The Illinois Environmental Protection Agency (IEPA) released new proposed groundwater quality standards for five per- and polyfluoroalkyl substances (PFAS). If formally adopted, the proposed regulations would establish the state’s first enforceable standards for PFAS. The proposed standards were included in a discussion draft of proposed amendments to Illinois’ Part 620 groundwater quality regulations, 35 Ill. Adm. Code Part 620, which provides a broader range of updates and modifications to the groundwater standards.[1]

The proposed amendments would establish standards for the following PFAS compounds: 1) Perfluorobutane Sulfonic Acid (PFBS); 2) Perfluorohexane Sulfonic Acid (PFHxS); 3) Perfluorononanoic Acid (PFNA); 4) Perfluorooctanoic Acid (PFOA); and 5) Perfluorooctane Sulfonic Acid (PFOS). In addition, the proposal would classify PFOA as a carcinogen, based on its 2B classification by the World Health Organization’s International Agency for Research on Cancer (“IARC”), which means that it is considered possibly carcinogenic to humans.

PFAS are a class of over 5,000 manufactured chemicals discovered in the late 1930s, and they have been widely manufactured since the 1950s. Often referred to as “forever chemicals,” PFAS are highly stable in the environment and can be detected at very low concentrations (parts per trillion). Due to their unique physical and chemical properties, they have been used in a wide range of applications, including firefighting foams, consumer products, fast food wrappers and containers, and industrial processes.

The public comment period on the discussion draft expired on June 25th. It is expected that after considering the comments submitted on the discussion draft, the IEPA will prepare and file a formal rulemaking proposal before the Illinois Pollution Control Board (“IPCB”). The proposal will be subjected to a formal rulemaking process before the IPCB, including public hearings and the opportunity to submit public comments before the adoption of final regulations.

Illinois’ move to adopt PFAS standards follows a growing trend in states across the country. Given that no enforceable drinking water standards for PFAS have been adopted at the federal level, many states have stepped in and established their own PFAS regulations. The resulting state efforts have created a patchwork of regulations, with standards that can vary widely from state to state.

The current proposal updates a prior discussion draft issued by IEPA in 2019 and reflects a significant tightening of the standards proposed at that time. The following table compares the standards in the current proposal to the 2019 discussion draft and to the recently adopted drinking water standards in Michigan.


2021 Standard in mg/L or ppm (ng/L or ppt)

2019 Standard in mg/L or ppm (ng/L or ppt)

Recently adopted Michigan Standards in mg/L or ppm (ng/L or ppt)

Perfluorobutane Sulfonic Acid (PFBS)

0.0012 (1,200)

0.14 (140,000)

.00042 (420)

Perfluorohexane Sulfonic Acid (PFHxS)

0.000077 (77)

0.00014 (140)

.000051 (51)

Perfluorononanoic Acid (PFNA)

0.000012 (12)

0.000021 (21)

.000006 (6)

Perfluorooctanoic Acid (PFOA)

0.000002 (2)

0.000021 (21)

.000008 (8)

Perfluorooctane Sulfonic Acid (PFOS)

0.0000077 (7.7)

0.000014 (14)

.000016 (16)

As a review of the standards shows, the limits established in the current proposal are, in all cases, significantly more stringent than the standards proposed in the 2019 draft.

For those PFAS chemicals currently regulated at the state level, standards can vary significantly from state to state. For example, as illustrated in the table above, Illinois’ proposed standard for PFBS is 0.12 ppm (or 1,200 ppt), significantly less stringent than Michigan’s recently enacted standard of 0.00042 mg/L (or 420 ppt). In contrast, Illinois’s proposed standards for PFOA and PFOS are 2 ppt and 7.7 ppt, respectively, which are more than twice as stringent as Michigan’s standards of 8 ppt and 16 ppt, respectively, for those compounds.