About EPA Transcriptomic Assessment Product (ETAP)
Background
Relatively few of the tens of thousands of chemicals in commerce, as well as those found in the environment, various waste streams, and the human body have traditional toxicity data or epidemiological data that can inform assessments of risks to human health. Typically, a human health assessment or science assessment is a multi-step process that includes hazard identification, dose-response analysis, and the integration of the information to that produce a reference value for the chemical. This, along with exposure information, is foundational for a risk assessment.
One reason for the limited number of human health assessments, and subsequent risk assessments, is that traditional toxicity testing and the human health assessment process are time and resource intensive - often taking eight or more years to complete. State agencies, the public, and various stakeholder organizations are in need of reference values for chemicals in a shorter timeframe in order to take an informed action to protect human health. The EPA Transcriptomic Assessment Product aims to help address chemicals lacking traditional toxicity testing data in a timely way. Transcriptomic-based reference values derived from ETAP can be developed in a matter of months, enabling more timely regulatory decision-making.
Transcriptomics is the study of messenger RNA molecules that are expressed in cells of the body. As the name implies, the messenger RNA carries the information from the genes in the DNA to specialized cellular organelles that translate that message into proteins, which performs the essential functions of the cell. Transcriptomics uses technology from the human genome project to read all these messages simultaneously and record changes in gene activity. Previous studies have demonstrated that doses of chemicals causing disruption of gene activity also cause toxicological responses in traditional chronic toxicity tests. The disruption in gene activity can be measured in shorter-term studies enabling quicker identification of doses that cause toxicity.
ETAP Reports
In July 2023, EPA’s Board of Scientific Counselors reviewed the reports documenting the scientific studies that support the development of the ETAP as well as a standard methodology that the EPA will use for performing the studies and developing the assessments. The first ETAP on a chemical was published in March 2024.
Read the reports:
- Scientific Studies Supporting Development of Transcriptomic Points of Departure for ETAPs
- Standard Methods for Development of ETAPs