Dr. Heather Stapleton, Ph.D | Principal Investigator
Heather received her PhD from the University of Maryland, College Park where she trained in environmental chemistry. After completing her PhD, she accepted an NRC Postdoctoral Fellowship at the National Institute of Standards & Technology in Gaithersburg, MD where she worked for two years in their Analytical Chemistry Division. In 2005 Heather accepted a faculty position at the Nicholas School of the Environment at Duke University, and became active in the Integrated Environmental Health and Toxicology Program. Her research interests focus on identifying and understanding the uses of flame retardant chemicals in consumer products, and evaluating human exposure, particularly in pregnant women and children. She seeks to understand how exposure to chemical mixtures impacts health, with a focus on metabolic outcomes (e.g. triglyceride formation). In addition, she is interested in understanding how persistent halogenated contaminants impact thyroid hormone regulation, and specifically during pregnancy.
She was an NIEHS ONES (Outstanding New Environmental Scientist) awardee (2008) and currently serves as the Deputy Director for the Duke Superfund Research Center, and Director of the Duke Environmental Analysis Laboratory. Furthermore, she collaborates with a number of investigators within and outside of Duke to investigate health effects related to flame retardant exposures, and other common contaminants in the indoor environment (e.g. phthalates, pesticides, and per-fluorinated chemicals).
Sharon Zhang | Research Project Manager
As a Research Project Manager with an M.S. in Chemical Engineering, Sharon joined the Stapleton Lab in December, 2016. She has work experience in both the pharmaceutical industry as an Analytical Scientist and in academia as a Researcher. Before she joined the Stapleton Lab, she was involved in metabolic and diabetic research in the Department of Nutrition at Case Western Reserve University. She is experienced in using various analytical instruments to perform drug development and metabolic research. In the Stapleton Lab, Sharon is responsible for LCMS system maintenance, method development and sample analysis to support students and lab projects. Her research gear is switched from how to eat healthier (Nutrition) to how to live healthier (Environment). She is involved in exploring the effect of flame retardant chemicals on both the environment and human health. As two boys’ mom, Sharon loves to cooking delicious foods for her family. She enjoys Zumba and hiking with her friends.
Dr. Nicholas J. Herkert, Ph.D | Research Project Manager
Nick grew up in Petersburg Il, a small town in the central Illinois before making the long trek north to attend the University of Iowa as an undergraduate. Early on as an undergraduate, Nick began working in an analytical chemistry lab under Dr. Keri Hornbuckle. This was what first piqued Nick’s interest in characterizing the chemical mixtures people are exposed to throughout their lives and inspired Nick pursue a degree in Environmental Engineering. During his senior year, Nick enrolled in a joint undergraduate/graduate degree program under Dr. Keri Hornbuckle. Nick graduated from the University of Iowa with a BSE in Civil Engineering and a Certificate of Sustainability in 2015, and immediately returned to continue working on his Ph.D. Nick graduated in 2018 with a Ph.D. in Environmental Engineering, after successfully completing his thesis entitled Development of the Polyurethane Foam Passive Air Sampler for Novel Applications in Ambient Air Across the Globe.
Nick joined the Stapleton Lab in June 2018 as a Postdoctoral Associate, where he has continued to work to better understand the exposures people experience in their everyday lives, the potential health effects form these exposures, and the subsequent sources for these exposures. Nick first started by putting is analytical chemistry background and modeling background to work on developing a high throughput methods for both target and untargeted analysis of silicone wristbands. This work is largely done on a high-resolution accurate mass (HRAM) Q Exactive GC hybrid quadrupole-Orbitrap GC-MS/MS system, of which Nick is the gatekeeper. The ultimate goal of the work is to provide a quantitative analysis of a suite of target SVOCs, as well and semi-quantitative analysis of suspect chemicals, which will provide a much broader picture of what people are exposure to in their day-to-day lives. Nick has also worked to study the levels of PFAS compounds in local utilities and characterize the effectiveness of various in-home filters at removing such compounds. When not in the lab, Nick is often out running to train for a half or full marathon, out hiking to take pictures, or laying on the couch watching movies with his wife, two dogs, hedgehog, and gecko.
Dr. Ellen Cooper, Ph.D | Research Scientist
Ellen Cooper is originally from Oxford, Pennsylvania. She received her BS (1994) in Plant Science from the University of Delaware, and her MS (1996, Thesis: “Chelate-assisted remediation of lead contaminated soils”) in Plant and Soil Sciences also from the University of Delaware, where she worked as an associate in research until 1998.
