances resulting in 12 journal publications published or in press in 2004. Intra-disciplinary advances concern the assimilation of a variety of knowledge bases within the environmental science discipline that cannot be integrated using classical approaches. A few examples of such intradisciplinary advances accomplished by Dr. Christakos' group in 2004 include the study of uncertainty in life support systems, recent developments in geophysical assimilation modeling, new conditional probability formulas based on stochastic deduction, and an epistemic cognition solution of the two-dimensional porous media upscaling problem. Interdisciplinary advances by the research group have extended the assimilation framework to consider toxicological, demographic and epidemiologic sciences, resulting in an interdisciplinary epidemic modeling framework and a case study in preparation for publication in 2005.
Progress of the researchers work in 2004 will be of important significance to future Superfund research, particularly in terms of an interdisciplinary integrated risk assessment of PAH and arsenic at specific Superfund sites which they are planning to undertake in subsequent years.