Dr. Celia Byrne is a tenured faculty member in the Department of Preventive Medicine and Biostatistics at the Uniformed Services University. She completed her Master’s and Ph.D. in Epidemiology at UCLA, conducting her dissertation research as an Epidemiology Fellow at the National Cancer institute (NCI). Her work at NCI established mammographic breast density as a risk factor for breast cancer, providing the early foundation for the efforts to inform women about their mammographic breast density, now a national requirement as of September, 2024. Dr. Byrne continued working to understand the environmental and genetic determinants of mammographic density as a faculty member at Harvard and Georgetown Universities. She was the first to publish the positive association between higher percent mammographic density and insulin-like growth factors and to determine the inverse association of mammographic density with endogenous estrogen levels in post-menopausal women. Her research established that the increased breast cancer risk associated with post-menopausal use of estrogen plus progestin was mediated by an increase in mammographic density in the first year of use among participants in the Women’s Health Initiative. As a Breast Cancer Environmental Research Project investigator, she evaluated the impact of heavy metal levels on change in mammographic breast density across the menopausal transition. During the SARS-COV-2 pandemic she provided her epidemiologic expertise to study the impact of Covid-19 infections within the MHS. Her study of the “Environmental Determinants of Breast Cancer Risk among Women in the Military” is evaluating the impacts of exposure to Polycyclic Aromatic Hydrocarbons (PAH) and Per- and polyfluoroalkyl substances (PFAS) on subsequent risk of developing breast cancer among active duty women.