Our Professionals

Meet our team of highly skilled and experienced epidemiologists.

Dr. Herman Gibb, Ph. D., M.P.H.

Dr. Gibb is an epidemiologist with an extensive background in health risk assessment. Prior to forming Gibb Epidemiology Consulting, he was President of Tetra Tech Sciences, an operating unit of the Tetra Tech Corporation focused on health risk assessment. At Tetra Tech Sciences, Dr. Gibb provided consulting to a variety of government, private, and international clients. Before joining Tetra Tech in 2004, Dr. Gibb had a career at the U.S. Environmental Protection Agency where he participated in the epidemiologic assessment of a variety of substances and was the primary author of an influential study on the risk of lung cancer among chromium production workers. He was a member of the Carcinogen Assessment Group - the beginning of U.S. EPA’s approach to carcinogen risk assessment and is the recipient of numerous EPA awards including the Gold Medal for his work on the risk assessment of arsenic. He was an invited participant on all of the World Health Organization’s (WHO) Final Review Boards on Concise International Chemical Assessment Documents and a member of WHO’s Risk Assessment Steering Group. He is an author of WHO's Principles for the Assessment of Risks to Human Health from Exposure to Chemicals.

Dr. Gibb has a Ph.D. in epidemiology from Johns Hopkins and an M.P.H. in environmental health from the University of Pittsburgh. He is an adjunct faculty member at the George Washington University (GWU) and has served as a preceptor for GWU public health graduate students. In 2011, Dr. Gibb was awarded the Practitioner of the Year award by the Society for Risk Analysis. He currently chairs a WHO task force on chemicals in food. He was a member of the Scientific Advisory Committee of the United States Transuranium (2007-2016) and Uranium Registry and a member of the Presidential Advisory Board on Science, Engineering, and Health at the Ana G. Mendez University System in San Juan, Puerto Rico (2001-2016). In 2019, he received the University of Pittsburgh Public Health Distinguished Alumni Award in recognition of "contributions to environmental and occupational risk assessment." Dr. Gibb is a Lieutenant Colonel (ret) U.S. Army Reserves.

Contact Dr. Gibb


(703) 888-6059

Dr. Keri Grace O'Leary (née Fulcher), Ph. D., M.S.

Dr. O'Leary is a Senior Epidemiologist at Gibb Epidemiology Consulting. She has experience in literature evaluation, exposure and health risk assessment, and statistical analysis. Dr. O'Leary specializes in evaluating individuals' exposure and work history and subsequent risk for disease. She has worked on all facets of epidemiological research including study development, data cleaning, data analysis, and interpretation.

Dr. O'Leary received her B.S. in Biology from The College of William and Mary. In 2012, she earned her M.S. in Epidemiology from The George Washington University (GWU). Dr. O'Leary received her Ph.D. in Epidemiology at GWU’s Milken Institute School of Public Health in 2020. Her dissertation focused on MRSA carriage and infection in a swine-dense region of North Carolina. She served as a Graduate Teaching Assistant in the Department of Epidemiology at GWU while working on her Ph.D. From 2008 through 2010, she prepared proposals for a biopharmaceutical company focused on the utilization of PRDM genes in cancer therapy (2008), reviewed clinical trials for a contractor at the National Library of Medicine (2008-2009) and managed pharmaceutical master files and researched food contact requirements at a food and drug law firm in Washington, D.C (2009-2011). From 2011 to 2014, Dr. O'Leary worked for Tetra Tech Sciences as an Epidemiologist. At Tetra Tech Sciences, she worked on various projects including peer reviews and consultations for government clients and the World Health Organization. She joined Gibb Epidemiology in 2014.

Contact Dr. O'Leary

Nicole Tashakkori, M.P.H.

Ms. Nicole Tashakkori is an epidemiologist at Gibb Epidemiology Consulting. She is experienced in epidemiological research, statistical analysis, and surveillance. In addition, she is skilled in conducting literature reviews and in health risk assessment.

Ms. Tashakkori has an M.P.H. in Epidemiology from the George Washington University Milken Institute School of Public Health. She has a B.S. in Community Health from the University of Maryland. In 2017 and 2018, Ms. Tashakkori worked for the Washington, D.C. Department of Health examining Behavioral Risk Factor Surveillance System (BRFSS) and Cancer Registry data. Her analyses were used to determine future cancer screening efforts in the city. In 2016, she was a Fellow at the National Cancer Institute’s (NCI) Center for Cancer Research. At NCI, she collaborated with the FDA on various projects regarding the progression of lung cancer treatment. Prior to her work at NCI, she was a full-time intern at the National Institute of Biomedical Imaging and Bioengineering (NIBIB) sector of NIH developing advanced imaging techniques to improve the detection of brain tumors and abnormalities.

Zsuzsanna Jeney, M.P.H.

Ms. Zsuzsanna Jeney has been an Epidemiologist with Gibb Epidemiology Consulting since 2014. She has extensive experience in health risk assessment, literature evaluation, and statistical analysis. She has worked on designing epidemiologic studies, conducting data analysis, including work on large datasets and complex survey data analysis, interpreting study findings, and communicating results to various audiences. In 2019, Mrs. Jeney co-authored a systematic review on phthalates. She is proficient in using both STATA and SAS for statistical analysis.

Ms. Jeney received her M.P.H in Epidemiology and Biostatistics from The George Washington University in 2013. She graduated magna cum laude from The University of Maryland with a B.A. in History, and a B.A. in Biological Anthropology. Prior to her work at Gibb Epidemiology, she worked as an external contractor on various health projects, which included pharmaceutical risk assessment and health policy evaluation.

Our work

Gibb Epidemiology Consulting puts its professionals' expertise to use conducting expert reviews; designing, conducting, analyzing, and reporting on studies; and conducting education and training programs.

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