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Exposure Research

Human Exposure & Atmospheric Sciences Staff

Karen D. Bradham

Title: Research Physical Scientist

EPA Division: Human Exposure and Atmospheric Sciences Division

EPA Branch: Methods Development and Applications Branch

Karen’s expertise is in the development and application of bioavailability methods for improved human exposure and risk assessments. Her research is focused on developing new, cost-effective tools to measure the bioavailability of arsenic and lead in soil and innovative chemical methods and techniques to evaluate soil chemical processes and soil components that control bioavailability. Karen’s research includes development of in vivo and in vitro methods designed for use in reducing clean-up costs and she is also applying these methods to nanomaterials. Her research also includes investigating housing related health hazards and human exposures to indoor environments by conducting methods development, measurements, and relating this information to questionnaire data. Karen is a member of EPA’s Technical Review Workgroup for Metals and Asbestos, where she serves as co-chair of the Bioavailability Committee. She is the USEPA technical lead for the American Healthy Homes Study, which is a collaborative USEPA and US Department of Housing and Urban Development study designed to assess national distributions of residential related hazards.


  • Ph.D., Environmental Toxicology, Oklahoma State University, 2002
  • M.S., Chemistry, Western Carolina University, 1999
  • B.S., Chemistry, St. Andrews College, 1997

Professional Experience:

  • Research Physical Scientist, USEPA, ORD, NERL-HEASD, RTP, NC 2005-present
  • Physical Scientist, USEPA, ORD, NERL-HEASD, RTP, NC 2002-2005
  • Research Assistant, Oklahoma State University, Stillwater, OK 1999-2002

Professional Societies and Affiliations:

  • Adjunct Assistant Professor, The Ohio State University School of Environment and Natural Resources
  • Co-chair EPA’s Technical Review Workgroup for Metals and Asbestos, Bioavailability Committee
  • Invited external advisor for Taipei Medical University (TMU) studies on children’s soil and dust ingestion exposure factors program in Taiwan
  • Member of the Bioavailability Research Group of Europe (BARGE)
  • Member of the Bioavailability Research Group of Canada (BARC)

Select Awards and Honors:

  • USEPA, Promotion to Senior Scientist, Technical Qualification Board, 2012
  • ORD Environmental Justice Award: Community Cumulative Risk Research-Working for Environmental Justice: For incorporating ORD science into community-based tools for environmental justice, 2011
  • ORD Honor Award, Exceptional/Outstanding ORD Technical Assistance to the Regions or Program Offices, ORD West Oakland Research Support Team, for providing integrated transdisciplinary scientific leadership to the sustainable remediation of residential yards to reduce the impact of lead in soils on children’s health, 2011
  • ORD Honor Award, Impact Award, ORD’s Bioavailability Research Team, for successfully implementing transdisciplinary research and effectively communicating the impact of ORD science within and outside EPA, 2010
  • Honorable Mention Scientific and Technological Achievement Award (STAA) for research publication: American Healthy Homes Survey: A National Study of Residential Pesticides Measured from Floor Wipes, 2010
  • ORD Honor Award for Exceptional/Outstanding ORD Technical Assistance to the Regions or Programs Offices: Federal Equivalent Method (FEM) and Federal Reference Method (FRM) Development for National Ambient Air Quality Standards (NAAQS), 2010
  • USEPA, National Exposure Research Laboratory Special Achievement Award, Leader in the Environmental Research Community for “Developing a new in-house research program in the area of Bioavailability,” 2007
  • USEPA, ORD Bronze Medal Honor Award for the American Healthy Homes Survey Team in recognition of the outstanding collaborationn between HUD and EPA in pursuing the first nationwide survey of additional residential hazards, 2006

Select Publications:

  • C. Nelson, T. Gilmore, J. Harrington, K.G. Scheckel, B.W. Miller, and K.D. Bradham. 2013. Evaluation of a Low-cost Commercially Available Extraction Device for Assessing Lead Bioaccessibility in Contaminated Soils. Environ. Sci.: Processes Impacts, 15, 573-578.
  • Samuel K. Mwilu, Amro M. El Badawy, Karen Bradham, Clay Nelson, David Thomas, Kirk G. Scheckel, Thabet Tolaymat, Longzhou Ma, Kim Rogers. 2013. Changes in silver nanoparticles exposed to human synthetic stomach fluid: Effects of particle size and surface chemistry. Science of The Total Environment, Volume 447, 1 March 2013, Pages 90-98.
  • Kim R Rogers, Karen Bradham, Thabet Tolaymat, David J. Thomas, Thomas Hartmann, Longzhou Ma, Alan Williams. 2012. Alterations in physical state of silver nanoparticles exposed to synthetic human stomach fluid. Science of the Total Environment, Volume 420, pages 334-339.
  • Bradham K, Scheckel K, Nelson C, Seales P, Lee G, Hughes MF, Miller B, Yeow A, Gilmore T, Harper S, D. Thomas. 2011. Relative Bioavailability and Bioaccessibility and Speciation of Arsenic in Contaminated Soils. Environmental Health Perspectives Volume 119(11), pages 1629-1634.
  • Medina-Vera M, Van Emon J, Melnyk L, Bradham K, Harper S, Morgan J. 2010. An Overview of Measurement Method Tools Available to Communities for Conducting Exposure and Cumulative Risk Assessments. Journal of Exposure Science and Environmental Epidemiology 20, 359-370.
  • Van de Wiele T, Gallawa CM, Kubachka KM, Creed JT, Bradham K. 2010. Arsenic Metabolism by Human Gut Microbiota upon In Vitro Digestion of Contaminated Soils. Environ Health Perspectives, Volume 118(7), pages 1004-1009.

Published & Presented Research (1999-Present)

Contact Info:
Karen Bradham
Human Exposure & Atmospheric Sciences Division
National Exposure Research Laboratory
US EPA Office of Research and Development
109 TW Alexander Drive
Research Triangle Park, NC 27709
Telephone: 919-541-9414
Email: bradham.karen@epa.gov

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