HESI’s skilled scientific staff and decades of organizational experience make it possible to efficiently convene collaborative teams and synergize resources. Each of HESI’s scientific committees is supported by one or more staff members who hold advanced degrees in science or public health. Every staff member fulfills a vital role in creating science-based solutions for a safer, more sustainable world.
Executive Director
Director, Center for Patient and Consumer Safety (CPCS)
spettit@hesiglobal.orgSyril Pettit is the Executive Director of the Health and Environmental Sciences Institute (HESI) and has been with the organization since 2000. Dr. Pettit holds a Doctorate in Public Health Leadership from the University of North Carolina’s Gillings School of Global Public Health, a Master’s Degree in Environmental Management from Duke University’s Nicholas School of the Environment, and a Bachelor’s Degree in Biology from Amherst College. As the organization’s senior scientific and organizational leader, Dr. Pettit guides the strategic and technical direction for the organization’s collaborative programs and its Board of Trustees. She has authored or co-authored dozens of scientific articles and lectured at international scientific meetings around the world on topics including public health, oncology, cardiac safety, genomics, collaborative approaches to science, and other drug and chemical safety issues. She is an avid runner and swimmer.
Deputy Director
Director, Center for Environmental and Ecological Health (CEEH)
membry@hesiglobal.orgMichelle Embry received her PhD in Toxicology in 2004 and her BS in Biology and Environmental Science and Policy in 1998 from Duke University. She is currently the Deputy Director of Environmental Science at HESI, where she provides leadership, technical direction, and guidance to varied, multi-stakeholder, collaborative committees on topics related to risk assessment and environmental protection worldwide.
Prior to joining HESI in 2006, Dr. Embry worked as an Ecological Risk Assessor at the US EPA’s Office of Pesticide Programs. She has expertise in both human health and ecotoxicology, with an emphasis on integrated approaches and alternative methods. Her current project portfolio includes the Animal Alternatives in Environmental Risk Assessment Committee and the Development of Methods for a Tiered Approach to Assess Bioaccumulation of Chemicals Committee, two of HESI’s projects aimed at improving ecological risk assessment. Dr. Embry’s work also includes the Risk Assessment in the 21st Century (RISK21) Committee, which developed a scientific, transparent, and efficient approach for human health risk assessment, including a web-based tool that has led to outreach and training activities on risk assessment approaches worldwide. In addition, she works with HESI staff and partners on project development related to chemical risk assessment issues.
Dr. Embry is an elected member of the SETAC North America Board of Directors (2014 to present), chair of the SETAC Global Partners Advisory Committee, and a member of the SETAC Bioaccumulation and Animal Alternatives Advisory Group Steering Teams. She is a full member of the Society of Toxicology (SOT) and a member of the SOT Risk Assessment and Mixtures Specialty Sections. She was a member of the ECETOC Task Force on Information to be Considered in a Weight-of-Evidence-Based PBT/vPvB Assessment of Chemicals (Annex XIII of REACH) in 2013 to 2014 and was a steering team member of the SETAC Adverse Outcome Pathway (AOP) Pellston Workshop (Spring 2017). Dr. Embry is also one of the founding partners on the “eco data hub” initiative, started in Fall 2016.
Associate Director
Director, Center for Translational Sciences (CTS)
jpierson@hesiglobal.orgJennifer Pierson received her BS in Biology in 2005 from Villanova University and her Master of Public Health in 2007 from Drexel University. She has been with HESI Global since 2012 and is currently the Associate Director. In addition to committee management, Jennifer provides strategic leadership in identifying emerging science topics as well as providing management and insights into grant activities for the organization. Her prior experience includes working in research laboratories and at a local health department, where she focused on epidemiological investigations. She also has extensive experience in project management and has published numerous papers, reports, guidelines, and white papers on public health issues.
Connie Chen received her BS in Psychobiology from UCLA in 2001. She also received her Master of Public Health in 2003 and her PhD in Environmental Health Sciences with a focus on Molecular Epidemiology and Biostatistics in 2007 from the University of California, Berkeley School of Public Health. As a Senior Scientific Program Manager at HESI, Dr. Chen manages the Developmental and Reproductive Toxicology (DART) Committee. Prior to joining HESI, Dr. Chen worked as a Health Scientist at ChemRisk, LLC in California, providing expertise to clients from the public and private sectors on toxicology and epidemiology, exposure, risk assessment, industrial hygiene, and consumer product risk assessment.
Senior Advisor, Center for Environmental and Ecological Health (CEEH)
sdeglin@hesiglobal.orgSandrine Deglin joined HESI in 2018 as a Scientific Program Manager. Prior to joining HESI, she worked with the Environmental Public Health Program at the State of Alaska Division of Public Health for four years, where she managed the program for nearly two years. Prior to that time, Dr. Deglin spent seven years as a consultant in the Toxicology and Mechanistic Biology Group of Exponent, Inc.
