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About EPA

About the Integrated Systems Toxicology Division (ISTD) of EPA's National Health and Environmental Effects Research Laboratory

What We Do

The Integrated Systems Toxicology Division (ISTD) focuses on the complex interdependency of environmental exposures, mechanisms of toxicity, and individual variability to improve our ability to evaluate and predict the potential for adverse outcomes. This research integrates advanced experimental and computational approaches to examine complex stressor-biological interactions across multiple levels of biological organization and identify early indicators of adversity and susceptibility factors. Results from this research provides mechanistic linkages among exposure, target dose, and response essential for designing, interpreting, and translating environmental health studies to inform public health decisions.

Programs and Projects Managed by the Integrated Systems Toxicology Division:

  • Developmental and neurological effects: The nervous system in developing infants and children is often more sensitive to chemical effects than in adults. Unfortunately, many chemicals present in the environment have not been adequately tested for their potential to cause developmental neurotoxicity (DNT). ISTD scientists are developing cutting edge approaches that will allow for rapid and cost-effective screening of chemicals for their potential to cause DNT. These approaches include Brain-on-a-Chip or Microelectrode Array, Zebrafish Models, Virtual Tissue Models, and Adverse Outcome Pathways.
  • Adverse Outcome Pathways for Cancer: ISTD scientists are conducting research focused on the characterization of tumors at the tissue, cellular, and molecular levels. Scientists are developing a set of novel methods, tools, and biomarkers to aid in the prediction of cancer outcomes based on early key events in an adverse outcome pathway employing epigenetics and genomics.
  • Lead: Lead-contaminated soils and sediments provide a significant pathway for lead exposure in children. Soil ingestion is the most dominant exposure pathway therefore there is a need to better quantify the contributions and key risk factors from this pathway. Scientists is ISTD are determining the bioavailable fraction of lead in soil and sediment. This is critical to evaluating risk and developing appropriate remediation strategies to minimize exposure.
  • PFAS: Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that includes PFOA, PFOS, GenX, and many other chemicals. There are thousands of PFAS in use for countless consumer products and industrial processes. These chemicals are very persistent in the environment and in the human body – meaning they don’t break down and they can accumulate over time. There is evidence that exposure to PFAS can lead to adverse human health effects. ISTD scientists are examining the development and neurological effects of these group of chemicals using Zebrafish and microelectrode array models.


Lisa Baxter, Acting Director