Published March 13, 2018

There are thousands of reported compounds in the per- and polyfluoroalkyl substance chemical class, known as PFAS, some of which have been used for decades in consumer products and industrial items. However, there is still very little risk information on many of these chemicals. EPA researchers note that one of the biggest challenges in understanding potential hazards of exposure to PFAS is the lack of toxicity information.

Toxicity and kinetic information shows how a chemical affects an organism and how the chemical moves through the organism—from being absorbed, to being distributed and metabolized, and finally to being eliminated. Scientists need this information to develop toxicity values for the chemicals which will help determine what levels of exposure are generally safe for public health, and to help communities communicate to residents about any potential risks related to exposure.

EPA researchers have partnered with researchers at the National Toxicology Program to develop a tiered testing approach to quickly generate toxicity and kinetic information for approximately 75 PFAS compounds. These compounds were selected to represent the whole of PFAS ‘chemical space’, based on occurrence in the environment, diversity of chemical structures, and suitability for high-throughput testing based on volatility and solubility of the compounds. High throughput testing gives researchers the ability to rapidly screen chemicals to generate toxicity and kinetic data for chemicals that have little to no existing data.

“The first phase of this testing casts a broad net for potential health effects,” said EPA toxicologist Dr. Reeder Sams. “This phase of research includes a range of high-throughput in vitro [cell-based and cell-free, biochemical assays] tests that cover a range of health endpoints such as immunotoxicity or neurodevelopmental toxicity.  It also includes tests that show estimates of absorption, distribution, metabolism, and clearance within an organism.”

He adds, “These tests will help determine if there is concern for a given compound and then we can decide which PFAS will need additional testing and what type of testing we need.”

The researchers note that once the first tier of testing is complete, the data generated will be used to inform risk assessment efforts, develop predictive models for PFAS with limited or no existing data, and help prioritize which PFAS should go on to a second phase of testing.

The second tier involves in vivo testing. These tests will focus on the PFAS that have the greatest potential for toxicity based on existing data, data generated through the tier one testing, and exposure information. This information will give EPA and partners the ability to estimate how potent the compounds are and will be used to inform future decisions on the risk of PFAS in the environment.

Learn more:

Per- and Polyfluoroalkyl Substances (PFAS) in Your Environment