PFAS Chemical Lists and Tiered Testing Methods Descriptions
The following webpage is historic and is no longer being updated.
Latest PFAS research information
EPA and NIH researchers are working together to use new chemical testing approach methods to test 150 PFAS chemicals. The testing is quickly generating toxicity, toxicokinetic and other types of data to help inform decisions made about the potential health effects of PFAS.
These new approach methods screen for potential liver, developmental neurotoxicity, developmental toxicity, immunotoxicity, and mitochondrial toxicity as well as help to better predict the disposition and excretion of PFAS from the body. Results from the new approach methods testing will be used to prioritize (tier) PFAS for risk assessment, provide support for gap-filling approaches such as chemical read-across, and to inform further testing. The testing being done is using a combination of innovative methods and high-throughput in vitro assays.
On this page:
PFAS Chemical Lists
EPA researchers have curated multiple lists of PFAS chemicals that have been developed by the Agency and the international community. The various PFAS lists are available on the CompTox Chemicals Dashboard. A subset of ~430 PFAS have been commercially procured by the Agency as part of a PFAS chemical library to support the development of analytical methods, environmental monitoring and toxicity testing.
EPA filtered several publicly available PFAS lists to exclude most high (>500) and low (<50) molecular weight compounds, aromatic compounds, metal-containing compounds, and chemicals with a low ratio of fluorine to carbon. There are three PFAS lists, which encompass EPA’s entire PFAS Chemical Library. These lists are published on EPA’s Computational Toxicology Chemicals Dashboard.
- EPAPFASINV
List contains the entire 430 PFAS chemicals in the current inventory found to be soluble in DMSO. - EPAPFAS75S1
A subset of the 430 PFAS Library, the list contains 74 unique chemicals (75 samples) prioritized for testing by researchers to generate data to inform read-across approaches. - EPAPFAS75S2
A subset of the 430 PFAS Library, this list contains a second set of 75 samples submitted for the testing screens conducted by EPA researchers in collaboration with researchers at the National Toxicology Program. Substances for both Set 1 and Set 2 were selected based on a prioritization scheme that considered EPA Agency priorities, exposure/occurrence considerations, availability of animal or in vitro toxicity data, and ability to procure in non-gaseous form and solubilize samples in DMSO. More information. - EPAPFASINSOL
List of 43 chemicals procured but found to be insoluble in DMSO at 5mM or lower. All or some subset of these 43 chemicals may be available in neat form.
Tiered Testing Methods
EPA and NIH researchers are working together to use new chemical testing approach methods to test 150 PFAS chemicals. The testing will quickly generate toxicity, toxicokinetic and other types of data to help inform decisions made about the potential health effects of PFAS.
These new approach methods screen for liver, developmental neurotoxicity, developmental toxicity, immunotoxicity, and mitochondrial toxicity as well as to better predict the disposition and excretion of PFAS from the body.
Results from the new approach methods testing can be used to help prioritize (tier) PFAS for risk assessment, provide support for gap-filling approaches such as chemical read-across, and to inform further testing. The testing being done is using a combination of innovative methods and high-throughput in vitro assays detailed in the table below.
Toxicological Response |
Assay |
Assay Endpoints |
Purpose |
|
Hepatotoxicity |
3D HepaRG assay |
Cell death and transcriptomics |
Measure cell death and changes in important biological pathways |
|
Developmental Toxicity |
Zebrafish embryo assay |
Lethality, hatching status and structural defects |
Assess potential teratogenicity |
|
Immunotoxicity |
Bioseek Diversity Plus |
Protein biomarkers across multiple primary cell types |
Measure potential disease and immune responses |
|
Mitochondrial Toxicity |
Mitochondrial membrane potential and respiration (HepaRG) |
Mitochondrial membrane potential and oxygen consumption |
Measure mitochondrial health and function |
|
Developmental Neurotoxicity |
Microelectrode array assay (rat primary neurons) |
Neuronal electrical activity |
Impacts on neuron function |
|
Endocrine Disruption |
ACEA real-time cell proliferation assay (T47D) |
Cell proliferation |
Measure ER activity |
|
General Toxicity |
Attagene cis- and trans- Factorial assay (HepG2) |
Nuclear receptor and transcription factor activation |
Activation of key receptors and transcription factors involved in hepatotoxicity |
| General Toxicity |
High-throughput transcriptomic assay (multiple cell types) |
Cellular mRNA |
Measures changes in important biological pathways |
|
General Toxicity |
High-throughput phenotypic profiling (multiple cell types) |
Nuclear, endoplasmic reticulum, nucleoli, golgi, plasma membrane, cytoskeleton, and mitochondria morphology |
Changes in cellular organelles and general morphology |
|
Toxicokinetic Parameter |
Assay |
Assay Endpoints |
Purpose |
|
Intrinsic hepatic clearance |
Hepatocyte stability assay (primary human hepatocytes) |
Time course metabolism of parent chemical |
Measure metabolic breakdown by the liver |
|
Plasma protein binding |
Ultracentrifugation assay |
Fraction of chemical not bound to plasma protein |
Measure amount of free chemical in the blood |