In 1999, she came to Duke University Nicholas School of the Environment to work for Dr. Dharni Vasudevan, and later Dr. Andrew Schuler (formerly of Dept. Civil and Environmental Engineering), and eventually matriculated and received her Ph.D. in Environmental Sciences (2009, Dissertation “Biodegradation of a Sulfur Containing PAH, Dibenzothiopene, by a Mixed Bacterial Community.”) under the advisement of Dr. Heather Stapleton, for which she worked as a post-doctoral associate until 2011. Her current research interests include analyzing environmentally important organic compounds in a variety of matrices including sediments, water, biological samples and polyurethane foam and using high resolution mass spectrometry to characterize chemical composition of a variety of samples types.
Apart from scientific research, Ellen actively pursues music, plays a variety of instruments, and studies early music notation and theory from the Medieval and Renaissance periods. She is an avid runner and hiker, a part-time freelance landscape gardener, and is kept firmly in line by three feisty black kitties.
Alyssa Wicks, PhD | Postdoctoral Associate
Alyssa Wicks grew up in Minnesota. She earned her B.S. in Chemistry and Physics from St. Catherine University in 2021, where she also competed on the university’s softball team. She went on to receive her Ph.D. in Chemistry from the University of Notre Dame in 2025. Her doctoral research focused on measurements of environmental contaminants, including PFAS in consumer products and lead in the home environment.
Alyssa joined the Stapleton Lab in June 2025 as a Postdoctoral Scholar, where she is studying exposure routes of PFAS in the home environment and PFAS excretion pathways in women.
Outside the lab, Alyssa enjoys reading, crocheting, and spending time in nature. She is also an avid traveler, with dreams of visiting all 63 US national parks (over half visited so far!) and every MLB stadium.
Dr. Catherine Wise, PhD | Postdoctoral Associate
Catherine Wise grew up in New England, mostly Maine, where she received her BS from the University of Southern Maine. As an undergraduate researcher, Catherine’s work focused on environmental and genetic toxicology using cell culture models and wildlife field work. She received an EPA GRO Fellowship to investigate the effects of the Deepwater Horizon oil spill on sperm whale cells, following field work out at sea. She then received her PhD from NC State in Toxicology.
Her doctoral research focused on using comparative genomics of urogenital carcinomas in pet dogs, California sea lions and humans as well as establishing an association between exposures in people and their pet dogs.
Catherine joined the Stapleton lab in August 2020 as a postdoctoral associate, where she has continued the work towards comparative environmental health studies and links between exposures and the development of bladder cancer in dogs.
Outside the lab, Catherine enjoys spending time with her dog, Simba and 2 cats, Loki and Nebula.
Dr. Candance Van Vleet, DHA | Research Project Manager
Candi, a native North Carolinian, has devoted much of her career to emergency services. Now a member of the Stapleton lab, she focuses on work that will enhance the health of emergency services personnel. Her extensive prehospital and nursing background includes roles as a paramedic field training officer, flight nurse, emergency department manager, trauma outreach coordinator, and intensive care nurse. As a Six Sigma Black Belt, she combined her clinical knowledge with quality improvement strategies to drive better patient outcomes.
Currently, Candi serves as the research project manager for the North Carolina Firefighter Cancer Cohort Study, investigating firefighters' occupational exposures to chemicals, such as per- and polyfluoroalkyl substances (PFAS), and their potential link to cancer.
Candi is a graduate of the Medical University of South Carolina with a Doctor of Health Administration. She also holds a Bachelor of Science in Emergency Medical Care from Western Carolina University, a Bachelor of Science in Nursing from Winston-Salem State University, and a Master of Business Administration from Elon University.
Eve Marion | Research Project Manager
Eve joined the Stapleton Lab and the NC Firefighter Cancer Cohort Study in 2024, bringing expertise in clinical research, public health, research translation and communication, community-based participatory and community-engaged research, along with grants and project management. Eve earned her undergraduate degree from Queen’s University in Kingston, Ontario and completed Duke’s master’s in Liberal Studies Program. Recently, Eve earned a master’s in Library Science from North Carolina Central University. She is driven to help translate research concepts to share knowledge to better support communities and health information needs.
Eve moved to North Carolina from Canada with her family in 1997. She is an avid reader and loves going to live music shows and traveling with her husband. Eve is always happy to chat about her dogs, books, music, travel, and food, preferably while hiking.
