Rounding out her second year in a combined bachelor’s and master’s program in public health at the University of Florida College of Public Health and Health Professions, Sarah Acra was shocked to hear her name called for first place in the undergraduate poster competition.
Emerging Pathogens Institute Research Day 2026 was an event filled with curiosity, and Acra’s poster was swimming in it. She and her team, led by UF PHHP Associate Professor Tracie Baker, Ph.D., studied the effect of per- and polyfluoroalkyl substances, also known as PFAS or “forever chemicals,” on zebrafish. These fish share 70% of their genome with humans and 80% of the genes that cause disease with us. The full study focuses on several different organs, but Acra’s poster focused on how a mixture of two PFAS — perfluorooctanoic acid, or PFOA, and perfluorooctane sulfonic acid, or PFOS — affects brain gene development.
“PFOA and PFOS are two of the most common types of PFAS found in the environment and human tissues. PFAS types are rarely found alone in the environment, so testing a mixture of them makes the study more realistic,” said Acra.
They even used environmentally relevant concentrations determined by the Environmental Protection Agency’s drinking water advisories, thereby strengthening the study’s real-world relevance. Most of the PFAS we consume are through our diet and drinking water. The study exposed zebrafish embryos to a water-based PFOA and PHOS mixture for five days, following the fish into adulthood 18 months later. The results were shocking.
Compared to the control, the mixture-exposed larval fish had increased hyperactivity and decreased locomotion. These changes negatively impact their quality of life. At the genetic level, they identified an extremely important brain gene negatively affected by PFAS that previous studies hadn’t identified.
“We found that NEUROD1, which is also found in humans, is down-regulated in male, mixture-exposed fish,” Acra said. “This gene drives the brain’s ability to regenerate neurons when needed, and the neurons’ ability to fully develop into adult neurons. Essentially, a major gene in brain health.”
Even more startling, the effects persisted into adulthood, even though the fish were exposed to PFAS only during embryonic development. There was also a marked surge in genes involved in inflammation compared with the control, and inflammation can lead to immune suppression, making the body highly vulnerable to pathogens.
“We saw immunoglobulin genes downregulated — that’s just a fancy way of saying antibodies,” said Acra. “This can lead to things like autoimmune disorders, which would then open us up to other things, because autoimmune disorders usually don’t occur alone.”
According to Acra, as she continues her journey into public health, she aims to explore how these effects fit into the bigger picture: which diseases are associated with the genes we observe to be dysregulated, and does the same occur in humans? As for now, Acra is excited to continue sharing her research with the UF community and collaborating with other scientists, no matter where they are on their journey.
“This was actually my first time presenting my research,” Acra said. “At EPI Research Day, I saw a lot of postdocs and graduate students — I was chatting it up. We were all like, ‘So, what year are you?’ and ‘What are you studying?’ It was a super cool environment. Everyone really wants to learn more. I would love to do it again.”
Developmental exposure to PFAS mixture suppresses genes associated with neural cell development in adulthood: NEUROD1 as a predicted transcriptional regulator
Collaborators
- Sarah Acra – Department of Health Science, UF Genetics Institute, College of Public Health and Health Professions, University of Florida
- Alyssa Meyers – UF Genetics Institute, College of Public Health and Health Professions, University of Florida
- Tracie Baker – Center for Environmental and Human Toxicology, Emerging Pathogens Institute, College of Public Health and Health Professions, University of Florida
Background
Per- and polyfluoroalkyl substances (PFAS) are a class of persistent man-made chemicals, often referred to as “forever chemicals,” that have been detected in water, human tissues, and wildlife globally. The two most prevalent PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), have been linked to neurotoxicity by epidemiologic and animal studies, but the effects of a PFOA/PFOS mixture remains understudied. This study investigated the lasting transcriptomic effects of developmental PFOA/PFOS mixture exposure on adult zebrafish, an animal model sharing ~70% of their genome with humans.
Methods
Zebrafish embryos were exposed from 0–5 days post-fertilization to environmentally relevant concentrations of PFOA, PFOS, or a mixture of both. Fish were raised to adulthood (~18 months) and brain tissue was collected for 3′ mRNA sequencing. Differentially expressed genes were identified and Ingenuity Pathway Analysis was performed to identify potential upregulators and disease associations.
Results
In mixture-exposed adult male zebrafish brain, there were 5304 differentially expressed genes and 327 dysregulated disease pathways compared to the controls. These genes were associated with multiple neurological pathways including neural cell development, seizure activation, and memory disorders that were significantly changed. Of interest, important upstream regulators essential for neurogenesis and nervous system formation (neurod1), and neuronal survival and dopaminergic neuron support (bdnf) were differentially expressed.
Conclusions
Developmental PFAS exposure may suppress neural cell development pathways in adulthood through NEUROD1-mediated transcriptional dysregulation, representing a public health concern and identifying NEUROD1 as a novel candidate mechanism for PFAS-induced neurodevelopmental toxicity.