Dr. Deglin holds a PhD in Applied Chemistry and an MS in Environmental Sciences and Engineering from the Colorado School of Mines. While studying in France, she also received a MS in Chemistry and a postgraduate degree in Public Health. Dr. Deglin is interested in all aspects of environmental health, including chemical fate and transport, toxicology, epidemiology, risk assessment, food safety and food security, and risk communication. She is currently involved in the HESI Bioaccumulation, Environmental Epidemiology, RISK21, UVCB, and Transforming the Evaluation of Agrochemicals (TEA) Committees.
Senior Advisor, Center for Patient and Consumer Safety (CPCS)
lmouries@hesiglobal.orgLucilia Mouriès holds an MS in Aquatic Sciences from the Institute of Biomedical Sciences Abel Salazar (ICBAS) at the University of Porto, Portugal, and a PhD in Biochemistry and Applied Biology completed in Paris, France. She was also a Postdoctoral Visiting Fellow at the NIH’ National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) where she conducted research on cartilage molecular genetics, for regenerative medicine applications.
Dr. Mouriès joined HESI Global in 2016 and currently serves as Senior Advisor for the Center for Patient and Consumer Safety, where she leads multi-stakeholder initiatives focused on novel therapeutic modalities and consumer products’ safety, with direct involvement in programs ranging from regenerative medicine and novel therapeutic modalities such as cell and gene therapies and targeted protein degraders, to food biotechnology.
While at HESI, Dr. Mouriès became a full member of the Society of Toxicology (SOT) and other specialty societies such as the American Society for Gene and Cell Therapy (ASGCT), International Society of Cell Therapy (ISCT), and the International MPS Society (IMPSS), serving in the capacity of abstract reviewer or mentor. She is tri-lingual in French, Portuguese and English.
April joined HESI Global in January 2026 as a Senior Program Advisor, supporting our chemical safety and risk assessment programs. April brings deep federal leadership experience spanning 2010-2025, including serving as a DOE Office Director and regulatory lead for PFAS, Deputy Director of Chemical Safety at the White House Council on Environmental Quality, Senior Toxicologist in the Executive Office of the President, and Senior Toxicologist at FDA. In 2019, April founded the first federal interagency PFAS Working Group of Executive Branch chief scientists. April is also a long-time HESI DART member, and we’re excited to welcome her expertise and collaborative spirit to the team.
Connie Mitchell is a Senior Scientific Program Manager at HESI. Prior to joining HESI in early 2020, she was an ORISE Fellow at the US Environmental Protection Agency working on chemical prioritization under the Toxic Substances Control Act. She completed her graduate studies in Environmental Toxicology at the University of California Riverside. There she investigated flame retardant-induced developmental toxicity. As a Senior Scientific Program Manager, she provides scientific, strategic, and management support to collaborative scientific committees involving academic, government, nonprofit, and private sector scientists. She manages the Emerging Systems Toxicology for Assessment of Risk (eSTAR) Committee, Next Generation Ecological Risk Assessment Committee (Eco-Risk), and the Botanical Safety Consortium (BSC).
Shermaine Mitchell-Ryan is a native Washingtonian and a product of the District of Columbia public school system. She holds a BA in Biology with a minor in Theater Arts from St. Mary’s Public Honor’s College in St. Mary’s City of Maryland, a Master’s Degree in Cancer Biology Prevention and Control from a dual-institution program at the University of the District of Columbia and Georgetown University, and a PhD in Cancer Biology and Pharmacology from the Department of Developmental Therapeutics at the Wayne State University School of Medicine. Prior to joining HESI, Dr. Mitchell-Ryan served as an AAAS Science and Technology Policy Fellow at the National Science Foundation’s ADVANCE program office, where she assisted in managing an $18 million federal program geared toward increasing the participation and success of women in STEM academic careers.
Dominick joined HESI Global in January 2026 as a Senior Scientific Program Manager, supporting a range of patient and drug safety programs. Dominick brings extensive experience leading cross-functional clinical and nonclinical development efforts, including work at Barinthus Biotherapeutics on vaccine development against MERS-CoV, and at the International AIDS Vaccine Initiative (IAVI) managing nonclinical and clinical programs for mRNA vaccines, including NIH grant-supported work. He also served as Director of Preclinical Models and Biomarker Discovery at AERAS, and holds a PhD in Pharmacological Sciences from the University of Pennsylvania.
Liisa Koski serves as the program lead for the COMPARE Allergen Database and as Communications Manager at the Health and Environmental Sciences Institute (HESI). With over 20 years of experience in bioinformatics, she has led and contributed to numerous international collaborations across academia, government and industry. She holds a B.Sc. in Molecular Biology and Genetics from the University of Guelph and an M.Sc. in Biology from McMaster University, where her research focused on identifying horizontally transferred genes using bioinformatics approaches. Her areas of expertise include data management and functional annotation.
Raechel Puglisi joined HESI Global in 2019. She holds a Master of Public Health (MPH) in Environmental Health Sciences and Policy from The George Washington University and a Bachelor of Arts in Human Biology from The University of Kansas.
She is interested in all aspects of environmental health, including toxicology, risk assessment & communication, and the translation of emerging technologies to advance research and inform regulatory decision-making.
