Skip Navigation
National Institute of Environmental Health SciencesNational Institutes of Health
Increase text size Decrease text size Print this page

Environmental Systems Biology Group

Statistical and Mathematical Methods

Christopher J. Portier, Ph.D.
Christopher J. Portier, Ph.D.
Principal Investigator

Tel (919) 541-3484
Fax (919) 541-1994

Curriculum Vitae (  Download Adobe Reader (193K)
P.O. Box 12233
Mail Drop B2-08
Research Triangle Park, North Carolina 27709
Delivery Instructions

Research Summary

The Environmental Systems Biology Group (ESBG) conducts a broad range of research into the development, understanding and implementation of statistical and mathematical methods for evaluating exposures and estimating risks, provides technical support to scientists and staff at NIEHS on methods and procedures in risk assessment, and provides risk assessment expertise to a large number of national and international agencies. The long-term objective is the development of methodology to facilitate the appropriate translation of "cutting-edge" research findings into future public health decisions.

Human illustration at center. Six transitions from molecular level to organ/system level: reproductive, immune, respiratory, nervous, cardiovascular, and gastrointestinal.
Environmental systems biology is the study of the impact of environmental stressors on the components of a biological system, and how the interactions between these components give rise to changes in the function and behavior of that system. Click to view larger image.

Providing the highest quality scientific methods for the evaluation of health risks from environmental exposures is a high priority research area for the NIEHS. The ESBG uses a combination of laboratory research and mechanism-based mathematical modeling to develop methods intended to expedite the use of "cutting edge" basic research into the identification and quantification of health risks resulting from environmental exposures.

The group's mechanism-based modeling research efforts focus in three general areas: toxicokinetics/biochemistry, toxicogenomics and morbidity/mortality endpoints. In each focused research area, approaches are directly linked to activities within the National Toxicology Program (NTP)( to ensure that they have both practical utility and an avenue for broader inclusion into public health decisions.

Major areas of research:

  • Development of new structures and methods for modeling of toxicokinetic data
  • Development of statistically sound, mechanism-based methods for the identification and quantification of gene-expression networks using microarray data
  • Development of mechanism-based models for toxicity endpoints

Current projects:

  • The application of systems-based tools to evaluating environmental health risks
  • The development of methods for the analysis of high-throughput screening data
  • The development of a stochastic model of growth of C. elegans following toxicant exposure
  • The development of a gene regulatory network for telencephalon development combining experimental and bioinformatics approaches
  • Linking genes to diseases through pathways
  • The development of a more efficient algorithm for analyzing quantitative real-time RT-PCR data (code available here (

Christopher J. Portier, Ph.D., heads the Environmental Systems Biology Group within the Laboratory of Molecular Toxicology. He is also Associate Director of the NIEHS, and Director of the Office of Risk Assessment Research. Previously he was Director of the Environmental Toxicology Program at the NIEHS, and Associate Director of the National Toxicology Program. He received his Ph.D. in biostatistics from the University of North Carolina in 1981. He has published over 150 peer-reviewed articles in leading biomedical journals, as well as more than 50 book chapters and reports. For more information about Dr. Portier, please see his biography (  Download Adobe Reader (213K).

Back to top Back to top Department of Health & Human Services National Institutes of Health
This page URL:
NIEHS website:
Email the Web Manager at
Last Reviewed: December 31, 2008