Emina Hodzic | Research Technician II
Emina grew up in Bosnia and Herzegovina but spent the last 12 years in the US. She received her Bachelor of Science degree in Chemistry from Methodist University and her M.S. in Chemical Engineering from NC State. Emina joined the Stapleton lab in August 2015 and her main responsibility is trace analysis of environmental samples for organic contaminants and their degradation products using the GC-MS and LC-MS systems for the Superfund Program. Outside the lab, Emina enjoys hiking, reading, trying new foods, and making sure her houseplants are thriving.
Duncan Hay | Research Technician II
Duncan grew up in western NC, near Asheville and moved to Durham after graduating from Elon University in 2017 with a BS in Chemistry and a minor in Spanish. Upon graduation from Elon, he has worked for the State of North Carolina in pharmaceuticals, quality testing diesel and kerosene. Duncan joined the Stapleton Lab in November 2019 to help support sample analysis for the Duke Environmental Analysis Lab (DEAL) and the Human Health Exposure Analysis Resource (HHEAR) program. When not in the lab, Duncan enjoys camping, hiking, golfing, and woodworking.
Alexander Beste | Research Technician II
Alex grew up in Wilmington, North Carolina. He received a B.S. in Chemistry from Wake Forest University where he studied organic synthesis and click chemistry. Alex joined the Stapleton Lab in October 2024 in order to assist the North Carolina Fire Fighter Cancer Cohort Study (NC FFCCS) and the Human Health Exposure Analysis Resource (HHEAR) program. In his free time, he enjoys reading, photography, going to the gym, and exploring.
Shaza Gaballah | PhD Student
Shaza is a second year PhD student in the Stapleton lab. Growing up, Shaza lived all over the triangle, and received her B.S. in Biology with minors in Chemistry and Medical Anthropology from UNC Chapel Hill in 2017. After graduating, she completed a two-year fellowship at the US EPA, where she investigated how exposure to GenX and other per- and polyfluoroalkyl substances (PFAS) impacts developmental toxicity and developmental neurotoxicity in zebrafish. Her work identified shared toxicity phenotypes in zebrafish based on varying PFAS chemical structures. Shaza’s work at the EPA was her first time delving into toxicology, and she loved it so much that she applied to Duke’s environmental toxicology program. Shaza is currently using BeWo cells to study how brominated flame retardants cross the placenta and impact fetal growth and development; she hopes to expand this work to study how PFAS may be crossing the placental barrier and to understand their potential involvement in endocrine disruption. When she’s not in the lab, Shaza loves cheating at crosswords, hiking in Durham, and hanging out with her cat, Olive.
Rebecca Hoehn | PhD Student
Rebecca is a 2nd year PhD student in the Stapleton lab. She earned her B.S. in Pharmacology and Toxicology at the University of Wisconsin-Madison in 2020, alongside certificates in Global Health and Environmental Studies. Her undergraduate research on the fate and transport of organic contaminants in crop plants fostered her interest in environmental chemistry and human health, which drew her to join Duke’s Integrated Toxicology and Environmental Health Program (ITEHP). Alongside her doctorate, Rebecca is also pursuing a Certificate in College Teaching. During her time at Duke, Rebecca is excited to investigate personal exposure to volatile organic contaminants and hopes her work will aid in deducing sources of contaminant exposure in the indoor environment. She is particularly interested in understanding the linkages between contaminant exposure and human health outcomes.
Outside of the lab, Rebecca enjoys spending time outdoors, trying new local cuisine, painting and crafting, and tending to her many houseplants.
Michelle Misselwitz | PhD Student
Michelle received her Bachelor of Science degree in Chemistry from the Pennsylvania State University in 2007. An analytical chemist by training, Michelle worked for 9 years as an environmental and food safety applications chemist with a focus on gas chromatography and mass spectrometry (GC-MS). In this role she spent time developing analytical methods for the analysis of flame retardants, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and pesticides. After having children, Michelle worked part-time for an environmental forensics consulting group with an emphasis on analytical data review, comprehensive literature research, and writing scientific reports used for litigious environmental cases. Michelle joined the Stapleton lab in 2021 to pursue her PhD. Her research utilizes high resolution mass spectrometry to measure human chemical exposure to determine potential associated health effects. She is particularly interested in exposures to multiple chemical classes and how that may impact pregnancy and birth outcomes. When Michelle is not in the lab or combing through big datasets, she is spending time with her husband and two daughters.