EPA Adds 5 PFAS Chemicals to Risk- Based Values Lists

In May of this year, five key per- and polyfluoroalkyl substances (PFAS) were added to a list of risk-based values by the U.S. Environmental Protection Agency (EPA). The Agency utilizes such values to ascertain the extent to which response or remediation measures may be necessary for chemical substances. In this blog post, we discuss both Regional Screening Levels and Regional Removal Management Levels, and review the recently added PFAS chemicals.

Per- and Polyfluoroalkyl Substances

Characterized by a chain of carbon and fluorine atoms linked via strong carbon-fluorine bonds, PFAS are synthetic chemical compounds that are strongly resistant to degradation. PFAS can present a wide range of human health risks, and many factors underlie those risks, including:

  • Bioaccumulation -- As PFAS absorption often exceeds elimination, concentrations within the human body can build up over time.
  • Exposure Frequency -- Their widespread use in a multitude of products means the opportunities for exposure to PFAS are numerous.
  • Persistence -- PFAS remain within the human body and in the environment for long periods of time.
  • Quantity -- There are several thousand known PFAS chemicals in existence.
  • Widespread Occurrence -- Studies have demonstrated the presence of PFAS in a very large percentage of the population.

PFAS-related health effects may include hypertension, kidney cancer, low birth weight and immunotoxicity (in children), testicular cancer, thyroid disease, and a variety of other problems. Research continues to be conducted to understand more fully the diversity of health effects and other risks posed by PFAS.

Regional Screening Levels and Regional Removal Management Levels

Risk-based values are vitally important tools used in efforts to help manage dangerous chemical substances, including PFAS. Examples include Regional Screening Levels (RSLs) and Regional Removal Management Levels (RMLs). RSLs are risk-based concentrations that are utilized in the identification of contamination at sites for which additional investigation may be necessary. RMLs are risk-based concentrations used in the justification of removal actions under CERCLA or other remediation efforts. In general, no additional investigation or action is required when a contaminant concentration is below a particular screening level. Conversely, additional investigation or action may be necessary when a contaminant concentration is above a given screening level.

5 PFAS Added by the EPA

The five PFAS chemicals recently added to the risk-based values lists are shown in the table below:

Substance NameAbbreviation
hexafluoropropylene oxide dimer acid and its ammonium salt(HFPO-DA (GenX))
perfluorohexanesulfonic acid(PFHxS)
perfluorononanoic acid(PFNA)
perfluorooctanesulfonic acid(PFOS)
perfluorooctanoic acid(PFOA)

Source: Environmental Protection Agency

  • A sixth PFAS chemical, perfluorobutanesulfonic acid (PFBS), was added to the RSL and RML lists in 2014, with updates in 2021.
  • For PFOA, PFOS, PFNA, and PFHxS, the most up-to-date information based on minimum risk levels from 2021 toxicological profiles was utilized. For HFPO-DA, a final peer-reviewed EPA toxicity value was utilized.

Accessing Critical Information on Chemical Substances

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