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About PFAS

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic organic chemicals that contain fluorine. There are more than 3,000 PFAS. Because many PFAS have useful properties, some of them have been used since the 1940s in products like textiles, paper, cookware, firefighting foams, and electronics. Though U.S. production of some of these chemicals has declined, many are still produced in other countries. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) have been among the most used PFAS. The U.S. Environmental Protection Agency (U.S. EPA) has added PFAS chemicals to the Toxics Release Inventory and is also developing rules to regulate exposures of certain PFAS chemicals.

PFAS in the Environment

PFAS are commonly present at fire training and response sites, certain industrial facilities, landfills, wastewater treatment plants, and in biosolids. PFAS persist in the environment, can bioaccumulate, and are often present in people and in wildlife. Due to the large volumes of PFOS and PFOA used in the past, these chemicals are the most frequently detected PFAS.

PFAS Health Effects

Both PFOA and PFOS are commonly found in the environment. Studies indicate that exposure to PFOA and PFOS above certain levels may result in adverse health effects. See additional resources.

Looking for PFAS

On July 30, 2021, the U.S. EPA published SW-846 preparation and analysis methods 3512 and 8327 for selected PFAS in surface water, groundwater, and wastewater. These methods are in addition to U.S. EPA’s 537, 537.1, and 533 methods for drinking water. Sampling and analysis methods for PFAS in other environmental media are under development. U.S. EPA has proposed nationwide drinking water monitoring for PFAS at smaller public water systems beginning in 2022.

PFAS Sampling Project for Community Public Water Systems

Since February 2021, IDEM facilitated PFAS monitoring at all Community Public Water Systems (CWS) throughout the state of Indiana (a CWS regularly serves drinking water to at least 25 year-around residents or has at least 15 service connections for residents). Samples were collected at all raw water (i.e. wells and intakes) and finished (after treatment) water points in a CWS’s supply. The purpose of the sampling program is to evaluate the statewide occurrence of PFAS compounds in CWS across the state and determine the efficacy of conventional drinking water treatment for PFAS.

Timeline for Sampling PFAS at Community Water Systems

IDEM’s sampling plan is outlined below and is dependent upon available funding. IDEM first sampled at community systems serving a population of less than 10,000 because most of these smaller systems were not sampled for PFAS during U.S. EPA’s Unregulated Contaminant Monitoring Rule (UCMR) sampling completed in 2014 and 2015. Systems serving a population greater than 10,000 were sampled last since they were sampled as part of U.S. EPA’s UCMR sampling. No verified PFAS detections were found in Indiana during the UCMR sampling event.

IDEM has received an Emerging Contaminants Grant extension to study PFAS in Indiana surface water bodies that are used for drinking water. This will be Phase 4. Phase 4 sampling is expected to begin Spring of 2024.

  Population Served Tentative Sampling Schedule
Phase 1 3,300 to 10,000 March 2021 - October 2021
Phase 2 <3,300 November 2021 - December 2022
Phase 3 >10,000 January 2023 - May 2023
Phase 4 Surface Water Bodies May 2024 - August 2024

Development of Standards

On March 14, 2023, U.S. EPA proposed a National Primary Drinking Water Regulation (NPDWR) to establish legally enforceable levels, called Maximum Contaminant Levels (MCLs), for six PFAS in drinking water. PFOA and PFOS as individual contaminants, and PFHxS, PFNA, PFBS, and HFPO-DA (commonly referred to as GenX Chemicals) as a PFAS mixture. U.S. EPA is also proposing health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs) for these six PFAS. The public comment period ended on May 30, 2023. U.S. EPA submitted the final PFAS NPDWR for interagency review in winter of 2023.

Compound Proposed MCLG Proposed MCL (enforceable levels)
PFOA Zero 4.0 ppt
PFOS Zero 4.0 ppt
PFNA 1.0 (unitless)

Hazard Index

1.0 (unitless)

Hazard Index

HFPO-DA (commonly referred to as GenX Chemicals)

Currently, U.S. EPA has only established the following Health Advisory Levels for PFOA, PFOS, GenX chemicals and PFBS:

  • Interim updated Health Advisory for PFOA = 0.004 parts per trillion (ppt)
  • Interim updated Health Advisory for PFOS = 0.02 ppt
  • Final Health Advisory for GenX chemicals = 10 ppt
  • Final Health Advisory for PFBS = 2,000 ppt

The Health Advisory Level is not a legally enforceable federal standard and is only advisory in nature; it is subject to change as new information becomes available. EPA is currently developing a legally enforceable standard.

Treatment Technologies

  • Activated Carbon, Ion Exchange Treatment, High Pressure Membranes (Reverse osmosis and Nanofiltration)
  • Some technologies are more effective against longer or shorter chains
  • Based on design choices, 100% removal of PFAS compounds can be achieved, but costs and remediation targets may make complete removal impracticable or unnecessary
  • None of these technologies destroy the PFAS molecule, so PFAS are essentially being concentrated, and the waste stream will have to be properly disposed of as a hazardous waste.

In 2020, Indiana law banned the use of Class B firefighting foam containing intentionally added PFAS, typically known as aqueous film-forming foam (AFFF), for training purposes. (See IC 36-8-10.7)

IDEM is partnering with the Indiana Department of Homeland Security and the State Fire Marshal’s Office to collect PFAS-containing firefighting foam from fire departments around the state. The IDHS Division of Fire and Building Safety provides more information on this joint initiative.

PFAS Remedies

Currently available remedies for PFAS in water include filtration and chemical treatment. Excavation and disposal, physical barriers, and heat treatment are among effective remedies for PFAS in soils. Other technologies are under development by U.S. EPA, U.S. Department of Defense, private industry, academic research institutions, and others.

Additional IDEM Activities

  • Development of Screening Levels
    • IDEM has published screening levels for three PFAS compounds listed in Table A-6 of the Remediation Closure Guide. Screening levels are concentration levels specific to individual chemicals, land uses, and media (soil, water, indoor air) that IDEM has determined to be protective of human health. IDEM’s current policy calls for publication of PFAS screening levels following U.S. EPA publication of the same. In 2019, U.S. EPA provided recommendations on interim cleanup recommendations to address groundwater contaminated with PFOA and/or PFOS and sought public comment on these recommendations in the summer of 2019; they are moving forward with the development of enforceable levels for PFOA and PFOS.
  • Partnering with Stakeholders
    • Since firefighting foam is known to contain these contaminants, military bases have been a concern. That is why the military is sampling at military locations around the state. Results have not been concerning.
    • IDEM/IDHS Class B PFAS Foam Collection Initiative
    • IDEM will be partnering with the Ohio River Sanitation Commission (ORSANCO), which will sample the Ohio River to determine background levels of these contaminants in the river.

Additional Resources

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