Lab Members

We are a fun group of chemists dedicated to environmental health.
Please scroll to read who is working on what research in our lab!

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.

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.

Rachel Smith | Program Coordinator 

Rachel joined the Stapleton Lab in 2019 to assist with a project funded by the National Institute of Environmental Health Sciences. This grant established the Duke Environmental Analysis Lab (DEAL), which will serve as a hub to support national environmental health research, and help develop new methods to measure inorganic and and organic chemical contaminants in human and environmental matrices. Rachel oversees the administrative needs for the lab, assists with findings reports, and manages the outreach and communications needs for DEAL and the PFAS projects.
Rachel has a B.S. in Environmental Science from the University of Missouri (2009). She worked as a wildlife biologist and program coordinator for six years on various estuary and terrestrial habitat restoration projects in Kauai, Hawaii. Post-island life, she earned a Masters Certificate in Environmental Conflict Management at Oregon State University (2017).
Outside of work she enjoys woodturning, bird watching, gardening, and listening to jazz.

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.


Madison Malone | Research Technician II 

Originally from Tennessee, Madison moved to North Carolina in early 2014 where he earned a B.S. in Analytical Chemistry with a minor in physics from Appalachian State University. While at App State, he worked in a faculty run environmental chemistry lab, testing for atmospheric PAH partitioning in sediment and water samples from local river systems and analyzing VOCs in mountain air currents. After graduating, Madison went on to work for an analytical chemistry consulting company, focusing on analytical method development on HPLC-MS/MS in clinical toxicology, high-level instrument engineering, data analysis, and laboratory management. He joined the Stapleton Lab in 2022, where he began work on investigating flame retardants, plasticizers, and other organo-contaminants in commercial products and their environmental/human exposure rates, using HPLC-MS/MS, GC-MS, and GC-ECD. When not in the lab, Madison enjoys cold weather hikes with his wife and dog, fly fishing, and cheering on the Appalachian state mountaineer football team.

Jessica Levasseur | PhD Student

Jessica grew up in Eastern Connecticut, though has spent the past 10 years moving around the US. She received her bachelor’s degree in Chemistry: Biochemistry from Colby College in 2010, where she graduated with honors and ACS certification. After some time working at a women's health center in Central America, she spent two years working in the development laboratories of a pharmaceutical company. Jessica graduated in 2015 from the University of Washington’s Department of Environmental and Occupational Health Sciences with an MS in Environmental Health (Risk Emphasis). Completing this degree led her to Durham, NC, where she spent three years consulting for the federal government. Her work included developing and maintaining exposure models for both residential chemical exposures and outdoor air pollution as well as evaluating the human health effects and risk associated with particular chemicals and microbial toxins. Jessica joined the Stapleton Lab in 2018, where she has since been investigating the association between particular household products and human exposure. Her research interests include quantifying non-occupational exposures, particularly those associated with the dermal pathway. Outside of the laboratory Jess enjoys traveling with her husband, cooking, being outside, and reading. Check out Jessica's latest publications about children's' exposure to phenols and plasticizers.

Taylor Hoxie | PhD Student

Taylor earned a B.S. in Chemistry with a concentration in biochemistry at Wake Forest University in 2017. As an undergraduate she conducted research in organic chemistry synthesizing novel PI3K inhibitors for prostate cancer treatments. Prior to starting grad school at Duke, she spent two years working at the Duke Human Vaccine Institute (DHVI). At DHVI, she genotyped human and non-human primate samples to characterize Fc gamma receptors and their role in HIV pathogenesis. During her time at Duke, she hopes to pursue research on per- and polyfluoroalkyl substances (PFAS), explore exposure science and complex mixtures, and implement analytical chemistry techniques. Taylor is working on the PFAS UNITEDD project on Aim 2 (evaluate uptake of PFAS into local foods through contaminated soil and water) and Aim 3 (assessing the relative role of the indoor environment in determining exposure for communities impacted by differing sources of PFASs - characterizing PFAS chemicals in dust, air and wristbands). Outside of school and the lab she likes to play with her dog Cocoa, enjoys outdoor activities, reading and traveling.

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.


Former Lab Members

Undergraduate StudentsMaster's StudentsPhD StudentsResearch TechniciansPostdoctoral Research Associates
Martin Trinh (2021)Leon Li (May 2021)Sam Hall
(June 2022)
George Tait
(2014 - 2021)
Dr. Chris Kassotis
Cara Peters (2020)Chengyang (Jared) Wang (May 2020)Kirsten Overdahl
(October 2021)
Amelia Lorenzo (2014-2017)Dr. Erin Kollitz
Deanna Badger (2016)Wanchen (Connie) Xiong (May 2020)Matthew Ruis
(March 2021)
Yu-Ping Huang
Dr. Tara Rafferty
Spencer Pecha (2015)Stella Wang (May 2020)Stephanie Hammel (July 2019)Spencer Pecha
Dr. Kate Hoffman (2013-2014)
Tom Neufeld (2015)Qianyi Xia (May 2019)Allison Phillips
(May 2019)
Albert Chen
Dr. Craig Butt
Amy Trey (2015)Allison Killilus (May 2017)Chris Leonetti
(July 2016)
Kylie Rock
Dr. Wu Dong
Nikalesh Raju (2013)Bridget Flaherty
(May 2017)
Mingliang Fang
(May 2015)
Alex Keller
Dr. Dongli Wang
Katharine Gifford (2014)Meredith Frenchmeyer (May 2017)Laura Macaulay
(July 2015)
Katie Douglas
Matthew Mrozek(2012)Rochelle Cameron
(May 2016)
Laura Dishaw
(May 2015)
Sarah Eagle
Alex Keller (2012)Rebecca Siebenaler
(May 2016)
Simon Roberts
(August 2014)
Shannon Kelly
Olay Ayinksku (2011)Peyton Ward (May 2015)Pam Noyes (May 2013)
Jenifer Fuh (2011)Genna Gomes (May 2015)Elizabeth Davis
(May 2013)
Stephen Lubin (2008)Brit’Ny Hawkins
(May 2014)
Aminah Cherry (2007) Zhuoyuan Chen
(May 2014)
John Blades (2007)John Misenheimer
(May 2013)
Lauren Gloeckler
(May 2013)
YuChun Kuo
(December 2011)
Josie Bamford (May 2007)



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