At HESI, Raechel currently manages various scientific programs across HESI including, the Genetic Toxicology Technical Committee (GTTC), the Cell and Gene Therapy (CGT-TRACS) Committee, and the Transforming the Evaluation of Agrochemicals (TEA) Committee.
She is an active member of the Virginia Public Health Association (VPHA), Genetic Toxicology Association (GTA), Society of Toxicology (SOT), and Environmental Mutagenesis and Genomics Society (EMGS), where she serves as Co-Chair of the Women in EMGS (WEMGS) Special Interest Group.
Chrissy Crute, PhD, is a human health toxicologist and Scientific Program Manager at HESI Global. She joined HESI in 2023 after earning her PhD in Environmental Health and Toxicology from Duke University and completing a Science Corps Fellowship in Morocco.
At HESI Global, Dr. Crute co-leads the Emerging Systems Toxicology for the Assessment of Risk (eSTAR) Committee, the OASIS Consortium, and the Immuno-Safety Technical Committee (ITC). Her work brings together scientists from academia, government, and industry to advance innovative approaches for evaluating human health and translating emerging science into more effective safety assessment strategies.
Dr. Crute is passionate about connecting science with real-world public health needs, with particular interests in global and community health, environmental justice, and public education.
Dr. Julie Krzykwa holds a PhD in Biology from Texas Christian University under the guidance of long-time HESI collaborator and advocate, Dr. Marlo Jeffries. Dr. Krzykwa’s dissertation research on fish embryo acute toxicity test (OECD 236) was awarded a SETAC/Procter & Gamble Fellowship for Doctoral Research in Environmental Science and received a STARS and Ida M. Green Fellowship awards from TCU. She brings post-graduate experience as a contractor to the USEPA working on aquatic toxicity testing methods and as Study Director (ecotox) for Smithers contract laboratory. Dr. Krzykwa will work on the Next Generation EcoRisk Project, UVCB Committee, and the Botanical Safety Consortium.
Dr. Claire O’Brien holds a PhD in Pharmacology and Toxicology from the University of California, Davis, and an MPH in Environmental Health from San Diego State University. She comes to HESI with experience a Regulatory Specialist at a biotech company where she helped to develop a regulatory strategy for bringing innovative infant nutrition products to market. She also has experience in safety assessment and toxicology of dietary supplements, educational outreach on environmental health topics within a community setting, and as a lead clinical trials coordinator for a major research study. Dr. O’Brien will work on the Cardiac Safety Committee, PBPK Committee, and the PATB program.
Alexandra Taraboletti joined HESI in 2024 as a Scientific Program Manager. She received her BS in Chemistry from the University of Central Florida and her PhD in Chemistry from the University of Akron. She completed her postdoctoral studies in Tumor Biology at Georgetown University. Prior to joining HESI, she served as an Assistant Professor at the University of the District of Columbia (UDC), focusing on omics-driven environmental biology. She also contributed to the National Heart Lung and Blood Institute (NHLBI) Workshop Support Program (WSP) as a scientific writer, authoring numerous publications, white papers, and executive summaries on human and environmental health topics. At HESI, she currently supports the Genetic Toxicology Technical Committee (GTTC) and the Cardiac Safety Committee.
Cissy Li holds a PhD in Molecular and Translational Toxicology from the Johns Hopkins Bloomberg School of Public Health, along with a Certificate in Risk Sciences and Public Policy.
Dr. Li brings eight years of experience at the U.S. Food and Drug Administration (FDA), where she worked in both the Center for Food Safety and Applied Nutrition (CFSAN) and the Center for Tobacco Products (CTP). At CFSAN, she spent two years conducting safety and risk assessments of chemical contaminants in food, including updating the fish consumption advice. She then spent six years at CTP, where she played a key role in product review, research, and regulatory science. Her work included leading large interdisciplinary teams and research projects focused on the toxicity of tobacco products and analyzing public health risks and benefits to inform regulatory decisions. Notably, she co-founded the Risk and Decision Analysis Branch at CTP, contributing to the advancement of regulatory science.
At HESI, Dr. Li will be actively involved in the Antibody-Drug Conjugate, Targeted Protein Degraders, and BIOME programs.
Hannah Richardson earned her Bachelor’s degree in Business Administration from Viterbo University in 2022. She currently serves as the Donor Relations and Operations Manager at HESI, where she manages donor and sponsor relationships, supports institutional operations, and oversees financial processes—all contributing to HESI’s mission of addressing global health and environmental challenges.
Before joining HESI in December 2024, Hannah worked as the Association Coordinator for the American Clinical Laboratory Association. In this role, she played a pivotal part in enhancing member retention, managing large-scale events, and improving operational efficiency. Additionally, since 2023, she has shared her expertise as a mentor with The Fund for American Studies, guiding young professionals in their career development.
hesi@hesiglobal.org
Phone: +1-202-659-8404
Fax: +1-202-659-8403
740 15th Street NW, Suite 600
Washington, DC 20005
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